forageresources potato leafhopper presentation by:
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Potato Leafhopper
Presentation by:
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Potato Leafhopper
• Damage– Physical injury to phloem– Leaves damaged– Growth stunted, delayed– Yield loss
• Potato leafhoppers cause more damage than any other alfalfa pest in North America.
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Potato Leafhopper
Proboscis
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Potato leafhopper migrates from Louisiana each spring
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PLH Life History Characteristics
1. Long range migration/locally dispersive
2. Wide range of host plants
3. Explosive growth potential
Management Implications for Alfalfa:• At the mercy of “regional” population• Must monitor and spray when
necessary
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Potato leaf hopper and damage
V-shaped damage on leaf
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Potato Leafhopper DamageDamage caused by Potato leafhopper
0
5
10
15
20
0 20 40 60 80 100 120# of Leafhoppers
Hei
ght o
f pla
nts
(inch
es)
Potato leafhopper effect on % Crude Protein
18
20
22
24
26
0 20 40 60 80 100 120# of Leafhoppers
% C
rude
Pro
tein
Source: Improving Alfalfa Forage Quality, CASC
Yield is reduced with plant stunting
Forage quality is lowered because crude protein is reduced
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Potato Leafhopper Damage
• New seedings of alfalfa are particularly susceptible to potato leafhopper damage
• Failure to control potato leafhopper in the seeding year results in yield loss in subsequent years.
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MonitoringWhen: Mid-June until end of
season
Detection: Sweep net
Sampling: Groups of 20 sweeps at 5 different locations, count potato leafhoppers per sweep
Threshold: Varies with plant height
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Potato leafhopper scouting and economic thresholds
Alfalfa LeafhoppersHeight per sweep(inches)
Under 3 0.2 adults
4 to 6 0.5 adults
8 to 111.0 adults/nymphs
12 to 14 2.0 adults/nymphs
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Potato leafhopper scouting and economic thresholds
If the average potato leafhopper count exceeds the height of alfalfa in inches
- treat
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Potato Leafhopper Economic Thresholds
• The previous economic thresholds are a starting point. To fine tune a treatment decision, spray cost and economic value of crop should be considered.
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Glandular-haired alfalfa and normal alfalfa
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Economic thresholds for spraying potato leafhopper in alfalfa (leafhoppers/10 sweeps),
less than 50% resistanceCrop Value of $80 per ton
Cost of TreatmentCanopy Height $8 $10 $12 $14 $16 $18 $20
4 29 37 44 52 60 68 768 33 41 48 56 64 72 80
12 37 45 52 60 68 76 8416 41 49 56 64 72 80 88
Crop Value of $120 per ton
Cost of TreatmentCanopy Height $8 $10 $12 $14 $16 $18 $20
4 18 24 29 34 39 54 698 22 28 33 38 43 58 73
12 26 32 37 42 47 62 7716 30 36 41 46 51 66 81
Source: Rice and Lefco, IA State.
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Economic thresholds for spraying potato leafhopper in alfalfa (leafhoppers/10 sweeps), greater than 50% resistance
Crop Value of $80 per ton
Cost of Treatment Cost of TreatmentCanopy Height $8 $10 $12 $14 $16 $18 $20
4 71 87 103 119 136 153 1708 75 91 107 123 140 157 174
12 79 95 111 127 144 161 17816 83 99 115 131 148 165 182
Crop Value of $120 per ton
Cost of Treatment Cost of TreatmentCanopy Height $8 $10 $12 $14 $16 $18 $20
4 49 60 71 82 93 104 1158 53 64 75 86 97 108 119
12 57 68 79 90 101 112 12316 61 72 83 94 105 116 127
Source: Rice and Lefco, IA State.
HR* = Highly Resistant (>50%)
R = Resistant (31% to 50%)
MR = Moderately Resistance (15% to 30%)
LR = Low Resistance (6% to 14%)
PLH Resistance Level CategoriesOnly a percentage of plants within a variety
have resistance to PLH‘Early generation’ glandular haired alfalfa
varieties were Resistant (Less than 50% level)
*Late generation glandular-haired alfalfa varieties have over 50% resistance (Highly Resistant = HR).
Glandular-Haired Alfalfa Variety PLH Resistance Ratingswww.uwex.edu/ces/forage
Under “select forage varieties” go to the “marketers …” and then click on the green “Alfalfa”
LR116FS Growmark; Olds Seed Soln.WL 357 HQ
LR100FS Growmark; Olds Seed Soln.WL 348 AP
HR.FS Growmark; Olds Seed Soln.WL 346 LH
LR104FS Growmark; Olds Seed Soln.WL 319 HQ
HR.Croplan GeneticsTrailblazer 5.0
R103Target SeedRUGGED
R102TrelayROOT 66
R.Target SeedREBEL
MR99Agripro SeedsInterceptor
HR.Farm Science GeneticsFSG 400LH
HR102Farm Science GeneticsFSG 300 LH
HR.NK Brand SeedsEvergreen 2
MR104America’s AlfalfaAmeriguard 301
HR99PioneerPioneer 54H91
HR.GarstGarst 6325
R.GarstGarst 6310
ResistanceRating
Avg. Yield
CompanyVariety
LR116FS Growmark; Olds Seed Soln.WL 357 HQ
LR100FS Growmark; Olds Seed Soln.WL 348 AP
HR.FS Growmark; Olds Seed Soln.WL 346 LH
LR104FS Growmark; Olds Seed Soln.WL 319 HQ
HR.Croplan GeneticsTrailblazer 5.0
R103Target SeedRUGGED
R102TrelayROOT 66
R.Target SeedREBEL
MR99Agripro SeedsInterceptor
HR.Farm Science GeneticsFSG 400LH
HR102Farm Science GeneticsFSG 300 LH
HR.NK Brand SeedsEvergreen 2
MR104America’s AlfalfaAmeriguard 301
HR99PioneerPioneer 54H91
HR.GarstGarst 6325
R.GarstGarst 6310
ResistanceRating
Avg. Yield
CompanyVariety
Glandular Haired Alfalfa
• History– early development in public sector– commercial development & ultimate
release (1997)– trait from “exotic” Medicago, but not GMO
• Mechanism of resistance?
Mechanisms of Plant Resistance to Insects
• ANTIBIOSIS: plants are “toxic”
• NON-PREFERENCE: insect will go elsewhere when given choice
• TOLERANCE: plants can withstand more injury without yield loss
Three “Snapshots” from Arlington, Wisconsin, in the Evolution of Glandular Haired Resistance
• 1997, 1st production year (part of 4 state trial)
• 2000, seeding year• 2003, seeding year
Conclusions from 1997• Overall performance of GH varieties
in WI was disappointing (variable but “low” levels of resistance)
• Resistance to hopperburn was apparent, and GH varieties supported fewer PLH, but this did not translate into a yield advantage
• GH varieties also showed yield “lag” in absence of PLH
UW Entomology/Agronomy Researchon Glandular-Haired Alfalfa Varieties
PIONEER 5454(no resistance)
DK 131 HG (53%
resistance)
EVERGREEN (79%
resistance)
Arlington 2000
David B. Hogg, John L. Wedberg and Dan J. Undersander
2000 YIELDS (Tons/acre) [Plots cut July 19]
0
0.5
1
1.5
2
5454 DK131HG Evergreen
WarriorWarrior 0.5No Spray
No PLHResistance
53% Resistance
79% Resistance
David B. Hogg, John L. Wedberg and Dan J. Undersander
Conclusions from 2000
• Performance of GH varieties definitely improved
• Clear yield advantage of GH varieties in untreated plots, and no yield lag in absence of PLH
• But GH varieties still lost yield when not protected
David B. Hogg, John L. Wedberg and Dan J. Undersander
2003 YIELDS (Tons/acre) [Plots cut July 30]
Thresholds:
0
0.5
1
1.5
2
1X20XNo Spray2X
Reid B. Durtschi, David B. Hogg, John L. Wedberg and Dan J. Undersander, 2003
No PLHResistance
53% Resistance
HR = High ResistanceMore than 50% Resistance
Conclusions from 2003
• Performance of GH varieties further improved
• Yield responses similar to 2000, but yield loss gap narrowing in unprotected plots*
* plus this was under the most extreme conditions – new seeding with heavy PLH pressure
Reid B. Durtschi, David B. Hogg, John L. Wedberg and Dan J. Undersander, 2003
Summary• GH-based PLH resistance has improved
substantially since its (premature?) commercial release in 1997– % resistance has increased from 30’s to >
80– agronomic traits, disease resistance also
improved• Monitoring still needed for PLH in new
seedings– Evidence from ’03 suggests using 2X
threshold– timing might be the more important issue
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Potato Leafhopper Resistance
• New seedings should be sprayed at same threshold as non-resistant varieties
• With potato leafhopper resistance greater than 50% thresholds can be increased up to 2 times before spraying is necessary.
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Credits:This presentation was created from a collaboration among the following individuals:Dan UndersanderDavid HoggBryan JensenEileen CullenUniversity of Wisconsin
Richard LeepMichigan State University
Paul PetersonUniversity of Minnesota