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Viruses Showing Up in Crop Fields

Viruses Showing Up in Crop Fields

MU Extension agronomists start scouting wheat and cornfields for disease.

Wheat and cornfields in southwest Missouri are showing signs of various foliar diseases but no worm damage yet according to Jay Chism, agronomy specialist with the University of Missouri Extension, Lamar.

Most of the corn scouted had emerged with the second leaf visible.

"I did not observe black cutworm or armyworm damage; however individual fields need to be scouted," Chism said. "If cutworms are detected or have already caused damage and you are replanting the field, an insecticide, such as Warrior, needs to be applied right after planting to deter more cutworm damage."

Wayne Bailey, MU Extension state entomologist, Columbia, says cutworms can cause damage up to the fifth leaf stage. 

Wheat in the scouting fields was already in the boot stage and had many foliar diseases present. "I saw barley yellow dwarf virus, transmitted by aphids as well as a few other viruses. It is important to remember fungicides are not effective against viruses, so there is no need to apply fungicide," Chism said.

Some wheat fields are beginning to flower. To suppress Fusarium head scab, fungicides are typically applied as flowering begins on the main stem. "Some fields and wheat varieties may be at different growth stages, so be sure to check your fields before fungicide applications," Chism noted.

According to Laura Sweets, MU Extension disease pathologist, Columbia, university research indicates products that provide good scab suppression will include Prosaro, Proline and Caramba.

"It is important to remember that no fungicides are considered to provide excellent control of head scab. The disease is very weather dependent; moderate temperature, frequent rain, and overcast days are favorable conditions for the development of scab," Chism added.

For more information on Missouri crop scouting reports or to learn how you can receive it by telephone each week, contact your local MU Extension agronomist.

 Source: MU Extension Southwest News Service

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