Arkansas weed control: Target red rice with Clearfield plan

I'm going back to the subject of Clearfield rice to keep you thinking as you make plans for next year.

As I wrote in previous articles, how we manage the outcrossing issue will determine whether this is a sustainable technology for red rice control or just a flash in the pan. I'll keep reminding you that two things are required for outcrossing to occur between red rice and Clearfield rice.

First, there has to be red rice and Clearfield rice growing intermingled. Therefore, if you can achieve 100 percent control in the field, there is no opportunity for outcrossing to occur.

Second, the two types of rice must flower simultaneously for outcrossing to occur. A lot of factors can influence this, but we can't control many of them or even predict the outcome.

The only thing we can assume is that if any red rice escapes, simultaneous flowering is always possible. We have to aim for 100 percent control of red rice, and then implement a rotation and stewardship program to deal with any outcrosses that may occur.

The drift label submitted to the Arkansas State Plant Board for approval has cleared up the issue of rates. Last year's label had the option for using 5 ounces per acre of Newpath for the soil application, followed by 3 ounces per acre postemergence, or the same scenario with 4 ounces per acre and 4 ounces per acre again.

For next year, assuming all clearances came through to market the rice, it will be only the 4-and-4 option. Our research has best supported the 4-and-4 option all along, and I am glad to see this simplification.

The label for these first varieties have only the option for a soil-applied treatment, followed by a postemergence treatment, the result of concerns about crop injury from the postemergence applications. We never receive injury from the soil-applied treatment, but sometimes do from the postemergence treatments.

As I have stated in a couple of previous articles, I have concerns over the potential for inconsistent performance by the soil-applied treatment in the field, due primarily to the moisture required for making it work.

If red rice comes through the soil-applied treatment untouched, then it will usually overpower the postemergence treatments. All we can do is use the soil-applied treatment the best we know how and commit to flushing if it doesn't rain.

From there, make a timely postemergence treatment and see what happens.

Ultimately, I think the performance in the field will be more consistent with two postemergence Newpath applications, instead of a soil-applied treatment followed by a postemergence treatment.

The first application will be made to two- to three-leaf rice, followed by a pre-flood treatment. This treatment has been equal to but no better than the ppi followed by post treatment in our research. However the ppi, followed by post treatment, provides 100 percent control for us.

I would have to ask, “If you are not confident you can make the soil-applied treatment work, do you use this technology now or wait another year or two until the varieties that will tolerate two post treatments comes along?”

I believe that for the soil-applied treatment to be consistent, it will need to be used preplant incorporated on a silt loam soil and flushed. I will continue along this theme later.

Ford Baldwin is an Arkansas Extension weed scientist. e-mail: [email protected]

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