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Drift problems continue in Arkansas rice

Calls continue to come in about drift problems; this is not a good thing.

Most are the normal glyphosate or Newpath drift onto seedling rice. With the increased corn acreage, however, several have involved glyphosate with atrazine and other tank mix partners.

I was called on one glyphosate plus atrazine drift where the atrazine banged up the soybeans next to the sprayed cornfield and then the glyphosate got the conventional corn field on the other side of the soybeans!

Most drift situations come down to wind speed and direction and the proximity of susceptible crops. You see the normal aerial and ground applications that never should have been put out.

As I pointed out last week, I have seen a couple of aerial applications where the glyphosate went a half-mile before it got to the rice and then went another mile or more. I have also seen ground applications that were made right across the turn row from a rice field with the wind blowing toward the rice.

There continues to be a misconception that a ground rig if drift-proof if it is running air induction nozzles with the boom low to the ground and perhaps some drift control agent in the tank.

Nobody seemed to like anything the Glyphosate Task Force or the Arkansas State Plant Board tried to do to help the drift situation. However, enough poor application judgment will likely result in increased regulation.

I have picked up on another thing in the field that may or may not be having an effect on drift. I lot of folks seem to be pushing additional surfactant with glyphosate formulations that already contain a surfactant. Most of the surfactant-containing formulations are loaded up pretty good to start with.

When a formulation includes a surfactant, the manufacturer has to assume a herbicide rate and spray volume in order to get the desired surfactant concentration in the final spray mix. I do not know what those figures are.

For example, though it is 1 quart per acre in a 20 gpa spray volume, rates are often higher than that now and spray volumes are generally lower. A lot of glyphosate is sprayed in 5 gpa volumes or less. This results in a concentration of surfactant in the spray mix.

If you turn around and add another surfactant to that, you may be spraying soap bubbles! Surfactants affect surface tension and surface tension can affect spray droplet size. You do not need additional surfactant in a formulation that already contains one.

The general weed control situation in much of the rice is excellent. In most areas, weed control has been even easier than last year.

However, there is also a lot of late planted rice due to prolonged wet conditions in some areas. It remains to be seen if we get the excellent conditions to make things easy in the later planted rice.

Regardless of how good things are, there will be some “big grass” situations and some of those calls are coming in. The big grass treatments can include Ricestar HT plus Facet preflood; Facet plus oil either just ahead of the flood or into a shallow flood if sprangletop is not in the mix; Regiment or Regiment plus Facet where barnyardgrass is the primary grass; and Clincher or Clincher plus Facet post-flood.

After the past couple of years, I am always reluctant to tell a grower just to flood and apply a post-flood treatment if the situation is bad and there are decent moisture conditions pre-flood. I always like to hit it hard preflood and then come back post-flood if needed. I will break some of these down next week.


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