AGRICULTURE REPORT
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February 12, 2002: Sharpshooters
By George Grow
This is the VOA Special English AGRICULTURE REPORT.
Farmers in the American state of California are guarding against an insect called the glassy-winged sharpshooter.
It carries Pierce’s disease, a bacterial disease that attacks grape plants and other crops. Government and industry
are working to fight the sharpshooter and the deadly disease.
California is a leading producer of wine, the alcoholic drink made from grapes. The California wine industry
provides thirty-three-thousand-million dollars for the state’
s economy.
For more than a century, California grape growers have battled Pierce ’s disease. It
has caused major damage to Los Angeles area farmers several times.
A new, more threatening glassy-winged sharpshooter arrived in southern California
twelve years ago. Scientists believe this insect came from the southern United
States. Officials estimate it has caused fourteen-million dollars in damage over the
past several years. Experts say it is now ready to attack other parts of California.
The glassy-winged sharpshooter feeds on hundreds of different kinds of plants. The
small insect spreads Pierce’s disease as it moves from plant to plant. The bacterial
disease slowly kills the plants. There is no known treatment. In addition, the insect
carries diseases that can harm peaches, oranges and other crops.
American scientists are studying ways to stop the sharpshooter. One method involves covering grapevines with
particles of kaolin, a fine white clay. The particles stick to the insects when they land on treated grapevines. The
insects do not eat the plants, and are unlikely to leave their eggs there. A similar treatment has successfully
protected other kinds of fruit from insects.
Other scientists are studying ways to safely kill sharpshooters. They found that some chemicals were very
effective. Some of the chemicals were still killing sharpshooters four weeks after the plants were treated.
However, scientists want to guarantee that the chemicals do not kill helpful insects, such as egg parasitoids. They
are a leading natural enemy of sharpshooters. Scientists have already released one kind of egg parasitoid in
California. Other scientists are studying parasitoids that eat the eggs of a native South American sharpshooter.
This VOA Special English AGRICULTURE REPORT was written by George Grow.
Glassy-winged sharpshooter
on a grape leaf
(Photo -Peggy Greb)
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