Integration of conservation tillage and herbicides for sustainable dry bean production

Development of conservation tillage practices for dry bean has lagged behind that of many other crops. A field study was conducted to determine the effects of various crop residues and herbicide treatments on weed management and dry bean yield within a zero-tillage system. Main plot treatments included wheat stubble, canola stubble, fall-seeded winter rye, fall-seeded spring rye, and a no-cover control. Subplot treatments included various preplant and POST herbicides. Wheat stubble, canola stubble, and winter rye residue provided sufficient ground cover to prevent soil erosion, and they effectively reduced weed density compared with the no-cover control in all years. Fall-seeded spring rye provided only partial soil-erosion protection and reduced weed density in only 1 of 3 yr. Dry bean emergence was 3 to 5 d slower in the crop residue treatments compared with the no-cover control, but crop density was not adversely affected. However, winter rye residue delayed dry bean maturity by 2 to 6 d. Fall-applied granular ethalfluralin followed by POST bentazon/imazethapyr or imazamox provided the most effective weed control. A sole POST imazamox application also provided good weed control when weed densities were reduced by winter rye residue or wheat stubble. Overall, results indicate that with suitable herbicide programs, similar yields were attained when dry bean was seeded directly into crop stubble or cover crop residues compared with the no-cover control. Information gained in this study will be used to encourage greater farmer adoption of conservation tillage practices for dry bean production on the Canadian prairies.