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A new strain of Russian wheat aphid has been identified in
Colorado by Colorado State University, causing crop losses on farms that
still are recovering from the drought. Since the voracious original strain
of Russian wheat aphid entered Colorado in 1986, it has cost the state's
14,000 wheat farmers more than $132 million in crop losses and insecticide
control efforts.
The aphid is attacking all wheat varieties this spring that were developed
to be resistant to the original strain of the insect, especially in
central and southern Colorado.
"A new biotype of the Russian wheat aphid is not a completely unexpected
development, but there was no way to prepare for it because we could not
forecast how the aphid would develop and what sources of resistance would
be effective," said Frank Peairs, Colorado State University Extension entomologist who, along with other experts at the university,
has spent 17 years developing tactics to control the aphid.
In particular, Prairie Red, a variety of wheat that has been resistant to
the aphid, is consistently infested with the new aphid biotype, known as
biotype B.
Prairie Red contains the same Russian wheat aphid-resistant gene as the
other resistant varieties developed by Colorado State University: Ankor,
Halt, Prowers 99 and Yumar. Another resistant variety, Stanton, which was
developed by Kansas State University, also is susceptible to infestations.
Combined, these varieties account for about one-fourth of wheat acres in
Colorado in 2003. All of these varieties continue to be resistant to the
original aphid, known as biotype A.
Researchers are not sure if the new biotype adapted in response to
resistant varieties of wheat or if it was introduced from another country,
where different types of the insect exist.
The aphid damages wheat and other grains by injecting saliva into grain
and sucking sap from plants. If left untreated, the aphid can destroy more
than half of a crop. The aphids begin to appear in crops in April and May
and their population peaks in July, the month most common for harvesting
wheat in the state.
They often survive in host plants such as wheatgrass and barley and begin
to winter in wheat crops in October and November, shortly after they are
planted. The aphid can survive the winter in most areas of the state where
wheat and grain is grown.
Farmers in Colorado have managed biotype A aphids with a combination of
predatory insects, insecticides, controlling weeds that host the insect
and by planting resistant varieties. In Colorado, 4.7 million acres has
had to be treated with insecticides to control the aphid since 1986. This
represents about 30 percent of the total wheat acreage in the United
States. Aphids prevent young wheat leaves from flattening out, or
unrolling, and live within the tubes formed by tightly curled leaves. This
makes it difficult to kill the aphids with predatory insects and
insecticides.
Reporters who are looking for more information about the following press release should contact the media contact listed at the top of the release. The media contact does not have appropriate information to share with the public. Members of the public who are looking for more information should contact their local Extension office, usually listed in the county government section of the local phone book.
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Uploaded Tuesday, November 27, 2007
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