Questions continue on what to do with late season pigweed breaking through the crop canopy. Most questions have been in cotton where escaped pigweed are more visible. More questions recently have been in soybean as escapes are poking up through the canopy (picture 1). Continue reading
It is back to the future in West Tennessee. Replacing hoses and solenoids on hoods and shovels on cultivators was common back in 2008 to 2010 when glyphosate failed on pigweed. There have been recent reports of folks trying to get hoods and field cultivators in working order. The reason for this is they are trying to knock down Palmer amaranth that has escaped dicamba + glufosinate applications. Continue reading
Another week and more reports and field visits to fields where Palmer amaranth is escaping glufosinate, glyphosate and dicamba. These escapes range from relatively small pockets in fields to almost complete Palmer amaranth jail breaks across large portions of fields (Picture 1 and 2). Continue reading
There have been too many reports of Palmer amaranth escaping multiple applications of dicamba, Liberty and/or dicamba tankmixed with Liberty. Of course, we all have known for sometime that we have an ever-spreading biotype of dicamba-resistant Palmer amaranth in West Tennessee. Liberty on the other hand has been much more consistent controlling pigweed. Until it wasn’t. Continue reading
All the frequent rain lately has made it difficult to spray fields timely. This has left some cotton fields with large goosegrass and Palmer amaranth. The typical post application to control both those weeds is a tankmix of Liberty and clethodim. This tankmix will typically provide fair control of large goosegrass. However, we have found some goosegrass populations where that tankmix is not very effective. Palmer amaranth too often will recover. In those cases, hooded or post-direct applications should be considered. Continue reading
There have been a good number of reports of prickly sida issues in soybean and cotton fields. Prickly sida or tea weed has increasingly become more of an issue in these crops. There are two reasons for this. First, the Group 15 herbicides (Dual Mag, Warrant, Zidua) are the most common PRE-applied herbicides utilized. Though that group of herbicides provides good residual control of pigweed and grasses, it provides no help on sida. Second, is that neither glyphosate nor dicamba has ever been very effective on this weed. The only popular POST option that can give some control is Liberty. However, even Liberty is limited to controlling only very small (<2”) prickly sida. Continue reading
Reports of Palmer amaranth escaping dicamba and/or glufosinate have been common the last couple of days. Based on our recent research this is not a surprise as we have field and greenhouse studies showing that some Tennessee populations cannot be controlled with either herbicide (Figure 1).
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JACKSON, Tenn. – The University of Tennessee Institute of Agriculture will host the annual Weed Tour June 17 at the West Tennessee AgResearch and Education Center. The guided tour will feature 40 weed management research tests in cotton, corn and soybean. Continue reading