In the News - September 2008
Gustav remnants could move soybean rust into Arkansas
UNDATED - So far Arkansas is free of Asian soybean rust, but that could
change as the remnants of Hurricane Gustav threaten to spread the disease here.
The rain also will delay the harvest of crops until next week for many
farmers. As of Wednesday afternoon, the storm had drenched Pine Bluff with 3.4
inches of rain, Monticello with 5 inches and Hot Springs with 8 inches in a
24-hour period, according to the National Weather Service.
"Corn has been ready for harvest two or three weeks, and the issue is whether
the stalks can survive the wind and rain," said Dr. Jason Kelley, extension
wheat and feed grains specialist with the University of Arkansas Division of
Agriculture.
But soybean and disease experts are more concerned with Asian soybean rust.
The disease has remained active in Texas and Louisiana for several weeks, and
has spread from Florida into Georgia, according to Dr. Scott Monfort, assistant
professor and extension plant pathologist.
"However, predicted rain moving in from the south because of Hurricane Gustav
could change the current status of soybean rust over the next couple of weeks,"
Montfort said. Because of this, Arkansas and most of the Mississippi Delta
region will remain at risk for the development and spread of soybean rust until
late September.
Monfort said county agents and volunteers are continuing to scout kudzu
patches, soybean sentinel plots and soybean fields throughout the state. Kudzu
is a host crop for the disease, so kudzu patches are watched closely.
"An estimated 60 percent of the nearly 3 million-acre soybean crop is in the
reproductive stage," he said. "With this in mind, county agents need to continue
monitoring soybean sentinel plots and/or kudzu patches and continue sending
suspicious samples to the diagnostic lab at Lonoke."
Monfort encouraged consultants and growers to also send suspicious kudzu
and/or soybean samples (at least 100 leaves) during the season if they think
they have soybean rust.
Asian soybean rust symptoms are most commonly found on the underside of the
lower leaves, starting around the flowering stage. Initial symptoms of infection
are difficult to detect because the lesions are small. It’s always detected
first in the lower plant canopy.
The first symptoms of soybean rust are small brown to reddish-brown spots on
the upper leaf surface. Hold leaves up to the sun, Monfort suggested. This will
help you see any tiny brown spots starting to form.
Asian soybean rust fungus was first identified in Japan in 1902. It was
discovered in South America in 2000, and a hurricane in the Gulf of Mexico later
carried spores into the southern United States.
Under the right conditions, the disease can cause premature defoliation and
reduce soybean yields by as much as 80 percent. The severity can double every
two to nine days, depending on environmental conditions.
Soybean rust tends to overwinter in the southern costal regions. It has been
estimated that the disease could cost U.S. soybean producers $240 million to $2
billion annually.
Monfort said an updated list of fungicides to treat soybean rust is available
from county agents with the Cooperative Extension Service. He urged growers to
carefully read the product labels before using the fungicides.
"Any suspicious leaves (soybean and/or kudzu) can be sent to the Lonoke
Diagnostic Lab. The Soybean Rust Hotline is continually updated with information
about the latest rust finds that number is 1-866-641-1847," he said.
If you have any questions or concerns please contact your county agent, Dr.
Scott Monfort (870-659-0648), Dr. Jeremy Ross (501-944-0621) or Amy Carroll
(870-258-2509).
September 5, 2008
Media Contact: Lamar James
Extension Communications Specialist
U of A Division of Agriculture
Cooperative Extension Service
(501) 671-2187 or (501) 753-0207
ljames@uaex.edu
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