California: Sheep Weed Vineyards

Sheep have an image that paints them as followers, woolly headed thinkers who can't make up their one mind, well this may be apt but sheep can be trained to weed vineyards and leave the grapes alone.

Sheep are capable of doing more than providing us with sweaters for our bodies and meat for our stews. Researchers working, out of the University of California, are training sheep to weed vineyards and to leave the grapes alone. Using the sheep reduces the need to use herbicides to remove the weeds and as long as the sheep do not develop a taste for the grape this will eliminate the need for tractors and reduce gasoline use. Sheep are well known for their appetite. They are not fussy and do love to tuck into a good meal which for them covers a wide menu. If left to their own devices the sheep would eat the weeds and the grapes too, thereby swallowing the profits. To keep sheep focused on the weeds and leave the tempting grapes alone, Morgan Doran, a researcher at the University of California, and his colleagues are using aversion therapy and other techniques in an experiment to teach the sheep to munch weeds only. If the team is successful then sheep ranchers get another market for their product, they can rent them out as organic weed whackers and vineyard managers get another crop management tool they can use to maintain their fields. Sheep are relatively easy to teach, according to Doran he believes that sheep have an unfair reputation as being woolly minded, when in fact they are very good at what they do. This ability to recognize the strengths that exist can lead to breakthroughs, in a variety of fields, as long as you are also aware of the existing weaknesses. It is always shortsighted to label any being by one characteristic without looking at the whole picture. Sheep are consummate eaters. They eat all day long.

"Everything that we're doing is based on their skills at eating different foods and detecting different flavors and associating positive or negative effects of those foods with different flavors. Doran

The basis of Doran’s work rests on the recommendations about aversion therapy techniques that have been developed by an animal behaviorist at Utah State University. The project began with sheep that have never tasted grapes. The sheep were left free to do their thing and munched away on grape after grape after grape. The next step was to give the sheep a small dose of lithium chloride, which leaves the sheep feeling queasy but does not have any outward signs. The sheep were divided into groups and some sheep got the dose in liquid form, some in capsules and two other groups of sheep got placebos to serve as a control. According to Doran, the sheep that were dosed left the grapes alone when they were set loose in an experimental vineyard. The experimental vineyard is located at the UC Hopland Research and Extension Center south of Ukiah. It is possible that sheep have grape preferences. The sheep who did not receive the dosage and who ate the grapes showed a preference for chardonnay, but did not touch a red grape known as aglianico. Who said chardonnay does not go with mutton? For vintners who use untrained sheep, which are still good weeders, it is important to put them to work in the colder months when the grape vines are dormant. Miniature breeds have been tried, breeds that are only able to reach the weeds and not the grapes but these miniatures are expensive and in short supply. Not everyone agrees that it is essential to use aversion therapy to have sheep perform a function as weeders. The owner of Wooly Weeders, Don Watson is one. Watson uses sheepherders and sheep dogs to keep the sheep moving once they have devoured the weeds. Watson uses sheep in the vineyards only at specific times of the year, for example, when the berries are at their most astringent and unpalatable to the animals. The use of lambs rather than full grown sheep is another technique that Watson employs.

"It's better to take a more direct route, observe animal behavior and merely adapt our management to suit that behavior," Watson

Doran and his co-workers are seeking to develop an alternative to lithium chloride and naturally occurring tannins are one direction in which they are focusing their efforts. The team is also looking at how soil and grape quality are affected by sheep and of course it is important to remember that sheep are good fertilizer providers. The co-owner of Navarro vineyards in Mendocino County's Anderson Valley, Sarah Cahn Bennett, is interested to see how the training comes out. Bennett says she is more comfortable using a natural agent to produce the aversion. Weed removal at Navarro is either done by hand or by tractor no herbicides or pesticides are used. Navarro does use sheep but has found that it takes considerable management and that the sheep can’t be employed in every setting.