A common food product, famous for its smorgasbord of uses in everything from the home to health to lawn care, has been found to be an effective herbicide in vegetable and high-value fruit production.

Vinegar, known to knock out a weed or two on the lawn, can also kill off ground cover to make way for the planting of vegetable crops, based on Ohio State University research results in first-year demonstration plots at Ohio State's South Centers at Piketon.

The significance of the results is that organic vegetable growers now have an alternative to chemical use.

Rafiq Islam, a soil and water specialist with Ohio State's South Centers, said that growing ground cover (annual rye, clover, wheat, hairy vetch, for example) is a common practice in vegetable production because the cover crops as mulch suppress weeds, reduce evaporation, control surface runoff and soil erosion, and fix atmospheric nitrogen for crops to use, eliminating the need to add chemical fertilizers. Before vegetables are planted, ground cover is normally mowed down or killed by herbicides.

"We found that the vinegar does a great job in killing off the ground cover without hurting the vegetable plants and without affecting yields from residual vinegar," said Islam. "So in high value crop production, or even in the home garden, vinegar may be used as a unique option to chemicals in organic production."

Researchers set up three small plots with winter Wheat as the ground cover, followed by a planting of such vegetables as tomatoes and squash. One plot was treated with Round-Up, one plot was mowed and a third was given a one-time treatment of commercial vinegar. Results showed that vinegar had the same impact on ground cover as the herbicide. Additionally, "laying" down the ground cover before treatment (that is, breaking the stems at ground level) increased the kill rate.

"Laying down the ground cover kills 50 percent to 60 percent of the Wheat plant. Vinegar does a good job of taking care of the rest," said Islam. "And the Wheat residue left over makes good mulch."

Islam said that the acidic nature of vinegar (4 percent acetic acid) is what makes it an ideal organic herbicide. The fact that it's a cheap alternative helps as well.

"All you need to do is make a one-time application of a quart of vinegar using a standard spray bottle," said Islam. "And vinegar can be found anywhere. We got ours at the Wal-Mart down the road."

Islam added that vinegar should be appled in the late afternoon to be more effective for killing cover crops.

Researchers plan to replicate the experiment next year.

Date: 7/19/05