Minor Issues Found in Missouri Corn, Soybean Fields

By CnAgri2012-06-29 19:55:45 Print

This week, Laura Sweets, MU disease pathologist, and Wayne Bailey, MU state entomologist, came from Columbia assist Wyatt Miller, an agronomy assistant with University of Missouri Extension, in crop scouting. Fields were scouted around the Lamar area and just south of Golden City.

Corn scouted this week was between stages v-15 and R-2. R-2 is the second stage of reproduction known as the blister stage. By this stage plants have reach maximum height and vegetative dry matter, and energy is spent on kernel growth. Several fields in the area are still at or near R-1, the silking stage, where both pollination and fertilization occurs.

"The silking stage is the most sensitive period; stress at this time can greatly reduce yields. Overall, corn looks good. Some Japanese beetle feeding was seen this week in corn, but did not warrant treatment," said Miller.

Treatment is justified when 3 or more beetles are present on green silks, or when silks are eaten to 1/2 in or less, when pollination is less than 50 percent complete. Because Japanese beetles tend to stay on the edge of fields, treatment is rarely justified.

Soybeans scouted this week were between stages v-6 to R-2. Flowering begins at R-1 with one open flower at any node on the main stem. R2 is considered full flowering with an open flower at one of the two uppermost nodes on the main stem.

"Soybeans appear to be disease free, but some significant defoliation was noticed. Treatment is justified when defoliation reaches 30 percent before bloom and 20 percent between bloom and pod fill," said Miller.