[NAFEX] Sheep Being Trained to Weed Vineyards (AP)
Brungardt, Sam
Sam.Brungardt at state.mn.us
Wed Jul 11 13:34:04 EDT 2007
Sheep Being Trained to Weed Vineyards
July 11, 2007 - By Michelle Locke, Associated Press
HOPLAND, Calif. -- Call them mutton mowers. University researchers are
training sheep to clean up vineyard weeds but stay off the grapes.
Enthusiastic and unpicky eaters, sheep are already being used in some
vineyards as a green alternative to tractors. They don't use gasoline
and keep down weeds -- a necessary task to deter pests and keep vines
healthy -- sans herbicides.
Unfortunately, sheep will chew up thousands of dollars worth of grapes
if left to their own devices.
That's why University of California, Davis researcher Morgan Doran and
his colleagues are experimenting with aversion therapy and other
techniques to turn sheep into better field hands.
Sheep ranchers get a new market for their flocks while vineyard managers
get "another tool in the tool box," says Doran. "It's a win-win."
But just how do you teach sheep?
It's not as tough as you might think, says Doran, who thinks sheep are
unfairly maligned as wooly minded creatures. They may not be the
brightest lights around, but "they're very good at what they do," he
says.
What they do is eat -- all day, every day.
"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," he says.
Doran's project is based on the recommendations of aversion therapy
techniques developed by an animal behaviorist at Utah State University.
Sheep that had never tasted grape leaves were brought in and allowed to
stuff themselves on vines. The animals then got a small dose of lithium
chloride, a drug that doesn't produce any outward signs in the dosed
sheep but leaves them feeling queasy, Doran said.
Some sheep got the dose in liquid form, some in capsules and two other
groups of sheep got placebos to serve as a control.
Sheep that were dosed generally left the grapes alone when set loose in
an experimental vineyard at the UC Hopland Research and Extension Center
south of Ukiah, Doran said.
A recent visit to the vineyard showed tangible results: bunches of fruit
hung on the vines weeded by trained sheep. Vines mowed by untreated
sheep were ragged and bare up to the sheep's head height.
Interestingly, it seems sheep may have discriminating palates. The
untrained sheep largely left alone a red grape called aglianico but
appeared to be big fans of chardonnay.
Untutored sheep make good mowers, but they must be deployed carefully.
Some vintners use them in the cold months, when vines are dormant and
there's not much to nibble on. Others have tried miniature breeds that
are too short to do much damage, though such animals are expensive and
in short supply.
Don Watson, owner of Wooly Weeders, a Colorado-based company that also
provides mowing services in the Napa Valley, doesn't think aversion
therapy is necessary.
He says he achieves excellent mowing results by using top-notch
sheepherders and dogs to move the sheep along before they can get to the
vines. He puts sheep into the vineyards only at certain times of the
year, such as when berries are at their most astringent and unpalatable
to the animals. He also employs lambs, which are shorter and less likely
to reach high enough to damage vines.
"It's better to take a more direct route, observe animal behavior and
merely adapt our management to suit that behavior," he says.
Doran says it's good to be skeptical of the aversion technique -- and
any new technology -- but he says trained sheep could be used more
widely and in the spring months when floor vegetation grows rapidly.
He and his colleagues would like to develop an alternative to lithium
chloride, such as naturally occurring tannins. They also hope to look at
what effect sheep may have on the soil and grape quality, not to mention
their fertilizing capabilities.
Sarah Cahn Bennett, co-owner and enologist at Navarro Vineyards in
Mendocino County's Anderson Valley, is interested to see how the
training comes out, although she'd be more comfortable using a natural
agent to produce the aversion.
Navarro doesn't use herbicides or pesticides so weed-removal is done
either by hand or by tractor. The winery also uses sheep, but that takes
a lot of management and can't be used in every setting, says Bennett.
Perhaps some day sheep may safely graze in a vineyard without putting
the fruit in danger. For now, a hungry flock of sheep can train humans
to stay alert, says Bennett.
"You're just going out there daily," she says. "That's probably the
biggest advantage."
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