Tobacco Budworm in Soybean
Crop Damage
Tobacco budworms (Heliothis virescens) occur throughout Mexico, the U.S., and southern Canada; however, they are a persistent pest in the southern tier states and along the eastern coastal states. They are a primary pest of tobacco and cotton but can also be a serious pest of soybean. Larvae feed on leaves, but the greatest economic injury occurs when they feed on flower buds, pods, and seeds.
Tobacco budworm representative leaf feeding.
Joseph Berger, Bugwood.org
Pest Description
Full-grown larvae are approximately 1½ inches long and vary in color, including pale green, pink, dark red, or maroon. A key identifying characteristic is the presence of large tubercles (bumps) with distinct spines (microspines) on the first, second, and eighth abdominal segments. Adult moths are green or brown with three light-colored bands crossing the forewings.
Blue arrows indicate microspines.
Arsel Oommen, Bugwood.org.
Scouting and Management
Tobacco budworms are attracted to several weed species, including groundcherry, lupine, mallow, morning glory, sunflower, toadflax, and velvetleaf. Larvae often feed on these weeds before moving into soybeans. Inspect field edges, especially weedy areas. If larvae are found, randomly select enough sampling locations to represent the field; larger fields may require additional sites. Use the Crop Protection Network’s Insect Defoliation Tool to accurately assess defoliation levels.
If larvae are confined to field edges, managing weeds in these areas and applying insecticide spot treatments may be warranted. If damage is widespread, standard soybean treatment thresholds are 30% defoliation during vegetative stages and 20% during reproductive stages. Additional caution is needed when other defoliators are present. Tobacco budworms have shown resistance to pyrethroid insecticides. When making management decisions, consider the presence of natural enemies, including predators, parasitoids, and pathogens.
Please contact your agronomist or extension specialist for management information.
Prepared and reviewed by Carol Pilcher and Robert Wright, with support from the United Soybean Board.
Tobacco budworm representative leaf feeding. Joseph Berger, Bugwood.org
Tobacco budworm. Blue arrows indicate microspines. Ansel Oommen, Bugwood.org.
Tobacco budworm. Joseph Berger, Bugwood.org
Tobacco budworm adult. J Michael Moore, University or Georgia, Bugwood.org.
Gallery image courtesy of Joseph Berger, Bugwood.org, J Michael Moore, University of Georgia, Bugwood.org, and Ansel Oommen, Bugwood.org.
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