A population of common waterhemp has developed resistance to
postemergent application of HPPD-inhibiting herbicides(e.g.,
Callisto, Laudis and Impact). This resistance occurred in a
seed-cornproduction system where these HPPD-inhibiting
herbicides were repeatedly used over the last five years. The
good news is that the resistance was identified at only one
location. The bad news is that this can easily happen in other
fields, as HPPD-inhibiting herbicides are commonly used in
Nebraska and the Midwest. Resistance is a phenomenon that
usually results from the repeated use of the same chemical. This
can occur with herbicides and many other pesticides. In addition
to the weeds already found in Nebraska to be resistant to
glyphosate – marestail, giant ragweed, kochia – a new type of
weed resistance has developed in the state. Repeated use of the
same herbicide can easily result in the evolution of weed
resistance, regardless of the type of herbicide used. We have
forgotten the time of atrazine and ALS resistance (