Researchers at the University of California, Davis are training sheep to weed vineyards. In most cases, sheep will eat the fruit in addition to the weeds, so scientists are using aversion therapy to train them not to eat the grapes.
Sheep that have never tasted grape leaves are brought in and allowed to stuff themselves on the vines, after which they are given a small dose of lithium chloride which makes them feel queasy. Sheep that are dosed with the drug generally leave the vines alone.
Others have found success using sheep to weed vineyards even without aversion therapy. They do this by grazing the sheep in cold weather when the vines are dormant or at times of the year when the berries are unpalatable, by using miniature breeds or lambs, or by using sheep herders to keep the sheep away from the vines.
Sheep and goats are increasingly being used to control unwanted vegetation in a variety of situations.
Read article in the Sacremento Bee