| ||||
|
|
Western Bean Cutworms hit soybean fields statewide
By Jeff Caldwell
Suspicion and speculation became fact July 16, when crop scouts across the state of Iowa confirmed the presence of Western Bean Cutworms.
Now, entomologists recommend crop scouts and producers monitor soybean fields closely for the pest.
During the first two weeks of July, traps were set throughout the state to monitor WBC numbers, and during the week of July 12, moth numbers increased, in some counties, exponentially.
"We've got a trap network across the state right now," Rich Pope, Iowa State University Extension entomology program specialist, said July 16. "We've just now documented they do go from border to border in Iowa."
As of July 20, the county with the highest confirmed number of Western Bean Cutworms was Ida County, in northwestern Iowa, where, between July 4 and 19, a black-light trap captured 1785 individual moths. In that time, numbers increased greatly during the second week of the month: On July 10, 55 moths were trapped and observed, and the following day, in the same location, that number mushroomed to 139. The highest documented daily count at the Ida County trap site, located near Galva, came July 13, when 238 were trapped.
Another area that saw a significant rise in Western Bean Cutworms in a short period of time was Adair County in southwest Iowa. On July 12, John Kennicker, who is responsible for checking the trap near Greenfield, documented no presence of WBC on July 12. But, the following day, 42 moths were discovered. Three days later, on July 16, that number reached 159.
In checking a trap site in northeastern Boone County, in central Iowa, Pope said he observed an egg mass hatching, the first he had seen this year. Once enough of the pests reach this point, he says it is crucial for scouts and producers to begin treatment programs quickly.
"The threshold we're working with right now is 8 percent of the plants. When they reach that point, you need to treat rapidly," Pope said. "People also need to be looking in fields where there have been noticeable problems in the past."
Historically, according to Pope, Western Bean Cutworms are typically limited to the northeastern part of Iowa. But, data now indicate a statewide infestation this year. With that knowledge, scouts and producers should begin their own frequent surveillance for the pest.
"This has just happened in the past two days," Pope said. "The main thing right now is to get out and look in the fields."
Unlike the soybean aphid, which decimated soybeans throughout Iowa in 2003, the Western Bean Cutworm has a very different set of characteristics. What sets it apart from other crop insect pests is damage it causes and the way it causes it.
"The insidious thing about Western Bean Cutworms is they go into the ears, and you don't see damage until harvest," Pope said. "There won't be any fear or panic until yield monitors show damage and losses."
Even though the cutworm numbers have skyrocketed, with proper monitoring and treatment of the insects, severe damage can be avoided. Furthermore, awareness of Western Bean Cutworms and the damage they cause, could explain why some soybean yields have dipped in the past.
"This should cause more awareness," Pope said. "Maybe this will be a way to explain hidden yield losses in the past."
For the latest information about Western Bean Cutworm levels throughout Iowa, go online to http://latrodectus.ent.iastate.edu/westernbeancutworm/ or call Rich Pope at 515-294-5899.
Jeff Caldwell can be reached by phone at 515-280-5405 or by e-mail at jcaldwell@mchsi.com.
Date: 7/21/04
Copyright 1995-2008. High Plains Publishers, Inc. All rights reserved. Any republishing of these pages, including electronic reproduction of the editorial archives or classified advertising, is strictly prohibited. If you have questions or comments you can reach us at High Plains Journal 1500 E. Wyatt Earp Blvd., P.O. Box 760, Dodge City, KS 67801 or call 1-800-452-7171. Email: webmaster@hpj.com
 
| |||||||||||||||||||
