Rice Farming

Third Time’s The Charm

California growers benefit from
new herbicide product

By Carroll Smith

Stringent regulations and fewer tools in the crop protection arsenal challenge California rice producers more than rice farmers in other states. Thus, growers out West are always glad to see a new product hit the market that can be of benefit to them.

In 1983, thiobencarb – the active ingredient in Bolero herbicide – was introduced in California. Bolero 10G was the first formulation that Valent marketed in the state, later followed by Bolero 15G. In 2002, the company began looking at new technology and carriers, which led to the registration of Bolero UltraMax in 2007.

2008 marks the first year that the granular herbicide will be commercially available for use in California rice production systems.

“The range of weeds it controls makes it unique,” says Greg Rich, Bolero UltraMax product development manager. “Bolero UltraMax provides consistent contact and residual control of the early emerging ‘big three’ weeds – sprangletop, watergrass and smallflower umbrellaplant. Because the herbicide has a different mode of action, it also helps manage herbicide resistance.”

From a researcher’s perspective
Joe Desmond, Butte County Rice Growers Association’s research manager, says, “Efficacy on watergrass, sprangletop and smallflower umbrellaplant makes Bolero UltraMax a great fit as a foundation herbicide where the watergrass is still susceptible. A herbicide that allows a grower to keep the water on a field is way ahead of the game in most instances.”

Desmond adds that the use of a granular herbicide like Bolero UltraMax early in the season in a permanent flood culture is the preferred method of production in most California rice-growing areas. Key weeds are controlled early for reduced competition with the crop, and off-target drift and fertilizer loss from drying a field are not an issue.

“These attributes make Bolero UltraMax an excellent fit for growers that don’t have risk factors for delayed phytotoxicity syndrome (D.P.S.),” he adds.

Take note of application timing
As with any rice herbicide, it’s far more economical to control small weeds and not allow them to compete with the rice plant.

“The yield parameters can often be affected by early competition for moisture, nutrients and light,” Rich explains.

For best results, Valent recommends applying Bolero UltraMax by air after flooding when rice is in the expanded two-leaf stage (first open leaf), watergrass and sprangletop are two-leaf or less, and smallflower umbrellaplant is three-leaf or less. The recommended rate is 23.3 to 26.7 pounds/acre.

“In my test work,” Desmond says, “Bolero UltraMax applied at 23.3 pounds/acre provided equivalent weed control to 26.7 pounds/acre of the 15G formulation.”

‘Works better and faster’
Todd Miller, a P.C.A. with Agriform-Woodland in Woodland, Calif., has conducted large field trials with Bolero UltraMax for the past two years.

“Bolero UltraMax’s new technology allows the product to release a lot faster, so we’re able to kill weeds faster than we could with the old 15G formulation,” he says. “Also, with the 15G we were starting to see some smallflower break through. But I was able to control the smallflower with Bolero UltraMax. It just works better and faster. I think it will be a frontrunner in the California rice market.”

Valent sales rep J.R. Gallagher points out that “with the new product, we are able to get a higher concentration into the paddy water earlier, which gives us more consistent and reliable foundation weed control.”

Potential reduced water hold
At this time Valent is working with the California regulatory agencies to determine Bolero UltraMax’s water hold requirement so California rice farmers will have greater flexibility in water management practices.

Contact Carroll Smith at (901) 767-4020 or csmith@onegrower.com.