Hemp exhibited high level of sensitivity to most of the tested herbicides. Visual injury levels ranged from almost no injury (~5%) with only one herbicide, to some temporary injury (~20%) with a few herbicides and severe injury or death (60%-93%) with about 10 out of 18 herbicides tested.
Hemp exhibited relatively good tolerance to several products that can be used postemergence in industrial hemp. It is important to note that the conclusions are based only on one year of data. This study will be repeated in 2021 season.
On Oct 27, 2020, The United States Environmental Protection Agency (USEPA) announced a new 5-year registration for XtendiMax® and Engenia, and re-registered Tavium (a premix of dicamba and S-metolachlor).
In order to calculate an herbicide resistance risk score, four years of crops need to be entered. Once herbicides are chosen for all four years and a weed species is selected, the model will calculate an herbicide resistance risk score for each herbicide site of action that was selected.
Herbicides registered for in-season weed control in industrial hemp are scarce, or nonexistent. To help with this issue, a greenhouse study was conducted this summer at the University of Nebraska-Lincoln to test tolerance of three industrial hemp varieties to preemergence herbicides commonly used in corn and soybean.
Fall, specifically October and early November, is a key time to chemically control thistles in pastures, both biennial and perennial thistles. Proper identification of thistles is key to picking the proper chemical control.