- Fruits: grapes
- Crop Production: cover crops, intercropping
- Education and Training: demonstration, extension
- Farm Business Management: budgets/cost and returns, feasibility study
- Pest Management: chemical control, economic threshold, field monitoring/scouting, cultivation, row covers (for pests), trap crops, traps
The California grape industry requires new economically competitive options for insect control to help reduce pesticide reliance and promote sustainable pest management. This proposal intends to investigate nectar cover crops (buckwheat and cahaba vetch) for grape pest management in southern California, including an evaluation of how these cover crops can be practically incorporated into the Code of Sustainable Winegrape Workbook. The potential outcomes of this project are relevant to Western SARE goals by investigating sustainable grape production that reduces grower reliance on insecticides, by potentially increasing profitability via reduced inputs and by providing growers with a unique marketing advantage.
This three-year project aims to determine:
(1) If sowing buckwheat and vetch between vine rows enhances spring and summer populations of natural enemies, promotes natural enemy recruitment, retention, and dispersal, reduces pest populations below economic thresholds, influences grape yield and quality, and affects vine vigor. Field trials will be conducted in a wine grape vineyard in Temecula and a table grape vineyard in Coachella Valley over two years. The number of natural enemies and grape pests will be monitored from April - September using visual counts and weekly sticky card catches. The economic thresholds suggested in CSWW will be used to determine whether cover crops reduce leafhopper and spider mite densities to acceptable levels, and data on fruit yields and Brix levels will be taken. Impacts on other pest species (e.g., mealybugs) will be compared statistically across treatments.
(2) How many rows require cover crops for pest control by investigating the rate of dispersal of natural enemies from buckwheat plots.
(3) When to sow buckwheat and vetch to maximize nectar availability for natural enemies.
(4) If buckwheat and vetch can out-compete unwanted weed species.
This project will complement previous research on cover cropping in vineyards by focusing on arboreal pest management rather than soil quality and nutrition. Our proposal will be the first cover crop study conducted in southern California, and the first to investigate the use of cahaba vetch for natural enemy enhancement, a plant that has been shown to reduce nematode populations in vineyards and to increase soil quality. This proposal is an important study that will contribute to the UC SAREP cover crop database and CSWW. Results will be available to growers and advisors through four major websites, presentations at key grower meetings and conferences and two ‘demonstration field days’ held in both Temecula and Coachella Valley. A color leaflet will be distributed to growers and advisors through grower meetings, while Cooperative Extension Specialists Carmen Gispert, Mark Hoddle and Nick Toscano, plus PCAs Ben Drake, Linda Kissam (Temecula Winegrowers Association) and Cliff Ohmart (Lodi Woodbridge Winegrape Commission) will also support outreach and education.
The potential short-ranged outcomes from this proposal include increasing awareness and knowledge of using cover cropping for pest control in the grape community, promoting profitability by reducing pesticide and nutritional inputs, contributing to cover crop knowledge data bases and CSWW. The potential medium-range outcomes include adoption of cover cropping practices by growers as part of IPM programs, reduction of pesticide inputs, lessening the detrimental effects of pesticides on the environment and human health,and increasing the profitability of grape growers by reducing pesticide inputs and subsequent advertisement of utilization of environmentally sustainable pest management strategies.
An evaluation plan will calculate the pounds of reduced pesticide use and associated cost savings, determine whether cover cropping is economically viable, record meeting attendance rates and pamphlet outreach, determine if objectives and educational products are produced within the prescribed given timeframe and determine grower adoption rates and percentage reduction of overall pesticide inputs.
Project objectives from proposal:
- Determine if buckwheat flowers and cahaba vetch extrafloral nectaries increase longevity and fecundity of key natural enemies. Determine when to sow cover crops to maximize nectar availability for natural enemies. Determine if buckwheat and cahaba vetch, sown in alternate rows, enhance natural enemy populations and reduce pest populations below economic thresholds in Coachella Valley and Temecula over two years. Determine if buckwheat and cahaba vetch influence grape yield and quality. Determine if buckwheat and cahaba vetch affect vine vigor. Verify that buckwheat and cahaba vetch do not provide refuge for grape pathogens (e.g., Xylella) or pathogen vectors (e.g., sharpshooters). Determine if buckwheat and vetch out-compete unwanted weed species. Determine the rate of dispersal of natural enemies from buckwheat and cahaba vetch plots. Extend the information gained from this research to the Californian grape community through outreach and education. Promote increased adoption of nectar cover cropping practices in Temecula, Lodi and Coachella Valley if research results merit application.