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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #218854
Title: COVER CROP SYSTEMS AFFECT WEED COMMUNITIES IN A CALIFORNIA VINEYARD

Author
item Baumgartner, Kendra
item Steenwerth, Kerri
item VEILLEUX, LISSA - USDA, ARS, CPGRU

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2008
Publication Date: 8/1/2008
Citation: Baumgartner, K., Steenwerth, K.L., Veilleux, L.M. 2008. COVER CROP SYSTEMS AFFECT WEED COMMUNITIES IN A CALIFORNIA VINEYARD. Weed Science. 56:596-605.

Interpretive Summary: In order to determine if cover crops favor certain weeds in California vineyards, we surveyed weed communities after planting four cover crop treatments: no-till annuals (rose clover, soft brome, zorro fescue; ANoT), no-till perennials (blue wildrye, California brome, meadow barley, red fescue, yarrow; PNoT), tilled annual (triticale; AT), and a no cover crop tilled control (NoCT). The study was carried out for three years in the section of soil between the vines (interrows) of a wine grape vineyard. Roundup (Glyphosate) was used to kill weeds directly beneath the vines, in the intrarows. Treatments significantly impacted weed growth, and the diversity of weed species in the interrows. Statistical analyses showed that tillage, and not the presence of a cover crop, impacted weed growth in the interrows. In the interrows, tillage favored two weeds (scarlet pimpernel and spiny sowthistle), and discouraged another species (California burclover). Our findings of no significant effects of the cover crop systems on weed biomass, community structure, or diversity in the intrarows demonstrate that the impacts the cover crop management systems had on the interrows did not carry over to adjacent intrarows. In addition, the fact that the cover crops did not affect vine yield, growth, or nutrition relative to the no cover crop control suggests that cover crops are likely to minimize soil erosion from winter rains, which is the primary purpose of vineyard cover cropping in northern California, without adversely affecting vine health or weed control.

Technical Abstract: Vineyard weed communities were examined under four dormant season cover crop systems representative of those used in the north-coastal grape-growing region of California: no-till annuals (rose clover, soft brome, zorro fescue; ANoT), no-till perennials (blue wildrye, California brome, meadow barley, red fescue, yarrow; PNoT), tilled annual (triticale; AT), and a no cover crop tilled control (NoCT). Treatments were arranged in a RCBD with four replicate blocks, and carried out for three years in the interrows of a wine grape vineyard. Glyphosate was used to control weeds directly beneath the vines, in the intrarows. Treatments significantly impacted weed biomass, community structure, and species diversity in the interrows. Orthogonal contrasts showed that tillage, and not the presence of a cover crop, impacted interrow weed biomass. Distance-based redundancy analyses (db-RDA) revealed significant effects of the cover crop systems and of tillage on weed community structure in the interrows. For scarlet pimpernel and spiny sowthistle, the combination of ANOVA and orthogonal contrasts confirmed their association with the tilled treatments, as revealed by db-RDA. This same approach identified the association between California burclover and the no-till treatments. Our findings of no significant effects of the cover crop systems on weed biomass, community structure, or diversity in the intrarows demonstrate that the impacts the cover crop management systems had on the interrows did not carry over to adjacent intrarows. In addition, the fact that the cover crops did not affect vine yield, growth, or nutrition relative to the no cover crop control suggests that cover crops are likely to minimize soil erosion from winter rains, which is the primary purpose of vineyard cover cropping in northern California, without adversely affecting vine health or weed control.