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ARS Home » Research » Publications at this Location » Publication #121285


item Boydston, Rick
item Vaughn, Steven

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2001
Publication Date: 3/1/2002

Interpretive Summary: Public concern with undesirable environmental impacts of pesticides has led to increased emphasis on reducing pesticide use in crop production systems. More U.S. potato acres are treated with the herbicide metribuzin than any other pesticide, and over 90% of the PNW potato acreage is treated with herbicides. Use of cover crops in crop rotations has many benefits including weed suppression. Brassica and rye green manures used alone or combined with low input chemical control have shown potential for providing control of weeds, nematodes, and soil-borne diseases. This study evaluated potato yield and weed control using several weed management systems that combine weed suppressive fall-planted cover crops, cultivation, reservoir tillage, and band-applied herbicides to reduce herbicide inputs in potatoes. Combining cultivation, a rye cover crop, and banded herbicides controlled weeds in potatoes and prevented yield losses associated with weeds, while reducing metribuzin input by 66%. The standard herbicide system controlled weeds and prevented potato tuber yield losses and would be the easiest and least cost system for growers to implement. However, the many known benefits of cover crops would not be realized in the standard herbicide system. Rapeseed residues combined with reservoir tillage did not adequately suppress weeds enough to prevent potato tuber yield loss, but controlled weeds and prevented potato tuber yield losses more than the no herbicide and no cover crop systems. Cultivation alone controlled weeds early in the growing season, but potato yield was reduced and input costs were substantially higher than the standard herbicide system. The rye system consistently controlled weeds, decreased preemergence applied herbicide inputs 66%, and maintained potato yield.

Technical Abstract: Five weed management systems utilizing combinations of cover crops, herbicides, and cultivation were tested in Russet Burbank potatoes in 1994 and 1995 near Paterson, WA. A standard herbicide treatment of metribuzin applied preemergence at 0.4 kg ai/ha (STD) was compared to: 1) fall-planted cover crop of winter rye followed by metribuzin at 0.4 kg/ha applied in a 29 cm band in the potato hill, followed by reservoir tillage between rows (BR)(RYESTD); 2) cultivation with tine tooth harrow at potato emergence followed by hilling with shovels and rolling cultivators (CULT); 3)fall- planted cover crop of rapeseed followed by reservoir tillage BR(RPSD); and 4) reservoir tillage BR(RESTIL. In both years, the STD, RYESTD, and CULT systems reduced early season weed density and final weed biomass greater than RPSD and RESTIL treatments. Total potato tuber yield and yield of U.S. #2 or better were greatest in the RYESTD system and STD system in both years. CULT system reduced early season weed densities, but potato yield was reduced 15% in 1994 and yield of U.S. #2 or better was reduced 25% in 1995 compared to STD. The RPSD system reduced early season in row (IR) weed density in potatoes from 60 to 70%, and final weed biomass from 29 to 40% compared to a nontreated check (CHECK), but remaining weeds reduced potato yield 27 to 30% compared to STD. RESTIL reduced early season BR weed densities, but not IR weed densities, which reduced potato tuber yield 40 to 77% compared to the STD system. Potato yields in CHECK were reduced 63 to 86% compared to STD system. The RYESTD system was an effective alternative weed management system, which consistently controlled weeds, decreased preemergence herbicide inputs 66%m and maintained potato yield.