EFFECTS OF WEED MANAGEMENT PRACTICES ON ABOVEGROUND AND SEEDBANK WEED COMMUNITIES IN A CALIFORNIA VINEYARD

Authors: VEILLEUX, LISSA - UC-SAREP; Baumgartner, Kendra

Submitted to: American Society of Enology and Viticulture Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2003
Publication Date: 6/18/2003
Citation: Veilleux, L., Baumgartner, K. 2003. Effects of weed management practices on aboveground and seedbank weed communities in a california vineyard. American Society of Enology and Viticulture Annual Meeting Abstracts.

Interpretive Summary: California winegrape growers are under increasing pressure to decrease the use of preemergence herbicides in order to achieve water quality standards established by public regulatory agencies. Alternative weed control practices are available, but their effects on weed ecology are not known. In this study, alternative methods of controlling weeds under the vine were tested for their effects on aboveground weed biomass and numbers of weed seed in the soil. The following treatments were applied under the vine in a commercial vineyard in Oakville, CA USA: 1) fall cultivation + spring cultivation, 2) spring cultivation only, 3) fall cultivation + spring application of Round-up®, 4) fall cultivation + spring application of MatranTM, 5) winter application of Round-up® + spring application of Round-up®, 6) winter application of MatranTM + spring application of MatranTM, 7) cover crop of Idaho fescue and 8) mowing of natural vegetation. Soil quality characteristics and weed seed numbers were sampled before the different treatments were applied. Small differences in soil quality characteristics and weed seed numbers were found between different areas of the field but not between treatments. (This data will be compared to similar data that will be collected in three years to determine if weed control method affects soil quality and weed seed numbers.) Total weed biomass was assessed in the spring. There was lower weed biomass in the winter Round-up® + spring Round-up® treatment compared to all other treatments. There was higher biomass in the spring cultivation only treatment compared to all other treatments, except the natural vegetation treatment. Biomass was similar among all other treatments.

Technical Abstract: California winegrape growers are under increasing pressure to decrease the use of preemergence herbicides in order to achieve water quality standards established by various public regulatory agencies. Alternative weed control practices are available, but their effects on weed ecology are not known. In this study, eight alternatives to preemergence herbicides were evaluated for their effects on aboveground and seedbank weed communities. Research plots were established in a commercial vineyard in Oakville, CA USA in a complete randomized block design with 5 blocks and 8 treatments: 1) fall cultivation + spring cultivation, 2) spring cultivation only, 3) fall cultivation + spring application of Round-up®, 4) fall cultivation + spring application of MatranTM, 5) winter application of Round-up® + spring application of Round-up®, 6) winter application of MatranTM + spring application of MatranTM, 7) cover crop of Idaho fescue (Festuca idahoensis) and 8) natural vegetation. Soil quality characteristics and weed seedbanks were sampled in each treatment plot before treatments were applied. Small differences in soil quality characteristics and weed seedbank composition were found between blocks but not between treatment plots in the preliminary analysis. Peak weed biomass was assessed in the spring. There was significantly lower weed biomass in the winter Round-up® + spring Round-up® treatment compared to all other treatments. There was significantly higher biomass in the spring cultivation only treatment compared to all other treatments, except the natural vegetation treatment. Spring peak biomass was similar among all other treatments.