Picture of pests on paper
Updated: April 26, 2024

Optimizing Early Season Pest Management for Maryland Field Corn

Kelly Hamby, Associate Professor and Extension Specialist, Department of Entomology Maria Cramer, Ph.D. Candidate, Department of Entomology

Field corn insect pest management decisions begin before planting, including selecting hybrids with or without different plant incorporated protectants and/or insecticide seed treatments.

At planting, in-furrow insecticides can also be used. These products vary in their efficacy and residual control as well as impacts to beneficial natural enemies that feed upon pests. In addition, they redundantly target many of the same sporadic early season insect pests while potentially not controlling others. We compared pest management efficacy and pest pressure between an untreated control (bare seed), Poncho® 250 (clothianidin 0.25 mg/ seed) treated seed, and an in-furrow application of Capture LFR® (bifenthrin 13.6 fl oz/acre.)

This experiment was conducted in both a Bt hybrid with a plant incorporated trait package for above ground caterpillars and a non-Bt hybrid, with three replicate plots of each treatment at three farms over three years. Poncho more consistently reduced insect damage than Capture (which did reduce insect damage in non-Bt corn) and also improved stand. However, neither insecticide improved yield even in the one year and location where wireworms were controlled. To better understand their impact on natural enemies, particularly carabid ground beetles that may feed upon slugs, we also compared carabid beetle and slug abundance. In addition, we measured natural enemy feeding activity (predation) by placing sentinel caterpillars in the field overnight and evaluating how many were killed. Predatory carabid beetles commonly occurred and predation ranged from 0-100% across individual sentinel prey cards, with around 16% of the caterpillars killed on average. The insecticide treatments did not impact slugs captured in shelter traps, slug damage, carabid beetle abundance, or amount of predation (caterpillars killed overnight). Ultimately, untreated non-Bt corn yield well at all sites and years of our experiment and the pest pressure we observed did not reach treatment thresholds. Using foliar insecticides to target specific issues as they reach levels of economic concern more effectively and economically controls insect pests.

For more results and details see our Agronomy News Article: https://blog.umd.edu/ agronomynews/2023/11/28/optimizing-early-season-pest-management-for-maryland-field-corn/.

We would also like to thank the Maryland Grain Producers and Utilization Board for providing funding for this work.