An early-killed rye (Secale cereale) cover crop has potential for weed management in edamame (Glycine max)

Authors: CRAWFORD, LAURA - University Of Illinois; Williams, Martin; WORTMAN, SAM - University Of Nebraska

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2018
Publication Date: 2/27/2018
Citation: Crawford, L., Williams, M., Wortman, S. 2018. An early-killed rye (Secale cereale) cover crop has potential for weed management in edamame (Glycine max). Weed Science. 66(4):502-507. doi.org/10.1017/wsc.2018.5.
DOI: https://doi.org/10.1017/wsc.2018.5

Interpretive Summary: Domestic production of edamame, the vegetable version of soybean, continues to be threatened by weed interference. Although progress has been made in recent years on the registration of several herbicides for use on edamame, non-chemical weed management tactics are needed to combat herbicide resistance. Studies were conducted to identify a cover crop residue management system that provided weed suppression without negatively affecting edamame emergence. Three years of field experiments revealed that a fall-planted, spring-terminated cereal rye cover crop holds promise for managing weeds in edamame. The impact of this research is that it will guide the use of cover crops in the development of integrated weed management systems in edamame.

Technical Abstract: The potential role of fall-seeded cover crops for weed management in edamame is unknown. Field experiments were conducted over three edamame growing seasons to test the following objectives: 1) determine the extent to which cover crop residue management systems influence edamame emergence while selectively suppressing weed fitness, and 2) determine if cultivars differed in emergence in cover crop residue management systems. Cover crop treatments included a winter-killed oilseed radish, two canola treatments (early-killed and late-killed), two cereal rye treatments (early-killed and late-killed), and a bare soil control. Two spring timings of a herbicide burndown application created ‘early-killed’ and ‘late-killed’ treatments for canola and rye. Twelve soybean cultivars were tested, including 11 edamame cultivars differing in seed size and a grain-type soybean control. Spring residue biomass in cover crop treatments ranged from 43.8 g/m2 for winter-killed radish to 900.3 g/m2 for late-killed rye. Cultivars responded similarly to cover crop treatments, and, with the exception of late-killed rye, cover crop treatments resulted in similar crop emergence as the bare soil control. While all cover crop treatments reduced weed biomass six weeks after planting compared to the bare soil, winter-killed radish and both canola treatments increased weed density. Early-killed rye has potential for weed management in edamame, as evidenced by the fact that the treatment did not interfere with planting or crop establishment, yet reduced weed density 20% and suppressed early-season weed growth 85%.