We've talked a little bit about
pesticide resistance let's look at this
phenomenon that is a concern where
they're applying insecticides herbicides
fungicides or any type of pesticide. Any
time you apply pesticide not all of the
individuals in that population will be
killed and removed. One in a million may
actually resist the treatment. That one
in a million is not obvious to the pest
manager the first few years, but after
repeated applications and the
reproduction of the resistant
individuals a population of resistant
pests becomes apparent. The chemical that
historically controlled that population
is now ineffective. If you use products
that have similar modes of action those
resistant individuals will not be
controlled so alternate between
chemicals having different modes of
action to manage for resistance. If
pesticides are frequently applied during
a growing season resistance can show up
more quickly. Chemicals that are
persistent tend to have resistance show
up more readily than products that don't
remain active over time. 
-Would you
recommend having using two products at
one time just to get rid of that
resistance or should you always break
the part and use them separately?
-Most herbicide
labels have a an area on the
label that's refers to the mode of
action and there are any number of
different modes of action. It's not as
much about using two different types as
it is switching from a different chemistry
when you are trying to control a
specific pest. You can in fact
mix different kinds of chemicals
together but if one of the past you're
trying to control is resistant to one of
the modes of action that you're using
then effectively the other the other
pesticide may kill the insect but
anything that survives will also be
resistant to that original product.
Chemicals that are persistent and tend
to have resistant show up more readily
than products that don't remain active
over time. The pest biology is also a key
factor. If the pest has a high rate of
reproduction resistant individuals show
up more quickly as the
population of those individuals
increases. Also pests that have many
offspring for generation tend to have a
greater chance of resistance developing.
Obviously they're producing more. The
pest manager must consider resistance
management techniques when using
pesticides in an integrated pest
management program.
