Cover Crops Suppression of Palmer Amaranth (Amaranthus palmeri) in Cotton

With the recent confirmation of protoporphyrinogen oxidase (PPO)-resistant Palmer amaranth in the US South, concern is increasing about the sustainability of weed management in cotton production systems. Cover crops can help to alleviate this problem, as they can suppress weed emergence via allelochemicals and/or a physical residue barrier. Field experiments were conducted in 2014 and 2015 at the Arkansas Agricultural Research and Extension Center to evaluate various cover crops for suppressing weed emergence and protecting cotton yield. In both years, cereal rye and wheat had the highest biomass production, whereas the amount of biomass present in spring did not differ among the remaining cover crops. All cover crops initially diminished Palmer amaranth emergence. However, cereal rye provided the greatest suppression, with 83% less emergence than in no cover crop plots. Physical suppression of Palmer amaranth and other weeds with cereal residues is probably the greatest contributor to reducing weed emergence. Seed cotton yield in the legume and rapeseed cover crop plots were similar when compared with the no cover crop treatment. The seed cotton yield collected from cereal cover crop plots was lower than from other treatments due to decreased cotton stand.