Management Of Horseweed Escapes Prior To Planting
JACKSON, TENN.
Horseweed (marestail) still
present in fields after
dicamba and glyphosate
applied 2 to 3 weeks ago has
been the most common call of
the week. Many want to know
if the twisted up horseweed
will go ahead and die or if it
will recover.
Some of this can be determined by pulling
some individual horseweed plants out of these
fields and breaking the stem in half. If the stem
is beginning to discolor or hollow out, my experience
would be that it will go ahead and die. If
that stem remains a bright solid white then it
could recover to some extent. Often, but not always,
these recovering horseweed are very slow
growing and not overly competitive. The question
then follows should I apply another burndown
application prior to planting my cotton or
soybean to remove this surviving horseweed?
If the field is to be planted to a glufosinate-tolerant
cotton then these surviving horseweed
can easily be controlled with Liberty early postemergence.
The only reason to follow up with,
say, a paraquat application is if there is any
newly emerged horseweed or Palmer amaranth.
If the field is going to non-glufosinate tolerant
cotton and there is a considerable population of
horseweed that could survive then a follow up
application of paraquat or Liberty is a good way
to go. On the other hand, if the population of
this surviving horseweed is minimal then an application
of Envoke or even Staple in season will
likely keep them in check.
Similarly, if the field is going to be planted to
Liberty Link soybean the surviving horseweed
can be easily controlled with Liberty in crop
when the weather is warm. If however, the field
is going to be planted to Roundup Ready soybean
or conventional soybean then a follow up
burndown may be warranted. The options for a
follow up treatment to remove this escaped
horseweed would be paraquat, Liberty, Sharpen
or Verdict. Δ
DR. LARRY STECKEL: Extension Weed Scientist,
University of Tennessee
Horseweed Stem Starting to Hollow Out
Horseweed 17 days after 12 oz dicamba/22 oz Roundup PowerMax