Soybean Variety Selection Consideration: Do Not Spray Dicamba Near High Value Crops
DR. LARRY STECKEL
JACKSON, TENN.
Dicamba training is well under way across the state. As of last week we have had over 1500 applicators who have taken the dicamba training. That should be about 60 percent of the total number of folks that will need to take this training. Please remember if you’re the operator of the sprayer you must go through the dicamba training. Moreover, in Tennessee you must also be a Certified Pesticide Applicator to apply dicamba.
It is clear to me that once again in 2018 Tennessee will plant a large majority of Xtend cotton. The change will be that the herbicide trait platform for soybean will move from roughly 60 percent Xtend in 2017 to greater than 80 percent Xtend this year.
My concern is that we have fields in this state where we have no business spraying any form of dicamba in June or July. These would be fields near high value crops like tobacco, vineyards, greenhouses and vegetable production.
One of the reasons that states like Georgia had a lack of drift complaints in 2017 was because applicators did not spray dicamba near high value crops. This was one of the points of emphasis in their “Using Pesticides Wisely” training.
So what did they spray in fields near valuable crops? My understanding is that if an Xtend cotton field was near a cowpea field, they frequently used Liberty, not dicamba, to control their pigweed. In fields of Xtend soybean they could often use Flexstar to control the Palmer amaranth instead of dicamba near high value crops. The reason they could do this is that their Palmer amaranth is still susceptible to Flexstar in the southeast. Unfortunately, that is not the case in Tennessee.
In a recent survey of Palmer amaranth in West Tennessee fully 80 percent of our population is resistant to both glyphosate and POST applied Flexstar. Therefore in Xtend soybean the only POST applied option to control Palmer amaranth is dicamba. However, applying dicamba is a high risk proposition near high value crops. Therefore, I would strongly suggest that Liberty Link soybean be planted in fields near these crops.
I know it is a hassle to raise both Xtend soybeans and LL soybeans. However, it would be better to suffer a little dicamba damage on your LL soybean than to have to go through all the drama, time and expense if the finger is pointed at you for drifting on a neighboring high value crop. ∆
DR. LARRY STECKEL: Extension Weed Specialist, University of Tennessee