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Oct. 27, 2016
2016 Logan County Fall Farm Outlook Magazine
Lincoln Daily News
weeds will become more difficult to control, as they
have adapted to the same conditions after multiple
years.
Rotating crops creates a different environment
for weeds, making it harder for them to adapt to
conditions. Additionally, rotating in a new crop
requires different herbicides and weed killers, which
provides an opportunity to remove old, stubborn
weeds from previous seasons. Rotating herbicides is
useful in weed management, as it can prevent a long-
term problem of weed resistance.
A third reason to consider rotating crops is to prevent
disease. Continuous corn planting increases the
amount of leftover corn residue left behind in the
fields. This residue is a haven for pathogens and
diseases that will wait for the next growing season
to latch on to corn crops. One of these diseases is
Diplodia.
This year, Diplodia has proven to be a nuisance
for Illinois farmers. Figures from the University of
Illinois indicate that Stenocarpella maydis, the fungus
that causes Diplodia, has been sighted more frequently
this year. Diplodia infects corn ears after the
beginning of the silking stage. Diplodia overwinters
on leftover corn debris, which means that it can
survive cold temperatures and reappear the next year.
What does this mean for farmers who find Diplodia in
their crop?
Diplodia causes a straw-brown discoloration of the
lower portions of the ear. Stalks will begin to lose
firmness, and small black dots begin to appear on the
kernels. As a result of these symptoms, corn kernels
and stalks become brittle and lose mass. Infected
corn may not harvest completely, breaking away
during the process and reducing the overall harvest
size. A reduction in weight comes with a reduction in
nutritional value, which makes the corn harder to sell.
On top of that, grain elevators may discount what they
pay out to farmers because of the fungus.
So what can the farmer do to prevent Diplodia in the
future?
If Diplodia is an issue, corn can be harvested early to
prevent further spread of the fungus. Keep infected
corn separated from healthy corn in storage. There are
fungicides available that treat Diplodia, and tillage can
help reduce the presence of the fungus in the soil by
breaking up leftover corn debris.
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