SAREP, USDA-ARS cooperate on sustainable vineyard floor management research

SAREP's Associate Director Jenny Broome, cover crop analyst Robert L. Bugg, and Kendra Baumgartner of the USDA-Agricultural Research Service (ARS) are teaming up to develop sustainable practices for vineyard floor management. This new ARS-UC cooperative agreement allows SAREP to hire two new staff members for the project, Lissa Veilleux and Xiaomei Cheng, who are working on the research with wine industry cooperators Mitchell Klug and Daniel Bosch of Robert Mondavi Winery.

The California winegrape industry played a key role in creating the new ARS sustainable viticulture position housed at UC Davis. Baumgartner, a UC Davis plant pathology graduate, was hired a year ago for the ARS position; with these new funds she and her lab will be able to target weed management challenges for the industry.

Vineyard floor management practices include weed control and cover crop management, which typically are carried out in different parts of the vineyard floor. Weed control is focused on the vineyard floor directly beneath grapevines, in an effort to prevent weeds from competing with grapevines for water and nutrients and to keep climbing weeds from growing up into the grapevine canopy where they interfere with harvest. Cover crops are planted and managed in the vineyard middles (between rows of grapevines) to reduce soil erosion from winter rains, to improve soil chemical and physical properties, and/or to attract and support beneficial predatory insects.

Weed control in California vineyards frequently relies on the use of preemergence herbicides. Preemergence herbicides remain active in the first few centimeters of soil for up to a year. While their persistence in the soil makes them effective against weed species that germinate months after herbicide application, this characteristic also makes them more likely to contaminate groundwater than contact herbicides. Most research on weed control in vineyards has focused on evaluating the efficacy of different herbicides; less research has been done on non-chemical alternatives. One objective of this research is to compare the efficacy of chemical, mechanical, and cultural weed management practices and evaluate how these practices affect weed population dynamics over time. The effects of weed management practices on soil chemical and physical properties and on grapevine growth and yields will also be monitored.

Cover crop management is often used to modify soil chemical, physical, and biological properties. The extent to which modifications to the soil in the vineyard middles actually impact the soil in the vineyard rows and the grapevines likely depends on the proximity of grapevine roots to the cover crops. A second objective of this research is to study the effects of vineyard cover crops on grapevine fine root distribution, nitrogen availability, soil organic matter, and arbuscular mycorrhizal fungi.