corn rootworm situation in 2004 distance education workshop february 4 and 11, 2005 mike gray and...
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Corn Rootworm Situationin 2004
Distance Education Workshop
February 4 and 11, 2005
Mike Gray and Kevin SteffeyDepartment of Crop SciencesUniversity of Illinois
Corn Rootworm Management IssuesIllinois, 2004
Severe rootworm larval damage(northern half of Illinois)
June
Reports of poor performance of granular and liquid insecticides, insecticidal seed treatments
July, August
Corn rootworm control trials; numerous reports of lodging; reports of greater-than-expected damage in YieldGard Rootworm corn
More widespread distribution of variant western corn rootworm—distribution extended west and south
Corn Rootworm Management IssuesIllinois, 2004
Performance issues with corn rootworm control products
Granules, liquids, seed treatments Planting time (~80% of corn planted in IL by 4/30/04) Windy conditions during planting Soil conditions Application and incorporation
YieldGard Rootworm Corn Low dose Planting time (declining expression of Bt) Hybrid and environmental interactions
1.18 1.91
1.62.12
1.44
1.9
1.911.9
2.74
1.842.0
2.022.86
2.042.06
2.0
1.82
1.64
1.8
1.971.98
2.01.9
1.74
Numbers areaverage root ratings:
10 fields per county5 roots per field
Orange = confirmed variant WCRYellow = “fringe”
Survey forCRW larval injuryCorn after soybeans2004
Corn Rootworms:Lessons (re)learned in 2004 No corn rootworm control product is “bulletproof.”
Despite our best expectations, environmental conditions can affect the performance of any rootworm-control product.
Some products do not perform well when corn rootworm larval pressure is heavy.
Accurate granular insecticide application and incorporation is particularly important in early planted fields.
Overheard “solutions” to CRW problems
Control adults in soybeans, use rootworm control product in corn the following year
Low-rate insecticidal seed treatment + soil insecticide
YieldGard Rootworm corn + soil insecticide
Control adults in soybeans+
YieldGard Rootworm corn following year+
High-rate insecticidal seed treatment
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DATES CORN ROOTWORM LARVAE FIRSTOBSERVED IN CORN ROOTS, TIPPECANOECOUNTY, INDIANA, 1982-2004
26-27
18-19
20-21
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24-25
28-29
30-31
June 1-2
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May 16-17
11-12
Statewide WCRW SurveyLate July-Early August
About 70 of 92 Counties
1-3 Fields Per County
5 X 20 Sweeps/Field
1997 1998 1999 2000
2001 2002
Western Corn Rootworm Sweep Net Surveys in Soybean (#/100 Sweeps)
2003 2004
Western Corn Rootworm - Variant
• Management strategies:– recognize high risk areas– be observant of damage in unconfirmed areas– monitor for WCRW beetles in soybean fields
– rootworm soil insecticides, treated seed, and Bt RW
Corn Rootworm Situation in Iowa. 2004
Dr. Jon Tollefson
Professor of Entomology
Iowa State University
Corn Rootworm Situation in IA
2004 weather corn rootworm phenology rotation-resistant western corn
rootworm extended diapause northern corn
rootworm insecticide performance
Adult Corn Rootworm Emergence, 2004
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Corn Rootworm Situation in IA
2004 weather corn rootworm phenology rotation-resistant western corn
rootworm extended diapause northern corn
rootworm insecticide performance
Ostlie © 2005
Corn Rootworm Situation in Minnesota
Ken OstlieDepartment of Entomology - University of Minnesota
[email protected](612) 624-7436 office (612) 750-0993 cell
Ostlie © 2005
Corn Rootworms in Minnesota WCR reach the northern edge of their distribution in MN,
SD and ND. WCR most common in areas with higher incidence of corn following corn (e.g., SE MN).
NCR distributed statewide, but are most common in areas with rotated corn. NCR also exhibit S →N gradient.
Severe, open winters have only slight impacts on NCR, but routinely knock back WCR populations. NCR typically comprise 90% or more of the corn rootworms in MN.
2003-4 winter was fairly severe and open until late January Heavy, repeated rains and cool weather dominated early
summer. The MDA Plant Pest Survey Program conducts an annual
survey of corn rootworms (3 continuous and 3 rotated fields per county) in corn during the first two weeks of August.
Ostlie © 2005
What Happened with
Corn Rootworms in 2004? ♦ Corn rootworm survival was better than expected, perhaps due to deeper egg laying during the drought of 2003.♦ Widespread insecticide use in soybean for soybean aphid potentially reduced corn rootworm populations foraging in soybean. ♦Early season rainfall favored shallow root systems and enhanced leaching of insecticides. ♦ Later-season thunderstorms were common leading to greater lodging problems than observed in drought of 2003.
Ostlie © 2005
Corn Rootworm Dynamics:Continuous Corn in SE MinnesotaData supplied by MDA – Plant Pest Survey Program
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Bee
tles
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WCR
NCR
Mild Winters Favor WCR
Ostlie © 2005
Corn Rootworm Dynamics:Relative Species Success
Data supplied by MDA – Plant Pest Survey Program
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CR Severe
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Ostlie © 2005
Western Corn Rootworm: Abundance and Distribution in MN - 2004
WCR populations declined dramatically from 2002-3 levels. Probably reflects winter mortality and heavy early-season rains.
Ostlie © 2005
3-Crop Rotation
2-Crop Rotation
Jim BoersmaJim BoersmaPicture taken south of Olivia Minnesota 2002
Crop Rotation and Extended Diapause: A Minnesota Problem Since Late 1970s
Ostlie © 2005
NCR Exhibit Similar Patterns Regardless of Crop Rotation
Map supplied by MDA - Plant Pest Survey Program
Ostlie © 2005
Comparative Population Dynamics of Rootworms and Soybean Pests, 2003
Ostlie – Rosemount, MN
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5/23 5/30 6/6 6/13 6/20 6/27 7/4 7/11 7/18 7/25 8/1 8/8 8/15 8/22 8/29 9/5
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Timing ofInsecticideApplication
Ostlie © 2005
Risk Management of Corn Rootworms is Becoming More Complicated
Different Strategies to Succeed in Rotated Corn!
Western corn rootworms have lost their fidelity to corn and now lay eggs in other crops.
Northern corn rootworms have extended their
overwintering diapause to 2 or even 3 years.