Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
Vol. 11, No. 6
Feb 6, 2012
Start Looking For Army Cutworms in Alfalfa, Canola, and Wheat
Tom A. Royer and Phillip G. Mulder, Extension Entomologists
This is the time of year when army cutworm activity will become visible. Glenn Detweiler, Extension Educator for Washita County (SW Oklahoma) sent in some digital photos of army cutworms to the Plant Disease and Insect Diagnostic Lab that were collected from a canola field in Washita County. Army cutworms can cause severe stand loss in canola and winter wheat if numbers exceed thresholds and are not controlled. More information can be found by consulting EPP-7089, Caterpillars in Canola.
Army cutworms grow slowly during the winter and don’t cause noticeable damage until temperatures warm in the spring. In alfalfa, signs of injury include slow production of new growth and stand loss (Figure 1). They can be particularly damaging to newly planted stands, causing severe stand loss. Injury in alfalfa is often associated with fields lacking significant amounts of stubble. If alfalfa or wheat has been grazed, army cutworms will often hide under cow pats during the day and feed on the crop at night.
Fig 1. Army cutworm damage in alfalfa. (Photo courtesy KSU.)