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Clearfield rice: Where to from here?

Performance calls on Newpath and Beyond herbicides in the Clearfield rice system were light again this year. For the most part the herbicides seem to work.

In addition, BASF lowered the price of Facet herbicide, making it a more appealing tank mix partner or encouraging the use of ClearPath (premix of Newpath and Facet). The combination of Newpath with Facet or Command, plus or followed by Newpath has been an outstanding program for broadleaf and grass control, not just red rice. These programs do not miss much.

Approximately two years ago, we made some of the first discoveries of red rice in a commercial field that had out-crossed with Clearfield rice the year before in a continuous rice rotation field. Most weed scientists assumed that it would not be long before red rice was resistant to Newpath.

It is out there, but it is not near the epidemic level that many of us feared. I believe judicious crop rotation, rouging, and the use of Beyond herbicide to prevent out-crossing has helped limit the problem. This basically follows the original guidelines we talked about so much for stewardship.

The lack of seed this year may actually help prolong the technology by forcing some soybean rotations. I understand there will be plenty of CL 161 and CL 171 next year.

Out-crossing with the conventional varieties tends to produce only late-maturing, large F2 hybrid plants, a blessing in managing out-crossing. Those plants in fields in the fall serve as warnings to not let them go to seed.

With the hybrid Clearfield varieties, the danger for out-crossing and results of out-crossing are more severe, and becomes more and more of a concern as the hybrids become more and more popular. This is cutting edge technology, with red rice control technology built into the highest-yielding varieties.

Hybrid rice is essentially an F2 plant to begin with. Seeds from F2 plants begin to segregate out. When out-crossed with red rice, more biotypes are created than with out-crossing from a regular Clearfield variety.

University data have shown that out-crossing is more likely with hybrids due to a prolonged period of heading and flowering. This makes stewardship with the hybrids most critical.

RiceTec recently pulled back the recommended timing of late Beyond applications to hybrids from 14 days after panicle initiation to prior to panicle initiation (green ring). This makes it more difficult to make late applications of Beyond to prevent out-crossing of red rice that has escaped a sequential Newpath program. Our data do not support that late applications of Beyond on the hybrid varieties cause yield loss. Recent experiences in the field, however, have led them to be concerned.

One thing to keep in mind about possible yield losses from late applications of Beyond is competition from the red rice. That can severely hurt yields in cases where red rice is present late in the season. Season-long competition may have hurt the yields in those areas of the field prior to any Beyond being applied.

Whatever the timing, it is critical to prevent out-crossing in hybrid Clearfield rice fields.

Herbicide resistance is basically inevitable with the imadazolinone family of herbicides (Newpath, Beyond, Scepter, etc.). With judicious use, crop rotation and tank-mixing, however, it can be delayed or even prevented.

I have heard that BASF plans to seek a full section 3 label for Beyond herbicide for use in Clearfield rice. Do not expect this label before 2009 or 2010. This will help alleviate the crop rotational issues with Newpath, if the Beyond label allows for two to three applications.

Also, I think Beyond is a better basic postemergence herbicide than Newpath. This will make programs like Newpath pre followed by Beyond a legal option. Beyond has shown good activity on most grass weeds in rice and it controls ducksalad.

A Beyond-only program in Clearfield rice may take up to three applications in a season for complete red rice control. The price may have to come down before this is a viable option.

I can see growers choosing to grow Clearfield rice even if red rice control is not the primary reason, once Beyond is labeled. The main hurdle to this right now is hybrid availability and/or having a conventional variety with a disease package and 200-bushel yield potential — something breeders are working on.

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