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Arkansas weed control...

Section 18 requests under review This is the time of year we are revising our Arkansas Extension weed control recommendations, working on Section 18's and getting ready for next year. We just received word that Aventis will not be supporting any Section 18s in rice-producing states for Liberty Link rice in 2001. As I understand it, the primary concerns are marketing issues.

They have told us the technology isn't dead but rather "on hold" until the GMO controversy sorts itself out. This decision is disappointing but understandable. We were prepared to write a Section 18, but realistically the timing just wasn't right.

The Clearfield (Imi-rice) rice technology is going forward because it is not a GMO. We have an excellent database to support a Section 18 for the use of Newpath (Pursuit in other crops) in Clearfield rice. We have had a Ph.D. student working on the project for three years, and we have had roughly one-third of our rice weed control plots in Clearfield rice.

I am a big supporter of the technology. I want to see it available to our growers as soon as possible. As scientists, however, I and most of my co-workers have some concerns about this first version of the technology.

The primary public concern about any herbicide-tolerant crop is outcrossing - gene flow from the crop to a weed or weedy version of the crop. Many of the public concerns are a result of misunderstanding what gene flow would do. Some believe it would create some sort of monster super-weed. In reality, all it would do is result in a weed that is tolerant to yet another herbicide or family of herbicides.

In the case of gene flow from Clearfield rice to red rice, it would create Newpath-tolerant red rice. If that were to happen, it would do nothing more than put us right back where we are now - not being able to control red rice in drill-seeded rice. Although we would not create a monster or superweed if we got significant outcrossing to red rice, it would render the technology useless for growers.

How long do you want this new technology to last?

A lot of management strategies can be used to prevent or prolong the occurrence of outcrossing, but two things are very important in the whole scheme of outcrossing management.

First, you want to have a chance to get as near 100 percent control as possible with the herbicide program - at least get control to the point you can rogue any escapes. I have some concerns that the draft label presented to me for the Section 18 falls short in that area in certain situations.

The second thing you want is a good separation in the flowering period between the herbicide-tolerant rice and the red rice. They can't outcross if they don't flower at the same time. In our student's red rice plots this year, two of the new Clearfield varieties flowered simultaneously with the red rice. That might still be manageable, but it certainly isn't what we would like.

The student now is evaluating seed collected from the plots to see how much, if any, outcrossing occurred. That will play a big role in our decision about what to do in 2001. There are two ways for us to approach the issue. One is to make the technology available, since everyone wants it, and hope for the best (keep in mind there would probably only be a maximum of 50,000 acres of seed available to Arkansas anyway). The other approach would be to back up a year and see where we are on the outcrossing issue. If we have good evidence that perhaps waiting for a variety that flowers well apart from any red rice would prolong the life of the technology, that could be the best move.

We will be discussing the decision a lot this fall. I would guess this will promote some grower feedback as well. I always welcome it.

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