The use of allelopathic cover crops in dry bean (Phaseolus vulgaris L.) cropping systems may provide an ecological alternative to chemical weed control. Winter rye (Secale cereale L.) was spring planted with dry bean in field experiments at two locations near Lansing, MI in 2006. The effects of rye planting time, herbicide application, and dry bean row spacing on weed suppression and dry bean yield were determined. Two rye planting timings were examined, early planting (7 DBP) and simultaneous planting (0 DBP). Three chemical control strategies were examined: no control, broadleaf chemical, and broad-spectrum chemical. The experiments were each arranged in a complete factorial design. All rye treatments suppressed weed shoot biomass compared to plots with no rye. Early rye plantings were more effective at suppressing weed biomass than simultaneous plantings when compared to plots with no rye. Early rye plantings reduced weed shoot biomass by between 51-98% compared to plots with no rye. Simultaneous rye plantings reduced weed shoot biomass by between 30-96% when compared to plots with no rye. Early plantings of rye reduced dry bean yields by 50-98% compared to plots with no rye. Simultaneous plantings of rye decreased dry bean yields by as much as 98% yet also increased yields in one treatment by as much as 37% compared to plots with no rye. The results of the first year of this study indicate that spring-seeded rye has the potential to greatly reduce both weed biomass as well as dry bean grain yield. Additionally, if rye is controlled by herbicide application, dry bean grain yields may be comparable to yields in monoculture dry bean cropping systems.
Abbreviations: DBP, days before planting.