When it comes to new auxin herbicides small and fine droplets are out while large and coarse very extremely ultra droplets are in  Throw your old flat fan or hollow cone tips in the trash

When it comes to new auxin herbicides, small and fine droplets are out while large and coarse (very, extremely, ultra) droplets are in!! Throw your old flat fan or hollow cone tips in the trash.

Tailgate Talk: General thoughts about 2,4-D and dicamba-resistant crops

While improvements in the formulations of both 2,4-D and dicamba will significantly reduce potential to volatize from a field, it will not replace the need for common sense application techniques.  Tailgate Talk is a semimonthly series of articles by University of Georgia Extension specialists Eric Prostko and Bob Kemerait.

The hot weed science topic this winter will most likely be the launch (???) of 2,4-D and dicamba-resistant cotton.  Soybean growers in the Southeast region who may also be eagerly awaiting the arrival of this technology will have to wait at least one more year (2016) before getting their hands on this stuff.  As with any new technology, there will some bumps, bruises and a new learning curve. 

Hopefully, my colleagues and I can help lighten the load and prevent any major catastrophes.

Eric Prostko, UGA Extension

Since I do not work specifically in cotton, I will not comment on the pros and cons of these new systems in cotton.  I will let my cotton friends handle those questions.  However, there is one thing common to soybeans and cotton: off-target movement.  Off-target movement is mine and should be your No. 1 priority and concern.  Quite frankly, growers who choose to use these new systems will have to become better pesticide applicators.

(Editor’s note: Tailgate Talk is a semimonthly series of articles by University of Georgia Extension specialists Eric Prostko and Bob Kemerait, covering weed and disease management strategies for peanut, corn, soybean and cotton production in 2015.)

Examples of spray nozzles used in 2,4-D and dicamba resistant crop research. Left = TTI02; Right: AIXR11002

While improvements in the formulations of both 2,4-D and dicamba will significantly reduce their potential to volatize from a field, it will not replace the need for common sense, good judgment, and better application techniques.  With these new technologies, growers will have to pay even closer attention to application details such as adjacent/nearby crops, buffers, ground speed, boom height, wind speed/direction, spray pressure, droplet size, and sprayer clean-out.

Speaking of droplet size, you should be prepared for a big change with these technologies.  Small and fine droplets are out while large and coarse (very, extremely, ultra) droplets are in!!  Throw your old flat fan or hollow cone tips in the trash.   BASF, DowAgroSciences, and Monsanto will provide very specific recommendations about the type of spray nozzles that can be used with each of their herbicide products.

University weed scientists and agronomists have had the opportunity to evaluate this technology for the last several years.  It has given us a chance to get some practical field experience and work out some of the bugs for sure.  However, more will need to be learned after the technology is used at the farm-level.  That has been the case with almost every new herbicide or technology that has been released during my professional career.

Residuals still needed with timely applications

With the 2, 4,-D and dicamba resistant crop technologies, there are two important things that I must emphasize.  1: Residual herbicides will still be needed and 2: POST applications will still need to be timely (2-4” weeds).  There are no corners to cut!  Hopefully, we all have learned valuable lessons from the successes and failures that occurred since the release of glyphosate-resistant crops 19 years ago.     

Lastly, many specialty crop growers are nervous about the release of these technologies.    In Georgia, significant educational efforts will be made by UGA and the Georgia Department of Agriculture to inform growers about drift management, the value of specialty crops, their potential sensitivities to 2,4-D and dicamba, insurance, and what could happen in an off-target complaint situation.    

For example, many folks probably do not know that tomato plants are sensitive to dicamba at a 1/300th use rate and 1 acre of staked/plasticulture tomatoes is worth about $35,000!!  Info such as that should be more than enough to motivate better product stewardship for sure!

At the time I penned this article (December 19, 2014), the green light for 2,4-D and dicamba resistant cotton was not yet on.  2,4-D resistant soybean and field corn will be available on a very limited basis to growers in select regions in 2015 (Iowa, Illinois, Indiana, Ohio, South Dakota, Wisconsin and maybe 10 other states). 

Only time will tell how much the 2,4-D and dicamba resistant crop technology will be adopted by growers.  My hope is that growers will approach this technology with the upmost respect and heed the advice of local experts.  As always, good weed hunting and I look forward to seeing you in the field or at a county production meeting!

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