Biologically Active Substances in Cotton and Related Plants That Affect Boll Weevil Behavior and Development 45–49.Development of Cotton Plants Resistant to Heliothis spp.Host Plant Resistance to the European Corn Borer 42.Effects of Ecdysones and Analogues on Insect Development and Reproduction 40–41.Behavioral and Chemosensory Background of Host Specificity in Phytophagous Insects 38–39.Some Population Aspects of Plants in Insect Suppression 36–37.Chemical Components in the Cotton Plant and Their Effect on Boll Weevil Behavior 29–30.Effects of Juvenile Hormone on Sarcophaga bullata 25–28.Effect of Juvenile Hormone and Ecdysterone on Rectal Pad Development during Adult Development of Hyalophora cecropia 24.Electrophysiological Studies of Food-Plant Relationships of Lepidopterous Larvae 20.Natural and Synthetic Compounds with Juvenile Hormone Activity 19.Biology and Biochemistry of Insect-Plant Relationships 16–18.Hornworms with these cocoons should not be included in your counts because they are no longer feeding. These are cocoons of a tiny wasp that develops inside the hornworm and kills it. Late in the growing season, many of the hornworms may have small, white, football-shaped objects on their backs. If 5 or more hornworms are found per 50 plants, then a spray should be applied prior to harvest. Hornworms feed in the upper 1/3 of the plant and can be found hanging from the underside of the leaf. Use a minimum of 5 locations per field, more are better, especially for large fields. This should allow time for a “clean-up” spray and the harvest interval to pass before tobacco is cut and taken to the curing structure.Ī list of recommended insecticides can be found in ENT-15, Insecticide Recommendations for Tobacco Beds and Fields.Īn assessment of hornworms can be made by carefully examining groups of 20 plants at randomly selected locations over a field. If this is not practical, then plants should be checked about a week before harvest. Ideally, tobacco should be checked weekly from topping until harvest to determine if hornworm numbers justify treatment. Hornworm infestations must be handled in the field before housing. There are no registered or effective treatments to control hornworms feeding on tobacco in the curing barn. Hornworms present when the tobacco was cut will be taken to the barn where they will continue to feed until they complete their development and drop to the barn floor. That leaves plenty of time for late-flying moths to lay eggs that lead to infestations. The residual protection from the application usually lasts for 5 to 7 days. The long flight period means that infestations can develop even if the crop was sprayed with an insecticide soon after topping. Tobacco hornworm moths fly during much of August and early September, attaching single eggs to the undersides of tobacco leaves in the upper 1/3 of the plant. University of Kentucky College of Agriculture ENTFACT-151: Keeping Hornworms from the Curing Barn | Download PDF by Lee Townsend, Extension EntomologistĪnd Bob Pearce, Extension Tobacco Production Specialist
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