Grubs are the larvae of scarab beetles of which the most common are the May or June beetles and the Japanese beetle. The grubs are 'C' shaped and range from 3/4" to 1 1/2" in length.
The grubs feed on the root systems of corn plants - and if abundant - may reduce plant stand early in the season.
Damaged corn plants in early development develop a wilted appearance due to pruning of the plant's root system.
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If grubs are readily found in a number of digs, a soil insecticide should be applied at planting time. The abundance of grubs observed should be weighed in relation to the presence or absence of wireworms and the potential threat of rootworm activity.
Corn following soybeans which had a heavy infestation of Japanese beetle the previous season should definitely be checked for presence of grubs.
If replanting is required due to grub activity, use of a soil insecticide is recommended. Materials labeled for control of grubs when applied as a planting treatment include:
Aztec* (tebupirimphos) + (cyfluthrin)
Capture* (bifenthrin)
Counter* (terbufos)
Force* (tefluthrin)
Fortress* (chlorethoxyfos)
Lorsban (chlorpyrifos)
Regent*
Commercially applied seed treatments including Gaucho/Prescribe (imidacloprid) and ProShield (tefluthrin) are also labeled against white grubs.
* Use is restricted to certified applicators.
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