Louisiana GrowersWaiting For Confirmation Of New Disease Found In Corn
BATON ROUGE, LA.
Louisiana corn growers are waiting for confirmation
that Goss’s wilt disease has been
found in some corn fields in Madison
Parish.
“Unless I have skipped something in the literature,
this is the first report of Goss’s wilt in
Louisiana,” said LSU AgCenter plant pathologist
Clayton Hollier.
On June 18, samples were taken from corn
fields in Madison Parish that had both classic
leaf symptoms and disease spread pattern of
Goss’s wilt in the corn hybrid DK 6694, he said.
“During the 2011 corn growing season, there
were reports of Goss’s wilt in northeast
Louisiana, but further investigation found that
these were fertilizer burn, herbicide burn and
drought symptoms that were widespread that
year,” Hollier said.
In Madison Parish, a local aerial applicator
who flew over the field first noticed a 50-foot circle
of affected plants.
The grower called in several people from industry
and the LSU AgCenter to investigate,
Hollier said.
They found several circles of damaged plants
radiating out from a central source that suggested
seed transmission, he said.
“Leaf blighting symptoms were elongated with
water-soaked lesions with ‘freckles,’ a characteristic
of the disease,” Hollier said. “Upon microscopic
investigation, bacterial streaming was
evident.”
Since those observations the field has been
isolated, and Hollier and his team are awaiting
positive identification of the bacterium.
Additional symptoms have been found in the
corn hybrids DK 6469 and in DK6696 in the
same region of the state, Hollier said.
There are several implications for Louisiana
growers:
• The disease does not seem to be widespread
at this point. Scouting is continuing.
• The disease pattern in the field indicates
seed transmission.
• The plants affected in the “circular” pattern
will be the most damaged, with losses ranging
from 100 percent in the “epicenter” to minor, if
any, losses at the edge of the circle.
• Since the bacterium survives in infested
residue, any type of tillage operation that buries
residue to encourage decomposition may be effective
in reducing the rate of new infections.
• Rotating out of corn into other crops such as
soybeans or small grains will help reduce primary
inoculum sources in corn residue.
• Additional hosts for the pathogen include
green foxtail, shatter cane and barnyard grass;
therefore, weed control may also be important
for disease control.
The environmental conditions in Louisiana are
expected to be harsh on the bacterium because
it is not native. Overwintering survival is not expected
with tillage and decomposition of
residue. “But we are dealing with nature, so
there are no guarantees, Hollier said.
Hollier said more updates will be provided as
the information becomes available. Additional
information on the disease is available from LSU
AgCenter parish offices. Δ