Two additional products recently received Environmental Protection Agency (EPA) approval under State Local Need Section 24(c) registrations for use against insect pests on hemp. These are Gemstar, a naturally occurring nucleopolyhedrovirus (HzSNPV), and Agree WG, a biological insecticide effective against a wide range of caterpillar pests. Gemstar uses a highly specific virus to control corn earworm and tobacco budworm. Agree WG has Bt aizawai as its active ingredient; this product disrupts the digestive tract of susceptible insects including yellow-striped armyworm, corn earworm, and European corn borer.
The effectiveness of these products is somewhat dependent on larval size, environmental conditions, application and feeding behavior of the pest. These products act more effectively on newly hatched and small larvae, so scouting and proper timing will improve control. Also, good coverage is important as both products need to be ingested to be effective. Poor results may be expected if these do not reach actively feeding larvae.
In order to use these products on hemp, applicators will need to have a copy of the respective labels, be certified applicators, and check with their hemp buyers to make sure this is acceptable. For a list of pesticides products approved for hemp in Kentucky, click here.
Ric Bessin and Raul T. Villanueva, Extension Entomologists