Control of Botrytis by Compost Tea Applications on Grapes in Oregon Vineyards

Project Overview

SW00-039
Project Type: Research and Education
Funds awarded in 2000: $141,572.00
Projected End Date: 12/31/2003
Region: Western
State: Oregon
Principal Investigator:
Shepard Smith
Sunbow Farm/Soil Foodweb Inc
Co-Investigators:
Elaine Ingham
Soil Foodweb Inc/ Southern Cross University
Elaine Ingham
Sustainable Studies Institute

Annual Reports

Commodities

  • Fruits: grapes

Practices

  • Animal Production: probiotics
  • Crop Production: biological inoculants, foliar feeding, nutrient cycling, organic fertilizers, application rate management
  • Education and Training: on-farm/ranch research
  • Farm Business Management: feasibility study
  • Natural Resources/Environment: biodiversity, indicators, soil stabilization
  • Pest Management: biological control, compost extracts, prevention
  • Production Systems: agroecosystems, holistic management, integrated crop and livestock systems
  • Soil Management: composting, soil analysis, nutrient mineralization, organic matter, soil quality/health
  • Sustainable Communities: new business opportunities, sustainability measures

    Abstract:

    Use of Foliar Compost Tea Applications to Protect Against Fungal Diseases

    Use of foliar applications of compost tea to control mildew and botrytis was successful in reducing fungicide applications by 85% to 93% in both 2001 and 2002. Both years exhibited unusually intense mildew incidence, but low botrytis incidence. In 2001, the weekly plot in one vineyard required no fungicide application, while untreated controls showed mildew outbreaks by the second or third week of June, and were put into tea treatments immediately and were not repeated in year two. In both years, in the bi-monthly compost tea treatments, mildew outbreaks occurred in the last week of August or the first week of September. The outbreak spread from the bi-monthly treatment to the weekly tea treatment. Mildew outbreaks were controlled by fungicide (potassium hydroxide) application in both years. In severe mildew years, it would be reasonable to apply fungicide in the last week of August, while using compost tea containing adequate fungal biomass the rest of the summer. Once the outbreak of mildew was controlled by fungicide, compost tea was adequate in controlling mildew and botrytis. Initial lab studies showed that control of botrytis required a minimum of 5% fungal biomass to be applied to the leaves, and that this level of fungal coverage on leaf surfaces required a minimum of 2 ug of active fungal biomass per ml of compost tea. Foliar applications of compost tea alone were not adequate to completely replace use of fungicides. Use of other chemical applications (Roundup, copper sulfate) in the vineyard prevented any improvement in soil life, even though foliar fungicide applications were reduced. Maintaining quality tea production, based on adequate fungal biomass in the tea was difficult. Maintaining aeration was critically important in preventing bacteria from attacking and consuming fungi in the tea. The machine used was critically important. In year one, the compost tea machine used was difficult to clean (up to two hours to clean; the machine is no longer commercially available), while in the second year, the machines used took only 20 minutes to routinely clean. Effects of different recipes on tea biology were assessed, showing that fungal foods were required to obtain the fungal component on the leaf surface that would allow adequate coverage and protection of the plant surfaces from pathogen growth. The likely mechanism of action was coverage by the non-pathogen organisms, and growth of these organisms, thus leaving no space or food or un-occupied infection sites free for pathogen growth.

    Project objectives:

    To assess the ability of different compost teas to reduce disease in grapes.

    The proposal was to focus on botrytis, but in the two years of the study, botrytis was not a significant disease factor. Mildew was a significant factor, and thus, this became a study of whether compost tea could control mildew, instead of botrytis.

    This study focused on foliar applications of compost tea alone, without any attempt to alter the soil or the litter in the vineyards.

    Can disease control be obtained with just foliar applications of the needed biology — biology that has disappeared and no longer exists in the vineyards because of the toxic chemical applications and high fertilizer use in previous years and that may still be on-going in these orchards?

    One objective was to assess recipes for compost tea to improve fungal biomass in the tea, to achieve the results seen in the lab studies.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.