Friday, July 19, 2013

Southwest Missouri Field Crop Report for July 17, 2013

Contact: Jill Scheidt, agronomy specialist
Tel: (417) 682-3579

LAMAR, Mo. –Jill Scheidt, agronomy specialist with University of Missouri Extension in Barton County, scouted area fields on July 17 to prepare this week’s field scouting report.


According to Scheidt, corn flea beetle feeding was seen on corn. Corn flea beetles are smaller black insects that can jump very high when disturbed.

“Flea beetles usually cause the most damage to corn if flea beetles are causing significant damage before the 4 leaf stage,” said Scheidt.

Flea beetles feed on corn leaves. Feeding looks like gray, rectangular tracks on the leaves when the top layer of the leaf is stripped off. Threshold levels for corn flea beetle in corn are five or more flea beetles per seedling up to the 4 leaf stage of corn.

Corn flea beetles can transmit Stewart’s Wilt virus.

Other insects to watch for in 8-leaf to tasseling corn are armyworm, stalk borer and root worms.

Stewart’s Wilt, transmitted by flea beetles, can be identified by linear pale green to yellow streaks that tend to follow the veins of leaves where beetles have fed. Streaks soon become dry and brown.

“Damage of Stewart’s Wilt is common in Missouri, but damage is seldom of economic significance,” said Scheidt.


A small amount of rust was seen on corn. Rust begins as green or yellow lesions that develop to reddish-brown, raised pustules. Rust usually does not justify a fungicide.

“Rust does not overwinter in debris and crop rotation is the best management practice to prevent rust,” said Scheidt.

Non-threshold levels of Japanese beetle and grasshopper feeding were seen again this week in soybean. Defoliation threshold levels for soybeans are 30 percent defoliation before bloom and 20 percent defoliation during or after bloom. No diseases or other pests were seen.


There are some good resources available online. Corn Insect Pest Guide: and Corn Disease Guide: .

The weekly field scouting report is sponsored by University of Missouri Extension and Barton County Extension. For more information on this scouting report, or to learn how to receive it a week earlier by telephone, contact the MU Extension Center in Barton County, (417) 682-3579.

Labels: ,


Post a Comment

Let us know how you have been helped by this article or what you have learned from this story.

<< Home