All posts by Delaney Foster Graduate Research Assistant

Dicamba-Resistant Waterhemp Confirmed in Tennessee

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Results from greenhouse experiments and in-field research this summer confirm that our state now has dicamba-resistant (DR) waterhemp. Moreover, our survey of weed escapes this fall sponsored by the Tennessee Soybean Promotion Board has found that waterhemp has spread quickly. Continue reading


Points to Consider when Choosing Soybean Herbicide Trait Platform

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(Picture 1) Palmer amaranth in this field in 2020 and 2021 escaped multiple applications of dicamba, glyphosate and glufosinate

Several retailers and growers in recent weeks have asked about switching away from Xtend soybeans due to the poor pigweed control they have seen in consecutive years in some fields. There are a lot of moving parts when one attempts to answer this question and some different points need to be considered. Continue reading


Manage Large Palmer amaranth Escapes

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Picture 1. Palmer amaranth escapes from Engenia + glyphosate. Picture taken 30 days after application.

We have visited fields where growers assumed their Engenia or XtendiMax + glyphosate had controlled Palmer amaranth only to find that many had escaped and are now quite large (Picture 1). The question is what are some approaches to manage these escapes? Continue reading


Management of Auxin-Herbicide Resistant Palmer Amaranth

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In fields where dicamba and 2,4-D are no longer effectively controlling Palmer amaranth what are some options to help manage this weed?  We conducted research at several locations this year trying to answer this question.

Picture 1. Palmer amaranth escapes from dicamba + glyphosate on 4″ Palmer followed by dicamba + glyphosate 7 days later.  Picture taken 21 days after last application

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Dicamba and 2,4-D: No longer “Palmer amaranth Herbicides” in Some Fields

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Picture 1. Palmer amaranth escapes 18 days after 12.8 ozs Engenia+ 32 ozs glyphosate. A farmer’s field, Lauderdale county, TN

For the past week we have been getting reports along with a good many pictures of Palmer amaranth escaping dicamba application/s from retailers and consultants scouting fields (Picture 1 and 2).  As one retailer so aptly described it today “there are spots in fields where the lack of Palmer control is frightening”. Continue reading


Managing Dicamba or Enlist One Resistant Palmer Amaranth

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(Picture 1) 20 DAA: Palmer amaranth escapes from 22 ozs XtendiMax + 16 ozs Clethodim + 32 ozs glyphosate applied on 1 to 4″ weeds

Judging from research tests and walking a few farmers’ fields many of the PRE applied herbicides in soybean and cotton played out about a week or so ago.  Timing is everything on trying to do the best job on Palmer amaranth that has broken through the PREs.  With respect to Palmer amaranth that has low-level dicamba or 2,4-D resistance (2 to 3x), timing is even more important.  Moreover, herbicide selection is also critical in controlling resistant Palmer. Continue reading


Start Scouting for Palmer Amaranth that Escapes Dicamba or 2,4-D

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(Picture 1) Dicamba + glyphosate on 3″ Palmer 4 DAA

This picture (Picture 1) was taken just 4 days after a dicamba + glyphosate + clethodim application on 3” Palmer amaranth. Judging from some experience with this Palmer population, the growth after application would suggest it will likely survive. When we revisited the site indeed it had (Picture 2). Fields infested with similar Palmer populations are scattered about in a few counties in West and Middle TN. As such, there will be no substitute for first hand observation to determine if Palmer amaranth is recovering from a dicamba or Enlist application.

In our research more dicamba sensitive Palmer amaranth will often be dead or well on their way under good heat and moisture conditions in 7 days or so.  Palmer that is showing regrowth from the apical meristem or lateral buds around  7 to 10 days after application often will live. Experience from last year would indicate that not only will they live but after a short pause will become quite competitive. Continue reading