E-208
DEPARTMENT OF ENTOMOLOGY
field crop's insects

INSECT OUTLOOK FOR CORN AND SOYBEAN FIELDS PREVIOUSLY IN SET-ASIDE PROGRAMS
Marlin K. Bergman and C. Richard Edwards, Extension Entomologists

At this time, it appears that most of the corn acreage idled under the 1983 Acreage Reduction, Paid Land Diversion and Payment-In-Kind programs will be returning to corn or soybean production in 1984. One of the management questions, therefore, producers need to consider is, "What special insect problems, if any, might be anticipated in 1984 because of the 1983 set-aside programs?"
It is unlikely that any major insect problems will develop in corn or soybeans in 1984 just because of a one-year set-aside program. The chances of any particular insect becoming a problem
in 1984 will depend largely on the combined influence of four factors: (1) the crop, if any, that was planted on the set-aside acreage in 1983; (2) tillage operations prior to planting the 1984 crop; (3) whether that specific insect is present; and (4) environmental conditions. Consequently, each field should be considered individually when making pest management decisions.
The following information describes specific situations which may increase the potential for certain insect problems and presents appropriate pest management guidelines.

If Planting Corn in 1984

ALL FIELDS
Corn Rootworms. If corn rootworm beetles were noted in set-aside fields during August or September scouting, tillage or mowing operations, some potential exists for larval damage in 1984. Therefore, if corn is to be planted in these fields, a soil insecticide should be used in 1984 to prevent potential economic larval damage. The alternative would be to plant soybeans to break the rootworms' life cycle since larvae can't survive on soybeans. On the other hand, if no beetles were observed during the August-September egg-laying period, the potential for economic larval damage in 1984 is low, and no insecticide should be needed.
Producers who did not scout, till or mow their set-aside acres during August or early September and, thus, have no knowledge of the presence or absence of rootworm beetles, should consider the following to determine potential for economic larval damage in 1984:

1. If volunteer corn populations exceeded 4,000 plants per acre or sorghum-sudan grass was planted as a cover crop in 1983, these fields were possibly more attractive to beetles than others during egg laying and should probably be treated with a soil insecticide in 1984 or planted to soybeans.

2. Fields which had little or no volunteer corn and those not planted to sorghum-sudan grass in 1983 are not likely to sustain economic larval damage in 1984, and a soil insecticide is, therefore, probably not needed.
All growers who plant corn and elect not to treat for corn rootworms at planting should check their fields during the first part of June for rootworm larvae and damage. If necessary, an insecticide can be applied at cultivation to prevent economic damage.

Wireworms/White Grubs. The odds of encountering increased problems with wireworms and/or white grubs on set-aside acres planted to corn are low. It

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