Washington Evening Journal, IA
08-29-06
SDS, White mold reported in Washington County soybeans
By:David Hotle
08/29/2006
Soybeans in Washington County are starting to look about ready for harvest.
Experts predict Iowa will lead the nation in soybean production this year. Iowa
State University reports some disease has been found among the plants, but
only in small amounts.
Soybeans in Washington County are starting to look about ready for harvest.
Experts predict Iowa will lead the nation in soybean production this year. Iowa
State University reports some disease has been found among the plants, but
only in small amounts.
The good news is, the high temperatures of the summer and the rain this month
promise soybeans will be ready for harvest sooner than expected. The bad news
is that sudden death syndrome (SDS) and white mold have been seen in the
county.
Iowa State University Crop Field Specialist Jim Jensen says the crops this
year look very good and he believes Iowa can, as predicted, lead the nation in
soybean production. He says there has not been much of an insect problem. He
has seen cases of SDS and white mold, which cause soybean plants to die, in
limited quantities in Washington County.
"There were no major problems this year," Jensen said. "We do have sudden
death and white mold. If we have a problem, it would be them."
In most cases the disease is found only in portions of a field, but in rare cases,
the plant diseases can lay waste to an entire field.
SDS becomes evident after the flowering stage, two to three weeks after being
planted, which occurred earlier this month. Leaves on the infected plants have
scattered yellow or white spots between leaf veins. These spots begin to die and
enlarge to form brown streaks between veins. Eventually infected leaves drop off,
but petioles remain on the stems. SDS is a look-alike disease for brown stem rot,
which displays the same symptoms in plants.
Soybean white mold, also known as Sclerotinia stem rot, is caused by soilborne
fungus. As the soybean flowers, the fungus can germinate, forming a mushroomlike structure. Infection takes place when spores are projected into the air and
then the fungus enters the plant.
Jensen says once the plants have contracted either disease nothing can be
done.
"There are a lot of things you can do about these in hindsight," Jensen said.
"Before you plant, you can pick varieties that have a tolerance to the diseases.
Early planting can sometimes trigger sudden death. Once it happens, though,
you are pretty much stuck."
Jensen also says the intense heat of the summer, with many days approaching
100 degrees, and several rains this month have caused soybeans to mature
sooner this year. He predicts an early and strong harvest.