Category Archives: Soybean

Burndown Timing is Critical for Ryegrass Control

Italian ryegrass is still a significant problem in many Tennessee fields due to failed herbicide burndown applications.

Our recent research suggests that there are two critical factors in burning down ryegrass. First, timing of herbicide application is extremely critical to gain the most consistent ryegrass control.  The second is herbicide choice.

Timing is a very important component in ryegrass control.  Our recent research has shown that burndown applications applied in early February provide better control than the same application in March and is worlds better than applications in April (Picture 1.)

In general, clethodim is the most consistent choice to control this weed.  Glyphosate at best will only provide ryegrass suppression.  The tankmix of the two often will enhance the consistency of ryegrass control.

There have been calls this spring about ryegrass that has escaped multiple clethodim applications.  The concern of course is that resistance has developed as it has in Louisiana and Mississippi.  We plan to conduct a survey this year to determine if resistance to clethodim is present in Tennessee ryegrass.


Still Seeing Good Control with Liberty on Palmer amaranth

Picture 1. Good Palmer amaranth control 7 days after application on Lauderdale county populations

Results from our greenhouse screens of Palmer amaranth to Liberty have been very encouraging.  We feared that the Liberty resistance documented in Arkansas had crossed the river.  The good news is that we have seen good control with a 32 oz/A rate of Liberty on all the Palmer populations tested (Picture 1). Continue reading


Herbicide Strategy in Extend Soybean With No Dicamba

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A big question this spring is how does one control Palmer amaranth in Xtend soybean with no dicamba option?  The fundamentals of leaning heavily on herbicides that provide good residual control of pigweed is the answer. Starting in about 2019, the most consistent strategy to control Palmer amaranth has been overlaying residuals.  That was because POST options started becoming less reliable due to the evolution of dicamba/2,4-D resistance stacked onto pigweed already resistant to glyphosate, PPO and ALS- inhibiting herbicides. Continue reading


Horseweed and Grass Burndown

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Horseweed recovering from 12.8 ozs of Engenia

Horseweed recovering from 12.8 ozs of Engenia

Ryegrass and poa control can become more problematic when horseweed must also be controlled. Simply dropping dicamba in the tank with glyphosate and/or clethodim to control the horseweed will compromise the grass control of those two herbicides. So, is there a herbicide that can be added to glyphosate or glyphosate + clethodim that will provide horseweed control while not sacrificing ryegrass control? There is really only one option that is in good supply that would fit the bill. Continue reading