While spring has seemed to be forever coming, the fact is the winter of 2021-22 was generally mild. Unfortunately, that is good news for insects and bad news for those hoping to avoid pressure in 2022.
“The weather now influences how fast they develop,” says Iowa State University Extension entomologist Erin Hodgson.
Insects such as corn rootworms winter in the soil and are thus fairly well insulated during the cold months. Insects such as the bean leaf beetle tend to winter in crop debris and are more impacted by a harsh winter or cold spring conditions. This spring’s wild temperature swings could impact those above-ground pests and delay their spread.
Cool, wet soils could delay the development of seed corn maggots or various grubs, but planting has also been delayed so far this spring, so many of these pests would not have anything to feed on if they were to emerge now. The delay in their emergence may simply align with delays in planting.
Strong winds may push some pests north this spring, Hodgson says. Last year heavy storms pushed the jet stream north and led to more pests pushing north early in the season. That trend seems likely to continue as weather patterns trend toward warmer and more volatile storm conditions, she adds.
Of course, storms such as the derecho that hit Iowa in 2020 also weaken corn and soybean plants, making them more vulnerable to pest infiltration. Pests tend to feed on damaged plants.
Scouting for pests problems in fields remains important.
For example, now is a good time to start scouting for alfalfa weevils, Hodgson says. Scouting for bean leaf beetles is always more important if the soybean field is planted near an alfalfa field or if food-grade beans are being planted.
