DECATUR, Ill. — As the crops enter their stretch-run toward
maturity, an agronomist in southern Illinois is seeing both the usual and
unusual disease suspects popping up.
Jared Webb, DeKalb technical agronomist, said the most
apparent problem is the lack of rain in large portions of Illinois in the latter
part of the growing season.
“We’re starting to see corn going backwards. We’re starting
to see a lot of tip-back occur in the corn,” he said in an interview during the
Farm Progress Show.
The same holds true for soybeans.
“The soybeans look really good from a distance, with pretty
good plant height, and the foliage is there, but early on we didn’t get as high
of a pod count as I had hoped,” Webb said.
There also are some other factors besides the lack of rain
that is impacting some soybeans.
“We’re starting to see downy mildew in about every soybean
in my territory,” Webb said. “That probably started when we were cooler and
wetter, and we continued to keep really dewy mornings.
“This heat is probably keeping it in check a little bit, but
if we return to cooler, wetter weather, it could go on to develop into problem
to affect the soybeans.
“Downey mildew is usually pretty easy to identify. You’ll
have little yellow specks and kind of irregular-shaped specks on the top of the
leaf. You flip that leaf over, it will have fungal growth directly below the
spot that’s on the top of the leaf.”
“Nothing terrible yet, but you can see it just starting to
become apparent in a lot of fields. Hopefully, it doesn’t progress too much, but
something that could take the top out of our soybeans,” he said.
Southern rust, a corn disease that hasn’t been seen in a few
years, now is showing up in the southern part of Illinois.
“We’ve seen a lot of it in the corn,” Webb said. “Gray leaf
spot is picking up, something we see every year, but southern rust in kind of
new and something we may be not as accustomed to. It’s pretty prevalent in the
southern one-third of the state.
“If a grower applied fungicide, it would have helped with
southern rust and gray leaf spot.”
Webb said cornstalk quality looked “pretty good” as of the
end of August, but growers need to monitor the stands.
“But we are seeing a lot of the corn fire up with the
drought stress. It’s running out of nitrogen, so you can really tell the
difference in nitrogen management programs out there,” he said.
“Although the stalks are good now, the fields that are
running out of nitrogen are ones that guys are going to really need to keep an
eye on because that’s going to suck out of that stalk and we could have weaker
“A lot of the corn has a long ways to go. A lot of the corn
is just around dent to maybe just starting that milk, so it has maybe 20 days to
get to black layer. You start adding 20 days and then a certain amount of time
to dry down and we’re looking at an October harvest for most corn.
“If it is really firing up now, it has to stand a while
before you have to go get it.”
He said a lot of the corn in southern Illinois was planted
in the latter half of May to the first half of June.
“There was corn down there just starting to tassel in
mid-August,” Webb said. “It’s going to be close on a frost. If we get an early
frost, we could still be affected even in the southern part of the state.”