Here’s two recent articles from U/K.

STALK BORERS CAN HIT PLANTS IN BORDER ROWS

by Lee Townsend

Stalk borers are caterpillars that feed inside a wide range of plants. Small larvae can easily fit into grass stems but must move as they get larger or as their host plant declines. Displaced stalk borers will tunnel into the first plant they find that will accommodate them and will stay there as long as the plant remains relatively healthy. As a result, they can cause wilting tobacco plants along field borders or waterways. The larva first may chew into a stem causing a single leaf to wilt and turn yellow, then move into the stalk affecting the entire plant. While an infested plant is stunted, the borer usually remains in it rather than attacking others. This helps to minimize what appears to be a potentially significant loss.

Foliar sprays will not enter the plant and kill borers. It would take a very lucky application to catch wandering borers before they enter plants, well before symptoms appear. Check wilted plants to rule out other causes.

WATCH FOR CORN ROOTWORM BEETLES TO MAKE DECISIONS FOR NEXT YEAR

by Ric Bessin

Western corn rootworm beetles have begun emerging throughout the state. Unlike other corn producing states to our north, western corn rootworm continues to be a problem only in continuous corn in Kentucky. Each year in late June the adults begin to emerge after a just less than a month of feeding on corn roots. Over the next several weeks the adults will be active in and about corn fields, mating and laying eggs in soil cracks around the bases of corn. These eggs will remain dormant until next spring when they will hatch and the larvae will search again for corn roots.

During the next few weeks, corn producers should routinely monitor their fields for adult corn rootworm activity as this information is needed to determine rootworm risk in 2008.
If at anytime during the next few weeks, the number of rootworm beetles per plant exceeds an average of one then a control for rootworms will be needed next year.
Possible options consist of rotating to another crop, using a soil insecticide or seed treatment, or using a Bt hybrid that controls corn rootworm.

In some fields large numbers of rootworms are emerging before corn has pollinated.
The beetles can feed heavily on corn attacking the upper surfaces of leaves and, when available, the corn silks. If there are sufficient numbers of beetles that are keeping the silks clipped back to 1/2 inch or less and the corn has not yet pollinated, then an insecticidal control for the adults may be warranted. Generally this may require 10 or more adults per silk and has not bee common in Kentucky.

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