North American Blueberry Research and Extension Workers ...North American Blueberry Research and...

North American Blueberry Research and Extension Workers Conference

University of Maine Wells Conference Center, Orono, Maine

AUGUST 12-15, 2018http://digitalcommons.library.umaine.edu/nabrew2018/

ORONO

2018

2018 NABREW CONFERENCE

Table of ContentsSunday Program Schedule ..................................................................................... 2

Monday Program Schedule ..................................................................................... 2

Poster Session ..................................................................................................... 4

Tuesday Program Schedule .................................................................................... 6

Wednesday Program Schedule ................................................................................ 8

Planning Committee .............................................................................................. 9

Conference Presenters & Authors ...........................................................................10

Conference Participants ........................................................................................12

Welcome Reception .............................................................................................13

Lobster Banquet ..................................................................................................13

Blueberry Bus Tour ..............................................................................................14

Bus Tour Participants & Pickup Locations .................................................................15

Bee Hive Tour Participants ....................................................................................15

Monday Abstracts ................................................................................................16

Tuesday Abstracts ...............................................................................................24

Poster Abstracts ..................................................................................................31

Conference Sponsors ...........................................................................................42

University of Maine Campus Map ............................................................... back cover


Orono, Maine August 12-15, 2018

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Sunday, August 12, 2018 – Wells Conference Center

Time Event

6:00-8:00 PM Registration, Welcome Reception, and Poster Setup

Monday, August 13, 2018 – Wells Conference Center

7:30-8:30 AM Registration

8:30-8:45 AM Welcome - Dr. Ferrini-Mundy, President of the University of Maine

AM SESSION MODERATOR: DR. LILY CALDERWOOD

8:45-9:25 AM History of Maine's Wild Blueberry Industry - David Yarborough*, University of Maine

9:25-9:45 AM Blueberry Certification: Towards Efficient Movement of Plants Across Borders - Robert Martin, USDA-ARS Horticulture Crops Research Unit; Ioannis Tzanetakis*, University of Arkansas

9:45-10:05 AM Drowning in the Blue Wave: The Impact of Increased Foreign and Domestic Blueberry Production on the U.S. Blueberry Industries - Mark Longstroth*, Michigan State University Extension

10:05-10:20 AM BREAK (15 mins)

10:20-10:40 AM Floral Bud Cold Hardiness of Southern Highbush Blueberry in Response to Late Season Fertilization - Erick Smith*, University of Georgia; Lauren Redpath, North Carolina State University

10:40-11:00 AM Availability of Nitrogen from Ammonium Sulfate Fertilizer as Influenced by Weed Species and Density in a Lowbush Blueberry Commercial Field in Lac-Saint-Jean, Quebec - Maxime C. Paré*, Josée-Anne Lévesque, Université du Québec à Chicoutimi; Robert L. Bradley, Université de Sherbrooke; Jean Lafond, Agriculture and Agri-Food Canada

11:00-11:20 AM Report on Phytotoxicity on Blueberries in New Jersey During the Growing Season of 2017 - Gary C. Pavlis*, Peter Oudemans, Thierry Besançon, Dan Ward, Rutgers University

11:20-11:40 AM Remote Assessment of Phenological and Phenotypic Variability in Wild Blueberry Fields - David Percival*, Dalhousie University; Daniel Gallant, Bragg Lumber Company; Wayne Reid, Dalhousie University

11:40 AM - 12:00 PM Benefits of Using Liquid Sources of Potassium Fertilizer in Northern Highbush Blueberry - David Bryla*, USDA-ARS; David Leon, Oregon State University; Scott Orr, USDA-ARS

12:00-1:00 PM LUNCH (60 mins)

PROGRAM SCHEDULE

* PRESENTER



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PROGRAM SCHEDULE


PM SESSION MODERATOR: DR. SEANNA ANNIS

1:00-1:20 PM Dynamics of Phenology and Growth of Wild Blueberries (Vaccinium sp.) According to Various Agricultural Practices - Marie-Pier Fournier*, Maxime C. Paré, Annie Deslauriers, Université du Québec à Chicoutimi

1:20-1:40 PM An Agronomic Solution to Green Fruit Drop, a Genetic Condition in ‘Draper’ Blueberry - Eric Gerbrandt*, British Columbia Blueberry Council; Michael Dossett, BC Berry Cultivar Development Inc.

1:40-2:00 PM Using Next-Generation Sequencing Technology for Pathogen Discovery - James Polashock*, USDA-ARS Rutgers University; Peter Oudemans, Rutgers University; Joseph Kawash, ORISE Postdoctoral Scholar

2:00-2:20 PM Improving Control of Mummy Berry Using Predictive Models - Seanna Annis*, Frank Drummond, University of Maine; Hongchun Qu, Chongqing University of Posts and Telecomunications; Rachael Martin, Elissa Ballman, University of Maine

2:20-2:40 PM Susceptibility to Botrytis Blight at Different Floral Stages of Wild Blueberry Phenotypes - Joel A. Abbey*, David C. Percival, Kwaku Samuel Asiedu, Balakrishnan Prithiviraj, Dalhousie University; Annemiek Schilder, Michigan State University

2:40-3:00 PM BREAK (20 mins)

3:00-3:20 PM Molecular Approaches for Leaf Rust Detection and Quantification in Wild Blueberry - Nghi Nguyen*, Seanna Annis, University of Maine

3:20-3:40 PM Understanding and Mitigating Botryosphaeria Stem Blight and Crown Dieback in Blueberry - Renée M. Allen*, University of Georgia Extension;, Phillip M. Brannen, Harald Scherm, University of Georgia; Philip Harmon, University of Florida

3:40-4:00 PM Exploring the Genetic Structure of Mummy Berry Disease, Monilinia vaccinii-corymbosi in Lowbush Blueberries, Vaccinium angustifolium - Katie Ashley*, Seanna Annis, University of Maine

4:00-4:20 PM High Risk Blueberry Viruses by Region in the United States, Implications for Certification, Nurseries and Fruit Production - Robert R. Martin*, Karen E. Keller, USDA-ARS Horticulture Crops Research Lab; Dan E.V. Villamor, Ioannis E. Tzanetakis, University of Arkansas

4:20-4:40 PM Fungicide Use and Colletotrichum acutatum (fioriniae) Levels Over the Past Two Years - Carrie Denson*, Dean Polk, Rutgers Agricultural Research and Extension Center

4:45-6:15 PM Poster Session



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POSTER SESSION MODERATOR: JENNIFER D’APPOLLONIO

Phosphorus Mobility in Acidic Wild Blueberry Soils in Quebec, Canada - Jean Lafond*, Agriculture and Agri-Food Canada

Effect of Phosphorous Acid and Pruning Height on Renovated ‘Woodard’ Rabbiteye Blueberry - Eric Stafne*, Mississippi State University; Barbara J. Smith, USDA-ARS Thad Cochran Southern Horticultural Laboratory

Ammonium-enriched Amendments for Production of Northern Highbush Blueberry - Bryan K. Sales, Oregon State University; David R. Bryla*, USDA-ARS Horticultural Crops Research Unit; Dan M. Sullivan, Oregon State University; Kristin M. Trippe, USDA-ARS Forage Seed and Cereal Research Unit

Management of Botrytis Blight in Wild Blueberries with Honey Bee Vectored Clonostachys rosea - Rebecca Apperley-Ryan*, David C. Percival, Dalhousie University

Monilinia vaccinii-corymbosi Sensitivity to Demethylation Inhibitor Fungicides and Its Effect on Monilinia Blight Control in Wild Blueberry - David Percival, Sherin Jose*, Ling Guo, Dalhousie University; Annemiek Schilder, Michigan State University; Balakrishnan Prithviraj, Randall A. Olson, Dalhousie University

A New Luteovirus Infecting Highbush Blueberry - Dan E.V. Villamor, University of Arkansas; Robert R. Martin, Karen E. Keller, USDA-ARS Horticulture Crops Research Unit; Ioannis Tzanetakis*, University of Arkansas

Green Mosaic: A New Vitivirus Associated with Symptoms - Thanuja Thekke-Veetil, University of Arkansas; James Polashock, USDA-ARS Blueberry and Cranberry Center; Robert R. Martin, USDA-ARS Horticulture Crops Research Unit; Ioannis Tzanetakis*, University of Arkansas

Genetic Variability of Xylella fastidiosa Isolates Causing Bacterial Leaf Scorch of Blueberry in Georgia - Dario DiGenova, Kippy J. Lewis, Jonathan Oliver*, University of Georgia

Unraveling the Blueberry Stem Pathogen Complex - James Polashock*, USDA-ARS Blueberry and Cranberry Center

Understanding the Fungal Umwelt and How Flowers Communicate with Fungal Pathogens - Timothy J. Waller*, Peter V. Oudemans, Rutgers University

Bacterial Wilt of Blueberry - Nrupali Patel, Donald Y. Kobayashi, Peter V. Oudemans, Rutgers University

What is Sooty Blotch and Fly Speck on Blueberries? - Peter V. Oudemans*, Timothy Waller, Rutgers University; James Polashock, USDA-ARS Blueberry and Cranberry Center

POSTER SESSION



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Crown Gall-An Emerging Disease for Blueberries in the Northwest - Wei Qiang Yang*, North Willamette Research and Extension Center/Oregon State University; Virginia Stockwell, USDA-ARS Horticultural Crops Research Lab

A Six-Year Study of Spotted Wing Drosophila in Maine - Frank Drummond, Elissa S. Ballman*, Judith A. Collins, University of Maine

Erythritol and Two of Its Derivatives Reduce Survival and Reproductive Rate of a Serious Blueberry Pest, Drosophila suzukii (Diptera: Drosophilidae) - Blair J. Sampson*, Christopher T. Werle, Michael W. Easson, Stephen J. Stringer, John J. Adamczyk, USDA-ARS

Comparisons of Single Versus Split Post-Emergence Mesotrione Applications for Spreading Dogbane Control in Wild Blueberry Fields - Jennifer D’Appollonio*, David Yarborough, University of Maine

Crop Tolerance and Weed Control with Sulfentrazone-based Combinations in Highbush Blueberry (Vaccinium corymbosum) - Thierry E. Besançon*, Rutgers University

ARS 05-171: A Mid-late Highbush Cultivar with Concentrated Ripening - Mark Ehlenfeldt*, USDA-ARS Blueberry and Cranberry Center

Genetic Diversity of Lowbush Blueberry (Vaccinium angustifolium) in Managed and Non-Managed Populations - Lee Beers*, Ohio State University; Frank Drummond, University of Maine; Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

RNA-seq Combined with a Bulked-Segregant Analysis Identifies Candidates For The Waxy Coating On Blueberry Fruit - Xineng Qi, Elizabeth L. Ogden, Jose V. Die, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory; Mark K. Ehlenfeldt, James J. Polashock*, USDA-ARS Blueberry and Cranberry Center; Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

Carotenoid Biosynthesis During Bilberry (Vaccinium myrtillus L.) Fruit Development and Ripening - Katja Karppinen, Laura Zoratti, Marian Sarala, University of Oulo; Elisabete Carvalho, Fondazione Edmund Mach Research and Innovation Center; Jenni Pukki, Helmi Mentula, University of Oulo; Stefan Martens, Fondazione Edmund Mach Research and Innovation Center; Hely Häggman, University of Oulo; Laura E. Jaakola*, UiT The Arctic University of Norway/Norwegian Institute for Agricultural and Environmental Research

Texture Profile Analysis of ‘Rahi’ Blueberry (Vaccinium ashei) During Postharvest Storage - Daniel Hutchins*, Gourmet Blueberries, New Zealand

Development of an Irrigation App for Blueberry - Erick D. Smith*, Vesileios Liakos, George Vellidis, University of Georgia

Updated Costs and Returns for Michigan Blueberry Growers - Mark A. Longstroth*, Michigan State University Extension

Wild Blueberries in a Changing Climate - Yongjiang Zhang*, University of Maine

POSTER SESSION



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Tuesday, August 14, 2018 – Wells Conference Center

Time Event

7:30-8:30 AM Registration

AM SESSION MODERATOR: DR. DAVID HANDLEY

8:30-8:50 AM Towards Understanding Rain-Induced Fruit Splitting in Blueberry - Michael Dossett*, BC Berry Cultivar Development Inc; Chaim Kempler, Agriculture and Agri-Food Canada (Retired)

8:50-9:10 AM V. corymbodendron as a Bridge Between Taxonomic Sections and Ploidies in Vaccinium - Mark Ehlenfeldt*, USDA-ARS Blueberry and Cranberry Center

9:10-9:30 AM Cold Hardiness and Association Analysis of Lowbush Blueberry (Vaccinium angustifolium) using EST-PCR and SSR Molecular Markers - Lee Beers*, Ohio State University; Francis Drummond, University of Maine; Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

9:30-9:50 AM Hybridization and Introgression Between Deerberries and Blueberries: Problems and Progress - Paul Lyrene*, University of Florida

9:50-10:10 AM BREAK (20 mins)

10:10-10:30 AM U.S. Fish and Wildlife Service Pollinator Conservation Approaches and Collaborative Conservation Initiatives - Anna Harris*, Mark A. McCollough, U.S. Fish & Wildlife Service

10:30-10:50 AM USDA-NRCS Opportunities for Pollinator Conservation: The Nexus of Grower Priorities and Conservation Goals - Eric Venturini*, The Xerces Society; Jeremy Markuson*, Tony Jenkins, USDA-NRCS

10:50-11:10 AM Changes in Wild Bee Diversity and Abundance in Highbush Blueberry Between 2004-2017 - Kelsey K. Graham*, Michigan State University; Jason Gibbs, University of Manitoba; Rufus Isaacs, Michigan State University

11:10 AM-11:30 AM The Temporal Nuances of Wild Blueberry Pollination - Frank Drummond*, University of Maine; Daniel J. Bell, University of Maine (formerly); Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

11:30-11:50 AM Blueberry Insect Pest Management: Historical Trends and Future Challenges - Rufus Isaacs*, Michigan State University; Charles Vincent, Agriculture and Agri-Food Canada; Cesar Rodriguez-Saona, Rutgers University

11:50-12:50 AM LUNCH (60 mins)

PROGRAM SCHEDULE



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PROGRAM SCHEDULE

Tuesday, August 14, 2018 – Wells Conference Center

PM SESSION MODERATOR: DR. FRANK DRUMMOND

12:50-1:10 PM Influence of Fertility and Disease Management Practices on Sap-Feeding Insects, Premature Flowering, Stem Characteristics, Leaf Spot, Leaf Retention, and Foliar Nutrients in Wild Blueberry - Judith Collins*, Frank Drummond, University of Maine

1:10-1:30 PM Dynamics of Secondary Infection in Wild Blueberry Fields - Elissa S. Ballman*, Frank Drummond, Seanna Annis, Rachael Martin, University of Maine; Hongchung Qu, Chongquing University of Posts and Telecommunications

1:30-1:50 PM The Impacts of Spotted Wing Drosophila (SWD) on Fruit Quality and Pesticide Use in New Jersey - Dean Polk*, Rutgers Agricultural Research and Extension Center

1:50-2:10 PM Community Composition of Insects in Galls Formed by Blueberry Stem Gall Wasp, and Implications for Highbush Blueberry Pest Management - Phillip D. Fanning*, Steven VanTimmeren, Rufus Isaacs, Michigan State University

2:10-2:30 PM BREAK (20 mins)

2:30-2:50 PM Evaluation of ALS/AHAS-Inhibiting Herbicides for Red Sorrel (Rumex acetosella L.) Management in Wild Blueberry - Scott White*, Dalhousie University

2:50-3:10 PM Evaluation of Herbicide Options for Bracken Fern Control in theSprout Year of Wild Blueberries in New Brunswick in 2016 - Gavin Graham*, New Brunswick Department of Agriculture, Aquaculture & Fisheries

3:10-4:10 PM Glacial Geology of Maine's Blueberry Barrens - Harold W. Borns, Professor Emeritus, University of Maine

4:10-5:15 PM Business Meeting, Overview and Discussion of the Blueberry Industry, and Removal of Posters

6:00 PM Lobster Bake Banquet - Music by Tough End Band



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Wednesday, August 15, 2018 – Blueberry Tour

Time Event

7:00-8:00 AM Blueberry Bus Tour Pickup (University Inn & Academic Suites, Steam Plant, Black Bear Inn)

8:00 AM Depart for Tour of Blueberry Barrens and Processing Plant (a box lunch will be provided)

10:00 AM Tour Blueberry Barrens (T19, drive across barrens with machine harvest stop)

11:30 AM Depart for Blueberry Hill Farm (Route 1, Jonesboro)

12:00 PM Blueberry Hill Farm (lunch, hand harvest, bee hive tour, research activities)

2:30 PM Organic Field Visit and Talk at Jenny & Hugh Lassen's Intervale Farm (Route 193, Cherryfield)

3:30 PM Tour Wyman's Processing Plant with Homer Woodard (Route 193, Deblois)

5:00 PM Depart for Orono

6:30 PM Arrive at Hotels and Steam Plant

PROGRAM SCHEDULE



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Dr. David Yarborough, Chair Extension Blueberry Specialist Professor of Horticulture University of Maine Cooperative Extension 5722 Deering Hall, Rm. 414 University of Maine Orono, ME USA 04469-5722Tel: 207.581.2923 [email protected] Dr. Seanna Annis Associate Extension Professor Plant Pathology Specialist Associate Professor of Mycology, School of Biology & Ecology 5722 Deering Hall, Rm. 13 Orono, ME 04469-5722 Tel: 207.581.2621 [email protected]

Jennifer D’AppollonioAssistant Scientist School of Food & Agriculture University of Maine 5722 Deering Hall, Rm. 411 Orono, ME 04469-5722 Tel: 207.581.2924 [email protected]

Lily CalderwoodWild Blueberry Specialist & Assistant Professor of Horticulture5722 Deering Hall, Rm. 103 Orono, ME 04469-5722Tel: [email protected]

Dr. Francis Drummond Entomology Specialist Professor of Insect Ecology School of Biology & Ecology University of Maine 5722 Deering Hall, Rm. 305 Orono, Maine 04469-5722 Tel: 207.581.2989 [email protected]

Dr. David Handley Extension Vegetable & Small Fruit SpecialistHighmoor FarmPO Box 179Monmouth, ME 04259-0179Tel. 207.933.2100 ext. [email protected]

Patricia KontourDirector of ProgramsWild Blueberry Commission of Maine5784 York Complex, Suite 52Orono, ME 04469-5784Tel: [email protected]

Phoebe Nylund (Retired)Administrative Specialist UMaine Cooperative [email protected]

Pam St. PeterAdministrative Specialist Highmoor Farm PO Box 179 Monmouth, ME 04259-0179 Tel. 207.933.2100 ext. [email protected]

PLANNING COMMITTEE



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CONFERENCE PRESENTERS & AUTHORSJoel Abbey [email protected]

Renée M. Allen [email protected]

Seanna Annis [email protected]

Rebecca Apperley- Ryan [email protected]

Katie Ashley [email protected]

Samuel K. Asiedu [email protected]

Elissa Ballman [email protected]

Thierry Besançon [email protected]

Lee Beers [email protected]

Daniel J. Bell [email protected]

Harold Borns [email protected]

Robert L. Bradley [email protected]

Phillip M. Brannen [email protected]

David Bryla [email protected]

Judith Collins [email protected]

Jennifer D’Appollonio [email protected]

Carrie M. Denson [email protected]

Annie Deslauriers [email protected]

Jose V. Die [email protected]

Michael Dossett [email protected]

Francis Drummond [email protected]

Mark Ehlenfeldt [email protected]

Phillip D. Fanning [email protected]

Marie-Pier Fournier [email protected]

Dario Di Genova [email protected]

Eric Gerbrandt [email protected]

Jason Gibbs [email protected]

Gavin Graham [email protected]

Kelsey Graham [email protected]

Ling Guo [email protected]

Philip Harmon [email protected]

Anna Harris [email protected]

Daniel Hutchins [email protected]

Rufus Isaacs [email protected]

Joseph Kawash [email protected]

Sherin Jose [email protected]

Donald Kobayashi [email protected]

Jean Lafond [email protected]

David Leon [email protected]

Kippy J. Lewis [email protected]

Josée-Anne Lévesque [email protected]

Vesileios Liakos [email protected]



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Mark Longstroth [email protected]

Paul Lyrene [email protected]

Jeremy Markuson [email protected]

Robert Martin [email protected]

Rachael Martin [email protected]

Mark McCollough [email protected]

Nghi Nguyen [email protected]

Elizabeth Ogden [email protected]

Scott Orr [email protected]

Peter Oudemans [email protected]

Maxime Paré [email protected]

Nrupali Patel [email protected]

Gary Pavlis [email protected]

David Percival [email protected]

James Polashock [email protected]

Dean Polk [email protected]

Balakrishnan Prithiviraj [email protected]

Xinpeng Qi [email protected]

Lauren Redpath [email protected]

Cesar Rodriguez [email protected]

Lisa J. Rowland [email protected]

Bryan K. Sales [email protected]

Harald Scherm [email protected]

Annemiek Schilder [email protected]

Barbara J. Smith [email protected]

Erick D. Smith [email protected]

Eric T. Stafne [email protected]

Virginia Stockwell [email protected]

Dan Sullivan [email protected]

Thanuja Thekke-Veetil [email protected]

Ioannis Tzanetakis [email protected]

Steven VanTimmeren [email protected]

George Vellidis [email protected]

Eric Venturini [email protected]

Dan Villamor [email protected]

Charles Vincent [email protected]

Timothy Waller [email protected]

Scott White [email protected]

Wei Qiang Yang [email protected]

David Yarborough [email protected]

Yongjiang Zhang [email protected]

CONFERENCE PRESENTERS & AUTHORS



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Joel Abbey [email protected] Alamo Bermudo [email protected] Allen [email protected] Annis [email protected] Apperley-Ryan [email protected] Ashley [email protected] Elissa Ballman [email protected] Lee Beers [email protected] Besançon [email protected] Borns [email protected] Bryla [email protected] Burgess [email protected] Burlakoti [email protected] Calderwood [email protected] Carroll [email protected] Collins [email protected] D’Appollonio [email protected] Denson [email protected] Dossett [email protected] Drummond [email protected] Ehlenfeldt [email protected] Fanning [email protected]

Marie-Pier Fournier [email protected] Gerbrandt [email protected] Gilmour [email protected] Graham [email protected] Graham [email protected] Handley [email protected] Harris [email protected] Hutchins [email protected] Rufus Isaacs [email protected] Laura Jaakola [email protected] Jose [email protected] Kontour [email protected] Lafond [email protected] Longstroth [email protected] Lyrene [email protected] Markuson [email protected] Martin [email protected] Martin [email protected] McBrady [email protected] McDermott [email protected] Melanson [email protected]éronique Moreau [email protected]

Nghi Nguyen [email protected] Oliver [email protected] Oudemans [email protected] Paré [email protected] Percival [email protected] Polashock [email protected] Polk [email protected] Rodriguez-Armenta [email protected] Sampson [email protected] Sandefur [email protected] Schwab [email protected] Smith [email protected] Ed Smith [email protected] Spencer [email protected] Stafne [email protected]Étienne Thériault [email protected] Ioannis Tzanetakis [email protected] Venturini [email protected] Waller [email protected] White [email protected] Qiang Yang [email protected] Yarborough [email protected]

CONFERENCE PARTICIPANTS



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WELCOME RECEPTION

Registration will begin at 6:00 p.m. on Sunday, August 12th at the Wells Conference Center.

A reception to welcome all participants and their guests will be held from 6:00 to 8:00 p.m. This is a good time to meet and mingle with other blueberry and Extension colleagues.

LOBSTER BANQUET

A lobster banquet will be held on Tuesday, August 14th at the Lyle E. Littlefield Ornamental Garden on Rangeley Road at 6:00 p.m. The Ornamental Garden has nearly 2,500 plantings, with an extensive collection of cold-hardy landscape plants that makes a beautiful backdrop for the evening activities.

DIRECTIONS: From College Avenue, turn onto Long Road. Follow Long Road to Rangeley Road. Turn right on Rangeley Road and the ornamental garden will be on your left. (The Rangeley Road entrance from Route 2 is temporarily closed due to construction)



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BLUEBERRY BUS TOURThe Downeast Maine blueberry bus tour is on Wednesday, August 15th, which falls during the height of Maine’s blueberry season. Maine currently has 44,000 acres of wild blueberries that grow naturally in the fields and barrens that stretch along Maine’s Downeast coast.

The tour will include a visit to• Downeast Maine’s blueberry barrens with a machine harvest stop• the Blueberry Hill Research Farm in Jonesboro• a bee hive tour with Frank Drummond and local beekeepers• a visit to an organic blueberry field in Cherryfield• and tour of a blueberry processing plant in Deblois

Pickup for the bus tour will begin at 7:00 a.m. The tour will depart from Orono at 8:00 a.m. arriving back in Orono around 6:30 p.m. Everyone who wants to go on the blueberry barren tour must ride on the tour bus – no personal vehicles will be allowed on the tour.

Pickup locations for the bus tour are:• University Inn & Academic Suites (College Avenue)• Steam Plant (College Avenue)• Black Bear Inn (Godfrey Drive)



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BLUBERRY BUS TOUR PARTICIPANTSUNIVERSITY INN Joel AbbeyRenee AllenRebecca Apperley-RyanPeter BurgessRishi BurlakotiJuliet CarrollMichael DossettMark Ehlenfeldt & Jean StockGavin GrahamDaniel HutchinsLaura JaakolaMark Longstroth & Kimmly LongstrothPaul LyreneRobert MartinLaura McDermottMichel MelansonJonathan OliverDavid PercivalJames PolashockHilda Rodriguez-ArmentaErick SmithJohn Ed SmithJessica SpencerEric StafneÉtienne ThériaultScott White

STEAM PLANTSeanna AnnisKatie AshleyHarold BornsJennifer D’AppollonioCarrie DensonFrank DrummondPhillip FanningKelsey GrahamDavid HandleyRufus IsaacsJeremy MarkusonRachael MartinNghi NguyenJacob SchwabIoannis Tzanetakis

BLACK BEAR INNThierry BesançonLily CalderwoodEric GerbrandtRyan GilmourSherin JoseDean PolkTimothy Waller

BEE HIVE TOUR PARTICIPANTSJoel AbbeyRenee AllenRebecca Apperley-RyanRishi BurlakotiJuliet CarrollJennifer D’AppollonioMichael DossettFrank DrummondMark Ehlenfeldt & Jean StockPhillip FanningEric GerbrandtRyan GilmourKelsey GrahamDavid HandleyDaniel HutchinsRufus IsaacsLaura JaakolaSherin JoseMark Longstroth Paul LyreneJeremy MarkusonRobert Martin Laura McDermottMichel MelansonJonathan OliverDavid PercivalDean PolkJacob SchwabJohn Ed SmithErick SmithJessica SpencerÉtienne Thériault



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ABSTRACTS - MONDAY, AUGUST 13TH

1. History of Maine’s Wild Blueberry Industry.David Yarborough*, University of Maine

Wild blueberry plants were first established as the glacier receded 10,000 years ago and usedby native Americans, but the beginnings of the commercial industry was in the 1800’s to the1950’s, when Maine was the largest blueberry producer in the country. Wild blueberries werefirst picked fresh, then canned and now are 99% frozen and used principally as an ingredientin products. The crop increased over time from less than one million pounds produced in1896 to the bumper crop of over 110 million pounds in produced in 2000, and now averagesabout 100 million pounds on 44,000 acres, half of which are harvested each year. Changesin harvest techniques from hand-picking to hand-raking to the current practice of machineharvesting 24/7 have developed over time. Challenges that have faced the industry include theblueberry maggot in 1919 to the introduction of the newest pest, the spotted wing drosophilain 2010. Changes in pruning from burning to mowing began when the price of oil increasedin the 1970’s, when fields were de-rocked, leveled and mowed to reduce cost and facilitatemechanical harvesting. Wild blueberry growers were early adopters of IPM techniques whichinclude fruit fly trapping and border spraying to minimize applications, use of sweep nets tomonitor for chewing insects, monitoring weather conditions to apply fungicides, leaf sampling todetermine fertilizer needs and the use of sulfur to reduce pH as a cultural management tool tosuppress weeds. These improved weed, disease and insect management techniques, and theincreased use of imported pollinators and irrigation, have increase yields and reduced the costof production to keep wild blueberries economically competitive.

2. Blueberry Certification: Towards Efficient Movement of Plants Across Borders.Robert Martin, USDA-ARS Horticulture Crops Research Unit; Ioannis Tzanetakis*, University ofArkansas

For the past seven years there have been significant efforts to modernize and harmonize thecertification standards for blueberry in the United States. This includes a clear designation ofeach propagation tier (generation), a list of targeted pathogens and best management practicesincluding testing at the final generation for pathogens that are prevalent in the geographic areawhere a nursery is located. A draft of the proposed standard (available at ncpnberries.org) wasused as the guideline in three-year long pilot studies in Michigan, Oregon and Washington Stateto evaluate the feasibility to implement the new rules in the nursery industry of the respectivestates. After industry feedback, states work together to harmonize rules, which will allow forstreamlined movement of propagation material between the aforementioned states as well asother states that adopt the rules in the future.

3. Drowning in the Blue Wave: The Impact of Increased Foreign and Domestic BlueberryProduction on the U.S. Blueberry Industries.Mark Longstroth*, Michigan State University Extension

The Blue Wave refers to the increasing supply of blueberries as worldwide blueberry productionexpands rapidly. Historically, blueberries were temperate fruit requiring a long chilling period.Blueberry breeders have developed Southern Highbush blueberries with fruit characteristicssimilar to Northern Highbush berries. Low chill and no-chill varieties have been developed whichcan be grown in semi-tropical areas. This has greatly expanded the growing regions availablefor blueberries production. The United States is the principle blueberry consuming market in theworld and most Western Hemisphere blueberries are produced to be exported to the US. Thevolume of fresh blueberries available year around in the United States market are squeezing



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the profits of many blueberry growers. When more fresh fruit is produced than the fresh market can absorb, excess fruit is frozen and sold on the frozen market. Increased frozen blueberry supplies have depressed frozen blueberry prices. Traditional market niches are disappearing as U.S. blueberry growers compete in a global market. To compete with rising costs and declining profits, blueberry growers need to become more efficient increasing blueberry yields per acre.

4. Floral Bud Cold Hardiness of Southern Highbush Blueberry in Response to Late Season Fertilization.Erick Smith*, University of Georgia; Lauren Redpath, North Carolina State University

The objectives were to identify the effects of late season fertilization on southern highbush blueberry (SHB) dormant floral bud cold hardiness, flower timing, and plant nutrient uptake. Treatments included two fertilizers 10-10-10 (Super Rainbow) and 46-0-0 (urea) and two cultivars, ‘Emerald’ and ‘Star’, grown in pine bark media. There were four treatments 1) 10-10-10 fertilization ending in August (28 g/container); 2) 10-10-10 fertilization ending in September (20 g and 10 g/container applied September and October, respectively); 3) 10-10-10 fertilization ending in October (10 g/container applied monthly; August-October); 4) urea fertilization ending in September (3 g/container applied August and September). Dormant root and shoot tissue were analyzed for mineral nutrients. Floral bud tissue was freeze tolerance (FT) tested and growth stages were recorded from 24 Jan. to 14 Mar. The FT of ‘Star’ was unaffected by fertilization treatments or sample dates. In contrast, ‘Emerald’ on Jan. 17 was hardiest in treatment 3 (at -12.0 C°) and on Feb. 8, the hardiest floral buds of ‘Emerald’ were treatment 2 (at -13.5 °C). The 10-10-10 N concentration was similar for both cultivars in the shoots, while urea N concentration was significantly lower in ‘Emerald’. In both cultivars, late fertilization increased root N concentration. All fertilizer treatments in ‘Emerald’ bloomed earlier than ‘Star’. No significance was seen between treatments of bloom progression for ‘Emerald’. Treatment 3 advanced bloom progression in ‘Star’. This work demonstrates that urea and mid-October fertilization had no effect on floral bud cold hardiness and bloom timing was cultivar dependent.

5. Availability of Nitrogen from Ammonium Sulfate Fertilizer as Influenced by Weed Species and Density in a Lowbush Blueberry Commercial Field in Lac-Saint-Jean, Quebec.Maxime C. Paré*, Josée-Anne Lévesque, Université du Québec à Chicoutimi; Robert L. Bradley, Université de Sherbrooke; Jean Lafond, Agriculture and Agri-Food Canada

Numerous studies have speculated that relative to weeds, wild blueberry (Vaccinium angustifolium) is a poor competitor for mineral nitrogen (N) derived from fertilizers. Here, we test this hypothesis by comparing the proportion of N from fertilizer recovered (PNFR) of wild blueberry with that of two common weeds found in Lac-Saint-Jean (Quebec) commercial blueberry fields—sweet fern (Comptonia peregrina) and poverty oat grass (Danthonia spicata). In 2015, we manually applied labeled ammonium sulfate (5% of 15N) at the recommended rates to 1 m2 field plots containing wild blueberry and four different densities of weed (0–6 plants·m-2 and 0–25 plants·m-2 for sweet fern and poverty oat grass, respectively). In 2016, we harvested the above and below ground parts of all individual plants and determined the PNFR for each. Sweet fern assimilated more N from fertilizer (+10%) than did poverty oat grass. However, unlike sweet fern, an increased density of poverty oat grass significantly increased the PNFR in this weed. The PNFR in wild blueberry remained constant (~30%) as sweet fern density increased, whereas the PNFR in wild blueberry decreased by two-fold as poverty oat grass density increased. Our results indicate that adding mineral N fertilizers is




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beneficial only when the blueberry crop is well established, as wild blueberry requires about four times more roots than sweet fern and poverty oat grass to assimilate equivalent amounts of N from ammonium sulfate. Therefore, compared to these two distinct weed species, wild blueberry is a poor competitor for mineral N fertilizers.

6. Report on Phytotoxicity on Highbush Blueberries in New Jersey During the Growing Season of 2017.Gary C. Pavlis*, Peter Oudemans, Thierry Besançon, Dan Ward, Rutgers University.

New Jersey produces approximately 9% (50-60 million lbs) of the total US blueberry crop which represents approximately $70 million or 8% of the total value of utilized production for North America. The majority of the NJ crop is hand-picked for the fresh market and the product is widely distributed through North America and some is even exported to Europe. In 2017, bud break was seen around March 28th and bloom began around April 14th. Reports of unusual symptoms began in mid-May. Plant materials were tested for virus and nutrient levels; however, nothing conclusive was found. By May 25th more reports had been received and it appeared that the problem was widespread. By late May field professionals from Helena and Crop Production Services were receiving increasing grower complaints and approximately 20 farms were identified where similar symptomologies were seen. In reviewing pesticide application records it appeared an herbicide may be involved, although it was not clear which herbicide since growers typically utilize a cocktail. These field professionals subsequently contacted representatives of the chemical producers to inform them of an impending problem. Visitations to numerous farms ensued. Growers provided pesticide application records for investigative purposes. Based on these results, it appears that pendimethalin was overwhelmingly a common denominator in fields with damage. No other herbicide was correlated with damaged bushes. The purpose of this report is to convey the methodology used to determine the source of the phytotoxicity.

7. Remote Assessment of Phenological and Phenotypic Variability in Wild Blueberry Fields.David Percival*, Dalhousie University; Daniel Gallant, Bragg Lumber Company; Wayne Reid, Dalhousie University

Research and development activities using PrecisionHawk Lancaster M4 and M5 unmanned aerial vehicles (UAV) equipped with a high resolution, low distortion 18.4 megapixel camera were conducted during the 2016 and 2017 field seasons to determine if the UAV system could accurately assess wild blueberry coverage, phenotypic population structure, and vegetative and floral bud growth stage. This was complimented with field level validation of blueberry coverage, vegetative and floral bud growth stage, and phenotypes identification. In addition, hyperspectral VIS/NIR scans of selected blueberry phenotypes were obtained using a radiometer equipped with a 10⁰ foreoptic. Results indicated that it was possible to provide precise and accurate assessment of: (i) blueberry coverage and topographic features, (ii) the distribution of Vaccinium angustifolium Ait. and V. myrtilloides Michx. phenotypes, (iii) canopy growth and development stage, and (iv) several weed species including goldenrod, sheep sorrel and fescue grasses that were present within the fields. However, use of the high resolution digital camera did not consistently provide an accurate estimate of bloom intensity or yield potential. Therefore, results from the study have indicated that these technologies have the potential to significantly improve field assessment for blueberry plant coverage and pest related factors. This can be integrated with emerging agrochemical application technologies to significantly reduce agrochemical usage, decrease the cost of production and improve the overall sustainability of the wild blueberry production system.




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8. Benefits of Using Liquid Sources of Potassium Fertilizer in Northern HighbushBlueberry.David Bryla*, USDA-ARS; David Leon, Oregon State Unviersity; Scott Orr, USDA-ARS

Fertigation with N increases growth and production relative to granular N applications innorthern highbush blueberry (Vaccinium corymbosym L.), but little information is availableon whether there is any benefit to fertigating with other nutrients. The objective of this studywas to compare fertigation to granular application of K fertilizer in a mature planting of ‘Duke’blueberry. The plants were grown on raised beds and irrigated using two lines of drip tubingper row. Treatments were initiated in 2016 and included fertigation (once a week from April toAugust) with potassium sulfate (K¬2SO4) or potassium thiosulfate (KTS), a single application(April) of granular K¬2SO4, and no K fertilizer. Each K fertilizer was applied at a total rate of75 kg·ha-1 K2O per year. So far, the treatments have had no effect on yield or fruit quality.However, fertigation with K-2SO4¬ or KTS resulted in lower pH and higher concentrations ofK, Ca, Mg, and S in soil solution under the drip emitters than either no K or granular K¬2SO4,while granular K-2SO4 resulted in higher concentration of K than any other treatment at 6inches from the drip emitter (edge of the wetting front). The fertigated treatments also hadgreener leaves (based on SPAD meter readings), greater leaf K concentrations, and nearly twiceas much extractable K in the soil as the non-fertigated treatments. Additional measurementsare underway to determine whether K fertigation will have any effect on yield or fruit qualityover the long term.

9. Dynamics of Phenology and Growth of Wild Blueberries (Vaccinium sp.) According toVarious Agricultural Practices.Marie-Pier Fournier*, Maxime C. Paré, Annie Deslauriers, Université du Québec à Chicoutimi

Several factors influence the physiology of wild blueberry plants (Vaccinium sp.). Indeed, theagricultural practices can increase the access to nutrients and decrease fungal diseases. Thisstudy aims at determining the effects of agricultural practices on growth of wild blueberryplants during their vegetative year in both V. angustifolium and V. myrtilloides. The experimentwas carried out in 2017 on a blueberry commercial field in Northern Lac-Saint-Jean. Threeagricultural practice were tested, such as mechanical or thermal pruning, the application offungicide and the supply of mineral or organic fertilization. Buds phenology, height growthand branch ramification were periodically measured. The blueberry specie was determined aseither V. angustifolium and V. myrtilloides based on visual criteria. Blueberry having mineraland organic fertilizers had greater shoot growths compared to control. However, a species effectwas found as blueberry shoots growth differently responds to pruning, fertilizer and fungicidein V. angustifolium and V. myrtilloides. These primary results suggest that agricultural practicesdifferently affect the two species. In the future, this long-term research should lead to a betterselection of agricultural practices in Northern Lac-Saint-Jean.

10. An Agronomic Solution to Green Fruit Drop, a Genetic Condition in ‘Draper’ Blueberry.Eric Gerbrandt*, British Columbia Blueberry Council; Michael Dossett, BC Berry Cultivar Development, Inc.

For several years, blueberry growers in southwestern British Columbia and northwestern Washington have lost considerable revenues in ‘Draper’ plantings due to spontaneous green fruit drop (GFD) that occurs just prior to ripening. The severity of the condition ranges from 5-75% of the total crop, depending on the field and season. GFD was also recently observed in New Jersey, but it is not as prevalent in production regions such as Oregon where climatic




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conditions are warmer during fruit development. In 2014, preliminary field experiments determined that the GFD disorder is related to a localized calcium deficiency in the fruit, like blossom end rot in tomato or bitter pit in apple. Increased severity under high rates of nitrogen fertilization, and near complete resolution with corrective foliar calcium sprays, provide strong evidence for this explanation. Subsequent multi-site trials in 2015 and 2016 were used to develop an agronomic solution for commercial growers, identifying rates and timings for foliar calcium applications. Adaptation of this agronomic solution to different production regions, that have access to different foliar chemistries, should be effective in mitigating dramatic yield losses resulting from GFD. However, the genetic nature of the condition requires further investigation because it is possible that this trait will manifest in future highbush blueberry cultivars that have ‘Draper’ in their parentage. Initial investigation into the heritability of fruit calcium content in ‘Draper’ progenies in the BC Berry Breeding Program provides the first information that can be used to study tendency toward green fruit drop in breeding populations.

11. Using Next-Generation Sequencing Technology for Pathogen Discovery.James Polashock*, USDA-ARS Rutgers University; Peter Oudemans, Rutgers University; Joseph Kawash, ORISE Postdoctoral Scholar

Blueberries are woody perennials that, with proper care, can produce a crop each year for decades. In some fields in New Jersey, fruit yields and plant health are declining. Replanting often does not solve the problem, suggesting the issue might be soil related. It is well known that the microbial communities in the soil can directly or indirectly affect plant health. Thus, determining what soil organisms are associated with decline, might provide clues for developing approaches to remediation. Until recently, it was difficult to characterize the soil microbial community. This due to several causes: the soil microbes can reach high numbers in small amounts of soil, the microbes vary widely in taxonomic class, and variation across even short distances can be extensive. Although these issues can be addressed using modern next-generation sequencing, there remain several challenges: classification can be difficult, delineation of what constitutes a ‘healthy soil’ community is undefined, and methods to manipulate the microbial community are not well established. We have identified thousands of organisms that inhabit ‘blueberry’ soils. Bioassays were used to help define ‘healthy’ vs. ‘decline-associated’ soil. We used FUNguild to categorize the soil organisms. The next phase of this study will specifically determine which microbes are affecting the crop (positively or negatively).

12. Improving Control of Mummy Berry Using Predictive Models.Seanna Annis*, Frank Drummond, University of Maine; Hongchun Qu, Chongqing University of Posts and Telecommunications; Rachael Martin; Elissa Ballman, University of Maine

Mummy berry, caused by Monilinia vaccinii-corymbosi, is the most potentially damaging disease to wild blueberry (Vaccinium angustifolium). Mummy berry has a complex disease cycle starting with overwintering pseudosclerotia producing ascospores that are wind dispersed. The ascospores kill developing leaf and flower buds and produce conidia that are dispersed by pollinators. Conidial infection of pollinated flower ovaries leads to the production of pseudosclerotia. The mummy berry system is further complicated in wild blueberry by the clonal diversity in the fields, two-year crop cycle, and variation in the landscape surrounding fields. Over the past three field seasons (2016 to 2018), we have been gathering data to build a model of mummy berry that simulates ascospore dispersal, primary infection, conidia production and transmission by multiple pollinators, and secondary fruit infection. Parameters for the model have been developed from field collected and published data. The model includes




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variation in size and phenology of wild blueberry clones on different spatial scales and variation in surrounding vegetation. We are validating the model with field data collected over three years. The model can be used to run simulations on the effect of cropping cycle, different pollinator populations, clonal diversity and fungal inoculum sources, as well as landscape and weather effects. This model could be modified in the future for use in other blueberry cropping systems to explore other complexities of the mummy berry system.

13. Susceptibility to Botrytis Blight at Different Floral Stages of Wild Blueberry Phenotypes.Joel A. Abbey*, David C. Percival, Kwaku Samuel Asiedu, Balakrishnan Prithiviraj, Dalhousie University; Annemiek Schilder, Michigan State University

Botrytis blight is an important disease of wild blueberries (Vaccinium angustifolium, V. myrtilloides) with yield losses in excess of 20% frequently occurring. Two field experiments were conducted in 2016 and 2017 to determine the susceptibility of four phenotypes (V.a, V.a f. nigrum, V.m and V.a var. Fundy) at different floral stages [(Bud break (F5); bud prebloom; (F6), corolla fully open (F7), and senescent corolla (F8)] to Botrytis infection. Specific flower clusters on tagged stems from different phenotypes were inoculated with Botrytis cinerea conidial suspension (106 conidia·ml-1). Disease development were assessed eight days after inoculation. Disease incidence and severity in phenotype ranged from 14.1 to 22.6% and 37.4 to 42.3% in 2016, and 39.8 to 44.1% and 9.70 to 19.1% in 2017, respectively. Results indicated that V.a was the most susceptible followed by V.a f. nigrum and V.a var. Fundy. V. myrtilloides was found to be least susceptible. Incidence and severity on floral stages ranged from 2.95 to 36.4% and 7.81 to 75.5% in 2016, and 7.28 to 66.9% and 11.1 to 27.1% in 2017, respectively. Floral stage F7 was the most susceptible with incidence up to 66.9% and severity up to 75.5% followed by F6, F5 and F8. Therefore, results from this study indicated that V.m was less susceptible to B. cinerea than V.a phenotypes, and F6 and F7 stages were the most susceptible to Botrytis blight. These results will assist producers in making more informed decisions on Botrytis blossom blight control in wild blueberry production.

14. Molecular Approaches for Leaf Rust Detection and Quantification in Wild Blueberry.Nghi Nguyen*, Seanna Annis, University of Maine

Understanding the spore dispersal pattern and disease cycle of fungal pathogens in wild blueberry is crucial for the development of a more efficient disease management program. A molecular assay for rapid detection and quantification of Thekopsora minima, the cause of leaf rust in wild blueberry, is being developed to be incorporated with a spore trap sampling method and weather data to analyze spore dispersal. The molecular methods employed are quantitative polymerase chain reaction (PCR) and quantitative loop mediated isothermal amplification (qLAMP). Rust urediniospores were collected from four different fields in Maine, from which DNA was extracted and used to obtain the sequence of the internal transcribed spacer (ITS) regions of ribosomal DNA for T. minima. Two T. minima specific primers for qPCR and six primers for qLAMP are currently being tested for specificity and detection limits. The qLAMP assay is expected to be more specific and have a lower detection limit compared to qPCR. Afterwards, this assay will be used to estimate spore numbers collected using Burkard spore traps in multiple fields. Estimates of spore counts using the molecular method will be compared to microscopic spore count in duplicate spore trap collections. The qLAMP assay will later be incorporated with spore trap sampling and weather data such as air temperature, leaf wetness and humidity to determine factors affecting spore dispersal and infection to develop an efficient forecasting system for leaf rust in blueberry.




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15. Understanding and Mitigating Botryosphaeria Stem Blight and Crown Dieback in Blueberry.Renée M. Allen*, University of Georgia Extension; Phillip M. Brannen, Harald Scherm, University of Georgia; Philip Harmon, University of Florida

Mechanical hedging has become a common practice with perennial crops, and in wine grapes in particular, it has been demonstrated that the use of fungicides after such practices is justified in reducing disease pressure from plant pathogens of concern, such as members of the Botryosphaeriaceae complex. To date, there has been limited data on blueberry to demonstrate fungicide efficacy against infection by these fungi after post-harvest hedging. In 2016 and 2017, tops of southern highbush blueberry cultivar ‘Star’ were hedged flat. Fungicides from multiple FRAC classes were applied: azoxystrobin (Abound), fludioxonil (Cannonball), penthiopyrad (Fontelis), prothioconazole (Proline), potassium phosphite (Prophyt), and thiophanate-methyl (Topsin M). Plots were five plants long with each of the three middle plants inoculated with a different fungal isolate (five stems per plant): Neofusicoccum ribis SEGA 18, Neofusicoccum ribis SEGA 10a, or Lasiodiplodia theobromae SEGA 32. Inoculations were conducted 2 h after fungicide application by applying a 7-day-old potato dextrose agar culture of the isolate to the cut stems; this was accomplished by cutting the fungal colony on agar plates with an inverted centrifuge tube (covered with white tape), and then sticking the tube of inoculum on the stem and attaching with parafilm. The untreated control included plots that were hedged and to which no fungicide was applied. Stems were assessed for Botryosphaeria stem blight lesion length 10 and 20 days after treatment. Thiophanate-methyl was the only product that significantly reduced disease severity in both years and at both assessment dates.

16. Exploring the Genetic Structure of Mummy Berry Disease, Monilinia vaccinii-corymbosi in Lowbush Blueberries, Vaccinium angustifolium.Katie Ashley*, Seanna Annis, University of Maine

Monilinia vaccinii-corymbosi (MVC), the fungus that causes mummy berry, is a significant pathogen of both highbush and lowbush blueberries. In Maine, lowbush blueberry is an economically important crop, where approximately 80 million pounds of blueberries are produced annually. Because of the large impact of mummy berry on lowbush blueberries, it is important to have a more comprehensive understanding of the pathogen’s life cycle. The genetic structure of the fungus is being examined in fields that are in different crop cycles (single production or split production), management systems (organic and conventional), and unmanaged areas. Using available tissue harvested from these locations, isolates will be prepared from ascospores, conidia, and pseudosclerotia. Then, using existing microsatellite markers developed from MVC of highbush blueberries, the population genetics of MVC in lowbush blueberry will be explored. A deeper understanding of the reproductive strategies of this fungus could lead to improved understanding of how management practices may be affecting this fungus and its production of disease.

17. High Risk Blueberry Viruses by Region in the United States, Implications for Certification, Nurseries and Fruit Production.Robert R. Martin*, Karen E. Keller, USDA-ARS Horticulture Crops Research Lab; Dan E.V. Villamor, Ioannis Tzanetakis, University of Arkansas

There is limited information about the distribution of blueberry viruses in the U.S. or around the world other than where the viruses were first discovered and characterized. A survey for blueberry viruses was carried out in the U.S. in 2015-2017. With the lack of a reliable woody




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indicator, most blueberry viruses have been characterized to the point that sensitive diagnostic assays have been developed. These assays are based on ELISA or various variations of PCR, which were employed to determine the presence of blueberry viruses in major production and nursery areas of the U.S. In the Pacific Northwest, blueberry shock virus (BlShV) was the most widespread virus, with blueberry scorch (BlScV) and tomato ringspot (ToRSV) detected in a limited number of fields. In the upper mid-west, the nematode-borne (ToRSV and tobacco ringspot (TRSV)) and aphid-transmitted (blueberry shoestring, BSSV and blueberry virus A, BVA) and pollen-borne blueberry leaf mottle (BLMV) transmitted viruses were most widespread. In the northeastern U.S., TRSV, ToRSV, BlScV, were detected most frequently. In the southeast, TRSV, blueberry red ringspot (BRRSV) and blueberry fruit drop (BFDaV) were the most widespread. Blueberry latent virus (BBLV) was present in all regions, this is a cryptic virus with no known symptoms or effect on plant growth or yield in either single or mixed infections. There are other viruses present at low levels in each of the areas, and as such they pose a lower threat to nursery systems or fruit production. The information presented highlights the high risk viruses for nursery production, where efforts are made to control all viruses, and fruit production, where efforts are made to control virus diseases. Additionally, symptomatic plants that tested negative for known viruses or exhibited unusual symptoms were subjected to High Throughput Sequencing, which has led to the discovery of several viruses not previously known to infect blueberry.

18. Fungicide Use and Colletotrichum acutatum (fioriniae) Levels Over the Past Two Years.Carrie Denson*, Rutgers Cooperative Extension; Dean Polk, Rutgers Agricultural Research and Extension Center

Current NJ recommendations for anthracnose control call for several fungicide applications starting at the beginning of bloom, and continuing shortly afterwards, and longer on more susceptible varieties; and rotating chemistries for a resistance management program. Numerous growers have been having problems with anthracnose infections, Colletotrichum acutatum (fioriniae) control in New Jersey blueberry production. This observation has also been observed in field and post-harvest incubation samples. The objective was to examine grower fungicide programs to see if there was a weakness in the anthracnose programs over a two year span. Commercial packed pints of ripe blueberries, cv. Bluecrop, were collected along with grower spray records. Fruit was stored at room temperature 24°C for 10 days and read for percent infection. The timing for bloom infection periods was identified and compared to fungicide application records. In 2016 results ranged from 1 to 72% infection, and 2017 results ranged from 0 to 63% infection. Data analyses attempted to correlate grower fungicide use with resulting anthracnose infections, along with the timing of fungicide applications. Observations show that there is a more complex picture to anthracnose control other than knowing when the degree day dates of bloom timing are, starting fungicides on time, and rotating fungicides. Some growers who were following current recommendations for anthracnose control still produced fruit with high infection rates, while others obtain excellent control. Further work will include looking at sprayer type and spray coverage.




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19. Towards Understanding Rain-Induced Fruit Splitting in Blueberry. Michael Dossett*, BC Berry Cultivar Development Inc; Chaim Kempler, Agriculture and Agri- Food Canada (retired)

Rain-induced fruit splitting is a common problem in many blueberry production regions. Following a 2011 survey of British Columbia blueberry growers in which reduced splitting tendency ranked highly as an industry need, this trait has become one of the objectives of the BC blueberry breeding program. Over the past four growing seasons, we have studied genetic parameters related to fruit splitting in highbush germplasm in the BC breeding program. Over three seasons in which fruit was screened in the lab, narrow-sense heritability (h2) has been moderately high, averaging 0.61. Wet weather in 2016 prevented us from screening large numbers of progeny, but ratings of naturally occurring split fruit in the field were well correlated with data obtained from lab assays in 2014, 2015, and 2017, validating our approach. Splitting tendency did not show any strong correlations with fruit firmness, indicating that progress from selection for both of these traits can take place concurrently. Finally, we measured splitting tendency in segregating populations descended from ‘Reveille’, and found that splitting tendency was not correlated with objective measures of fruit firmness, or with subjective ratings of firmness, texture, and skin toughness in these progeny.

20. V. corymbodendron as a Bridge between Taxonomic Sections and Ploidies in Vaccinium. Mark Ehlenfeldt*, USDA-ARS

The species V. corymbodendron of section Pyxothamnus has shown value as a potential bridge between taxonomic sections and ploidies in Vaccinium when involved as either a first generation or second generation parent. Tetraploid V. corymbodendron has hybridized successfully with 2x and 4x section Cyanococcus species and 2x section Vitis-idaea. Hybridizations with other sections are currently being tested. Second generation allotetraploid V. corymbodendron - V. vitis-idaea hybrids have hybridized successfully with 4x section Oxycoccus (cranberry), 4x section Cyanococcus (blueberry), and 2x section Vitis-idaea (lingonberry). It appears that these allotetraploid hybrids may allow gene movement among these diverse sections at the 4x level. Further test-crosses are being made to evaluate the range of crossability of 4x V. corymbodendron and the V. corymbodendron allotetraploids with other taxonomic sections of Ericaceae.

21. Cold Hardiness and Association Analysis of Lowbush Blueberry (Vaccinium angustifolium) Using EST-PCR and SSR Molecular Markers. Lee Beers*, Ohio State University; Francis Drummond, University of Maine; Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

Lowbush blueberry (Vaccinium angustifolium) is a genetically diverse fruit crop that is cultivated throughout New England, Quebec, and the Canadian Maritimes. Although lowbush blueberries will persist under very cold conditions, flowers can be damaged if exposure to freezing temperatures occur during critical stages of growth. Some clones within a field may show characteristic browning of floral tissue after exposure to freezing temperatures, while an adjacent clone may be unharmed. The goal of this study is to identify genetic regions within lowbush blueberry associated with cold hardiness of closed and open flower buds. To accomplish this DNA was isolated from 160 clones in 8 fields (20 clones/field) that represent the predominant blueberry producing regions of Maine. Amplification of lowbush blueberry DNA using a combination of expressed sequence tag polymerase chain reaction (EST-PCR) and short simple repeat (SSR) molecular markers, developed for highbush blueberry (Vaccinium

ABSTRACTS - TUESDAY, AUGUST 14TH



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corymbosum), produced 606 polymorphic bands. Cold hardiness of closed and open flower buds was assessed by collecting 30 buds from each clone at multiple stages in the dormant, and early growing season and exposing them to decreasing temperatures. Flower buds were placed in a programmable freezer with buds removed at different temperatures and allowed to incubate at room temperature for 48 hours before dissection. Damage from low temperature was rated based on percent browning of ovaries and surrounding tissue viewed via dissection. A rating of 50% or more was considered to be significant. Here we report our current progress on associating genetic and phenotypic data.

22. Hybridization and Introgression Between Deerberries and Blueberries: Problems and Progress. Paul Lyrene*, University of Florida

Several hundred F1 hybrids between highbush blueberry and colchicine-induced tetraploids of tall-growing (2-4m) deerberries (Vaccinium stamineum) from north-central Florida were evaluated. Nine selected F1 hybrids were backcrossed to highbush cultivars, and more than 2,000 BC1 seedlings were evaluated in field nurseries. Fifty-seven of the most vigorous seedlings were transplanted to 20-liter pots or to a field with drip irrigation at 1m x 3m and evaluated a year later for plant and berry characteristics after open pollination. BC1 plant architecture was similar to highbush, but plants were slightly less vigorous. Flowers on many plants had short corollas and exserted stigmas, making pollen and stigmas more accessible to honeybees. Plants flowered heavily, and fruit set was not lower than highbush; almost every flower made a berry. Berries were fully seeded. Berries ripened 2 to 4 weeks later than highbush, were as large as highbush berries, had green-white pulp and medium to high firmness. Most had black, somewhat tough skins. Stemminess varied from near zero to 30%, with low to medium berry shattering. Picking scar ranged from small to large. Berry flavor averaged lower than for highbush. The main problem was lower sugar. Some clones had aromatic flavor components, not always pleasant. Berries on a few plants were near cultivar quality. Promising possibilities for V. stamineum introgression include flowers with short, open, corollas to improve pollination, purple berry pulp, (seen in some F1 but no BC1 plants), very open flower clusters, and increased drought tolerance.

23. U.S. Fish and Wildlife Service Pollinator Conservation Approaches and Collaborative Conservation Initiatives. Anna Harris, Mark A. McCollough, U.S. Fish & Wildlife Service

Native bee populations are declining and the causes are not fully understood. In March of 2017, the U.S. Fish and Wildlife Service (Service) listed the rusty patched bumble bee as endangered under the Endangered Species Act. Since 2000, it has seen a 60% decline in range and a 95% decline in population. At one time, the rusty patched bumble bee was found throughout the southern two-thirds of Maine, unfortunately the rusty patched has not been seen in Maine since 2009.The yellow-banded bumble has been petitioned to be listed as endangered under the Endangered Species Act. The Service is evaluating whether or not it warrants listing and is in the process of writing a species status assessment. A decision on the listing will be made in late 2018. The yellow banded bumble bee is still buzzing around Maine. All of these species, and many other at-risk Bombus species, have a mutual relationship with agricultural landscapes; land management actions can benefit these insects and, to some extent, they provide pollination services that improve yields for important crops, like blueberries. To promote conservation, the Natural Resources Conservation Service and the Xerces Society for Invertebrate Conservation have partnered with the Service to promote collaborative efforts with a goal of encouraging growers to continue supporting pollinators on farmland and providing




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them with some assurances to assuage their ESA concerns.https://www.fws.gov/midwest/endangered/insects/rpbb/

24. USDA-NRCS Opportunities for Pollinator Conservation: The Nexus of Grower Priorities and Conservation Goals. Eric Venturini*, The Xerces Society; Jeremy Markuson*, Tony Jenkins, USDA-NRCS

Bumble bees are key pollinators of wild lowbush blueberry (Vaccinium angustifolium). Bumble bee queens, which actively forage during spring blueberry bloom, are more efficient and effective pollinators than honey bees. Populations of these important pollinators are in flux across North America, including New England and the Canadian Maritimes. The rusty patched bumble bee (Bombus affinis), for example, once common in northeastern North America, is listed as endangered in both the US and Canada. Bombus affinis is the first, but seems poised not to be the last federally protected bumble bee; the yellow-banded bumble bee (B. terricola), is at the top of a long list declining bumble bees in North America. The Maine NRCS, in cooperation with the Xerces Society for Invertebrate Conservation and the USFWS is spearheading a New England-wide effort to prioritize existing NRCS cost-shared pollinator conservation practices through our recently proposed Working Lands for Wildlife effort. Our proposal incentivizes grower participation through cost-share funds and Endangered Species Act regulatory predictability.

25. Changes in Wild Bee Diversity and Abundance in Highbush Blueberry Between 2004-2017. Kelsey K. Graham*, Michigan State University; Jason Gibbs, University of Manitoba; Rufus Isaacs, Michigan State University

Highbush blueberry is pollinator dependent. Honey bees are typically brought in for pollination, however, wild bees are much more effective at accessing blueberry pollen through sonication (“buzz pollination”). The combination of wild bees performing sonication to dislodge pollen and the large numbers of pollinators provided by rented honey bee colonies optimizes pollination through complementarity. However, there has been significant concern about the decline of wild bees, particularly in and around agricultural fields. Here, we present findings from a study looking at wild bee abundance and diversity during bloom in highbush blueberry fields in southwest MI, sampled across three time periods: 2004-2006, 2013-2014, and 2017. The same 14 farms were used across all three sampling periods, and the same methods were used to sample bees (raised bowl traps). We found a significant decline in wild bee abundance in the latter two sampling periods compared to the 2004-2006 sampling period. However, we find that the bee community (at the genus level) shows greater similarity in 2017 to the earlier sampling period (2004-2006) than to the middle period (2013-2014). Potential causes for abundance decline and changes in community composition include significant weather events and an increase in pesticide use due to increasing pest pressures in highbush blueberry.

26. The Temporal Nuances of Wild Blueberry Pollination. Frank Drummond*, University of Maine; Daniel J. Bell, University of Maine (formerly); Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

Wild blueberry, Vaccinium angustifolium Aiton, pollination is dependent upon pollen movement between genotypes by bees. Most genotypes require obligate outcrossing, for the most part, although 20-25% of genotypes are characterized by high rates of fruit set after self-pollination. However, environmental and ecological conditions, and evolutionary reproductive strategies result in temporal nuances of pollination ecology across multiple scales. Over the past 30 years we have studied the temporal dynamics of wild blueberry pollination across multiple




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scales. This study reports on the time dependence of flower receptivity via stigma viability, seasonal phenology of self-compatible genotypes temporal asynchrony of flower/fruit abortion, phenology of fall bloom, and the inter-annual variation of the number of days that constitute a viable window for pollination. This is the story of a crop in dynamic flux, asserting its will on the blueberry grower.

27. Blueberry Insect Pest Management: Historical Trends and Future Challenges. Rufus Isaacs*, Michigan State University; Charles Vincent, Agriculture and Agri-Food Canada; Cesar Rodriguez-Saona, Rutgers University

In the historical regions of blueberry production, integrated pest management (IPM) programs have been developed and provided effective control of key insect pests. We reviewed the literature on blueberry entomology to reveal trends in adoption of monitoring programs as well as physical, cultural, biological, behavioral, and chemical controls to meet the intense demands of consumers and modern food systems. Globalization has resulted in new pest-crop associations and the introduction of invasive pests such as spotted wing Drosophila into existing and new blueberry-growing areas. Reduced-risk insecticides have become increasingly common but increasing international trade has constrained insecticide use because of maximum residue limits (MRLs), which are often not standardized across countries. There remains great potential for new methods to contribute to blueberry insect management, and we expect increasing development of regionally-relevant IPM programs.

28. Influence of Fertility and Disease Management Practices on Sap-Feeding Insects, Premature Flowering, Stem Characteristics, Leaf Spot, Leaf Retention, and Foliar Nutrients in Wild Blueberry. Judith Collins*, Frank Drummond, University of Maine

Little is known about the possible impact of the application of fungicides and fertilizers on insect pests of wild blueberry particularly sap-feeding insects. The objective of this three-year study (two replicated trials) was to evaluate the influence of fertility and disease management practices on sap-feeding insects, premature flowering, stem characteristics, leaf spot, leaf retention, and foliar nutrients in wild blueberry. We studied the potential affects from late spring/summer applications of two fungicides, Pristine® (a mixture of pyraclostrobin + boscalid) and Bravo Weather Stik® (chlorothalonil). We also looked at a combination of Pristine and DAP (diammonium phosphate) fertilizer. Pristine and DAP in both prune years appears to enhance leaf spot disease; however, the combination of Pristine and DAP does not appear to suppress yields. We found a significant and diverse community of sap-feeding bugs colonizing blueberry. Fungicide applications affected sap-feeding bug incidence in the 2016-17 trial, but not in 2015-16. In 2015, the Pristine and DAP treatment enhanced sap-feeding bugs. Our data suggest that it is fertilizer applied in the prune year that is the mechanism behind increased disease levels and sap-feeding bug enhancement and not the fungicide applications. The increase in yields directly due to fertilization might be indirectly compensated by an increase in crop loss due to increased weed abundance and increased disease and insect sap feeding.

29. Dynamics of Secondary Infection in Wild Blueberry Fields. Elissa S. Ballman*, Frank Drummond, Seanna Annis, Rachael Martin, University of Maine; Hongchun Qu, Chongqing University of Posts and Telecommunications

During three field seasons (2016-2018) we studied how bees interact with and transmit conidia of mummy berry the disease pathogen, Monilinia vaccinii-corymbosi, in wild blueberry. We measured the number of conidia that are picked up by three common bee taxa in blueberry fields: honey bees, bumble bees, and andrenid bees. We also recorded bee behavioral




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responses to healthy and infected leaf and floral tissue. Bees exposed to mummy berry conidia were allowed to forage on healthy non-infected flowers to measure the probability of conidia transmission per initial visit and subsequent visits. Honey bees visited infected leaf tissue significantly more often than the other taxa, whereas bumble bees spent significantly more time on uninfected plant parts. We found that individual bees were capable of picking up large numbers of mummy berry spores ranging from 100 to more than 80,000. Field captured honey bees also had mostly higher conidial density than bumble bees and andrenids although not always consistently significant differences were seen across all three years. In cage studies, floral visits by conidia contaminated bees resulted in flower infection, though the likelihood of infection ranged from 0-16%. These dynamics were incorporated into a computer simulation model of mummy berry disease progression throughout the season. Simulation runs using different bee taxa and bee densities are discussed.

30. The Impacts of Spotted Wing Drosophila (SWD) on Fruit Quality and Pesticide Use in New Jersey. Dean Polk*, Rutgers Agricultural Research and Extension Center

We have tracked fruit quality and pesticide use in NJ highbush blueberries since the arrival of SWD in NJ production areas. An average of 60 field sites have been monitored for adults and infested fruit during each of the last 7 years. Fruit evaluations have shown that almost 100% of commercial fields have been free of larvae, except in the cases where the market was depressed and the growers had stretched spray intervals or stopped insecticide use altogether. Maintaining clean fruit has come at a considerable expense of more than doubling insecticide use compared to pre-SWD arrival. Pyrethroid use has increased while the use of neonicotinoid insecticides has decreased. The use of 1-2 day PHI materials has consisted largely of malathion and some pyrethroids, but more recently (2018) of spinosyns. The transition by some growers to overseas markets has hampered pest management practices by restricting the use of allowed materials for those markets.

31. Community Composition of Insects in Galls Formed by Blueberry Stem Gall Wasp, and Implications for Highbush Blueberry Pest Management. Phillip D. Fanning*, Steven VanTimmeren, Rufus Isaacs, Michigan State University

The introduction of Spotted Wing Drosophila, Drosophila suzukii Matsumura has led to significant changes in the management practices used for insect pests in conventional and organically managed highbush blueberries, Vaccinium corymbosum. Traditional integrated pest management practices of scouting and targeted sprays for insect pest that incorporated effective reduced risk insecticides, have been replaced with calendar sprays of broad-spectrum insecticides. This has coincided with much greater occurrence of galls of blueberry stem gall wasp, Hemadas nubilipennis. Incidence and severity of galls differs greatly among varieties of V. corymbosum, but it is found in conventional and organically managed sites. The pest is active during bloom, making chemical control of the species difficult due to pollinator protection needs. Field surveys of galls reveal that natural enemies of the species, which can act as direct parasitoids or inquilines, are strongly influenced by insecticide use, with conventionally managed sites showing very low presence of these natural enemies compared to organically and minimally-managed sites. In this talk, the link between invasion by D. suzukii, these natural enemies, and the resurgence of H. nubilipennis and implications for highbush blueberry pest management will be discussed.




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32. Evaluation of ALS/AHAS-Inhibiting Herbicides for Red Sorrel (Rumex acetosella L.) Management in Wild Blueberry. Scott White*, Dalhousie University

Red sorrel is the most common weed species in wild blueberry fields in Nova Scotia, Canada. Recent herbicide screening research identified tribenuron-methyl as a promising herbicide for red sorrel management in wild blueberry, though comparison with other ALS/AHAS-inhibiting herbicides is lacking. The objective of this research was to evaluate currently registered, and promising new, ALS/AHAS-inhibiting herbicides for red sorrel management in wild blueberry. Herbicides were applied in spring of the non-bearing year, fall of the non-bearing year, and fall of the bearing year following pruning, with each application timing evaluated in a separate experiment. Experiments were arranged in a randomized complete block design with 5 blocks and 2m X 4m or 2m X 6m plot size. Treatments consisted of 1) nontreated control, 2) tribenuron-methyl (30g a.i. ha-1), 3) foramsulfuron (35 g a.i. ha-1), 4) nicosulfuron+rimsulfuron (13g a.i. ha-1 + 13g a.i. ha-1), 5) flazasulfuron (50g a.i. ha-1), 6) pyroxsulam (15g a.i. ha-1), and 7) halosulfuron (37g a.i. ha-1). Tribenuron-methyl and flazasulfuron were the most effective treatments evaluated across all three application timings. Spring non-bearing year tribenuron-methyl applications reduced red sorrel total ramet density, flowering ramet density, and seedling density by 84%, 99%, and 93%, respectively. Spring non-bearing year flazasulfuron applications tended to reduce total ramet density and also reduced flowering ramet and seedling density, indicating potential for this herbicide to contribute to red sorrel management in wild blueberry. Similarly, fall non-bearing year and fall bearing year tribenuron-methyl and flazasulfuron applications reduced spring ramet density by 57% to 58% and 92% to 94%, respectively. ALS/AHAS-inhibiting herbicides can contribute to red sorrel management in wild blueberry, and future research should focus on refining tribenuron-methyl and flazasulfuron use for this weed species.

33. Evaluation of Herbicide Options for Bracken Fern Control in the Sprout Year of Wild Blueberries in New Brunswick in 2016. Gavin Graham*, New Brunswick Department of Agriculture, Aquaculture & Fisheries

Bracken fern (Pteridium aquilinum) is a perennial species which is common in newly cleared wild blueberry fields. A trial was established in the spring of 2016 in a field near Halcomb, New Brunswick to evaluate broadcast herbicide options for control of this weed. No injury resulted from a mesotrione or foramsulfuron treatment. There was significant injury to blueberries following tribenuron methyl application, but plants did recover before the end of the sprout year. Bracken fern was suppressed following foramsulfuron applications, with the early application having the highest level of control. Mesotrione treatments had a higher level of weed control early after application, but control also declined as the trial progressed through the sprout year. The highest mesotrione alone ratings occurred when applied to fronds that were fully unfolded, although there was no significant difference between mesotrione application timings within the crop year. Tribenuron methyl had a low level of activity after application, but improved as the sprout year progressed and was increased to control in the crop year. There was no bracken fern control benefit to following foramsulfuron with mesotrione but using mesotrione twice did significantly increase weed control. Two applications of mesotrione in the sprout year significantly improved bracken fern control in the crop year, as compared to one application of mesotrione alone, with no difference between the application timings evaluated in this trial. The registration of two applications of mesotrione could improve the management of bracken fern in wild blueberry production in New Brunswick and provides bracken fern control similar to the commercial standard, tribenuron methyl.




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34. Glacial Geology of Maine’s Blueberry Barrens. Harold W. Borns*, Professor Emeritus, University of Maine

The latest continental glacier flowed across Maine and terminated on the outer edge of the continental shelf 23,000 years ago. About 19,000 years ago the warmth of the present Interglacial started, the glacier margin retreated across Maine’s preset coastal zone, accompanied by a marine transgression, 17,500 years ago. The late glacial warming climate reversed to a cold spell, which caused a short re-advance of the margin lasting 300 years, followed by abrupt warming to the levels of our present summers. Consequently, great volumes of melt water and sediment were produced and discharged into the sea, forming large deltas at the glacier’s margin at a relative sea-level elevation 250 feet above present. The many extensive flat, well drained, sand and gravel deltas, which include Pineo Ridge and Columbia Deltas in Maine, and Pennfield delta in New Brunswick, are the primary agricultural blueberry lands of the Northeast.




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1. Phosphorus Mobility in Acidic Wild Blueberry Soils in Quebec, Canada. Jean Lafond*, Agriculture and Agri-Food Canada

In the province of Quebec, more of 35,000 ha of land are cultivated in wild lowbush blueberry (Vaccinium angustifolium Ait.). Blueberry fields are managed on acidic soils, well drained, and with low nutrient contents. To ensure and maintain high crop productivity, fertilizers are applied in the spring of the sprout year. The objective of this project was to determine the effect of fertilizer applications on soil phosphorus (P) mobility under field conditions. Experiments were conducted in commercial stands of wild blueberries between 2004 and 2008 in Lake St. Jean area, Quebec, Canada. Four nitrogen rates (0 to 90 kg N ha-1) and four P rates (0 to 90 kg P2O5 ha-1) were applied in May of the sprout year. Soil P was determined after Mehlich 3 (PM3) extraction in the 0-5, 5-15 and 15-30 cm soil layers. Soil PM3 increased significantly after P application in soil surface and in the 5-15 cm soil layer in the sprout and production year. Phosphorus addition had no significant effect in the 15-30 cm soil layer. The (P/[Al+Fe])M3 molar ratio reached 10.7 % in the soil surface with the highest P application. In the other soil layers, this ratio was below 3.10%. Under field conditions, P leaching was limited in the 5-15 cm soil layer but a P build-up occurred in soil surface. Furthermore, the (P/[Al+Fe])M3 molar ratio measured in soil surface was very close to the critical value (11.3%) beyond which there is a risk of surface water contamination.

2. Effect of Phosphorous Acid and Pruning Height on Renovated ‘Woodard’ Rabbiteye Blueberry. Eric Stafne*, Mississippi State University; Barbara J. Smith, USDA-ARS Thad Cochran Southern Horticultural Laboratory

Phosphorous acid is a fungicide that may have other plant health-inducing properties. A previous study showed greater vigor in blueberry plants treated with phosphorous acid. In the current study, old, unproductive ‘Woodard’ rabbiteye blueberries were selected for renovation in 2017. The bushes had not been pruned or otherwise managed in several years. To test the hypothesis that adding phosphorous acid treatments (Agri-Fos) to the renovation process, three treatments were used; no addition of phosphorous acid, phosphorous acid applied as a drench at renovation pruning, and monthly foliar applications of phosphorous acid after renovation pruning and the following year. Two pruning height treatments were also done on July 14; bushes were pruned at ground level and bushes pruned at 50 cm. End of season shoot number was significantly different between the 50 cm cut and the ground level cut (35.6 50 cm vs. 21.1 ground). However, shoot length was greater for the ground cut (74.6 cm) vs. 50 cm cut (65.8 cm). Shoot diameters were not significantly different. Other factors such as first bud push after pruning and crop load rating were not significant. Interesting, phenological development recordings of flower stage did not differ at stages 2 to 4, but were different from stages 5 to 7. The 50 cm cut flower development was earlier by 9 days at stage 5, 10 days at stage 6, and 5 days at stage 7. There were no differences due to phosphorous acid treatments in data evaluated. More time may be needed to ascertain any differences among those treatments as it is not a direct, but rather induced, effect.

3. Ammonium-enriched Amendments for Production of Northern Highbush Blueberry. Bryan K. Sales, Oregon State University; David R. Bryla*, USDA-ARS Horticultural Crops Research Unit; Dan M. Sullivan, Oregon State University; Kristin M. Trippe, USDA-ARS Forage Seed and Cereal Research Unit

Organic substrates such as bark, sawdust, and compost are used in biofilters to remove ammonia and other odorous compounds from contaminated airstreams. A byproduct of the process is an ammonium-rich material that must be replaced periodically. A 12-week

POSTERS - MONDAY, AUGUST 13TH



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greenhouse study was conducted in Corvallis, OR to evaluate the potential of using such a material as a soil amendment for production of northern highbush blueberry (Vaccinium corymbosum L. ‘Duke’). One-year-old plants were transplanted from 72 cell trays into 4-L pots filled with silty loam soil that was amended (20% v/v) with one of six different substrates, including Douglas fir sawdust, shavings, and wood chips, alder wood sawdust, biochar (pyrolyzed mix of Douglas fir bark and wood fiber), and compost (produced from yard debris). The amendments were either enriched with ammonium-N or were left unenriched prior to incorporating them into the soil. Plants grown with the enriched and unenriched amendments were fertigated weekly with ammonium sulfate solution at rates of 0, 25, and 50 ppm N. Overall, plants grown with the enriched amendments showed little to no response to N fertigation and had greater leaf area, shoot length, total dry weight, leaf N concentrations, and SPAD meter readings than those grown with the unenriched amendments and fertigated with 0–50 ppm N. These findings indicate that ammonium-enriched amendments can be used safely in blueberry to increase growth and N fertilizer use efficiency. Further work is underway to develop enriched amendments for blueberry using spent biofilter materials from livestock facilities.

4. Management of Botrytis Blight in Wild Blueberries with Honey Bee Vectored Clonostachys rosea. Rebecca Apperley-Ryan*, David C. Percival, Dalhousie University

A field trial was conducted in 2017 near Diligent River, Nova Scotia, to examine the main and interactive effects of the bee vectored biofungicide Clonostachys rosea (Strain 7) with Vectorite®. A 22 factorial design was used with the factors consisting of the use of the biofungicide (+/-) and also the use of the conventional fungicide Switch® (a.i.’s: cyprodonil and fludioxonil) (+/-). The biofungicide treatments were introduced to the field site at the F4 stage of floral bud growth and development with the attachment of the biofungicide dispensers to one-half of the honey bee colonies. Two applications of the fungicide Switch® were made commencing at the white tip stage of floral development in accordance with the manufacturer’s label. The number of potential infection events for Botrytis were lower than normal for the area (n= 4) resulting in low disease pressures and no significant effects on Botrytis incidence or severity. However, the presence of the biofungicide appeared to reduce the incidence and severity of Monilinia blight in mid June. In addition, the application of the biofungicide increased set fruit (number of marketable berries per stem) and harvestable berry yields (g of hand raked fruit per m2) on average 47 and 76% respectively compared to the untreated control. Therefore, results from this preliminary investigation from this study have indicated that potential exists for floral blight disease control and increased berry yields with the use of the bee vectored biofungicide Clonostachys rosea (Strain 7). However further replication under conditions of higher Monilinia and Botrytis disease pressures and more frequent infection conditions are required before pertinent recommendations can be made.

5. Monilinia vaccinii-corymbosi Sensitivity to Demethylation Inhibitor Fungicides and Its Effect on Monilinia blight Control in Wild Blueberry. David Percival, Sherin Jose*, Ling Guo, Dalhousie University; Annemiek Schilder, Michigan State University; Balakrishnan Prithiviraj, Randall A. Olson, Dalhousie University

Monilinia vaccinii-corymbosi (Reade) Honey (M.vc), the causal agent of Monilinia blight of wild blueberry, is controlled primarily by fungicides. Demethylation-inhibiting fungicides (DMIs) have been used for over 30 years for Monilinia blight control due to flexibility of use (i.e., ability to use after an infection period) and disease control effectiveness and consistency. In the present study, the sensitivity of ten isolates to three DMIs- propiconazole, difenoconazole




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and prothioconazole-desthio were evaluated in vitro by a mycelial growth inhibition assay. In addition, four field trials were conducted during two crop seasons: 2012 and 2013, to examine the efficacy of DMIs to control Monilinia blight. All the tested DMIs were effective in inhibiting mycelial growth of M.vc isolates, although the mean EC50 values differed significantly. However, in field experiments, three of four trials had significant treatment effect on disease incidence and severity of vegetative buds. Prothioconazole-desthio and propiconazole provided consistent control against Monilinia blight. Conversely, difenoconazole was effective in in vitro analysis, but did not demonstrate satisfactory Monilinia blight control in all field trials. In the 2012 trials, both prothioconazole-desthio and propiconazole reduced disease incidence of vegetative buds by 100% compared to the untreated control. Prothioconazole-desthio reduced disease development in 2013 with 94 and 99.8% less incidence, and 75 and 99.5% less severity. Similarly, propiconazole also reduced incidence of vegetative buds by 88% and 99.8%, and severity by 54% and 99.7%. No phytotoxic symptoms were observed in any of the field trials. The results of the study serves as a benchmark to monitor shifts in M.vc sensitivity to these fungicides in the future.

6. A New Luteovirus Infecting Highbush Blueberry.Dan E.V. Villamor, University of Arkansas; Robert R. Martin, Karen E. Keller, USDA-ARSHorticulture Crops Research Unit; Ioannis Tzanetakis*, University of Arkansas

The use of clean planting material is the most important component in virus diseasemanagement. The production and release of such material is ensured through a battery of testsincluding biological indexing and a panel laboratory tests. Modern technologies known as highthroughput sequencing (HTS), has been shown to be superior to the current standard testingprotocols in being able to detect all virus variants as well novel viruses for which no laboratorytests are available. HTS aided in the discovery of a novel luteovirus confirmed by RT-PCR usingprimers designed from HTS-derived sequences. The virus most closely resemble nectarinestem pitting-associated virus. Further analysis revealed presence of the virus in six additionalblueberry selections; four of which were classified as virus-tested. Surveys are underwayto assess the distribution of this virus across the country; preliminary results revealed thepresence of the virus in fields from Washington, Oregon and Michigan. It has also been detectedin several northern and southern highbush blueberry cultivars held at the USDA-ARS NationalClonal Germplasm repository in Corvallis, Oregon.

7. Green Mosaic: A New Vitivirus Associated with Symptoms.Thanuja Thekke-Veetil, University of Arkansas; James Polashock, USDA-ARS Blueberry andCranberry Center; Robert R. Martin, USDA-ARS Horticulture Crops Research Unit; IoannisTzanetakis*, University of Arkansas

Several new diseases have been described and the causal agents characterized in the pastfew years. Green mosaic remains an elusive disease with unknown distribution. Symptomsresemble that of the well-characterized mosaic disease but in this case foliar symptoms show alight green color in contrast to its counterpart where symptoms vary greatly in color for yellowto orange to red to green and purple. A virus was detected in all symptomatic plants collectedin New Jersey and fully characterized. It belongs to the genus Vitivirus, members of which aretransmitted mechanically, by mealybugs or aphids. The presence of the virus in other majorproduction areas across the United States and British Columbia, Canada was investigated.Green mosaic associated virus was found in very low numbers in the Southeast, Northeast andMidwest, indicating that it does not pose a major issue for the industry at this point.




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8. Genetic Variability of Xylella fastidiosa Isolates Causing Bacterial Leaf Scorch of Blueberry in Georgia. Dario DiGenova, Kippy J. Lewis, Jonathan Oliver*, University of Georgia

Xylella fastidiosa (Xf) is a xylem-limited, gram negative, bacterial plant pathogen that is transmitted by xylem-feeding insects including sharpshooters. Xf is an important bacterial pathogen of numerous fruit and tree crops worldwide, and the species is recognized to consist of multiple subspecies that show subtle differences both in terms of genetics and host pathogenicity. On blueberry, Xf causes bacterial leaf scorch which can lead to plant decline and death. Originally characterized in Georgia in 2008, bacterial leaf scorch of blueberry is now widespread in the blueberry production regions of Florida and Georgia, and Xf-infected blueberries have been reported elsewhere throughout the southeastern US. Previous genetic characterization of Xf isolates from blueberry have shown that these isolates are Xf subsp. multiplex; however, relatively few isolates have been characterized to date. An exploratory study of southern highbush blueberry plantings in southern Georgia carried out in Fall 2017 indicated Xf-infected plants in eight of nine (88.8%) sites examined, and seven Xf isolates were cultured from infected, symptomatic plants within these sites. Initial genetic characterization of these isolates revealed unexpected genetic differences amongst them, and a multilocus sequence analysis approach was employed to allow further comparison between these isolates and other Xf isolates characterized previously. This analysis revealed three unique haplotypes among the seven new isolates from blueberry, including two variants that showed surprising similarity to Xf isolates from grapevine. Altogether, these findings provide new insights into the epidemiology of this pathogen and have potential implications for bacterial leaf scorch management.

9. Unraveling the Blueberry Stem Pathogen Complex. James Polashock*, USDA-ARS Blueberry and Cranberry Center

Stem pathogens in blueberry can be very difficult to control with fungicide applications. To develop better approaches to control, it is important to identify and characterize the species in the complex that cause stem diseases. We focused on stem blight and twig blight. Stem blight is thought to be caused by Botryosphaeria dothidea, but a study in Florida demonstrated that other fungal species contribute to stem blight. While stem blight usually kills whole canes, infections that reach the crown can kill the entire bush. Twig blight, reported to be caused by Phomopsis vaccinii, typically kills the tips of canes and reduces the flower number on affected canes. However, in recent years in New Jersey, twig blight symptoms have been more severe. We isolated fungi from stem blight and twig blight affected blueberry shoots in 2014 and 2016 and are continuing collections this season (2018). Species were identified using sequence comparison of the ITS region. The stem blight complex consisted of B. dothidea, and Neofusicoccum spp. In virulence testing on ‘Duke’, the Neofusicoccum spp. were more virulent. Phomopsis vaccinii was the only pathogen collected from plants with twig blight symptoms. Although P. vaccinii is reported to cause only cane tip dieback, inoculations on ‘Duke’ were severe, and symptoms were more like those of stem blight than twig blight. It is unclear why P. vaccinii seems to be increasing in severity and further study is warranted.

10. Understanding the Fungal Umwelt and How Flowers Communicate with Fungal Pathogens. Timothy J. Waller*, Peter V. Oudemans, Rutgers University

Why is blueberry anthracnose (Colletotrichum fioriniae in NJ) only adequately controlled during the bloom period? C. fioriniae and other fungal pathogens are able to ‘sense’ flowers. Floral recognition is critical to the success of fruit rotting pathogens, as flowers always proceed fruit




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(the site of latent infections and sporulation). Additionally, C. fioriniae preferentially overwinters in dormant floral buds, again pointing to floral recognition. Floral extracts (FEs) (extracted with water, chloroform, or rainwater run off of flowers) have been shown to increase the rate and magnitude of secondary conidiation (inoculum buildup), and most importantly appressorial formation (infection structures). In the presence of FEs C. fioriniae begins appressorial formation and sporulation at 6h, compared to water where these activities do not occur until 12-18h. This means that in the presence of flowers there will be a greater number of overall infection periods, pointing to the critical nature of anthracnose control during the bloom period. In detached fruit assays, conidia in the presence of FEs enabled more infection than conidia alone. Typically floral cues in water stimulate both secondary conidiation and appressorial formation, where chloroform extracts lead to a more appressorial directed response, indicating both commonality and differences in the composition of the extracts. FEs from susceptible ‘Bluecrop’ stimulated more appressoria than resistant ‘Elliot’, indicating that specific floral components are a critical to the disease cycle and their absence may confer resistance. C. fioriniae also responds similarly to FEs from multiple ericaceous species, indicating that this response is not unique to blueberry.

11. Bacterial Wilt of Blueberry. Nrupali Patel, Donald Y. Kobayashi, Peter V. Oudemans*, Rutgers University

During the summer of 2012 mature highbush blueberry plants c.v. Bluetta exhibited symptoms of wilting and rapid cane death. Although the symptoms superficially resembled stem blight, the pattern of leaf discoloration was unique. Also, entire bushes over 20 years old exhibited symptoms and rapidly died. The vascular tissue of the infected stems exhibited a watery, gray discoloration and significant bacterial streaming was observed when symptomatic wood chips were placed in water. Isolation of morphologically identical bacteria from streaming wood was consistent for all symptomatic bushes tested (n=18). The bacterium was identified by sequencing the 16S rRNA gene and compared with sequences deposited in GenBank. The bacterium was identified as Ralstonia solanacearum of an unknown biotype based on sequence of the 16S rRNA gene. Inoculation of potted blueberry plants (c.v. Duke) resulted in symptom development within 2 weeks and plant death within three weeks. In all cases the pathogen was re-isolated from the symptomatic stems. This is the first report of Ralstonia solanacearum as a pathogen of any species of Vaccinium. Results indicate it is not Race 2 Biovar 3 (a select agent) but that it does have a broad host range including tomatoes, peppers and eggplant as well as blueberry. Host range results indicate that of 23 cultivars tested Blue Jay, Darrow, Legacy, Sweetheart and Toro may offer some tolerance to the pathogen.

12. What is Sooty Blotch and Fly Speck on Blueberries? Peter V. Oudemans*, Timothy J. Waller, Rutgers University; James Polashock, USDA-ARS Blueberry and Cranberry Center

New Jersey growers have typically ranked in the top 2 states for production per acre until recently falling to 5th position. One of the contributing factors may be due to the recent increase in epiphytic fungi colonizing the green (1-2yo) stems. Preliminary research shows that the symptoms are analogous to sooty blotch and flyspeck an important disease of apple fruit. Colonization of blueberry by fungi such as Hormonema, Discostroma, Microcyclosporium and Rhizosphaera leads to a distinct and obvious darkening of green stems. The disease is locally referred to as black shadow because heavily affected fields have the appearance of standing in a shadow. Under this project we are investigating the impact these fungi may have on yield and to collect data for building a threshold model to evaluate the relationship between severity and yield. We are also investigating the diversity, ecology, spread and potential function of




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each species on the plant surface with the idea that some species may exhibit antagonistic activity towards some important blueberry pathogens. Finally, we will test the sensitivity of some species to common fungicides used in blueberry culture. Ultimately, the project is aimed at establishing a threshold for making disease management decisions in blueberry as well as developing a management method for growers to utilize.

13. Crown Gall – An Emerging Disease for Blueberries in the Northwest. Wei Qiang Yang*, North Willamette Research and Extension Center/Oregon State University; Virginia Stockwell, USDA-ARS Horticultural Crops Research Lab

Beginning in winter of 2012, sporadic crown gall infection in blueberries was found in Oregon. The symptoms of crown gall exhibit on the above ground canes are dramatic, while crown infection was only confirmed in one field. Most crown gall infestations have been found in ‘Draper’ cultivar in the northwest. Field surveys conducted in 2016-2017 seemed to indicate that crown gall symptoms were present in many fields harvested by machine. In fields harvested by hand only, there was no crown gall observed. The potential of crown gall infection spread by machine harvesters will be discussed. The isolation of Agrobacterium tumefaciens and further molecular characterization will be presented.

14. A Six-year Study of Spotted Wing Drosophila in Maine. Frank Drummond, Elissa S. Ballman*, Judith A. Collins, University of Maine

We monitored a new invasive blueberry pest, spotted wing drosophila (Drosophila suzukii), from its first year in Maine’s blueberry fields in 2012 through 2017. Each summer, we monitored spotted wing drosophila using baited cups placed along field edges that were changed and recorded weekly. Over the past six years we monitored its population fluctuations in over 90 fields in both the Downeast and Mid-coast blueberry growing regions. We recorded the first date of infestation, followed its population build up each season, and its population density near harvest. We have found a trend over time that this fly is appearing earlier each season. Our models indicate that an earlier infestation results in a larger population near harvest. The year 2017 had the earliest and largest population of spotted wing drosophila that we recorded. We also found over this period that insecticide applications reduced fruit infestation. In addition, we used this dataset to construct a risk based action threshold for spotted wing drosophila management. This probabilistic model provides thresholds based upon cumulative capture of male spotted wing drosophila in the field and provides a likelihood of fruit infection the week following male fly trap-capture. The threshold model was validated in 2016 and 2017 and proved to provide field infestation likelihoods consistent with model predictions.

15. Erythritol and Two of Its Derivatives Reduce Survival and Reproductive Rate of a Serious Blueberry Pest, Drosophila suzukii (Diptera: Drosophilidae). Blair J. Sampson*, Christopher T. Werle, Michael W. Easson, Stephen J. Stringer, John J. Adamczyk, USDA-ARS

The spotted wing Drosophila, Drosophila suzukii (Matsumura) is an Asian vinegar fly introduced unintentionally into the United States in 2008. Since then, D. suzukii has reduced annual berry yields anywhere from 6% – 100%. Effective control of D. suzukii populations during harvest requires weekly applications of low residual, broad-spectrum insecticides that are unavailable to organic berry farmers. A novel, ingestible and organic insecticide, a 4-carbon polyol, mesoerythritol (erythritol) was found to kill 75% to 100% of D. suzukii in laboratory and blueberry field tests. However, mesoerythritol, at effective concentrations, may be cost-prohibitive for use on commercial acreages. Therefore, we conducted laboratory tests to




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assess the effects of low cost derivatives of erythritol, namely the pentaerythritol series of 1,3-diols on D. suzukii pupal production, adult production, adult mortality, brood output, and reproductive increase. From 90% to 100% of adult D. suzukii died when fed food moistened with 1M solutions of mesoerythritol and pentaerythritol. Mesoerythritol and dipentaerythritol at a concentration of 1M were ovicidal/larvicidal, killing ≥85% of immature D. suzukii. Overall, 1M mesoerythritol killed 80% or more D. suzukii larvae and adults, thus bringing populations to near zero. The heaviest compound of this series, tripentaerythritol, at all concentrations, was largely benign to both adult and immature D. suzukii. Thus, we cannot recommend tripentaerythritol for D. suzukii control. However, a mix of 0.5M – 1.0M mesoerythritol and pentaerythritol would kill ~80% of adult and larval D. suzukii at ~50% of the cost of applying just a mesoerythritol solution.

16. Comparisons of Single Versus Split Post-Emergence Mesotrione Applications for Spreading Dogbane Control in Wild Blueberry Fields. Jennifer D’Appollonio*, David Yarborough, University of Maine

Spreading dogbane (Apocynum androsaemifolium) is a major weed pest in wild blueberry fields and is difficult to control, so in spring 2015 a trial was initiated to examine the effect of mesotrione (Callisto) and rimsulfuron (Matrix) on dogbane control. Dogbane was sprayed post-emergence either once with Callisto 6 oz/a or Matrix 4 oz/a or twice at 3 oz/a or 2 oz/a, both alone or in combination for a total of six herbicide treatments. The Callisto and Callisto+Matrix treatments resulted in higher dogbane injury and lower cover overall. The split Callisto treatment was the most effective in controlling dogbane along with the split Callisto+Matrix treatment, but considering the two had equal blueberry cover and phytotoxicity, the addition of Matrix did not improve control. Wild blueberry cover and dogbane control was assessed in the 2016 crop year; the most effective dogbane reduction was observed in the single and split Callisto treatments. Two Callisto applications resulted in better residual dogbane reduction compared to one application, regardless of whether it was combined with Matrix. In a 2016 trial initiated in a prune year field, dogbane was sprayed post-emergence with Callisto at 2 oz/a or 3 oz/a to six 1 x 4 m split plots, with one half receiving hexazinone (Velpar). Dogbane emergence and growth were tracked, and plots were sprayed when dogbane reached the 3-5 leaf stage for a total of three Callisto applications. Although the Velpar combinations and Callisto 3 oz/a alone almost eliminated dogbane and no new seedlings were observed at the fourth evaluation in July, dogbane was not completely controlled by any treatment. Some dogbane stems which appeared dead at the third evaluation showed regrowth of lateral leaves in July. The results of Velpar vs no Velpar indicate that the addition of Velpar slightly increased dogbane control and injury.

17. Crop Tolerance and Weed Control with Sulfentrazone-Based Combinations in Highbush Blueberry (Vaccinium corymbosum). Thierry E. Besançon*, Rutgers University

Field studies were conducted in 2017 and 2018 at commercial blueberry farms near Hammonton, NJ, to evaluate weed control and crop tolerance to various combinations of preemergence herbicides. Herbicides were applied pre-budbreak and consisted of diuron at 1.4 kg ai ha1 alone or mixed with either flumioxazin at 290 g ai ha-1, mesotrione at 160 g ai ha-1, or sulfentrazone at 210 g ai ha-1. Additional treatments consisted in mesotrione at 160 g ai ha-1, sulfentrazone at 210 g aiha-1 or sulfentrazone at 420 g ai ha-1. Herbicide programs that included flumioxazin or mesotrione yielded greater horseweed control 5 WAT (97%) than herbicide program containing sulfentrazone at 210 g ha-1 alone or tank mixed with diuron (85% and 75%, respectively). Sulfentrazone at 420 g ai ha-1 had greater horseweed control 5 WAT (94%). Mesotrione and flumioxazin alone or mixed with diuron provided greater toadflax




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control (≥ 93%) 5 WAT than treatments that contained sulfentrazone at 210 g ai ha-1 alone or mixed with diuron (84%). Slender goldenrod control by all herbicide programs was between 73% and 88% 5 WAT. Programs that included mesotrione and flumioxazin maintained excellent horseweed control (≥ 95%) 14 WAT, whereas programs containing sulfentrazone at 210 g ai ha-1 had 65% to 73% horseweed control. Sulfentrazone alone at 210 g ai ha-1 had significant lower toadflax control (71%) 14 WAT than when mixed with diuron (89%) or programs that included mesotrione or flumioxazin (≥86%). Greater goldenrod control (≥ 70%) 14 WAT was achieved with programs mixing mesotrione or flumioxazin with diuron than programs without diuron or relying on sulfentrazone at 210 g ai ha-1 (26% to 48%). However, increasing sulfentrazone rate to 420 g ai ha-1 helped to maintain higher goldenrod control 14 WAT (61%).

18. ARS 05-171: A Mid-late Highbush Cultivar with Concentrated Ripening. Mark Ehlenfeldt*, USDA-ARS Blueberry and Cranberry Center

ARS 05-171 is a mid-late ripening highbush blueberry cultivar (as yet un-named) derived from a cross of ‘Magnolia’ x ‘Elizabeth’. ARS 05-171 is notable for its productivity, its concentrated ripening, its easy removal force (making it suitable for machine harvesting), its narrow-based, stocky, robust plant structure, and its late flowering date.

19. Genetic Diversity of Lowbush Blueberry (Vaccinium angustifolium) in Managed and Non-Managed Populations. Lee Beers*, Ohio State University; Frank Drummond, University of Maine; Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

Lowbush blueberry (Vaccinium angustifolium) is native to Eastern North America spanning west to Minnesota, and from Quebec south to North Carolina. Despite this large native range, cultivation for commercial fruit production is limited to Maine, Quebec, and the Canadian Maritimes. Establishment of lowbush blueberry fields has historically consisted of clearing a forest to allow existing lowbush blueberry plants to grow while removing unwanted weeds through the use of burning or mowing, and more recently herbicides. Bare spots in the field become populated by seed or through the spread of rhizome. This cultural practice promotes genetic diversity within a field and it has been assumed that the resulting field maintains the genetic diversity found in non-managed populations. To test this assumption, the genetic diversity of managed and non-managed populations were compared at 4 locations throughout the primary growing regions of Maine. Each location contained a field currently managed for commercial production adjacent to a woodlot with no known history of commercial management. Leaf samples were collected from both managed and non-managed plants at each location creating a paired population. A total of 16 expressed sequence tag polymerase chain reaction (EST-PCR) molecular markers were used to create 123 reproducible polymorphic bands for analysis. Analysis of molecular variance (AMOVA) showed significant differences between each population (P<0.001). perMANOVA results also showed significant differences between management practices – managed fields were significantly different from non-managed populations (P=0.002). Although not significant, there is a trend of fewer polymorphic bands present in the managed populations compared to non-managed.




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20. RNA-seq Combined with a Bulked-Segregant Analysis Identifies Candidates for theWaxy Coating on Blueberry Fruit. Xinpeng Qi, USDA-ARS; Elizabeth L. Ogden, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory; Jose V. Die, USDA-ARS; Mark K. Ehlenfeldt, James J. Polashock*, USDA-ARS Blueberry and Cranberry Center; Lisa J. Rowland, USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory

Light blue fruit color is preferred for the blueberry fresh market. The most significant difference between blueberries with a light blue fruit color and black fruit color is the visible layer of an epicuticular waxy coating. This layer also functions in disease defense and prevention of water loss. In this study, we constructed a northern-adapted rabbiteye hybrid breeding population, ‘Nocturne’ x T 300, which segregated for fruit color (light blue versus black). We screened this population and selected plants of each extreme phenotype, waxy-coated plants with light blue colored fruit versus non-waxy plants with black colored fruit, then isolated RNA from fruit tissue of each bulk, respectively. We sequenced the transcriptome of each bulk using RNA-seq, which resulted in a total of 167,093,354 reads. We de novo assembled this data set into 171,678 contigs, and used the assembled transcriptome as a reference for differential expression analysis using EdgeR. A total of 515 differentially expressed genes were identified with at least a two-fold difference in expression, and efforts were made to functionally annotate them using publicly available databases. From these, one excellent candidate ‘waxy’ gene has emerged, which we are investigating further.

21. Carotenoid Biosynthesis During Bilberry (Vaccinium myrtillus L.) Fruit Developmentand Ripening. Katja Karppinen, Laura Zoratti, Marian Sarala, University of Oulo; Elisabete Carvalho, Fondazione Edmund Mach Research and Innovation Center; Jenni Pukki, Helmi Mentula, University of Oulo; Stefan Martens, Fondazione Edmund Mach Research and Innovation Center; Hely Häggman, University of Oulo; Laura E. Jaakola*, UiT The Arctic University of Norway/Norwegian Institute for Agricultural and Environmental Research

Bilberry (Vaccinium myrtillus L.) fruits are rich source of anthocyanin pigments but they also contain other bioactive compounds, such as carotenoids, which could be of interest for the breeding programs. In the present study, biosynthesis of carotenoids was studied in different stages during bilberry fruit development and ripening and as response to light treatments. Eight key carotenoid biosynthetic genes (PSY, PDS, ZDS, CRTISO, LCYE, LCYB, BCH, ECH) were isolated from bilberry and their expression was analyzed with qRT-PCR. Composition of carotenoids was analyzed of the same samples with HPLC-MS. The most abundant carotenoids in bilberries were lutein and β-carotene in addition to minor amounts of xanthophylls such as neoxanthin, violaxanthin and zeaxanthin. The expression of the carotenoid biosynthesis genes showed increase in transcript levels of phytoene synthase (VmPSY), phytoene desaturase (VmPDS), carotenoid isomerase (VmCRTISO) and lycopene β-cyclase (VmLCYB) at the onset of fruit ripening. However, the increase in the expression did not lead to the accumulation of carotenoids during ripening in ripe berries and the carotenoid levels decreased during the fruit ripening simultaneously with increased expression of the carotenoid cleavage genes. Red light treatment during fruit ripening increased the accumulation of both the carotenoid biosynthesis and the cleavage genes. The results suggest that the carotenoid levels in bilberry fruit are determined by their biosynthesis and degradation to apocarotenoids such as abscisic acid and volatile compounds.




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22. Texture Profile Analysis of ‘Rahi’ Blueberry (Vaccinium ashei) During PostharvestStorage. Daniel Hutchins*, Gourmet Blueberries, New Zealand

Firmness in blueberries is an important economic trait; soft berries are unpleasant to eat. In parts of the blueberry supply chain, firmness is often determined manually between the thumb and the index finger. This method is subjective and there is much room for improvement. Texture Profile Analysis (TPA) is a well-established method for assessing food products. TPA simulates chewing and can measure different aspects of texture such as hardness, springiness, cohesiveness, gumminess, chewiness and resilience (Meullenet et al., 1997: Letaief et al., 2008). This study determined the effect of TPA settings on the data collected from ‘Rahi’ blueberries. Berries were exposed to four post-harvest treatments known to affect berry firmness. Two deformation distances (15% and 30%) and two durations between cycles (2 sec and 10 sec) were used in combination to create four different TPA protocols. The usefulness of data collected was influenced by TPA settings. Tests at 15% deformation separated post-harvest treatments better than 30%. A cycle of 10 sec gave better data than a 2 sec cycle. In combination, 15% deformation and 10 sec between cycles gives the most useful data in ‘Rahi’ berries.

Letaief, H., Rolle, L., Gerbi, V., 2008. Mechanical behavior of winegrapes under compression tests. Am J Enol Viticult 59, 323-329.

Meullenet, J.F.C., Carpenter, J.A., Lyon, B.G., Lyon, C.E., 1997. Bi-cyclical instrument for assessing texture profile parameters and its relationship to sensory evaluation of texture. J Texture Stud 28, 101-118.

23. Development of an Irrigation App for Blueberry.Erick D. Smith*, Vesileios Liakos, George Vellidis, University of Georgia

Managing irrigation for shallow rooted perennial crops like blueberry (Vaccinium spp) is challenging in an environment of high heat and humidity, unpredictable rainfall, and well drained soils. The objective of this study was to identify blueberry response to varying irrigation rates under single line drip irrigation. The data from this study will be included as baseline inputs for development of an irrigation App for blueberries. Starting in 2016, a rabbiteye blueberry (V. virgatum syn. ashei) cultivar, ‘Vernon’, and a southern highbush blueberry (V. corymbosum interspecific hybrids), ‘Suziblue’, were measured for plant growth and fruit yield under three irrigations treatments: 1) Farm managed at 1 in/week, 2) blueberry evapotranspiration (ETc; App model), and 3) soil water tension threshold of -10 kPa. Across the treatments for both cultivars, plant growth and fruit yields were similar among the irrigation treatments. Our work showed that soil water deficit (relative to field capacity) was 20% and the soil water tension was 10 kPa, which addresses irrigation trigger point for either soil moisture % or soil moisture tension measuring devices.

24. Updated Costs and Returns for Michigan Blueberry Growers.Mark A. Longstroth*, Michigan State University Extension

Michigan has traditionally been a major blueberry growing state. Increased blueberry production has increased the volume of blueberries in the United States market. Increased supply is squeezing the profits of Michigan blueberry growers. An Excel workbook is used to calculate the costs and returns of growing blueberries for the fresh and process markets. The workbook contains multiple spreadsheets for calculating the costs of planting and establishment, pest control and machinery costs, as well as historic Michigan and national blueberry production numbers. Other sheets of the workbook calculate the costs per acre and the production costs




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per pound of blueberries produced. The workbook also calculates the annual and accumulated profit for planting or buying a blueberry field. The workbook allows the user to change input variables to see the impact of production changes on long term profitability. The workbook is distributed to growers and used at meeting and talks to demonstrate the fallacy of cutting input costs. Reducing inputs usually result in falling yields and profits. It is not how much it costs to grow an acre of blueberries, but how much it costs to grow a pound of blueberries.

25. Wild Blueberries in a Changing Climate. Yongjiang Zhang*, University of Maine

One of the largest threats to wild blueberries, with little information on its consequences, is climate change. Atmospheric CO2 concentration ([CO2]) and temperature have increased significantly in the past century, and the increases are predicted to accelerate in the future. At the end of this century, global mean surface temperature will increase by 1.5 to 4.8oC. In Maine, temperatures are expected to further increase by 1 to 2o C in the next 40 years. Further, increasing climate variability brings more climate extremes such as severe drought and frost events. Climate change could lead to changes in plant productivity and introduce new problems in the form of weeds, insect pests and diseases, but may also affect the pests that are currently being controlled with integrated pest management (IPM) strategies. Climate change has already altered crop growth patterns, increased the risk of frost damage due to reduced hardening and earlier budding, enhanced drought damage due to increased water use, affected pollination due to increased rainfall in spring, increased herbivore damage due to new invasive insect pests, and changed fungal pathogen infection. These changes have not yet been quantified in the wild blueberry system. As different plants and ecosystems have distinct responses to climate change, it is critical to understand how the wild blueberry system will respond to climate change to allow development of new management strategies. The effects of climate change on wild blueberries and interactions with weeds, insects and pathogen pests will be studied.




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CONFERENCE SPONSORS

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The Wild Blueberry Commission of Maine was established to promote the ongoing prosperity of the Maine wild blueberry industry. It works on behalf of Maine’s 500+ growers and processers of wild blueberries in the areas of research and education, promotion, and policy. It has a 70 year history of close collaboration with the University of Maine and Cooperative Extension and has supported numerous studies over the decades regarding such subjects as IPM, food safety, wild blueberry diseases, weed management, and pollinator health.

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The U.S. Highbush Blueberry Council, established in January 2000, is an agriculture promotion group made up of blueberry farmers, processors and importers in North and South America, who work together to research, innovate and promote the fruits of their labors as well as the growth and well-being of the entire blueberry industry. The blueberry industry is committed to providing blueberries that are grown, harvested, packed and shipped in clean, safe environments.

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UMaine Cooperative Extension is your doorway to University of Maine expertise. For over 100 years, we’ve been putting university research to work in homes, businesses, farms, and communities — in every corner of Maine. Cooperative Extension provides practical, how-to agricultural solutions and our agriculture experts help keep Maine farms financially, environmentally, and socially sustainable by developing new crops, management strategies, soil health practices, irrigation and crop storage technologies, integrated pest management training, nutrient and waste management solutions, value-added products, precision agriculture, and more.

Cooperative Extension Blueberry Office 5722 Deering HallOrono, ME 04469-5722 (207) 581-2923 Website: https://extension.umaine.edu/blueberries/

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