Jim Martin,
J.D. Green, and
Bill Witt, Weed Specialists, University of Kentucky
On
July 14, 2011 the EPA approved a supplemental label for using of Simazat (a
premix of atrazine and simazine) for fall applications to control winter-annual
broadleaf weeds prior to next year’s corn crop. The recently approved
label is the only one that allows the use of atrazine in the fall in
Kentucky. A lot of resources have been invested over a period of
several years defending the registration of atrazine. In order to
maintain atrazine as a viable option for weed management in Kentucky, it is
important that applicators are not complacent in regards to its potential
impact on the environment. Label restrictions concerning Simazat’s use
near ground and surface waters are particularly important when it is applied in
the fall. Highly erodible fields with little to no vegetation, or residue
cover, are especially at risk of movement of atrazine or simazine from the
treated area. Certain watersheds, including portions of the Green River
and Rough River are being monitored for atrazine and simazine. It is
also important to consider the rate of atrazine and simazine. The
recommended rate for fall applications is 2.5 pt of Simazat 4L/A. This is
equivalent to 0.625 lb ai atrazine/A plus 0.625 lb ai simazine/A for a total
amount of 1.25 lb ai/A. If Simazat is applied in the fall, do not exceed
2.5 pt Simazat 4L/A preemergence the following spring. When tank mixing or sequentially
applying products containing atrazine and/or simazine, the cumulative amount of
active ingredient of atrazine and/or simazine per calendar year must not exceed
2.5 lb ai/A. If using the Simazat 90DF formulation, consult label for the
maximum use rates.