Golden pennycress (Thlaspi arvense) tolerance to herbicides applied preemergence

Authors: Bernards, Mark

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/27/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Golden pennycress (Thlaspi arvense) is a recently domesticated winter annual oil-seed crop intended for use as a sustainable aviation fuel feedstock and high-protein meal animal feed. A key constraint to pennycress adoption is the rotation interval following herbicides used in preceding crops. It is critical to identify products that will provide effective spring and summer weed control in a corn, soybean or small grain crop but not injure fall-planted pennycress. A second common question is what herbicides may be suitable to protect pennycress from weed competition. The objectives of this research were to 1) evaluate field-grown pennycress response to Group 3, 4 and 15 herbicides applied preemergence (PRE), or postemergence (POST) in the spring prior to pennycress bolting, and 2) measure pennycress sensitivity to Group 3, 4, and 15 herbicides applied PRE in greenhouse dose-response experiments simulating herbicide carryover. Experiments were conducted in Macomb, IL and Morris, MN. In field studies, pennycress was seeded using a no-tillage drill into silage corn (IL) or spring wheat (MN) stubble. Herbicides were applied using a backpack sprayer. Stand density and seed yield was measured. In greenhouse studies, 12 seeds were sown in field soil modified with perlite to improve drainage in 8.9 cm3 plastic pots, the soil was saturated and allowed to drain overnight, and herbicides were applied in spray chambers. Pots were watered as needed to maintain moist soil. Plant density, visual injury, and dry weight biomass data was collected 6 weeks after planting. Pennycress seed yield and dry weight was not reduced by the herbicide trifluralin (840 g ai ha-1) applied PRE and watered in immediately by irrigation or rainfall. Ethalfluralin (840 g ha-1) applied PRE did not reduce pennycress seed yield, but did reduce dry weight in one of two greenhouse experiments. Pendimethalin (1060 g ha-1) applied PRE reduced seed yield in IL but not MN, nor did it reduce dry weight in greenhouse experiments. Clopyralid applied PRE (105 g ha-1) and POST (210 g ha-1) did not reduce seed yield or dry weight. However, dicamba (70 g ae ha-1) and 2,4-D (266 g ha-1) applied PRE injured pennycress seedlings in the greenhouse and field. The response of pennycress to the Group 15 herbicides was not consistent between greenhouse and field studies, perhaps because frequent watering in the greenhouse makes more herbicide available to interfere with pennycress growth. Neither s-metolachlor (1420 g ha-1), acetochlor (1260 g ha-1) nor pyroxasulfone (119 g ha-1) affected seed yield in field studies but did reduce plant density and dry weight in the greenhouse. Dimethenamid-p (736 g ha-1) and flufenacet (584 g ha-1) reduced seed yield in IL but not MN, and also reduced plant density and dry weight in the greenhouse. None of the Group 15 herbicides injured pennycress or reduced pennycress yield when applied POST to pennycress in the spring prior to bolting. Group 15 herbicides applied in the spring in corn or soybean are unlikely to negatively affect pennycress planted in the fall.