Effects of a fall rye cover crop on weeds and productivity of Phaseolus beans.

Fall-seeded rye (Secale cereale) is known to suppress weeds through physical and allelopathic properties. This study examined effects of fall rye cover crops on weeds and dry bean (Phaseolus vulgaris) productivity over four site-years in Manitoba. In addition to rye, we tested early versus later spring rye termination time as well as herbicide use in a factorial experiment with 4 replicates. In the absence of herbicides, rye reduced early season broadleaved and grassy weed plant populations by 44% to 72% and 43% to 88%, respectively. Terminating rye at the four leaf stage (~1100 kg dry matter/ha) provided the same level of weed suppression as termination at booting (~3100 kg dry matter/ha). Early rye termination increased bean plant populations (significant at 3 of 4 sites), bean development (4 of 4 sites), bean biomass (2 of 4 sites) and bean yield (3 of 4 sites) compared with later termination. Lower bean yield with rye at one site-year was attributed to dry early season conditions where rye reduced soil water content. While the rye cover crop provided multiple benefits to bean production, early termination resulted in the best agronomic outcome. Rye was beneficial to weed control even where herbicides were used.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author