From Associated Press:
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.
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.
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.
Conservation officials in Taiwan are worried extensive efforts to save the islands' green turtles may not be enough. Those efforts include a
nesting reserve, a veterinary clinic and even a beach patrol.
