Use of Protective Covers to Reduce Fungicide Usages in Organic Wine Grape Production in Virginia

View the project final report

Commodities

• Fruits: grapes

Practices

• Pest Management: prevention, fruit bags to mitigate plant diseases by protection

The recent economic impact study on the VA wine industry showed an annual contribution of $1.3 billion dollars to the state’s economy. The total acreage of certified organic grape production has increased from 12,575 acres in 1995 to 38,664 acres in 2011. However, only three Virginia vineyards have been approved by the USDA for their organic management practices for wine grape production, and only one has a winery. The main reason why organic wine grape production is not common in VA or any other states located the east of Rockies is fungal diseases, which are driven by frequent rain events during summer months. Thus, the Nita lab has established two experimental vineyards with financial aid from the USDA/NIFA VDACS Specialty Crop Research Initiative Block Grant in 2012. Although we identified several cultivars that may do well with the organic practice, there are two big challenges: a disease called black rot, which none of the OMRI-certified chemicals works sufficiently, and a potential loss of copper fungicides due to a trend of tighter regulations in other countries. Rather than searching for other chemical components, which is usually in the hands of chemical companies, what we proposed is the use of paper bags or umbrellas to individually protect grape clusters. The experiments were conducted in two experimental vineyards in AHS AREC, Winchester, VA, and a commercial vineyard in North Garden, VA in 2017 and 2018. We found that the application of the fruit bag can reduce the incidence and severity of black rot up to 90% when it was applied around when grape berries are less than 1 cm in diameter. In addition, we found a combination of a biological control agent Double Nickel and a polyoxin-D, both are approved by the OMRI, are effective, especially when we used them with the fruit bag. Results from our study will help organic wine grape growers to have alternative tools to increase their sustainability.

1. Determine the efficacy of paper bags and umbrellas against the development of multiple fungal diseases on wine grape cluster grown with organic practices
2. Determine the timing of bagging/umbrella application for the optimal disease control
3. Examine the efficacy of different paper bags
4. Examine the economic benefits and hurdles of using the individual cluster protection method.