Recent Updates

Prickly Sida Management in Soybean and Cotton

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


Managing Dicamba and Glufosinate-Resistant Pigweed

Palmer amaranth escaping dicamba + glyphosate

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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Cotton plant growth regulator guide, variety classification publications now available

Snapshot of the 2026 Cotton Variety Guide for Plant Growth RegulationThe MidSouth Cotton Specialists’ Working Group has just released the 2026 Cotton Variety Guide for Plant Growth Regulation and a more in-depth publication entitled Plant growth regulator use in Mid-South Cotton.
The in-depth publication includes a relatively new breakdown to managing plant growth that considers variety responsiveness; current and expected growing conditions;  and plant size, measured by nodes.  It is our hope that these baseline rates, presented in Table 2 of the in-depth publication, might take some of the guess-work out of the time to initiate treatments, when to make follow-up treatments, and how much to apply in each application.  Please note that 1) the rates mentioned in the attached guide are for a 4.2% mepiquat chloride formuation; 2) a maximum single application should not exceed 24 oz per acre of a 4.2% mepiquat chloride product with a maximum season application rate of 48 oz per acre of a 4.2% mepiqaut chloride product; and 3) rates and initiations should serve as baselines but should be adjusted based on local expertise and past experiences that can be locationally specific.

Volunteer Canola Control

A common weed question recently is how to control volunteer canola in double crop soybean.  We do not have research on this “new” problem.  Fortunately, my colleague, Dr. Joe Ikley of North Dakota State University, has good information on what herbicides work best. His research indicates that auxin herbicides like 2,4-D are rated poor for control of volunteer canola.

Fomesafen (Prefix, Reflex, Flexstar, etc.) is rated as excellent on volunteer canola control. This provides growers with an option that is readily available, relatively inexpensive and can provide residual pigweed control.

Liberty is also rated very high on volunteer canola.  However, this will be incorrect if the volunteer canola is a Liberty Link variety.


UT Weed Tour Next Wednesday June 17

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.

Weed Tour runs from 9 – 11:30 a.m., with registration opening at 8:30 a.m. A light breakfast will be served. Continue reading