Poor Burndown Activity On Cover Crop Wheat And Horseweed
JACKSON, TENN.
There have been more reports
of unsuccessful
burndown of cover crop
and volunteer wheat this
spring. Indeed, in our research
here we have had some
very poor control with
glyphosate and glyphosate
tankmixes on wheat. Moreover,
even Gramoxone has shown some problems
controlling wheat. We had some issues
last year with wheat being hard to control prior
to planting but have had many more this year.
I can only speculate as to the reason but the
very cold temperatures probably have played a
role in the poor wheat control. Moreover,
glyphosate almost always goes out with
dicamba and dicamba will cause some antagonism
on glyphosate grass control. This can be
somewhat overcome with a higher glyphosate
rate but not so much under cold conditions.
The problem is once wheat has struggled
through that first burndown if becomes even
more difficult to control with follow up applications.
This is particularly true if glyphosate is
the follow up treatment as the sick wheat does
not translocate the glyphosate well. Contact
herbicides like Gramoxone or atrazine and crop
oil in corn have been the better choices for follow up
burndown treatments of wheat in our research
this spring.
There have been a number of reports of horseweed
not being controlled with tankmixes of
glyphosate and atrazine. This is surprising to
me but the results are what they are. It could
be that the surfactant in the glyphosate was insufficient
to get the atrazine into the horseweed
during the cold conditions. A quart of crop oil
added to the glyphosate and atrazine may have
improved the horseweed control. In crop Halex
GT tankmixed with atrazine or dicamba has
performed very well controlling horseweed in
our research. I would assume Capreno would
perform as well as Halex GT but I do not have
the experience with it on horseweed. Δ
DR. LARRY STECKEL: Extension Weed Specialist,
University of Tennessee
Volunteer Wheat Growing Through a Glyphosate Burndown
Photo credit Eric Alinger