D3185: Chemical control strategies to manage corn earworm, Helicoverpa zea, in hemp

Corn earworm, Helicoverpa zea (Lepidotera: Noctuidae), has emerged as an injurious insect pest
to hemp, Cannabis sativa. One of the biggest challenges in managing corn earworm is the
limited number of effective management tools for control. Chemical control is challenging due to
its complicated federal status and the lack of replicated research on effective pesticides. Given
the damage caused by this pest, we sought to explore the efficacy of insecticides in both field and
laboratory settings. The lack of replicated research on chemical control strategies and the unique
architecture this crop possess generates questions on how to conduct foliar applications
successfully. Therefore, laboratory bioassays were tested to evaluate insecticide effects providing
full coverage to flower buds. We compared insecticides currently registered in hemp with
conventional standards used against corn earworm in other crops in the laboratory. Corn
earworm larvae were fed hemp flowers treated with insecticides to identify age and rate-specific
mortality. In the field, the same insecticides were used and applied to flowering hemp. Following
application, caterpillar populations and damage were assessed. Results of both laboratory
bioassays and field will be discussed.