Five weed management systems utilizing combinations of cover crops, herbicides, and cultivation were tested in potato in 1994 and 1995 in central Washington. A standard herbicide treatment of metribuzin applied preemergence (PRE) at 0.4 kg ai/ha (standard herbicide weed management system [STD]) was compared with (1) fall-planted winter rye followed by metribuzin at 0.4 kg/ha applied in a band in the potato hill, followed by reservoir tillage (rye cover crop with herbicide-banded and reservoir-tilled weed management system [RYESTD]); (2) cultivation with tine-tooth harrow followed by hilling with shovels and rolling cultivators (total-cultivation weed management system [CULT]); (3) fall-planted rapeseed followed by reservoir tillage (rapeseed cover crop and reservoir-tilled weed management system [RPSD]); and (4) reservoir tillage alone (reservoir-tilled weed management system [RESTIL]). In both years, early-season weed density and final weed biomass were lower in the STD, RYESTD, and CULT systems than in RPSD and RESTIL. Total tuber yield and yield of U.S. #2 or better were greatest in the RYESTD and STD systems in both years. The CULT system reduced early-season weed densities, but tuber yield was reduced 15% in 1994, and yield of U.S. #2 or better was reduced 25% in 1995 compared with the STD system. The RPSD system reduced early-season in-row weed density from 60 to 70% and final weed biomass from 29 to 40% compared with a nontreated check, i.e., a no–cover crop, no-cultivation, no-herbicide weed management system, but tuber yield was 27 to 30% lower than in the STD system. The RYESTD system was an effective alternative weed management strategy that controlled weeds, decreased PRE-applied herbicide inputs 66%, and maintained tuber yield.

Nomenclature: Metribuzin; potato, Solanum tuberosum L.; rapeseed, Brassica napus; rye, Secale cereale L.

Additional index words: Banding, cover crops, cultivation, integrated weed management, glyphosate, reservoir tillage, tillage.

Abbreviations: BR, between row; CHECK, no–cover crop, no-cultivation, no-herbicide weed management system; CULT, total-cultivation weed management system; IR, in row; PRE, preemergence; RESTIL, reservoir-tilled weed management system; RPSD, rapeseed cover crop and reservoir-tilled weed management system; RYESTD, rye cover crop with herbicide-banded and reservoir-tilled weed management system; STD, standard herbicide weed management system.