Ames, Iowa
June 18, 2004
An Iowa State University plant disease expert says it is
unlikely that soybean rust will reach the continental United
States and impact soybean production this year.
X.B. Yang, a professor of plant pathology at
Iowa State University,
has studied the disease since 1989. He said rust has hit every
continent where soybeans are grown in the world except North
America.
Yang and
experts at St. Louis University are using maps and models to
track winds that could carry the rust spores to the United
States. Yang and other experts agree that the fungal disease
will eventually arrive but is unlikely to be carried to North
America by winds this year.
"The disease would take a long time to travel through the
Amazon basin," Yang said.
Pulling out an atlas as big as his desktop, Yang leafs through
its pages to point out how the Andes Mountains act as a
barrier. He also points out that although rust has hit hard in
Brazil, Argentina, a neighboring country, hasn't had many
problems.
"Currently the disease is causing the most damage in the
subtropical regions near the equator," Yang said.
Yang brings
out another map that compares the spread of rust in China to
what could occur in the United States. He and other experts
have developed models that predict how the pathogen might
travel if wind-borne spores land in the southern region of the
United States.
"A model is built by inputting environmental information,"
Yang said. "This helps us predict what will happen with
diseases just like a meteorology forecast predicts the
weather. We want to forecast what will happen in Iowa as well
as other states in the north central region."
Greg Tylka,
plant pathology professor at Iowa State University, said he's
concerned about the apprehension over a disease that hasn't
been found on this continent.
"This is the
first time I've seen people so anxious before a problem shows
up. I'm afraid that some are on the verge of overreacting,"
Tylka said.
To alleviate
fears, Tylka said it's important to give farmers and crop
professionals up-to-date information about soybean rust, which
is the goal of the Iowa Soybean Rust Team formed last fall.
The team includes representatives from Iowa State University,
ISU Extension, Iowa Department of Agriculture and Land
Stewardship, the Iowa Soybean Promotion Board/Iowa Soybean
Association and the United States Department of Agriculture
Animal and Plant Health Inspection Service.
Tylka advises people to look to the Iowa Soybean Rust Team for
timely, accurate and science-based information. The team has
developed a plan to train nearly 1,500 certified crop
consultants, certified professional agronomists and
independent crop consultants in July. The purpose of the
training is to assist in the accurate and rapid identification
of soybean rust if it arrives in Iowa.
"We want to emphasize that there a lot of people paying
attention to this, that we have a good system to check for
soybean rust and producers should be very cautious about any
unverified information they hear," Tylka said.
Rust can be treated with fungicides and researchers are
worried that farmers are stocking up on chemicals that have a
short shelf life. Yang said he's heard of farmers purchasing
tens of thousands of dollars in fungicides in anticipation of
the disease.
"We believe
that it will be very unlikely to have rust infestation this
season in Iowa," Yang said. "Some may be stocking chemicals
they won't need in the near future."
Tylka also
believes that rust will not land in North America this growing
season. And if it is carried by winds to the southern Untied
States it would not appear in Iowa until later in the growing
season.
"It likely won't arrive until August or later because it will
take time to get established," Tylka said. "If this disease
shows up with only a few weeks of the growing season left,
it's not going to cause as much damage as it would if it were
present throughout the season."
Asian soybean rust was first identified in Japan in 1902 and
was carried by the prevailing winds to Australia in 1934 from
there it traveled to Africa. It was found in South America in
2001.
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