B: In soybeans over the last
few years just about everyfarmer is paying attention
to insects like soybeanaphids, bean leaf beetles,
grasshoppers and spraying ona regular basis. We don’t
see as much insect sprayingin corn, but today we’re
going to talk about why youmay consider it this year on
your farm. D: When you thinkabout corn, a lot of times
you’re just concerned aboutweeds and fertility, weeds
and fertility. If we getthose two pieces right,
we’re going to do ok and Iagree with you, those things
are really important.However we’re seeing a
resurgence of insects lateseason in corn. Many of
those bugs could becontrolled with Bt products
that we’ve got. There weresome farms are choosing to
go conventional corn, maybeyou’ve done that on your
farm or maybe you’ve goneaway from SmartStax traits
and you’ve said, “no I’m notgoing to pay for that, I’m
just going to go with aboveground protection,” and you
think, “well I’m coveredabove ground, right?” Not
necessarily if you hadrootworm pressure for
example, you may startseeing those adult rootworm
beetles out in your fields.So it’s really important
that you’re scouting,because even if you’ve
stayed with some of thetraits and you’ve stayed
with your normal program,your neighbors haven’t and
that’s going to mean morepressure for you. D:
Alright, I don’t know if I’mgoing to agree with Darren
on this resurgence of allbugs, but I would say
certain insects, yes. We’reseeing more of them, corn
borers for example, backjust a few years ago almost
everybody was using thetraited products. So I
believe we were havingbetter mortality out there,
we were killing more cornborers. Well, when people
started going back toconventional corn that’s now
meaning we are seeing morecorn borers. So, let’s go
back to 30 years ago andhere was our advice, we
would always say, “Make sureyou are scouting early for
corn borers, about the timethe corn is knee high and
then you’re going to take alook again a little later on
in the season.” So in theMidwestern United States we
usually have two generationsof corn borers. So if you’ve
got conventional corn, youdon’t have any trait out
there to kill those cornborers, you may need to
spray insecticide. The goodnews is insecticides are
dirt cheap, you’re going tospend a couple bucks. The
problem is, you’re probablygoing to have to call a
plane in for a lateapplication, so there goes
maybe $8 an acre. But anywaythe point is you’ve got to
be scouting for these bugsand you want to catch them
before those corn borersactually bore into the
stalk. Once they’ve boredinto the stalk, now you’ve
got a real problem you can’tget in there to control that
insect. D: I mentioned cornrootworm beetles just a
minute ago and when youthink about that, they’re
not going to bore in thestalk they are going to be
on the outside of the plant,but what they will do is
chew off silks. They willaffect your plant above
ground and many people say,“Well they aren’t going to
cause a problem they aremore of next year’s problem
as they lay eggs.” Well theyare a problem for next year
if they do lay eggs, butthis year I’ve seen fields
where they’ve clipped allthe silks off the ears or
they’ve clipped enough ofthose silks off that you’ve
got poor pollination onears. That’s a substantial
yield loss right now. Andit’s very, as Brian
mentioned, inexpensive tocontrol these bugs. So if
you see rootworm beetles outin your field that means
you’ve had some rootwormpressure feeding on your
roots. You’ve already lostyield, don’t let them hit
this crop for a second time,wipe them out with a cheap
pyrethroid insecticide. B:The key thing with almost
all these insects is tospray early. Like the corn
rootworm beetles, if you canget them early enough, well
they haven’t had enoughchance to mate and lay eggs
for next year. So if youplant continuous corn, well
now you’re going to haveless rootworm pressure next
year if you just get theadults this year, before
they get the chance to layeggs. A couple other insects
that I wanted to mentiontoday, corn leaf aphids, and
then it’s not really aninsect, but spider mites.
Both of these can beproblematic, a lot of people
don’t spray for them, but Iwould just tell you as the
corn price goes higher andas you have good yield
potential, well there’s moreneed to spray, because
you’re hitting economicthresholds. In other words
you can justify treatment.If you’re going to go out
and control these corn leafaphids usually you’re going
to see them on the tassel.So be scouting right at
tasseling time, you’re goingto have to have a lot of
aphids. It’s probably goingto be 100 to maybe even 400
per plant, but if you do seethose corn leaf aphids you
absolutely could spray. Withspider mites there’s no real
established threshold, but Iwould just say the most
important leaf on the cornplant is the ear leaf. So if
you start seeing a bunch ofspeckling on that ear leaf,
damage from spider mites,you probably should spray.
D: Let’s talk about thetreatment options really
quick here. If you’ve gotspider mites, in the upper
Midwest typically bifenthrinis going to do a good job at
a pretty low price, so thatwould be our recommendation,
but that doesn’t workeverywhere. In some areas
we’ve got mites that areresistant to that and you
have to use one of the moreexpensive miticides. You’ve
got Oberon and Zeal and justa number of different
products that you can choosefrom. B: Hey, let’s not
forget about Lorsban.Lorsban does work in many
areas as well and that’spretty inexpensive too. D:
And then the other thing isif you just have aphids or
you just have corn rootwormbeetles, you can get by with
one of the cheaperpyrethroid type products. We
like the lambda-cy typeproducts they do a nice job
at a low price. B: Darrentalked about these cheap
pyrethroids, we’re talkingabout $2 per acre, that’s
all it costs. So I wouldjust again encourage you be
scouting in your fields. Ifyou see sometimes even lower
levels of insects you mighthave enough. Just check the
economic thresholds, run thenumbers for your farm, and
consider spraying. D: Oneother thing you definitely
want to consider spraying isour Weed of the Week, we’ll
show you how to stop itcoming up next.