Mississippi State, Mississippi
May 1, 2008
Ongoing efforts to track Asian
soybean rust and minimize its threat to Mississippi soybean
acres led researchers to note that some kudzu, a rust host,
resists the disease.
Billy Moore, plant pathologist emeritus working part time with
the rust program for the
Mississippi State University Extension Service, said the
team searching for rust in the state examines soybeans and kudzu
plots for signs of the fungus. They use global positioning
system coordinates to note the location of each plot searched
for rust.
“Some of the first Asian soybean rust found in the state in 2007
was found in patches of kudzu,” Moore said.
The first soybean rust found in each of the past four years on
soybeans was in the sentinel plots the Extension Service plants
each year scattered along the state lines to monitor for the
first appearance of rust.
“We plant these early so the soybeans reach the most susceptible
stage before the ones in commercial production reach that
stage,” Moore said.
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A plant
pathologist holds evidence of Asian soybean
rust on kudzu leaves found in Wilkinson
County, Mississippi, in August, 2007. (Photo
by Bob Ratliff/Mississippi State University
Ag Communications) |
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The team searching for rust uses
the information collected to determine if a soybean rust alert
is necessary, and if an alert is provided, in what areas of the
state should producers be concerned. Recommendations also are
provided to producers within counties of concern on action they
should take to protect their crop.
The Mississippi team annually assists researchers at Fort
Dietrick, a U.S. Department of Agriculture containment facility
in Maryland originally used for biological warfare research
during World War II. It is now used to establish research on
crop pests, including soybean rust.
The facility provides all soybean-growing states with needed
information on preventing losses. Research there on soybean rust
has been ongoing since 1972.
“We have been working with these researchers to collect kudzu
seeds over the last three years and track them with GPS
coordinates,” Moore said.
“We sent 68 samples last year. They have found that kudzu varies
in its susceptibility to rust.”
Moore said the research indicates kudzu may be very susceptible,
moderately susceptible or resistant to soybean rust. Originally,
all kudzu was thought to be susceptible to the fungus.
“Knowledge of how much kudzu is susceptible in the state
provides information on how important kudzu is in the
development and spread of soybean rust,” Moore said.
Kudzu patches that are known to be susceptible can be scouted
for the presence of soybean rust.
“Current technology may someday enable scientists to place these
genes for resistance to soybean rust into soybeans. However, in
the near future, we will have resistance obtained from soybean
lines from Asia,”
Moore said. “USDA is working quickly to get resistance to the
soybean farmers, and private seed companies are doing the same.
Schillinger Seeds plans to have resistance available by 2011.”
Another interesting discovery is that soybean rust is adversely
affected and the disease does not spread after a few days of
optimum night temperatures and high day temperatures.
Researchers at Fort Dietrick found that this off-on cycle over
time shuts the disease cycle down.
“This information helps researchers make recommendations to
producers on when to and when not to apply a fungicide,” Moore
said.
Tom Allen, Extension plant pathologist at MSU’s Delta Research
and Extension Center in Stoneville, said one application of
fungicide for rust control costs about $10-$16 per acre.
“With soybean prices at record highs, producers are more willing
to spend money on fungicide applications, but if they aren’t
necessary because the rust is not spreading, we want to
encourage our growers to wait and see if they can save that
money,” Allen said.
He said the warm, wet winter was favorable to rust, and it was
found active in Alabama and Louisiana in early March.
The Mississippi Soybean Promotion Board and BASF provide a
toll-free number during the soybean-growing season that gives
regular updates on Asian soybean rust. Producers are encouraged
to use this resource to learn the latest information and
management recommendations from the MSU Extension Service. Call
(866) 641-1847 to hear state-specific updates for Mississippi,
Louisiana and Arkansas.
By Bonnie Coblentz |
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