Root of the Problem

By Pam Smith
DTN Progressive Farmer Crops Technology Editor

DECATUR, Ill. (DTN) -- Rootworms took a bit of a breather in most of corn country this summer. However, entomologists are warning farmers not to underestimate the pest's ability to make a comeback in 2015.

Iowa State entomologist Erin Hodgson's annual review attributed the dampening of corn rootworm pressure in Iowa to a harsh winter and saturated soils in June -- environmental conditions that tend to increase corn rootworm larvae mortality. More crop rotation away from corn and cooler summer temperatures could have helped too, she said in a recent press release.

It could be that growers are doing a better job of managing corn rootworm in the wake of western corn rootworm's increasing resistance to Bt corn.

Bt resistance has been confirmed to one or more Bt rootworm toxins in Nebraska, Minnesota, Iowa and Illinois. It's suspected in Colorado, Kansas, Missouri, New York, South Dakota and Wisconsin. Entomologists in those states have reported significant damage in fields planted to corn hybrids containing Bt rootworm toxins.

To help U.S. corn growers and consultants tackle this growing issue, Robert Wright, Research & Extension Entomologist at the University of Nebraska-Lincoln, organized a seminar comprising five webcast presentations that focus on the many new and changing aspects of western corn rootworm management in the transgenic era.

Corn Rootworm in the Transgenic Era

<http://www.plantmanagementnetwork.org/… " This seminar is located in the Plant Management Network's 'Focus on Corn' resource. The presentations, produced with funding from the USDA's National Institute of Food and Agriculture, include:

Resistance Evolution and IRM for Rootworm

<http://www.plantmanagementnetwork.org/… by Dr. Aaron Gassman, Iowa State University. This talk reviews current developments of Bt resistance in the field and what is known about the consequences of resistance for feeding injury and pest survival during future growing seasons. Gassman also covers approaches for managing western corn rootworm and the development of Bt resistance by this pest.

Adult Corn Rootworm Suppression

<http://www.plantmanagementnetwork.org/… by Dr. Lance J. Meinke, University of Nebraska-Lincoln. This presentation helps users incorporate adult western corn rootworm control tactics into a broader corn rootworm management program. He reviews aspects of adult western corn rootworm biology and ecology -- and provides a general overview of the adult control strategy, tactics, and critical timing.

Decision Tree for Grower Management Options

<http://www.plantmanagementnetwork.org/… by Dr. Ken Ostlie, University of Minnesota. This webcast addresses the management challenges posed by resistance, review options, and provides growers, crop advisors, dealers, consultants and extension educators with a framework for making decisions on corn rootworm management. It also covers the pros and cons of individual management options, as well as points out which options are more effective.

Rootworm Biology and Behavior

<http://www.plantmanagementnetwork.org/… by Dr. Joseph L. Spencer, University of Illinois. This presentation helps users understand the biology and behavior of corn rootworms, especially the western corn rootworm. Dr. Spencer focuses on the details of basic corn rootworm biology, movement patterns and the characteristics of dispersing adults. He also highlights biological knowledge is one of the keys to making sound management decisions and understanding pest resistance.

Larval Corn Rootworm Management

<http://www.plantmanagementnetwork.org/… by Dr. Robert Wright, University of Nebraska-Lincoln. Since the introduction of Bt corn hybrids active against rootworm, larval control options and management practices have changed. This webcast helps growers understand the most current options for corn rootworm larvae control, factors affecting their efficacy, larval rootworm biology, and damage.

In addition to the webcasts, the seminar's homepage features articles, as well as a Bt trait table that outlines current Bt proteins and the insect targets or herbicide activity, trade names and other important information to make better management decisions.

'Focus on Corn' is a publication of the Plant Management Network, a nonprofit online publisher with a mission to enhance the health, management, and production of crops through quality, science-based crop management information for agricultural practitioners.

To help achieve its nonprofit publishing mission, PMN partners with more than 80 organizations, including universities, nonprofits and agribusinesses.

To sign up for PMN's free electronic newsletter, PMN Update go to: <http://www.plantmanagementnetwork.org/… .

For more information on rootworm populations during the 2014 season go to:

http://www.extension.iastate.edu/… and

http://bulletin.ipm.illinois.edu

Pam Smith can be reached at pamela.smith@dtn.com

(CZ/SK)

Copyright 2014 DTN/The Progressive Farmer. All rights reserved.