Submitted to: Western Society of Weed Science Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/1/1993
Publication Date: N/A
Interpretive Summary: Options for mechanical and chemical weed control in potato production are limited. Fall planted winter wheat was evaluated as a cover crop to suppress weeds in potatoes. Wheat was killed at various times in the spring with glyphosate, and potatoes were planted in standing wheat residue. Killing the wheat after potato planting controlled weeds better than killing the wheat earlier in the spring, but the wheat delayed potato emergence and reduced potato growth and yield severely. The presence of wheat residue suppressed weeds at Aberdeen, ID, and Prosser, WA, but in general, weed control was not acceptable and the presence of weeds and wheat reduced U.S. #1 potato yields from 48 to 99%.
Technical Abstract: Weeds are an economically important problem in potato production in the Pacific Northwest, but options for mechanical and chemical weed control are limited. Winter wheat is an effective competitor with summer annual weeds that infest potato fields in Washington, Oregon, and Idaho. Therefore, studies using a winter wheat cover crop system for weed control in potatoes were conducted at Aberdeen, ID, and Prosser, WA. Fall-planted 'Weston' winter wheat was killed chemically at various times after planting potatoes the following spring. In 1992, winter wheat competed well with weeds and reduced weed biomass 52 to 97%, depending on treatment. However, the wheat cover crop competed with the potato crop, delaying emergence, reducing potato growth, and reducing U.S. #1 tuber yields 21 to 97%. In 1993, the spring was much wetter than normal and the wheat cover crop system did not control weeds as well as in 1992. Weed biomass was reduced 19 to 94% at Aberdeen and 3 to 32% at Prosser. U.S. #1 yields were reduced 48 to 99% by the combination of weed and cover crop competition. In addition to the cover crop trials, 35 necrotic hybrids were evaluated for general and specific combining ability of the hybrid necrosis trait. Hybrids between a parent carrying the strong allele and one carrying the moderate allele produced the optimum combination of strong early season vegetative growth followed by strong senescence.