Sunflower field with cutworm damage in foreground.
Several species of cutworms, including dingy, dark-sided, sandhill and black, damage young sunflowers at or soon after emergence. Small, transparent windows appearing in young leaves may be caused by small larvae not capable of eating through the leaf. Notches in the leaves or cotyledons may appear if sunflowers are planted into fields with existing infestations. Older larvae inflict less subtle damage in the form of wilted, severed and dying seedlings. Excessively cool, wet soils tend to enhance stand reduction by slowing plant development relative to pest feeding.
Larger larvae of most cutworms feed nocturnally and remain concealed during the day, staying within a few inches of damaged plants. The discovery of cut plants and one or more larva per square foot warrants rescue applications of insecticides if the majority of the larvae have not pupated. Insecticides should be applied if most larvae are less than 1½ inches long and have caused plant stands to decline below 85 percent of recommended levels. Dry soil conditions will reduce the probability of achieving control by spraying.
Please refer to the latest Sunflower Insect Management Guide for management options.
MF2954 Kansas Crop Pests: Black Cutworms
Page last updated 09/19/2013 by J.P. Michaud.