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 This year was especially
challenging due to the late start of the growing season in Illinois.
Fortunately, there is an entire industry and network of experts to
draw on for advice on how to proceed.
Eric Gordon, the plant manager at the Lincoln branch of Brandt,
shared his own thoughts on the year farmers have had with regard to
pests in the area. When asked about what sorts of pests and diseases
he heard a lot about, Gordon spoke of weeds and foliar disease.
“We have always fought weed pressure and some disease pressure in
corn and beans. This year with the late season we seemed to fight
weeds more than in the past. We also dealt with some late season
foliar disease in corn that we typically don’t see as a problem, but
with late growing season the diseases came in at their normal time,
but the crop was not as mature as we are used to seeing,” said
Gordon.
Gordon is not the only one discussing weeds. University of Illinois
researchers also warn about the presence of a certain weed in fields
this year. Water hemp is described as “a broadleaf weed common to
corn and soybean fields across the Midwest. With resistance to
multiple common herbicides, water hemp is getting much harder to
kill,” according to one report from Illinois Farmer Today.
Historically, about nine herbicides have been useful for fighting
water hemp. Unfortunately, it seems that the weed is growing
resistant to at least seven of those nine.
“In some areas, we’re one or two mode of actions (MOAs) away from
completely losing chemical control of water hemp and other
multiple-herbicide-resistant weeds…And there are no new herbicide
MOAs coming out. There haven’t been for 30 years,” says Illinois
weed scientist Aaron Hager. “We don’t want to panic people, but
farmers need to be aware this is real. It continues on with the
challenges we’ve warned people about for years.”
In June, Hager said that we may not notice the poor performance of
these herbicides, since water hemp is constantly germinating. “When
a weed pops up mid-season, it’s hard to tell exactly when it emerged
and whether it was exposed to residual soil-applied herbicides,”
says Hager. “As we get into the era of metabolic resistance, our
predictability is virtually zero. We have no idea what these
populations are resistant to until we get them under controlled
conditions,” Hager says in the report.
As for why these problems have come up this year, Eric Gordon
pointed to the late start for crop planting this year, much like
other experts have stated. “I think most all was weather
related…timing plays a key role in control. We did not get the crop
canopy as early as we typically do allowing for added pressure,”
said Gordon.
The old adage “Nature
abhors a vacuum” was well documented this growing season. Waterhemp
and other troublesome weeds filled the gap in low lying patches
where crops failed due to ponding and soggy soils.
Gordon echoed reports that
certain weeds have developed resistances to herbicides. However,
this is also something that happens every year, so it is not the
sole cause for problems regarding current weeds in fields.
As for diseases, a document published by the University in early
October discusses findings on tar spot in the fields.
The report states that “tar spot has made annual appearances in
Illinois since its initial detection in 2015.” Last year, the right
conditions that favored disease development allowed tar spot to grow
well before the crop matured. Many farmers in the state saw losses
in recent year because of tar spot.
“To add further insult to injury, the conditions that favored tar
spot also favored other, more commonly encountered diseases
including grey leaf spot, ear rots, and several types of stalk
rots,” according to the report. As a result, much of the state,
especially in Northern Illinois, saw an increase in tar spot.
This season, the overall
incidence rate of tar spot really didn’t change much. However, the
overall severity of the disease is actually significantly lower.
“The combination of the heat and dry conditions could have delayed
the onset of tar spot, resulting in disease developing later in the
season and to a lesser degree than in 2019.”
This suggests that the late
start to the growing season resulted in a significant amount of
crops that could not host tar spot. The fungus needs a large amount
of healthy plants to move from one field to the next, and less crop
early on this year made it difficult for the fungus to thrive.
Finally, temperature shifts leftover from winter may have reduced
potential survival of the fungus.
“We would expect [the fungus] to overwinter, simply due to fewer
corn acres planted and less corn infection in 2019. This could
result in lower inoculum loads and potential disease in 2020,”
according to the report.
Finally, Eric Gordon spoke of any future treatment options farmers
in the area could look forward to next year. From his perspective,
the effective treatment does not necessarily call for something new.
Rather, farmers should practice good timing on applying herbicides
to their fields.
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“There has not been much new
on the chemistry front as of late. Dicamba and enlist have been out
for a couple of years, they seem to help on some of the resistant
weeds, but timing of application is still key. There is a lot of new
chemistry emerging as far as foliar diseases. Most are not after new
diseases as much as they are about lasting longer.”
Aside from diseases and weeds, certain insects are posing problems
during harvest. A report by Phyllis Coulter published in Illinois
Farmer Today indicates that rootworm has been on the decline this
season, which could save farmers next year in terms of money and
potential headaches over the pest.
Joe Spencer, an entomologist and principal research scientist at the
University of Illinois, was quoted in the report as saying, “This
year has one of the lowest occurrences of western corn rootworm In
Illinois, it looks like 2020 will be a low-pressure year for western
rootworm populations,” he said at the university’s Agronomy Day in
August.
According to the same report, certain traits in pesticides seem to
still be providing adequate protection against western corn
rootworm. However, experts still warn against overuse of current
chemicals, or the pests will build up resistances. “You may want to
throttle back on BT protection next year,” says Spencer.
The report adds that, “most of the western corn rootworm was found
in only two counties. Possible reasons for higher counts would be in
areas with organic crops or where resistance built up.”
The annual pest survey also counts Japanese beetles and stink bugs.
Kelly Estes, a surveyor for the University of Illinois, added her
own thoughts to the same report.
“Overall the insect population is low this year,” Estes said.
Previously, most experts thought the lead insect problem for 2019
would be the Japanese beetle, since they were quite numerous in
2018. Yet the Japanese beetle, while present, was not as
troublesome.
According to the same report, while some pests are in decline, at
least one thrived this year. Green stink bugs were very populous in
southern Illinois. They reduce grain quality by causing seed
discoloration. The best time to check for them is on a wet or
relatively cool day. Insecticide can control them, but they are
unusually stubborn for pests.
Further reports suggest that farmers should be careful to check for
stinkbugs during pod fill. In addition, spidermites, stem borers,
and leaf beetles continue to be a problem leftover from last year,
especially in soybeans.
It seems that the late start to the growing season was both a
blessing and a curse. Certain fungi and diseases did not get off on
the same foot they usually do. However, as is the case every year,
weeds and pests will only continue to adapt.
In summary, every year weeds and diseases claim a percentage of
production. New pesticide and herbicide chemicals, even natural Bt
incorporated into seed, all lead to resistance development when
doing the same thing over time. For optimal results, the best option
to control pests remains the same, utilized good farming practices:
This time tested, common sense
approach to managment delivers more consistent yields over the
long-term with the greatest profit benefit.
Smart farmers keep ahead of returning pests by reading reports,
talking with their chemical suppliers and consulting with expert
field consultants such as those found at university research centers
to learn what has been a problem this past year and get
recommendations on how to prepare for next year.
Sources
Insect monitoring
in soybean: what to look for during pod fill
Peanut country soybean disease shows up in Illinois in 2019
Rootworm decline may save farmers money next season
Superweed resists another class of herbicides
What
do low tar spot disease levels and prevent plant acres mean for 2020
corn crop?
Photos: Water Hemp and other pigweed seed heads
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Read all the articles in our
new
2019
Fall Farm Outlook Magazine
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