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More data needed

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The On-Farm Network will be looking for corn rootworm beetles across the state this growing season.

By Allie Arp, ISA research communications specialist

Having a year’s worth of data is a good start, but for it to be the most beneficial, it should be aggregated across multiple years and locations.

After the success of last year’s corn rootworm (CRW) sampling project, the Iowa Soybean Association (ISA) On-Farm Network is continuing the project this year and accepting fields in continuous corn or fields rotated from soybeans. Fields that have received a soil-applied insecticide at planting are not eligible.

“Corn rootworms are very important and adaptive pests,” said Scott Nelson, On-Farm Network director. “This research seeks to understand rootworm populations emerging from a variety of management practices used in the state including rotation, resistant genetics and insecticide-use. Results will provide farmers with information that will help them choose the best management strategies to reduce populations of this pest.”

Beginning in mid-July, interns will trap corn rootworm beetles in 100 fields across the state. Four sticky traps will be placed in a 200-foot line at each location. Each trap will be recorded and replaced weekly through the middle of August.

The traps allow researchers to determine if the field is above the Iowa State University threshold of two beetles a day or 14 a week. By surveying fields statewide with diverse histories and practices, the On-Farm Network hopes to determine which management styles are most vulnerable to a CRW outbreak.

“With a handful of exceptions, last year was not a particularly exciting year for finding outbreak levels of beetles,” said Rich Stessman, On-Farm Network operations manager. “But between winter weather, trait susceptibility, cultural practices and summer stress every season sees a new dynamic. The most predictable aspect of CRW scouting is that you will learn something different than what you thought you knew the year before. This year it may be a hot spot in a particular sector of the state, or extended dispause or an expansion of the variant. We’ll have to wait and see.”

In order to be part of the survey farmers must report field location, planting date, previous crop, hybrid(s) and a full list of included traits. The sampled fields also must not be sprayed with an insecticide or fungicide/insecticide combination before mid-August. Growers will be notified if their counts are extremely high and need immediate attention.

Farmers interested in signing up for CRW sampling are encouraged to send this completed form to their regional agronomist.

For permission to republish articles or to request high-res photos contact Aaron Putze at

©2017 Iowa Soybean Association On-Farm Network®. All rights reserved. On-Farm Network® is a registered trademark of the Iowa Soybean Association, Ankeny, IA.Portions of some On-Farm Network trials are paid for in total or in part by the soybean checkoff.

Iowa Soybean Association | On-Farm Network | 1255 SW Prairie Trail Pkwy | Ankeny | IA | 50023 | US

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Iowa Soybean Review

August 2017 Contact Ann Clinton for past publications.