Corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), has emerged as an injurious insect pest to hemp, Cannabis sativa L., a crop newly reintroduced to the United States. Growing hemp presents a potential alternative economic opportunity for farmers but can be challenging with a market that is unstable and just developing. One of the most notable production challenges is managing corn earworm, an insect pest that is particularly damaging when it feeds on flower buds produced in cannabinoid varieties, creating extensive bud tunneling and wounds that allow entry of pathogens that can aid development and presence of bud rot. Damage to seeds is of lesser concern in hemp cultivars grown for grain and minimal risk is associated with hemp grown for fiber. Our ability to research hemp has only recently been allowed as production was largely suspended following World War II and, as such, there has been limited opportunity to develop information for empirically-based pest management recommendations. Further complicating development of integrated pest management (IPM) strategies are regulatory challenges associated with providing registration support to add hemp to pesticide labels, as it was not formally recognized as a crop by U.S. regulatory agencies until late 2019. Research needs and challenges to develop effective IPM programs for corn earworm on hemp are discussed here.

Hemp and marijuana, both Cannabis sativa L., are revitalized crops to U.S. agricultural and horticultural industries. Hemp (Δ⁹-Tetrahydrocannabinol content <0.3%) was reintroduced in 2014 under a pilot research program and legalized in 2018. Hemp can now be grown in all 50 states. Marijuana (Δ⁹-THC content > 0.3%), though classified as a Schedule I narcotic by the U.S. Drug Enforcement Administration (DEA), is legal in 40 states and the District of Columbia for medical and/or recreational use. Although C. sativa is often promoted as a pest-free crop, multiple diseases and arthropod pests have been identified and confirmed in recent years. There are limited options for control of diseases and pests affecting hemp. A survey of diagnosticians, researchers, and industry leaders conducted in 2021-22 sought to determine the distribution and occurrence of 76 common diseases and pests on C. sativa across the U.S. A total of 148 responses were collected and grouped by U.S. region: Western, Great Plains, North Central, Northeastern, and Southern. Survey results suggest that while some pathogens and pests are widely distributed across the U.S., others occur more frequently in specific regions. This finding may indicate variations in economic importance by region. Results from this survey provide a foundation for regional and national prioritization of research and regulatory activities.

No abstract