Developing weed management strategies for the new winter oilseed crops pennycress (Thlaspi arvense) and camelina (Camelina sativa)

Authors: Bernards, Mark

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/14/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Over the past decade, plant breeders have made significant progress in domesticating field pennycress through genetic engineering, mutagenesis and conventional breeding techniques to create varieties with reduced shattering, non-dormant seed, and oil and protein profiles with reduced concentrations of erucic acid and sinigrin. Camelina, in contrast, has been grown as an oilseed crop in Europe for at least 3,000 years, but its cultivation was largely displaced by oilseed rape (Brassica napus) in the middle of the 20th century. More recently, commercial interest in the unique oil profile of camelina has led to renewed breeding efforts in North America. Both pennycress and camelina are extremely winter-hardy and have successfully overwintered in Minnesota and Saskatchewan. Anticipated biofuel demand, especially for the aviation industry, will necessitate large increases in oilseed production in the U.S. and Canada. Camelina and pennycress are being promoted as oilseed cash cover crops that can grow in the Midwestern U.S. without displacing large acreages of corn or soybean production, and as crops that can increase cropping diversity in wheat- and pulse-based cropping systems. However, farmer adoption of camelina or pennycress will depend upon the availability of effective tools and strategies for weed management before, during, and after their cultivation. Herbicide carryover from the preceding crop is one risk. Field and greenhouse experiments conducted in western Illinois have shown no negative impact to pennycress stand or yield from most of the common herbicides applied in corn. Field experiments with widely used soybean herbicides conducted in Minnesota in 2023 during a very dry summer showed severe injury (>70%) to pennycress seedlings from acetolactate synthase inhibitors (ALS) herbicide carryover, and moderate injury (20-35%) from some protoporphyrinogen oxidase inhibitors (PPO) herbicides. Data measuring carryover of wheat herbicides to both camelina and pennycress is needed, as is data on corn or soybean herbicide carryover to camelina. Several herbicides are labeled for preemergence (PRE), hooded spray, postemergence (POST) (Group 1 herbicides only), or harvest aid applications in camelina (usually listed on herbicide labels as "gold of pleasure") primarily through its inclusion in the EPA’s Oilseed Crops Group 20A. Only one herbicide label, Assure II (supplemental), lists field pennycress as an approved crop. PRE and early POST herbicide evaluation experiments in Illinois and Minnesota show that pennycress and camelina likely have acceptable tolerance to additional herbicide active ingredients not yet labeled for either crop. Weediness assessments of camelina show that it is unlikely to become a persistent weed in fields where it is grown. Systematic field studies and weediness assessments are needed to demonstrate that domesticated pennycress varieties will not become persistent weeds. While herbicides are useful tools, the most important weed management aspect for either crop is rapid and uniform emergence after planting. When pennycress and camelina establish commercially acceptable stands, they suppress weed biomass by >90% at harvest. Less is known on the potential benefit of each to suppress summer annual weeds in the subsequent double- or relay-crop. Additional work to refine agronomic best management practices to maximize crop canopy, and the identification of additional chemical, physical and cultural tools to minimize weed interference are critical for the commercial success of each crop.