WOOSTER, Ohio – An alternative method for protecting rootstock while controlling weeds and promoting environmental sustainability may be available to grape producers, specifically those who grow the crop in cold climates.
Ohio State University scientists with the Ohio Agricultural Research and Development Center have found that herbicide-treated mulch, popular in the green industry for its myriad of environmental and production benefits, is proving successful in vinifera grape production. Vinifera grape varieties are used to make wine.
"Vinifera grapes produced in the United States have to be grafted onto an insect-resistant root stock to grow and stay healthy. That graft union must be protected from the cold weather and to do that growers usually cover the graft union with a layer of soil in the fall," said Doug Doohan, an OARDC weed ecologist. "However, over time the organic matter of the soil degrades, the soil complicates weed control and any vineyards situated along hillsides become severely eroded."
Researchers replaced the layer of soil with a layer of mulch (either wheat straw or shredded bark), sprayed the mulch with an herbicide, and discovered a whole host of benefits that the soil couldn't provide.
The mulch did a better job at protecting the grape vines from frigid temperatures and helped conserve moisture for later use by the plants. The herbicide application enhanced weed control and the mulch/herbicide combo reduced the amount of leaching and soil runoff. In addition, researchers found that yields had improved, mostly likely because of the increase in organic matter, and, curiously, the quality of the juice improved as well.
"For grape growers who want to demonstrate sustainability and produce a successful crop, this is a system they can use," said Doohan, who also holds an Ohio State University Extension appointment. "This approach is useful anywhere freezing temperatures threaten the life of the grape vine."
The study, "Herbicide-Treated Mulch May Reduce Soil Erosion and Pesticide Off-Site Movement in Vinifera Vineyards," was recently reported at the 2009 Ohio Grape and Wine Conference and at the 34th Annual Eastern Section Conference of the American Society for Enology & Viticulture. The abstract was published in the December 2009 issue of the American Journal of Enology and Viticulture. The four-year research was funded by the Ohio Grape Industries Committee.
Doohan said that the study is a jumping off point for future research.
"One of the outstanding questions from the study is the cost of implementing the alternative system, which compared to the traditional method is much more expensive in basic cost and inputs," said Doohan. "But the indirect savings -- from reduction of soil erosion to the reduction of leaching to savings in herbicide applications -- needs to be calculated."
Other researchers involved in the study include OARDC viticulturist Imed Dami, OARDC soil microbiologist Warren Dick, and OARDC research assistant Linjian Jiang.