Hemp Harvest is Approaching

Many hemp growers are beginning to harvest or are gearing up to harvest. Growers are spending more time in the field observing plants and collecting samples for testing to measure THC (tetrahydrocannabinol), CBD (cannabidiol) and CBG (cannabigerol). Growers should also continue to scout for pests.

Corn earworm is one of the most concerning pests of hemp this time of year. Last year we observed corn earworm (CEW) from late August to October, feeding on seed heads (grain production) or female flowers (cannabinoid production). The damage results in browning and die back of flowers and seed heads. I am now getting a few reports of CEW damage. Unlike last year though, there are insecticides available for use on CEW in hemp.

Corn earworm has caused yield loss in hemp across the country and in Indiana. Purdue and OISC worked to develop 24(c) Special Local Needs labels for Venerate® XC, Gemstar® LC, and Agree® WG insecticides. Refer to the 24(c) labels for rates and timing of application for the various products, which can be found at the OISC pesticide site. EPA also approved Spear®-Lep, which is used for many different caterpillars, including CEW. These biopesticides are most effective when larvae are very young, instars 1-3. Using the corn earworm trapping network as a guide, you can look at moth flights across the state to see when flights are high in your area. https://extension.entm.purdue.edu/veg/cornearworm/
However, we do not have action thresholds for hemp yet. Smaller hemp farms may opt to hand pick CEW larvae off of their plants, but this can be very time consuming. With several insecticide options available, we hope to see better control of CEW this year.

Corn earworm feeding on hemp grown for grain

Corn earworm feeding on hemp grown for grain

 

Corn earworm feeding on hemp grown for CBD

Corn earworm feeding on hemp grown for CBD

Share This Article
It is the policy of the Purdue University that all persons have equal opportunity and access to its educational programs, services, activities, and facilities without regard to race, religion, color, sex, age, national origin or ancestry, marital status, parental status, sexual orientation, disability or status as a veteran. Purdue is an Affirmative Action Institution. This material may be available in alternative formats. 1-888-EXT-INFO Disclaimer: Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current directions of the manufacturer.
Pest&Crop newsletter - Department of Entomology Purdue University 901 Mitch Daniels Blvd West Lafayette, IN 47907

© 2024 Purdue University | An equal access/equal opportunity university | Copyright Complaints | Maintained by Pest&Crop newsletter

If you have trouble accessing this page because of a disability, please contact Pest&Crop newsletter at luck@purdue.edu.