Soybean Aphid

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Soybean Aphid Seed TreatmentUpdates Heading
into 2005

• Insert your name here
• UW Extension YOUR County

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Seed Treatments for Soybean
Cruiser 5FS thiamethoxam nicotinoid Syngenta Y
es early season protection SBA, BLB, wireworm,
maggot
Gaucho imidacloprid nicotinoid Bayer
CropSci Pending Label pending
Active ingredient Chemistry Company EPA
Reg? Insects
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Supplemental Label Registration Dec.
2004 Cruiser 5FS Seed Treatment Potatoes and
Soybeans
For Soybeans Active ingredient (a.i.)
thiamethoxam Rate 1.28 fl oz per 100 lbs. of
seed 50 g a.i./100Kg seed to provide early
season protection of seedlings against injury by
aphids, bean leaf beetle, Mexican bean
beetle, pea leaf weevil, pea weevil, plant leaf
hopper, seed corn maggot, thrips and wireworm
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Figure from recently released promotional
material for CruiserMaxx Pak (Cruiser 50g ai/100
kg seed ApronMaxx)
Planting date? 9 June
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(No Transcript)
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• CruiserMaxxPak promotional material
• omitted late planting date June 9th
• when presenting the UW 2003 trial.
• Why Late Planted?
• Spring 2003, prior to soybean aphid outbreak,
• late planting was done to obtain insecticide
• efficacy data. 2000-2002 trend observed that
• late planted fields tended to be hit harder
• by soybean aphid good chance to obtain
• efficacy data.

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UW 2003 Seed Treatment TrialsSoybean Aphid
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Soybean Aphid Seed Treatment Trial 1, Arlington
WI 2003. Planted Late June 9th. Mean Aphids/Plant
by sampling date
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Soybean aphid seed treatment trial 1, Arlington
WI 2003 Yield (bu/A) by Treatment. (P 0.002 F
6.59 df, 5)
Treatment Yield (bu/A)
Untreated 38.1 c
Cruiser 30 43.6 bc
Cruiser 50 49.7 ab
Gaucho 62.5 41.3 bc
Means followed a different letter are
significantly different at ? 0.05
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In a second UW 2003 seed treatment trial, soybean
aphid density exceeded 250 aphids/plant by August
13th. -Same planting date (June 9th) -Cruiser
rate of 62.5 g a.i./100 Kg seed -higher rate than
CruiserMaxx Pak 50g -still exceeded 250
aphids/plant
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Soybean Aphid Seed Treatment Trial 2, Arlington
WI 2003. Planted Late June 9th. Mean Aphids/Plant
by sampling date
Aphids/ plant
June
May
Sample Date
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Soybean aphid seed treatment trial 2, Arlington
WI 2003 Yield (bu/A) by Treatment. (P 0.1151
F 2.33 df, 4)
Treatment Yield (bu/A)
Untreated 38.1 b
Poncho 62.5 42.2 ab
Poncho 125 44.3 ab
Gaucho 62.5 43.2 ab
Cruiser 62.5 52.8 a
Means followed a different letter are
significantly different at ? 0.05
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• Lab bioassay Univ/ of Minnesota
• aphids placed on leaves from
• thiamethoxam-treated plants
• - mortality after 24 48 hours

University of Minnesota, 2003, 2004 preliminary
data, D. W. Ragsdale and B. P. McCornack. Not
for distribution or publication. This slide may
not be reproduced or redistributed without
permission from the authors.
Percent Mortality () SEM
Days after planting
Mortality lasts for 35 days V3/V4 plant stage
(Adapted from Ragsdale and McCornack 2004)
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Lab bioassay for fecundity,U of MN
University of Minnesota, 2004 preliminary data,
D. W. Ragsdale and B. P. McCornack. Not for
distribution or publication. This slide may not
be reproduced or redistributed without
permission from the authors.
thiamethoxam reduced aphid fecundity ( the
number of nymphs produced)
(Adapted from Ragsdale and McCornack 2004)
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From the Cruiser label Early season
protection From the Cruiser web page The
early-season pests, which suck and chew on the
crop during its most vulnerable and tasty phase
(the first 30 to 40 days of growth) are
intoxicated when they try to feed on the treated
crops.
Chris DiFonzo, Michigan State University
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Bottom line

• Seed treatments provide early-season protection

• Seed treatments may fit well
• in production areas w/ early-season
• insect problems (for ex. BLB)

• Seed treatments ALONE may not be enough
• under high, or late season, SBA pressure

• In fields lacking early-season pests, a well-
• timed foliar spray, based on aphid scouting
• threshold, is the recommended practice
• for optimal yield protection.

Midwest University Extension Entomologists
Consensus Recommendation