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Field Crops Insect Pest Updates
David Owens, Extension EntomologyUD Carvel REC, 16483 County Seat Highway, Georgetown
[email protected](302) 698-7125@OhBuggers
Excessive Rain is Good For Something…
Critical Crop Protection Periods
• Emergence• Mid-season canopy development• Reproductive stages
• Corn – Emergence and R-stage corn• Sorghum – R-stage sorghum• Soybean – Emergence, Mid-season, R-stage
2019 Corn Preparation
• Sample wireworms and white grubs, especially in weedy fields
• Wire trap – 25% SCM, 10% WW, 5% WG, 5% Unknown
• Solar bait trap: Purdue extension video: https://www.youtube.com/watch?v=t3VUKw_TfKc
• Digging for grubs: 8 inch square 6 inches deep in fall or spring
• 1 whitegrub/ sample in spring. 1.6 in fall.
What’s In The Corn Seed?
• Handy Bt Trait Table• ECB regional suppression• CEW not an issue in timely corn;
only Vip3A or a triple pyramid • CRW – not needed for rotated
corn• BCW – Vip3A, Cry1F
• https://cropwatch.unl.edu/2018/which-bt-traits-do-you-need-buy
ECB Still Present, Be Vigilant
Late Planted CEW in Corn
Late Planted Field Corn
• Agrisure 3122 – Cry1ab and Cry1F, mCry3A and mCrya34/35Ab1• Besiege 10 oz 5 DAS
05
10152025303540
Besiege UTC
Mean # Clean Ears and Worms Per 25# Clean Ears # of worms
*
Sorghum – R-stage period
• 1 larva per head = 5% yield loss ~ $12.60 assuming 80 bu/a, $3.15/bu(https://extension2.missouri.edu/g7110)
• Spots of sorghum in SW Delaware exceeded threshold
Sorghum Aphids
• Examined 4 sorghum fields for white sugarcane aphid, found aphids in 2 fields. • Sorghum acreage has declined in VA and throughout the country• Evolving picture. Is it going to cause problems here?
John C. French Sr., Retired, Universities:Auburn, GA, Clemson and U of MO, Bugwood.org
Yellow Sugarcane Aphid, Sipha flava. Hairy body
White Sugarcane Aphid, Melanaphis sachari.Not hairy; short, black cornicles, black feet
Bottom line with sorghum: It’s not a ‘plant and forget’ crop, particularly when flowering – milk corresponds to earworm flight. Be on the lookout of aphids. If they are going to cause problems, they will be easy to find
Soybean Survey
• Top Pests: Bean Leaf Beetle, Soybean Looper, Corn Earworm, Stink Bugs• Critical Times For Scouting: Emergence, mid-season canopy, R1-R6
• Between 2 – 5% yield impact, 50% automatic insecticides
Stand Establishment
A Highly Unusual Stand Reducer
A Potential Stand Reducer
Seedling threshold 40% with 2-3 beetles/plant
Soybean Defoliation
• Full season bean threshold: 40% pre bloom, 15-20% R1-R6, 35+% R6• Double crop fields with small canopies cannot tolerate nearly as
much.
How Much Does Vegetative Defoliation Influence Yield?– Angus Catchot, Mississippi State
V3 D
efol
iatio
n
V6 Defoliation0 33% 66% 100%
0 100% 97% 96% 77%33% 105% 93% 88% 83%66% 100% 95% 101% 92%
100% 86% 75% 79% 75%
Yield (% of UTC)
Rain Rain Go Away – uh oh.• Cant neglect field interiors, but – most mites show up on edges first• Cool temperatures, high humidity, heavy dew in field crops can lead
to mite declines – August crash, but – collected large numbers out of a corn maze in October
July 19
R-stage Soybean
Impact of Drought – Corn Earworm• Fields in SW Delaware experienced heavy (for us) corn earworm
pressure• Non-irrigated fields, dry corners, double crop fields at greatest risk.
Irrigated fields less pressure
05
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30-A
pr
7-M
ay
14-M
ay
21-M
ay
28-M
ay
4-Ju
n
11-Ju
n
18-Ju
n
25-Ju
n
2-Ju
l
9-Ju
l
16-Ju
l
23-Ju
l
30-Ju
l
6-Au
g
13-A
ug
20-A
ug
27-A
ug
Georgetown CEW Per NightGT BL GT Ph
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30-A
pr
7-M
ay
14-M
ay
21-M
ay
28-M
ay
4-Ju
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11-Ju
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18-Ju
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25-Ju
n
2-Ju
l
9-Ju
l
16-Ju
l
23-Ju
l
30-Ju
l
6-Au
g
13-A
ug
20-A
ug
27-A
ug
Laurel CEW Per NightLl BL Ll Ph
https://www.ces.ncsu.edu/wp-content/uploads/2017/08/CEW-calculator-v0.006.html
CEW Resistance
• Management becoming increasingly frustrating
• 20-40% survivorship in DE worms 2018
3.31.81.92.04.3
19.624.7
29.831.437.1
22.732.433.2
43.237.6
26.0
0102030405060708090
100
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
Perc
ent s
urvi
val
Mean % H. zea moth survival, 5 µg cypermethrin—2003-2018
137 moths treated, 126 untreated
21.40%26.80%
32.30%
68.40%
42.80%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
June July August September Overall
Mean % H. zea moth survival, 5 µg cypermethrin—DE 2018
CEW in Soybean• Drought/nematode stressed, open canopy, R1-R4/5 fields or portions
of fields most attractive
0
1
2
3
4
5
corn
ear
wor
ms
per 1
5 sw
eeps
3 dat 7 dat
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Cor
n ea
rwor
m p
er 1
5 sw
eeps Suffolk - 3 & 7 DAT Sprayed 14 Aug
0
2
4
6
8
10
12
Untreated Warrior II @0.96
Intrepid Edge@ 6
Brigade @ 6.4 Prevathon @14
Baythroid XL@ 2.8
Steward @ 9 Besiege @ 7
Cor
n ea
rwor
ms
per 1
5 sw
eeps Gates Co. - 4 & 7 DAT Sprayed 10 Aug
Data from Dr. Sally Taylor, Virginia Tech Tidewater AREC, Suffolk
CEW in Soybean
• Pyrethroid alone may or may not be satisfactory. • Natural enemy reduction following pyrethroids
0123456789
Sussex worms per 100 sweeps
CEW
Loopers
Texas A&M Horticulture
Soybean Looper vs Green Cloverworm• GCW – very active worm, present June – September,
easy to kill• Count prolegs – 3 abdominal vs 2. Loopers present
August – October, difficult to kill A. Herbert - Newsletter
Video showing green cloverwormviolent wiggling when prodded. Soybean looper does not respond the same way. Courtesy of Nick Seiter, Univ. Illinois
Loopers in Soybean
• Grasshopper + Looper• Paired 2 ‘heavy defoliation’ with ‘lighter
defol.’• 29 vs 40 bu/a
Loopers in Soybean
• Estimate entire canopy defol. (BLB)
• Loopers tend to start from the lower canopy
• What stage are the beans?• What stage are the worms?
• Eat 80% in the last 3 days
Soybean Looper Damage 2010
42. 9 Bu/ A 9.8 Bu/ A
•Grower challenged consultant’s recommendation to treat•Beans were early R5•Left the strip out to show that worms wouldn’t hurt his yield…
Photo: Gus Lorenz/University of Arkansas
Delaware in 2010
Cory Whaley
Soybean late-season: soybean loopers
0123456789
10
soyb
ean
loop
ers p
er 1
5 sw
eeps
3 dat 7 dat 23 dat
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10
Soyb
ean
loop
ers p
er 1
5 sw
eeps
30-Aug 8-Sep
2017 2018
Treated 24-Aug
Soybean Summary
• Scouting is key, especially after a previous pyrethroid• Coverage is key• ID is key• Judicious insecticide selection is key
Calling For Dove Plots
Insecticide Update
• As of right now, EPA is appealing 9th Circuit panel decision on Lorsban removal to the full bench. We expect Lorsban to be available through the 2019 season
• Torac (tolfenpyrad, G21a) now has supplemental labels for brassicas, fruiting vegetables, cucurbits, potatoes. Broad spectrum contact only.
• Vydate usage restrictions proposed lengthening REI’s to 3 days for all cucurbits, 4 days for potato, and 5 days for onion. Maximum application rates would be 1 lba.i./acre. Remove celery, eggplant, peanut, tobacco, tomato, and orchard uses
• Inscalis (Afidopyropen) Sefina and Versys now labeled on tree fruit, vegetable fruit, and soybean. Translaminar aphid, scale and whitefly product.
• Neonic interim decisions to be released this quarter• Pyrethroid interim decisions in Q2
Acknowledgements
• Sussex County Council• Delaware Soybean Board – insect survey• Bill Cissel, Joe Deidesheimer, Samantha Cotton,
Kevin Troyer, Joe Wheeler, Carolina May, AgostinaArmondo
• Area Consultants