WEST LAFAYETTE, Ind. — Mild temperatures and moderate
rainfall during corn and soybean planting created prime conditions for avoiding
severe problems with spring pests, a Purdue Extension entomologist said. But
that doesn’t mean growers should let their guard down when it comes to summer
Indiana’s two largest cash crops have not been affected by
as many spring insects as in past years, partly because of the lack of extreme
temperatures and rainfall once planting got underway.
“The lack of spring insects is mostly a factor of the crops
getting planted into conditions that were virtually ideal. Soils were mostly
moist but not wet at planting, and we did not have extended cool and rainy
conditions,” Christian Krupke said.
Cool, wet spring weather can delay planting, causing the
emergence of spring larvae to coincide with emerging crops.
Under these conditions, spring feeders reach the later
larval stage — when most feeding occurs — as crops begin to grow. This can hurt
developing crops by stunting or stopping growth as these insects use the plants
as a primary food source.
But while spring insects have not had a large presence in
Indiana fields, Krupke said, farmers still need to be out scouting their crops
for summer insects.
“As we reach midsummer, ear feeders and root worms, as well
as soybean aphids might come on the scene,” he said.
Common summer-feeding insects in Indiana corn include
western corn rootworms and western bean cutworm in northern parts of the state.
At high infestation levels, both can cause major yield reductions, but recent
years have seen very low populations.
Soybean aphids, one of Indiana’s most common and serious
summer soybean pests, attacks the crop until September and can reduce yields by
10 percent to 15 percent but, again, no problems of this magnitude have been
seen in at least four years.