What's Up at the USDA Office?

Upcoming Deadlines/Dates
May 15 – August 1: Primary Nesting Season
July 15: Spring Crop Reporting

Cover Crops More Effective than Insecticide
by LuAnn Rolling, District Conservationst
In a newly published study researchers from Penn State’s College of Agricultural Sciences found that early season plant cover, such as cover crops, can be more effective at reducing pest density and crop damage than insecticide applications.

“Plant cover, such as cover crops, can provide habitat for populations of natural enemies of pests, “said study co-author John Tooker, entomology professor at Penn State speaking to No-Till Insider magazine.  “Winter cover crops, for example, can harbor predator populations outside the growing season of the cash crop.”  

The goal of this study was to investigate how conservation practices including cover crops, no-till planting and crop rotations, interact with two pest-management strategies that employ insecticides. These strategies are preventive pest management, in which growers plant seeds treated with systemic insecticide for the control of early-season pests; and integrated pest management, or IPM, an approach that involves scouting for pests and using insecticides only when pest numbers exceed economic thresholds, and then only when nonchemical tactics are ineffective.

The researchers, who recently reported their results in Ecological Applications, found that using any insecticide provided some small reduction to plant damage in soybean, but no yield benefit. The findings suggested that in corn vegetative cover early in the season was key for reducing pest density and damage.

The researchers concluded that planting cover crops and fostering natural-enemy populations protected corn and soybeans from damage and that promoting early season cover was more effective at reducing pest density and damage than either intervention-based strategy.

According to Agricultural Research Service Research Entomologist Louis Hesler, one way to help ensure a diverse and balanced insect community on your operation is to limit tillage.  “Tillage is a disturbance,” Hesler said. “It disrupts where insects overwinter, or a disk or plow can directly kill insects. It’s a disturbance that has direct and indirect impacts on those beneficial insect populations in the soil.”

Producers should consider avoiding insecticide seed coatings, especially if they have no history of problems with early season pests, Hesler said. “Various studies have shown that it’s hard to realize a consistent benefit to these seed treatments in terms of economics in corn and soybeans in the Upper Midwest,” he said. “In a lot of instances, the seed treatments don’t provide enough benefit to justify their cost, and we know they’re having some type of negative aspects off-site that’s very difficult to quantify economically.”

The negative effects of insecticidal seed coatings can include harm to pollinators and other beneficial insects, harm to aquatic life, and harm to wildlife.