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PREDICTING DISEASE INFECTION PERIODS: TOOLS, TRICKS, AND UPDATES
Kari Peter, Ph.D.Department of Plant Pathology and Environmental MicrobiologyPenn State University Fruit Research and Extension CenterBiglerville, PA [email protected] 717-677-6116 Ext 223 @drtreefruit
Apple scabFire blightSooty blotch and Flyspeck
Bacterial spot
Disease cycle Infection conditionsTools to help predict
infectionManagement
Predicting disease infection periods: tools, tricks, and updates
Disease cycle of Venturia inaequalis:
Spores overwinter
Spring: primary inoculum
Secondary inoculum
polycyclic
APPLE SCAB
Ascospores: • Mature at GT• Temperature• Discharged by
early spring rains
• **Peaks: Bloom - PF
• Primary infection can last until mid-June
0 2 12
1370
3550
7500
12750
15000
1950
40 00
2000
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10000
12000
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16000
Asc
osp
ore
Co
un
ts (
Pri
mar
y Sp
ore
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Phenology of apple trees
Primary Period for Dispersal of Apple Scab Ascopores
Disease conditions present = control is critical
Temperature (°F)3436373941434546485052
54 – 5657 – 59 61 – 75
7779
Wetness hours4135302821181513121198768
11
Lesion appearance (days)
-----
17171717161514
12 - 13 9 - 10
--
Predicting apple scab infection: Mills Table
Severe: rainy springLittle: hot and dry
Manually estimating:• Average
temperature (max and min temperatures during wetting event
• Calculate leaf wetness hours: When wetting event starts and then when leaves dry
Utilizing NEWAto predict infection periods
www.newa.cornell.edu
Stations in PA:Piney Mountain, PABiglerville (Hollabaugh), PAYork Springs (Lerew), PANew Paris (Boyer), PANew Tripoli (NWLHS), PAScott Township, PARock Springs, PANorth East Escarpment, PAHarborcreek, PA
13 Airports available
In Maryland:Woodbine, MD (Howard -Carroll Counties)
Utilizing NEWA:
Select a disease:Fire blightApple ScabSooty blotch and Flyspeck
Weather station
Date of Interest
Utilizing NEWA: Apple scab infection periods
It’s April 29:Scab infection period predicted for April 30 –May 1 Protection needed BEFORE infection invent
0 2 12
1370
3550
7500
12750
15000
1950
40 00
2000
4000
6000
8000
10000
12000
14000
16000A
sco
spo
reC
ou
nts
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rim
ary
Spo
res)
Phenology of apple trees
Primary Period for Dispersal of Apple Scab Ascopores
Disease conditions present = control is critical
Scab infection period presents itself, keep in mind where we are during the ascospore dispersal
Management – ½” Green Tip to 1st Cover
• 1/2” Green Tip and Tight Cluster: Syllit + mancozeb (3 lb/A)
• Pink and Bloom: Fontelis + mancozeb
• Petal Fall and 1st cover: Vangard + mancozeb
• Other products can be substituted:Examples: Flint + mancozeb
Inspire Super + mancozebLuna Tranquility + mancozebIndar + mancozeb*Aprovia (2016: new SDHI) + mancozebMerivon/Luna Sensation + mancozeb
• Adding several pounds of sulfur = For powdery mildew suppression
• Rusts controlled with EBDCs (mancozeb/manzate/penncozeb etc.)
Primary infection can last until mid-June
*Protectant:Omega
Rule of thumb: Use contact fungicides in combination with at least 3 different chemistries/modes of action (SPRAY BY THE NUMBERS)
Management – Additional considerations
Be sure your sprayers are calibrated to ensure good coverage!
In very wet weather: ABSOLUTELY MUST RE-APPLY FUNGICIDES IN THE RAIN
• Mancozeb, captan, and sulfur will all provide several days of protection if applied in the rain
• Assume all fungicide protection, regardless of product, will be removed after 2 inches of rain• If extended warm rains occur over the next few days:
AN ABSOLUTE MUST to get out and renew coverage by spraying a protectant (mancozeb, captan, or sulfur) in the rain
• Duration of product: Avoid spraying in pouring rain = product washes off
• Duration of product: Applied during a drizzle = Uncertain about duration, but could expect 2 – 3 days
Management – Additional considerations
Be sure your sprayers are calibrated to ensure good coverage!
• Biggest problem: Poor coverageRight equipment Set up properly
• Ideal: Able to cover acreage in 3 days (or less) if needed to recover during a 2 week wetting period in a wet scab year
Alternate Row Middle sprays…good for wet years
PRIORITIZE COVERAGEMOST SCAB SUSCEPTIBLE CULTIVARS
Getting back through blocks quickly if rain removes all protection and continued wetting is predicted
www.apsnet.org
Activecanker
Oozing bacteria: Attracts insects – insects dispersebacteria to flowers (wind and rain also disperse bacteria)
Bacteria colonizestigmas (favors warm temps): does not cause disease (yet)
Fire Blight Disease Cycle
Wetting event + warm temps
Blossom Blight
Shoot BlightCanker BlightTrauma Blight
Rootstock Blight
5 – 30 days
Bloom time
Predicting Fire Blight Infection Periods: NEWANEWA: Predicts fire blight infection periods using Cougarblight
Requirements for infection:• Orchard fire blight history• Starts at first bloom• 4 day accumulation of
degree hours (today + yesterday + 2 days ago + 3 days ago)
• Wetting event (dew, rain, spray treatment)
**Can be calculated by hand using available tables
It’s May 4 and a fire blight infection period is occurring: Spray now
Management – Bloom – Petal Fall
http://www.omafra.gov.on.ca
Blossom sprays protect only flowers that are open (Protect blooms during 20% - Full Bloom)
Antibiotics – complete, + adjuvant or surfactant*Most effective when they are applied the day before or the day after an infection event (within 24 hrs!)
• Streptomycin – Still the best option• Partial systemic activity
• Kasugamycin – Kills bacteria, but not systemic• Oxytetracycline – Suppresses bacteria• 4 spray maximum (resistance management)
*Be mindful of rattail bloom
Management – Bloom – Petal Fall
http://www.omafra.gov.on.ca
Tank mixing with strep: To help manage shoot blight New for 2016: Actigard (Syngenta)• Induces plant resistant• Use mixed with strep (NOT alone)
Regalia @ 64 oz/A
Plant growth regulator: Prohexadione-calcium (Apogee, Kudos) @ 2 – 6 oz/A + organosilicone adj. + ammonium sulfate• Begin king bloom thru petal fall (several apps thereafter)• Hardens off shoots = not susceptible to shoot blight
• Occurs 10 - 14 days after application• Can be tank mixed with strep (NOT a strep replacement)
Do not tank mix copper with strep
Alternatives to antibiotics• Blossom Protect – Yeast antagonist
• Restrictions of what fungicides/insecticides can be used when using product
• Ceuva + Double Nickel• Serenade Opti• 2% Lime Sulfur + 2% Fish Oil• Phosphonate (phosphorous acid) products are not
effective (Rampart, Phostrol, ProPhyt, etc.)
Management – Bloom – Petal Fall
http://www.omafra.gov.on.ca
Management – Post Bloom to terminal bud set
Plant growth regulator: Prohexadione-calcium (Apogee, Kudos) @ 2 oz/A + organosilicone adj. + ammonium sulfate
VIGILANCE: Monitor regularly for infections if there were blossom blight conditions – prune as necessary
• Symptoms manifest 5 – 30 days post infection• Shoot blight infection: risk continues until shoot growth
ceases• Beware of pruning too much – makes fire blight worse
DO NOT spray antibiotics post petal fall• Hail/Severe wind event – the exception
• Cultivar susceptibility, fire blight history, PHI, spray within 24 hrs, crop value justifies cost
Control piercing-sucking insects***
K. Peter
Predicting Sooty blotch and flyspeck infection:Accumulation of leaf wetness hours beginning 10 days after petal fall
Risk threshold varies depending on what model you use:• PSU: 225 hours• SkyBit: 350 hours• NEWA: 170 hours
It’s June 10 and threshold will be met for risk June 11: Spray now
Predicting SBFS Threshold for control: NEWA
Managing summer diseases
• Weather conditions: Warm (70°F and higher) and wet (rain events)
• Be mindful of fruitlets that don’t completely abscise from fruit thinning Source for fruit rot fungal spores (2015 was bad year for this in PA/MD)
• Remove fire blight cankers : dead/cankered wood a source for fruit rot spores Another reason why it is important to prune out dead/cankered wood
during dormancy
• Previous season fruit mummies (due to apples left on the tree to rot): spore source
• Sooty blotch and flyspeck (~ 2nd cover – NEWA also predicts SBFS infection start): Topsin M + Captan
Oso (Polyoxin D salt; Certis)Omega (fluazinam; FRAC Group 29 Fungicide; Syngenta)
• Fruit rots: QoI fungicides (FRAC Group 11)-- Merivon (0 d PHI); Luna Sensation
and Flint (14 d PHI) [tank mix with Captan] Serenade Opti @ 16 oz/A
Bacterial Spot Disease Cycle
Spring
SummerFall/Winter
Polycyclic diseaseOptimum conditions:Warm and wetDisease slows down:Hot and dry
Overwinter in cankers, infected buds, leaf scars
First infect leaves
Infect leaves and fruit
Left untreated: bacterial
populations “explode”
Bacterial Spot Management
A plan…– Start applications late petal fall to early shuck split
– Spray 7 – 14 days according to conditions
– Rotating other products with oxytetracycline (21 day PHI) and copper (PHI varies)
• Serenade Optimum (14 oz/A) or Double Nickel (1 qt/A)
– Works well in rotation
– Can be tank mixed with oxytet
– For apricots, plums, etc: Cueva, Badge, Kocide, etc; Serenade Optimum, Double Nickel
– ** Always double check the label**
– Phosphorous acid products ineffective
Take home messages:
• Warm and wet favor many diseases
• Monitor orchard conditions and infection events (NEWA)
• Apply control before infection event
• Apple scab: May need to spray during the rain
• Fire blight: tank mix another product with strep to minimize shoot blight (Apogee, Regalia, Actigard)
• Sooty blotch/Flyspeck and fruit rots: Sanitation is important
• Bacterial spot: infection conditions may prompt weekly sprays
2016 – 2017 Penn State Tree Fruit Production Guide
Order Publication
Hard Copy: $35.00 + shippingCode AGRS-045. The nearly 380-page, spiral-bound, hard copy publication.
PDF: $15.00Code AGRS-045D. The complete publication in PDF format containing an interactive table of contents, hyperlinks, and bookmarks. Orders will be distributed via email.
Bundle: $45.00 + shipping (Hard Copy +PDF)Code AGRS-045 Bundle.
Ordering InstructionsCall toll-free 877-345-0691 from 8:00 a.m. to 4:30 p.m., Monday through Friday.
http://extension.psu.edu/plants/tree-fruit/tfpg
PREDICTING DISEASE INFECTION PERIODS: TOOLS, TRICKS, AND UPDATES
Kari Peter, Ph.D.Department of Plant Pathology and Environmental MicrobiologyPenn State University Fruit Research and Extension CenterBiglerville, PA [email protected] 717-677-6116 Ext 223 @drtreefruit
QUESTIONS?