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Pest Control
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From the Ancient Neem Tree,
a Natural Insecticide
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The neem tree grows as tall and wide as
an oak, thrives in hot, dry weather, and its
roots, which reach deep into the soil, make it ideal
for reforesting lands in the tropics that have
been stripped bare by ranchers, farmers and people needing firewood. It also thrives in the
Caribbean and it has become a popular tree in Florida and Southern California.
The National Research Council reports that as
far back as the 1920's, Indian scientists
were studying what farmers had long noted: that
neem trees could withstand locust plagues. But
the world didn't take notice until 1959, when a German entomologist watched billions of
locusts swarm over the Sudan and reported that
neem trees were the only green things left standing.
Scientists estimate that the chemical compounds from neem can combat more than
200 species of insects, including Mexican bean beetles, cabbage loopers, gypsy moths,
cockroaches, fleas, head lice and mosquitoes.
Its active ingredient, azadirachtin, which
is derived from the neem seed, controls insects by disrupting the metamorphosis of insect larvae.
The Council also reports that the compound inhibits molting, thus keeping the larvae
from pupating and producing a new generation.
Sometimes, insects won't even come near
the stuff. "Azadirachtin is frequently so repugnant
to insects," the Council's report says, "that scores
of different leaf-chewing species (even ones that normally strip everything living from plants)
will starve to death rather than touch plants that
carry traces of it."
Its compounds do not build up in soil or water. Harmful insects don't develop
immunities to them. But they do spare
butterflies, ladybugs and bees, and are not harmful to
humans.
The state approved Bioneem, also made by W.R. Grace, in November of 1994 for use
on ornamental plants. Bioneem is available in some garden centers, including Roger's
Gardens.
8/98
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