(Editors Note: The organic production of grapes in eastern U.S. is largely dependant on copper based fungicides for disease control. The copper has plenty of negative effects on the vines, the soil, on humans and on the environment in general as well as on equipment. Thus Ms. Patricia Iubelt sought to identify alternatives to the use of copper containing fungicides in a spray program for wine grapes grown in the east.)
(Editors Note:. Ms. Iubelts experiments were specifically directed at the disease Gwinardia bidwellii (black rot). Black rot is a major disease affecting graper production in Ohio. This disease is said to have decimated vineyards in Ohio in the early and mid eighteenth century. It is then that the use of copper containing fungicides came into use and allowed vineyards to flourish once again. However, constant use of such fungicides led to the accumulation of copper in the soil, killing beneficial microbes and insects and posing the threat of increased levels of toxicity for plants, humans and fish and shoots. Ms. Iubelt mentions that toxicity to vines resulted in foliar injury, reduced growth, and reduced yields. Ms Iubelt further states that conventional commercial synthetic fungicides cause numerous other problems and are developing resistance to the diseases. It is in the backdrop of this situation that Ms Iubelt felt the need to undertake efforts to reduce the use of copper in organic programs and sought to document the effectiveness of microbial inoculants on grape yield, fruit quality (brix), pest and disease incidence, and the quality of micro fauna in the soil. This was to be accomplished by:
1. Enhancing vine and soil health through the use of compost, compost tea, and beneficial organisms in the soil.
2. Removing Over wintering inoculum, which would reduce sporulation.
3. Developing a bio-pesticide spray program to reduce usage of copper containing fungicides.)
Microbial inoculants were produced or purchased and were applied to vineyard sites. The inoculants were made of compost, compost tea, or purchased endomycorrhizal inoculants . Wine was made from the grapes of the plants receiving the inoculants. In December 2004 articles describing the progress made the first year in the project was published on our website, another web site and in a pamphlet for distribution at the Ohio Grape and Wine Short Course.
Two compost tea machines and a centrifugal pump sprayer (best for not destroying microbes while they are being applied) were purchased in the fall of 2003. Quality compost tea was mad eon site. Using composted horse manure, grape pomace, bark mulch , and humus from rotted stumps collected from an undisturbed area of mature hardwood trees at the back of the Maple Ridge Vineyard property. The tea was tested by Soil Foodweb Inc. three times during the summer for microbial populations to verify that the tea applied contained the necessary organisms.
Four different plots were set up in the initial growing season using three replications at each site. The plots were designed to evaluate, vine health, soil health, fruit diseases and foliage diseases in Chardonnay grapes. Fungicides and fertilizers were applied constantly between test rows and control rows.
Experiment number 1 applied compost tea to soil and foliage of mature Chardonnay grape vines throughout the growing season, beginning with a first soil drench in December 2003.
Experiment number 2 inoculated new Chardonnay vines with endomycorrhizal inoculant at planting to both control and test vines. The test vines then received compost tea treatments throughout the growing season.
Experiment number 3 inoculated test Pinot Noir vines with endomycorrhizal inoculant at planting. The control rows were not inoculated Both test and control rows received compost tea treatments throughout the growing season.
Experiment number 4 inoculated mature Chardonnay vines with endomycorrhizal inoculant in the spring of 2004. These vines were conventionally farmed using minimal inputs and integrated pest management techniques, but did not receive compost tea treatments.
IMPACTS AND OUTCOMES
Soil samples were collected and analyzed by Soil Foodweb Inc. prior to any applications. Soil Foodweb Inc. was also consulted about tea ingredients and made recommendations for inoculants according to soil tests. . Since all sites were deficient in vesicular arbuscular mycorrhizae or VAM (mycorrhizal) and fungi , test plots were designed to inoculate this.
After the first growing season , a subsoiler could pass 2” deeper in the rows receiving compost tea since December 2003. Pinot Noir vines inoculated with endomycorrhizae were 25 to 50 percent taller than control vines not inoculated. New Chardonnay vines receiving compost tea treatments were 25 percent taller than control vines. Mature Chardonnay vines receiving compost tea treatments had less diseased leaves and were 5’ taller higher in brix at harvest (Editors note: This indicated a higher quality of grapes). These vines did not require any foliar sprays of copper after August 1st to prevent downy mildew or botrytis. These diseases were controlled with foliar compost tea sprays only. Less foliar phyloxera were noticed in the tea treated vines.
Black rot was the only disease indicator that did not seem to be affected by the compost tea or mycorrhizal applications. Its incidence remained consistent throughout the treatments.
Wines made from compost tea treated vines did not require any further nutrient addition during fermentation beyond the initial yeast starter nutrients. Wines made from grapes of conventional farmers required at least two extra additions of yeast nutrients to prevent the formation of sulfide compounds (rotten egg smell in the wine). Yeast nutrients are composed of nitrates, thiamin, yeast hulls and other components to replace what is missing in poorly nourished grapes.
Treatments will continue next year (2005) after soil analysis. A field day is planned for summer 2005 along with presentations at viticulture courses.
As a result of discussions about this grant at our farmers market stand and with others referred to us by the OARDC, 24 additional growers have shown an interest in the results of the experiments and are interested in applying these methods to their production. My husband, James, and I were also nominated to attend the first Terre Madre in Turin Italy, the food symposium by Slow Food International, where they discussed the experiments with growers from other states and countries