2/6/2020
1
How much is seedborne Potato Virus Y costing the average WA grower?
Mark J. Pavek, Babette Gundersen, Debra Inglis, Alexander Karasev, Zachary Holden
WSU Annual Commercial Seed Lot Trial
2/6/2020
2
Percent of Potato Seed Lots Planted in WA with One Percent or Moreof Plants Displaying PVY Symptoms Across the Past 31 Years
198
81
989
199
01
991
199
21
993
199
41
995
199
61
997
199
81
999
200
02
001
200
22
003
200
42
005
200
62
007
200
82
009
201
02
011
201
22
013
201
42
015
201
62
017
201
8%
0
10
20
30
40
50
60%
0
10
20
30
40
50
60
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PVY levels in Seed lots planted in WA
2018 WSU Commercial Seed Lot Trial
% of all seed lots PVY (plants with symptoms)
47 0%
41 1 to 2%
4 3 to 5%
6 6 to 10%
2 10 to 21%
53% ≥ 1%
Background and Problem Statement
• Potato Virus Y persists in commercial seed lots
• Some growers perceive low PVY infection rates of 1‐2% as inconsequential
• Are low infection rates of 1‐2% costing growers money?
• Does this vary by PVY strain or potato variety?
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Foliar and Tuber Reactions of 3 PVY Strains
• 2015‐ 2017 Greenhouse experiments, Mt Vernon WA• Debra Inglis, Babette Gundersen, Alex Karasev
• 2018 Field experiment at WSU near Othello, WA• All Blue, Chieftain, French Fingerling, Yukon Gold, Russet Burbank
• G3 daughter tubers from greenhouse inoculated plants
• Control, PVYO, PVYNTN, PVYN‐Wi, (ELISA tested)
• One‐row plots, 6 seed pieces each
• 4 replicates
• Regional standard cultural management
• Plots harvested at 100 DAP
2018 Data Collection and Analysis
• Foliar rating• Tuber yield, grade, size profile
• Culls (growth cracks, knobs, misshapen, undersized)
• Economic Return • Process value Russet Burbank
• Standard Columbia Basin prices and contract
• Fresh market value – All Blue, Chieftain, French Fingerling, Yukon Gold
• Economic values converted to a percentage of the control• Assigned on a per plant basis• Ability to predict various mixes of healthy and PVY plant populations
• 1% infection, 2%, etc.
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All Blue
Healthy/Non‐inoculated
PVYO
PVYNTN
PVYN‐Wi
Chieftain
Healthy/Non‐inoculated PVYO PVYNTNPVYN‐Wi
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Yukon Gold
Healthy/Non‐inoculated
PVYO
PVYNTN
PVYN‐Wi
Russet Burbank
Healthy/Non‐inoculated PVYO PVYNTNPVYN‐Wi
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PVY Infection can Lead to Tuber Cracking(But this appears to be variety dependent)
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Tubers with Growth Cracks(% of Total Yield)
1% 2% 2% 1% 0%0%
47%
0% 1% 0%0%
31%
0% 1% 2%1%
18%
1% 0%
11%
ALL BLUE CHIEFTAIN FRENCH FINGERLING RUSSET BURBANK YUKON GOLD
Control PVYO PVYNTN PVYN‐WI
*
*
*Significantly different from control (P < 0.05)
Marketable Yield (US 1 & 2 tubers, all sizes)(% of non‐inoculated control value)
‐19%
‐81%
‐50%
‐69%
‐97%
‐68%
‐6%
‐41%
‐14%‐22%
‐9%
‐22%
15%
‐45%
‐57%
‐21%‐2%
‐23%
ALL BLUE CHIEFTAIN FRENCH FINGERLING RUSSET BURBANK YUKON GOLD ALL VARIETIES
PVYO PVYNTN PVYN‐Wi
*
* *
*
*
* *
**
*Significantly different from control (P < 0.05)
*
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Grower Gross Return(% of non‐inoculated control value)
‐13%
‐76%
‐43%
‐79%
‐89%
‐55%
6%
‐40%
‐54%
‐25% ‐23%‐20%
‐11%
‐37%
‐17%
‐29%
3%
‐22%
ALL BLUE CHIEFTAIN FRENCH FINGERLING RUSSET BURBANK YUKON GOLD ALL VARIETIES
PVYO PVYNTN PVYN‐WI
*
* *
*
*
*
*
**
*Significantly different from control (P < 0.05)
PVY levels in Seed lots planted in WA
2018 WSU Commercial Seed Lot Trial
% of all seed lots PVY (plants with symptoms)
47 0%
41 1 to 2%
4 3 to 5%
6 6 to 10%
2 10 to 21%
53% ≥ 1%
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Russet Burbank Average Plant Value
• $5000/A, 19602 plants/A• Healthy Plants: $0.26/plant
• PVYO : $0.05/plant• ‐ 79% loss
• PVYNTN : $0.19/plant• ‐ 25% loss
• PVYN‐Wi : $0.18/plant• ‐ 29% loss
Impact of 1% PVY Infection on Russet Burbank Value
1% infection = 196 plants/A
• PVYO: ‐$42/A or ‐$42,000 per 1000 acres
• PVYNTN, PVYN‐Wi: ‐$15/A or ‐$15,000 per 1000 acres
• 2% PVYO= ‐$84/A
• 5% PVYO= ‐$210/A (Almost ¼ million loss per 1000 acres)
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Average Economic Losses by PVY strain• Averaged across all varieties
• PVYO
• ‐55% per plant, averaged across six varieties
• ‐13% (All Blue) to ‐89% (Yukon Gold)
• PVYNTN
• ‐20% per plant, across varieties
• ‐0% (All Blue) to ‐54% (French Fingerling)
• PVYN‐Wi
• ‐22% per plant, across varieties
• ‐11% (All Blue) to ‐37% (Chieftain)
Russet Burbank
Healthy/Non‐inoculated PVYO
Yield compensation by neighboring plants?
• Agronomic and Economic Impact of Missing and Irregularly Space Potato Plants, AJPR 2006 Pavek and Thornton
• Neighboring plants can compensate for up to 56% of the missing plants economic value
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PVY REDUCES POTATO YIELD AND ECONOMIC RETURN• Sick potato plants reduce overall yield and quality
• Sick plants cost growers money; PVY infection cost growers money• Even 1% infection
• Economic losses dependent on variety and PVY Strain
• Biggest losses come from PVYO • ‐55% per plant, averaged across six varieties
• PVYNTN and PVYN‐Wi ‐ losses not as severe, but significant• ‐20 to 22% per plant, across varieties
• More than half of the WSU tested 2018 commercial seed lots contained at least 1% of plants displaying VISIBLE PVY symptoms
Purchasing Seed?
• Does Certified Seed = Disease Free Seed?
• NO. Percent of disease within tolerance levels.
• Does the certified seed tag provide the level of diseases found?
• NO. Ask for the “Seed Health Certificate”
• The Seed Health Certificate provides specific findings from the winter grow‐out.
• Be informed, ask for the seed health certificate!
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American Journal of Potato Research Publication, 2020:
Foliar and tuber reactions of three strains of Potato virus Y on five fresh market potato cultivars through three successive potato generations
• Babette Gundersen, Debra A. Inglis, Mark J. Pavek, Alex V. Karasev
Primary Funding
• Northwest Potato Research Consortium,
• WSDA Specialty Crop Block Grant Program
• USDA NIFA Specialty Crops Research Initiative CAPS
• Washington State Potato Commission
