The Rural Voice, 2001-06, Page 49Myths concerning
chafer control
in field crops
By Trace} Baute,
Field Crop Entomologist,
OMAFRA-Ridgetown
There are many myths concerning
European chafer control strategies
this spring. In fact, some people are
recommending insecticide treatments
for chafer in field crops that make
little sense from both a biological and
economic perspective. Under these
circumstances, I feel a need to clarify
fact from fiction.
Fact: European chafer has been a
concern the past few years for
anyone growing corn or wheat in the
sandy areas of Southern Ontario. It is
a new pest in field crops so there
hasn't been a lot of research done on
possible control strategies, nor has
enough data been generated to put
registration packages together by the
companies to get products registered
for chafer control. But that also
doesn't mean that growers should be
spending money and time on
products or application methods that
are not going to work.
Fact: European chafer is a beetle
larva that has been a pest in turf for
years. So, why not look at what they
have been using there and apply it to
field crops, right? Well, it isn't that
simple. If you read any product label
that is registered for chafer grub
control in turfgrass, you will see one
commonality. The recommended
time of application is always late July
to early August. Why? Simple. It is a
matter of timing the control to when
the insect is most susceptible.
Remember the life cycle of European
chafer. Right now, in May it is the
largest size of larvae it can be, a third
instar. This larger stage of larvae is
extremely difficult to control. It will
then pupate the end of June and
emerge as adults in early July. These
adults will then mate and lay their
eggs in the soil mid-July to mid-
August. These eggs will then hatch
and "Voila"; you then have the most
susceptible stage of the insect, the
first instar larva. So, it makes sense
that all products used in turfgrass are
to be applied at that t jme of year. But
Advice
putting similar products on corn at
that time of the year is not practical.
Fact: The turfgrass industry has an
added advantage. In turf, it is a lot
easier to apply an insecticide to the
surface of the soil, ensure a good
coverage with little soil erosion or
runoff and be able to irrigate
immediately after to soak the
chemical into the ground to ensure
contact with the grubs feeding
beneath.' We would all agree that it
isn't as simple or cheap to do this in
a field crop situation.
So, what is my point? If someone
has been recommending you spend
$100/acre in your corn field on a
product that hasn't been registered or
at least had research done to prove its
effectiveness on chafer grubs, I
suggest you think twice before
spending your money. Currently .
field crop entomologists at major
institutions in the U.S. Corn Belt and
Ontario have been testing products
they feel are going to be the most
practical and economical for chafer
control for corn and wheat growers.
So far this research has been
concentrating on seed treatments and
soil applied in furrow insecticides
that will promise the highest dose
and most protection against the
larvae that are currently present in
the soil. They have not been working
on drench methods and surface spray
applications, as they do not see it as
practical or economical to be
attempting these methods on the
largest and most difficult stage of the
chafer to control at this time of year.
Bottom line: Leave the
experimentation to the researchers
and spend your money on the
products that they have proven to be
effective and worthy of pesticide
registration for that insect.0
Herbicide resistant
pigweed — could it
happen to you?
By Elaine Roddy
Vegetable Crops Specialist,
OMAFRA
Last summer, researchers at the
University of Guelph found Linuron
O�\/os
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