PPDL Picture of the Week
January 25, 2016
Fall Emerging Marestail: The lurking pest in your no-till
soybean field
Travis
Legleiter, Weed Science Program Specialist, Department of Botany and
Plant Pathology, Purdue University
The months of November and December 2015 felt more like
spring than the winter months we would expect in Indiana. The temperatures remained in the 40’s and
50’s and the majority of precipitation events were rain with the exception of
one snow that melted within days. Now
winter has officially arrived in January with multiple snow events and
seasonably cold temps. Many of the inquisitive
like to ask weed scientist: What does this winters’ weather mean for weeds this
next year? While you would think we would
have a quick definite answer, it is hard to predict what will happen this next
year. One characteristic that makes a
plant a weed is their plastic growth or adaptability to a range of environments,
this being said often odd weather conditions tend to mess with our minds more
than it does weed growth. That being
said, the only thing I can promise anybody for this upcoming growing season is:
There will be weeds that will need to be managed! I know it’s not a stretch and you already
know that, so here is what I think (key word: think) may happen this next
spring.
The warm fall and first half of winter has certainly given
an advantage to marestail as plants likely continued to emerge into the late
fall and even into December. If there
was a year to apply fall herbicides this was it, as crops came off early and
the weather held for several weeks following harvest. This was also a time when marestail continued
to emerge and grow before the winter weather arrived around the first of the
year. The marestail plants that survive
the winter will likely thrive in the early spring as the ground thaws and
things begin to green up. This will
allow for these plants to grow and reach uncontrollable sizes by late spring
when planting activities begin in Indiana.
This leads to my prediction that no-till fields that did not receive a
fall burndown may have high populations of large bolting marestail plants at
planting if not controlled by an effective early spring burndown.
Those who did not make a fall burndown are encouraged to get
into fields as soon as possible this spring to burndown marestail plants while
they remain small. A simple mixture of
glyphosate plus 2,4D and/or Dicamba or Sharpen will suffice. If a producer chooses they can add in a low
rate of a residual to help prevent further emergence, although they should
always plan to make another pass before planting to put down a full residual
and clean up any remaining marestail plants.
See the latest addition of the marestail fact sheet from
Purdue and Ohio State weed science that outlines marestial control in no-till
soybean (https://ag.purdue.edu/btny/weedscience/Documents/marestail%20fact%202014%20latest.pdf).