Insects and Disease May Have Survived Extreme Winter Weather
Extreme cold and snow cover in many parts of the country have growers guessing about the weather’s impact on pest pressures in the upcoming planting and growing season. Researchers say this winter’s weather could have some impact on pest populations, but many pests are just lying in wait.
“We see pest problems every year, regardless of conditions,” reports Paula Davis, senior manager for insect and disease traits at DuPont Pioneer. “This year it is a question of survival for crop pests. Some stinkbug species will not survive in extreme cold, and bean leaf beetles get knocked back when winter temperatures fall below 14°F. for sustained periods of time. However, most soil insects are buffered by the soil, crop residue, and snow.”
Migrating insects are one category that may give growers a break in 2014. Freezing temperatures reached far enough south to potentially reduce the populations of some insects that move north during the growing season. For example, cold temperatures in the Deep South could knock out pests that move up into southern Missouri fields.
“Most years, damage from early-season pests depends on how quickly the soil warms up,” Davis says. “Deep frost in the ground, cool springs, reduced tillage, and high residue result in cooler soil temperatures, which delays soil warmup, planting, and emergence. These conditions make plants more susceptible to insects.”
Davis suggests that growers scout their fields after planting to see how well their seed treatments are working. She advises growers to watch for various species of wireworms, grubs, and migratory pests — such as black cutworms — that won’t be affected by this winter’s cold temperatures.
William Dolezal, DuPont Pioneer research fellow, says the cold winter won’t have a big impact on disease organisms, but a cold spring will.
“Many of the pathogens that cause plant diseases are under a good blanket of snow cover and crop debris,” Dolezal says. “Disease organisms adapt to cold temperatures. As a result, the potential for plant diseases is present every spring. The key is to know what you have around you, and what you have on your farm.”
With that operation-specific knowledge, growers can select hybrids with the right disease-resistance packages, and support their choices by adding the protection of fungicide seed treatments.
Dolezal recommends rotating with nonhost crops to break disease cycles. He also asserts that the best defense is to get corn and soybeans up and out of the ground quickly.
“Planting too early gives the advantage to soil organisms,” he says. “Good weather at planting sets up good emergence, so growers should plant when the soil is warming and the weather outlook is good. This hastens faster early growth, moving plants away from the soil surface and debris that harbors many foliar pathogens.”
Dolezal also advises growers to scout early so there is still time for foliar fungicide applications to address some disease problems, and to plan for disease-resistance packages in their seed selection for next year. During scouting, growers should look for seedling blight, gray leaf spot, leaf blight, and Goss’s bacterial wilt.