FOR RELEASE: Feb. 11, 1997
Contact: Blaine P. Friedlander, Jr.
Office: (607) 255-3290
Internet: [email protected]
Compuserve: Larry Bernard 72650,565
http://www.news.cornell.edu
LIVERPOOL, N.Y. -- Once just an unnoticed arthropod minding its own
eight-legged business, the onion bulb mite -- Rhizoglyphus robini -- is
rearing the ugly side of its docile personality. Barely visible to the
naked eye, the mite has begun to attack some of New York's prized onion
fields, and Cornell University scientists want to stop it. "For a number of
years now, it has caused economic losses," said Charles J. Eckenrode,
Cornell professor of entomology and researcher at Cornell's Agricultural
Experiment Station in Geneva, N.Y. "We don't have a lot of answers right
now, because so little is understood about this problem. However we
believe that careful research will come up with the necessary answers."
Eckenrode will discuss the mite and other onion pests in "Onion Arthropod
Management" at the New York State Vegetable Conference on Thursday, Feb.
13, at 9:10 a.m. in the Cotillion Room at the Four Points Hotel in
Liverpool.
"Why is it suddenly a problem? I don't know, but we will be looking at
conditions in the field that may have caused the mite outbreaks," Eckenrode
said. The mite attacks the onion seed before it becomes a seedling or as a
very young seedling. Growers can recognize the problem by the reduced
stands or the wilted seedlings. One theory that Eckenrode's group is
investigating is the use of grasses as windbreaks, which keep valuable soil
from becoming dust in the wind. These grasses may be harboring the mite
until it moves to the onions.
However, windbreaks are very important in onion production. Traditionally,
New York's famous cooking onions are grown in muck -- a highly organic,
peat-type soil rich in nutrients -- and once the muck is gone with the
wind, it is lost forever. With an annual crop value of between $50 million
and $75 million, onions are one of New York's most valuable crops, and
growers don't want to be out of muck.
Onion growers are painfully aware that it does not take much to ruin a
valuable acre of onions. Orange County, N.Y., onion growers have noticed
R. robini is becoming more of a pest each year. Combined, there are about
12,000 acres of onions being grown in New York. The average grower invests
$2,500 to $3,000 into each acre, before any crop is harvested. Cornell
Cooperative Extension estimates that perhaps as many as 1,500 acres in
Orange County have been affected by the mite -- 25 percent of all the onion
acreage in that county and 12.5 percent of the onion acreage statewide.
Wind barriers, such as snow fences, or planting basket willows or growing
shaded plants, or even growing other crops such as barley or oats, serve to
keep the soil in its place. But, Eckenrode said that no matter what a
grower does -- even installing a windbreak -- may provide some kind of
niche for harboring pests. So it is the researcher's job to understand
what sort of niche a new pest is occupying and how this pest is affecting
the crop.
"Farmers always go through change. As soon as you change something, a
living system will take advantage of that change. That may be what's
happening with the bulb mite, but we won't know until we study it,"
Eckenrode said.
Other Cornell scientists are joining in the research. Richard W. Straub,
Cornell professor of entomology and located at the Hudson Valley Lab,
performs mite research in nearby Orange County. Michael G. Villani,
Cornell associate professor of entomology at Geneva, also is studying the
mite at the experiment station.
Ariel Diaz, Cornell graduate student in entomology from Ponce, Puerto Rico,
has initiated a research program dealing with the behavior of the mite. So
far, his worldwide literature search has found little on this pesky
arthropod as it relates to onions. That's why Eckenrode thinks that he
might have to literally start from scratch on this research.
While mite damage in Orange County onion fields increases, the researchers
have yet to find proven management techniques. If the windbreaks prove to
be an important link, then manipulating how they are planted may become
necessary. The entomologists have tested chemicals for control using mite
colonies in the laboratory, with only limited success.
In a survey of four infested onion fields last year to determine seasonal
patterns and abundance of the bulb mite, mite presence was detected, but
the numbers counted did not correlate with the economic damage.
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