Bug Scout 1978
Check for Rootworms
(Tom Turpin, Entomologist, Purdue University)
Gee, if one pound of herbicide works so well, three pounds ought to work that much better.
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July 15, 1978

Now is the time to evaluate your 1978 program for control of corn rootworm larvae. During mid-July, when rootworm feeding is at its peak, a trip into the cornfield can tell you plenty.

Pull a few plants and look for damage to the fifth to sixth nodes of roots. The first node is just above the seed root. Damage will consist of discolored root tissue or short roots where feeding has destroyed the growing point.

If damage is present, consider the following: The insecticide might have been applied at a lower than recommended rate. Insecticides applied as a 7-inch band in front of the press wheel work best. Insecticides applied in the seed-furrow give reduced rootworm control. When mixed with fertilizers, insecticides normally do not provide satisfactory results.

Remember, if an insecticide has failed to provide the necessary control, higher than recommended rates will not help. Lodged corn can be due to rootworm damage, but other factors may be involved. The only way to know for sure is to look at the corn roots.

by Tom Turpin, Entomologist, Purdue University

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