August 13, 2004
Source:
AgAnswers, an Ohio State Extension and Purdue Extension
Partnership
Growers who save seed from their wheat harvest for the following
season's planting should probably seek other seed sources for
producing next year's crop.
Pat Lipps, an Ohio State
University Extension plant pathologist with the Ohio
Agricultural Research and Development Center, said that seed
quality is an issue this year, mainly because of the late
development of Fusarium head scab. The disease was caused by
excessively wet weather during the crop's flowering period
through harvest.
"Incidence of head scab, on a
statewide average, was around 13 percent. A moderate low level,
but the late scab development didn't correlate well with the
earlier disease levels," Lipps said. "In other words, seed
infection and vomitoxin were higher that what we expected for
the level of disease we had in the field. Because of the wet
weather the fungus continued to colonize the grain and produce
toxin."
Vomitoxin levels, where
detected, ranged anywhere from 2 parts per million to 5 parts
per million, Lipps said. Grain elevators may turn away grain
with levels of vomitoxin 2 parts per million or higher.
"Germination tests from seed
companies are reporting high levels of seed infections, even in
seed that looks normal," Lipps said. "Test weights of 58 pounds
or better usually indicate good quality seed, but we've had
grain that's 60 pounds or higher that is heavily infected. So we
are telling growers to just don't trust any of it."
Ohio State Extension
specialists are recommending that growers who do not have
adequate facilities to clean, store and treat seed not save
their seed for next year.
"What growers have to do is
clean the grain, remove all the shriveled kernels and treat that
grain with a good seed treatment material," Lipps said. "Air
cleaning will not be sufficient to remove all diseased seed, but
a gravity table will do a much better job if set to clean out
sufficient light weight seed.
"Several seed processors have
reported that they are discarding about 20 percent of the grain
during the cleaning process, to improve seed quality."
In addition to treating seed
for head scab, growers also should clean and treat seed for
Stagnospora glume blotch. Both diseases can cause germination
and stand problems in plants, if infected seed is planted.
"What will happen is if you
plant that seed you may get a seedling blight, which will either
reduce stands or the plants will stay alive until winter. Then
they'll die out over winter and the stands will decrease in the
spring," Lipps said.
Lastly, all seed should be
tested for germination before planting.
"A germination test is an
indication of the level of possible problems that may arise from
using poor quality seed, and using poor quality seed can be
reflected in the yield of the crop," Lipps said.
Seed with germination
percentages below 80 percent should not be planted. |