Rice PGRs, new compounds and timing issues
Aug 9, 2006 9:50 AM,
By David Bennett
Farm Press Editorial Staff
Richard Dunand is studying plant growth regulators — compounds that modify plant growth and development — for rice.
“We want to know the ways PGRs can benefit rice farmers, primarily in increased yield,” said the LSU AgCenter rice researcher at the Rice Research Station field day in Crowley, La. “In the past, we did a lot of work with gibberellic acid to improve seed vigor. That product is now labeled for the market. It’s used quite a bit in drill-seeded rice and particularly in hybrid rice, especially Clearfield rice.”
Dunand is also studying Valent’s Prestige, a cytokinen-type PGR.
“We’re also working with gibberellic acid applied late-season to the first crop to see the effects on the ratoon crop. This was initiated last year and is being done in conjunction with work at the Beaumont station in Texas.”
Late season applications (after heading and pollination have occurred) have allowed increases in ratoon crop yields. At this point, the research is in the early stages.
“We don’t have many answers about what’s going on. But we are seeing anywhere between 10 percent and 30 percent yield increases in the ratoon crop. Hopefully that will hold up and we’ll have something to put in producers’ hands down the road.”
For the past three years, Eric Webster, an LSU AgCenter weed scientist based in Baton Rouge, has been working with Italian experimental compounds. One, Strada, shows promise.
“The way I describe herbicides is to compare them to those already on the market,” said Webster. “One that we use quite a bit is Permit. It has good activity on broadleaves like joint vetches when they’re small. It’s also a very good sedge material.”
Strada has much of the same activity as Permit.
“I think that’s where its fit will be. It will work well in water-seeded and drill-seeded rice.”
Strada also has something Permit doesn’t: a bit of grass activity.
“I wouldn’t consider it as something to control grass from one end of the field to the other. But it will suppress and keep the grass small. So, maybe, if you come back with a second application it may make grass control easier with Clincher or Ricestar.
“They’re hoping to have a label next February and we’ll have some for use on a limited basis.”
Webster and colleagues are also continuing Newpath/Clearfield studies.
“We got an increased rate this year: 6 ounces followed by 6 ounces. We’ve studied that 12-ounce rate — looking at it up front, even at one shot all the way through the season.”
An interesting thing about ALS products is they aren’t rate-reactive.
“Generally, where the companies tend to label these compounds is where they need to be. Twelve ounces is good because we can break it into 6-ounce shots. I’m not a big proponent of doing everything at one time. But we’ve tried that and the CL 131 and CL 161 are fairly tolerant of that rate.
“We’ve looked at it from very early post at 12 ounces all the way to late post applications, postflood applications in one shot. It’s still very important to get any rate of Newpath out early.”
Unfortunately, there isn’t much activity on tillering grasses even with the 12-ounce rate.
“It just doesn’t do well with larger grasses. It’s very important, with any herbicide, to get it out early. One- to 3-leaf grasses are best to put products on…I’ve yet to find a label that says, ‘Wait until the weed gets 3 feet tall before spraying.’ I’ve gotten a lot of calls, especially this year, from producers planting into large weeds. They were already behind the 8-ball.”
Some findings from several years ago indicated uncontrolled weeds up to about three or four weeks after emergence were key drags on yield.
Weed control concerns should begin “up front. I get a lot of calls from people saying, ‘I’m waiting (to spray) because I want to treat once.’ Well, if you’re only going to treat once, put it out early. Get the weeds controlled early and establish your flood. Don’t wait for the weeds to reach a uniform size because you’ll miss some. We’re losing our yield early from weed competition.”
e-mail: dbennett@farmpress.com
