A learning experience

New herbicide-tolerant system requires mindset change
and may not pay for everyone

Growers who tried new herbicide-tolerant rice last season could well have been enrolled in “Clearfield University” as they received first-hand education about a technology designed to help control grassy weeds and red rice.

“Just like everybody else, I am darn happy we only had 6,500 acres rather than 120,000,” says Louisiana State University rice breeder Steve Linscombe. “We learned a lot. We learned what to do and what not to do. We learned we can’t delay that flood.”

Many growers gave the new system a passing grade for grassy weeds and red rice control, and they believe the Clearfield system has a place in their operation. Some producers, who experienced what they considered were too many red rice escapes and poor yields, flunked the system and say they can’t justify its higher cost. But most of those who tried the new Clearfield rice agreed they still have a lot of unanswered questions.

First-generation releases
Linscombe, who has been involved with breeding the Clearfield varieties, is one of those still learning. All along he’s said that the first Clearfield releases would average yields closer to Cypress or about 10 percent to 15 percent less than high yielding Cocodrie and Wells.

One reason for the lower Clearfield yields is the varieties were rushed to market sooner than most public varieties would normally be, Linscombe says.

“This technology was important enough that the decision was made to put the materials out there without as much information as we would have had with, say, Cocodrie or Cypress,” Linscombe says. “With the very limited testing we had, they looked pretty good.”

CL 121 and 141 are based on a mutant of AS 3510, an old variety with poor agronomic characteristics. That meant breeders had to cross the herbicide-tolerant mutant with varieties having agronomic characteristics required by growers.

The next generation of Clearfield varieties—beginning with CL 161 (CFX 18)—is based on a direct mutant of Cypress, and those varieties should have better yields as well as true herbicide resistance, Linscombe says. The current varieties—CL 121 and CL 141—are merely tolerant, meaning high rates of the Newpath herbicide can cause a crop response.

Like other herbicides, Newpath will not provide 100 percent red rice control, Linscombe says. Even under the best cases, growers can only expect about 95 percent weed control from any chemical.
“It gives them a tool to start eliminating those heavy red rice seed banks they have built up over the years,” says Joe Edrington, BASF Clearfield specialist. “It’s going to take good agronomic practices for them to get red rice under control, and it’s going to take several years.”

A targeted use
When evaluating whether to use the Clearfield system, growers should look at how a field would yield, mill and grade planted to conventional varieties and whether it has significant red rice populations, says Michael Prudhomme, regional manager for Horizon Ag LLC, the entity marketing the Clearfield seed. Not only do large amounts of red rice reduce milling grade, but the weed also can also cause lodging, which results in yield losses during harvest.

“Of the 83 commercial IP (identify preserved Clearfield) fields, none registered below a #2 grade due to red rice,” Prudhomme says about 2001 milling grades. “This is phenomenal because historically, most averaged a #4 or #5 grade. On average, we also saw a yield increase where we had historical performance information.

“As a result, these should be the most profitable varieties you can plant in a red rice-infested field.”
But Prudhomme will be the first to admit that Clearfield is not intended for everybody or every situation.

“There’s a place where this technology fits and where it doesn’t,” Prudhomme says. ‘If you have fields that have little or no red rice and low weed pressure and you’re getting high yields, those may not be a target for this technology.”

A financial trade off
For David LaCour, an Abbeville, La., producer who had one field of CL 121 in 2001, the system’s grass and red rice control proved advantageous. The Clearfield field yielded 39 barrels green for the first crop and 13 barrels green for the second, which was comparable to his conventional fields. (A barrel is 162 pounds or 3.6 bushels.)

Red rice control was “excellent” with only 8 ounces of Newpath herbicide.

The Abbeville producer figures he spent about $30 per acre on herbicides and about $38.50 per acre on the Clearfield seed. The Clearfield seed runs about $55 cwt, and LaCour planted at 70 pounds per acre. His conventional seed runs about $15 cwt, and he plants at 140 pounds per acre.

A lot learned, a lot still to learn
Like many other growers, 2001 was a learning season for LaCour. Although he had experience drilling soybeans and other field crops, he had always water seed rice. Last year, he drilled the Clearfield rice and found he had to manage water differently than he did with his water-seeded fields.

“Getting water on and moving the flood needs to be improved,” LaCour says. “We have questions about fertility management, timing of the Newpath herbicide and timing of the permanent flood.”

LaCour has already made changes in his irrigation system so he can quickly flood up fields he plans to plant to the Clearfield system this season.

If Canada grants approval before the 2002 planting season, LaCour says he plans to use the system in his worst red-rice-infested fields.

A fit for the system
Like LaCour, Delaplaine, Ark., producer Terry Gray sees a fit for the new system in some of his worst red rice fields. Gray farms near the Cache River, which frequently floods, so soybeans aren’t an option in some areas.

Instead, Gray has zero-graded flood-prone fields and farms rice followed by rice.

“On this ground, you have a tremendous amount of risk of soybeans drowning out,” Gray says. “With Clearfield, you have a positive return on it.”

He also sees a place for the Clearfield system in fields with heavy soil that won’t grow soybeans. His CL 141 yielded 143 bushels dry per acre compared to his total farm average of 168 bushels per acre.
One of the lessons Gray learned was the advantages of using Quadris fungicide on CL 141, which is susceptible to sheath blight. In one 30-plus acre field, the disease really “blew up.”

“By the time we realized it, it was too late,” Gray says. “Fungicide would have done a world of good. I wouldn’t recommend anybody growing this without fungicide.”

In one of his Clearfield fields, Gray didn’t obtain the type of red rice control he expected. He believes deep-situated red rice seeds germinated from below the Newpath herbicide application. He also believes he may have put the second Newpath application out a little late, although he followed label instructions. BASF has changed those recommendations for the 2002 season.

System doesn’t work for everyone
But for Scott Matthews, a Wiener, Ark., producer, the Clearfield system just didn’t pay. “Before input costs—just on yield alone—I made $110 to $120 more [per acre] on my conventional fields than the Clearfield fields” Matthews says.

“I am not negative, but I think the product needs a lot more research, a lot more field work before it goes to the public.”

His Clearfield fields averaged 123 bushels per acre whereas his lowest-yielding Wells field yielded an average of 184 bushels per acre.

In his conventional fields, which were true no-till, Matthews used $9 worth of Command per acre as his sole weed control. In addition to the Newpath, he used a full rate of Facet on the Clearfield fields because weather delayed the second Newpath application, and Matthews was concerned about grass control.

He estimates he had about 85 percent red rice control in his Clearfield fields compared to 60 percent to 70 percent red rice control in his conventional fields.

Although Matthews has a reservoir and is able to get water across his fields quickly, he says not all growers have that option. One of the recommendations is growers need to flush within 48 hours of the first Newpath application.

“There’s only about 10 percent of growers that put out their own chemicals,” says Matthews, who used to work in the chemical business. “Only about 1 percent could put out Newpath, so they rely on the co-op.

“You have to be ready when they are ready, then turn around and be surveying, then start your water when you are still trying to farm your other fields. You get into time management.”

Contact Vicky Boyd at (209) 571-0414 or vlboyd@att.net.