• By Vicky Boyd,
At a recent field tour near Kaplan, Louisiana, Horizon Ag gave growers a preview of the newest Provisia rice variety, PVL03, which it plans to launch commercially for the 2022 season.
Tested for the past four years, PVL03 offers yield potential as good or better than its predecessor, PVL02, but with an improved disease package. PVL03 contains the Pi-ta and Pi-ks blast-resistance genes as well as a Cercospora-resistance gene.
To help preserve the technology, Horizon Ag general manager Dr. Tim Walker urged growers to diligently rotate Provisia varieties with conventional rice varieties, Clearfield varieties and soybeans.
“We need to preserve the Provisia technology much better than we did with the Clearfield technology,” he said. “In the long term, we may be able to bring Clearfield back into the system.”
For rice producer Christian Richard, who has a small demonstration field of PVL03 by his shop near Kaplan, the variety’s blast resistance is a big draw.
He applies fungicide to his PVL02 twice to pick up blast and sheath blight because the diseases have different treatment timings. With the PVL03, he should be able to apply just one fungicide that targets sheath blight.
With resistance to the Provisia grass herbicide, the Provisia rice lines have allowed him to clean up weedy rice in some of his worst fields and drill plant rice into dry ground.
Years ago, farmers in South Louisiana kept a flood on fields, water leveled them and water planted to keep red rice at bay. Not only was the water-based system hard on equipment, but Richard said it was more labor intensive and hard on the psyche.
“Without Provisia, we wouldn’t be farming the amount of ground we’re farming,” he said. “We just can’t grow rice like we used to on this scale.”
From the LSU AgCenter
From the Louisiana State University AgCenter breeding program of Dr. Adam Famoso, the variety was developed using traditional breeding techniques to tolerate over-the-top applications of Provisia herbicide. As such, it is not considered a genetically modified organism, or GMO.
Provisia rice varieties are paired with BASF’s Provisia herbicide, which contains the active ingredient quizalofop P-ethyl.
PVL03 is the latest in the Provisia line that began in 2018 with the commercial launch of PVL01. Although the first variety had good grain quality, kernels averaged 7.4 millimeters, making them prone to breakage during milling. PVL01 also yielded significantly less than many other varieties.
Famoso said the introduction was never intended to be long term but was fast-tracked to get the weed-control technology into the hands of growers.
PVL02, launched in 2020, had improved yield potential, but the kernel length was significantly shorter, averaging 6.5 millimeters. Although still within the range considered as Southern long grain, it still shorter than the sweet spot of 7 mm.
PVL03 kernel length averages 7 mm, and it has an attractive bold, translucent grain.
Plant height averages 3 to 4 inches shorter than PVL02, and PVL03 has improved stalk strength for reduced lodging. The new release also is two to three days later in maturity than PVl02.
In addition, PVL03 contains the same blast-resistance genes as the Clearfield variety, CL153, Famoso said. “So we expect this to give us some really good blast resistance.”
In trials, PVL03 has yielded as good or better than PVL02 and frequently up there with CL153, he said.
“I think this is going to be a big step forward,” Famoso said.
In variety trials across six Louisiana locations in 2020, PVL03 averaged 8,218 pounds per acre compared to PVL02 at 7,245 pound per acre.
Best practices for weed control
Provisia herbicide is labeled for up to two applications of 15.5 ounces each, or a total of 31 ounces during the season. The ACCase herbicide only targets grass, so growers may need to include other herbicides to control broadleaf weeds. In addition, Provisia is a contact material and has no residual activity.
LSU weed scientist Dr. Eric Webster, who has worked with the Provisia system for several years, recommended growers start preplant with a residual herbicide, such as Command or Prowl.
“Anything with a residual, like Command, takes the pressure off of that Provisia,” Webster said.
The first Provisia application should be made at the one- to two-leaf rice stage, followed by a second application to four- to five-leaf rice. Webster said he regularly has growers ask how late they can go with an application.
“My answer is always, ‘If you have to ask that question, you’re obviously getting late in the year.’ My answer is always to spray that rice. We don’t need outcrossing. We need to keep it as clean as we can.”
If possible, Provisia applications also should be made under warm, sunny conditions to avoid possible adverse crop response, Webster said. If they apply Provisia under cool, cloudy weather, growers could see what he called “yellow flash.”
PVL02 and PVL03 don’t seem to exhibit the issue as much as PVL01, but Webster said the crop response is likely inherent to the chemistry.
“I think this is something we’re going to have to learn to live with,” he said. “When you spray under adverse conditions, especially three to four days of cloudy weather, I think that’s just the technology. Last year, we got very little injury, but this year was a lot different. We had more adverse conditions.”
Webster recommended growers be patient, and the crop will typically grow out of it in seven to 10 days.
As part of his research, Webster looked at tankmix partners for Provisia. Although many appear compatible with the ACCase herbicide, he warned against tankmixing propanil or an auxin, such as 2,4-D. Tankmixes that include Regiment and Grasp also should be avoided.
If growers want to use proponil, Webster suggested applying Provisia first, then following two to three days later with propanil.