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2008-07-31 13:51:35
By TRACIE CONE, Associated Press WriterWed Jul 30, 3:17 AM ET
Just like people damage their skin in the sun, fruits and vegetables also can
get nasty burns. That's why farmers are increasingly applying sunscreen to
their crops to prevent skin blistering, heat stress and blemishes.
"With the costs of production going up, growers are looking to increase their
margins wherever they can," said farmer Ed Lagrutta, an adviser for Western
Farm Services who farms 20 acres and runs tests on hundreds more.
Sunspots on a Granny Smith apple can mean the difference between the lowest
price for juice or the more lucrative fresh fruit market. As for nuts, last
year buyers paid on average 3-cents a pound more for sunscreen-protected nuts
than untreated ones, said Lagrutta.
Climate change and drought in Australia and California's Central Valley have
meant challenging growing conditions for farmers that are affecting the
quality, yields and price of produce. Sunscreens alleviate at least one worry
for farmers, who lose money with each fruit or vegetable that develops sun
damage.
"Under climate change, heat stress will become a bigger issue for plants,
especially when it creates new heat-released disease," said Eric Wood, a
professor of civil and environmental engineering at Princeton University.
Plants react to sun stress like humans. They perspire a process called
transpiration which means the more temperatures rise, the more water they
need. As drought grips several of the world's key growing regions, scientists
are looking at ways to conserve by helping plants use less.
Liquefied clay has been used for years, but now a California company is finding
positive results with an SPF 45 product made of multicrystaline calcium
carbonate crystals that are engineered to specifically deflect ultraviolet and
infrared light from the plants and trees on which it is sprayed. The product
keeps out the bad light, but lets in the good photosynthesis rays that aid
ripening.
The sunscreen has been tested in Australia and Chile, where UV rays affect
production, and is in the second year of field tests in California.
Tests show its immediate impact is increasing yields by diminishing stress and
heat-related defects, but the company that makes it hopes the product also can
play a role in water and energy conservation by increasing a plant's water
efficiency.
The sunshield, Purshade, made by Purfresh Inc., recently lured 20 U.S. and
international farm product researchers and advisers to a walnut grove near
Visalia, Calif.
The product also is being tested on tomatoes, grapes, kiwis and lychees in
Australia, said Kerrie Mackay, who works for a company that sells crop
protection products in Queensland, which she says is in 140-year drought.
"Sunburning is a big problem for us," she said, watching Lagrutta compare the
telltale yellowing on one block of walnuts with a uniformly green plot sprayed
with Purfresh. "We have some of the highest UV intensity in the world. With
drought and climate change, finding ways to use water more efficiently is
always important to us."
Amador County's Shenandoah Valley in the arid Sierra Nevada foothills is far
from the temperate Napa Valley, but Dick Cooper of Cooper Vineyards has been
growing 100 acres of premium wine grapes since the 1980s by using vine canopies
to shade bunches.
In dry years, like this one, vine vigor is slow and exposed bunches of his
pinot grigio shrivel into something resembling an olive pit, he said.
For the second year, he sprayed Purshade sunscreen on several of his blocks of
white grape varietals to help protect them. He says that during the crush the
calcium carbonate crystals drop to the bottom of the fermentation tanks with
the rest of the sediment that comes in with grapes, so taste isn't affected.
"I'm not an expert on anything, but I'm always interested in trying anything,"
he said. "When my vines don't put up enough canopy, I like to give them a
little help."