Few activities are more frustrating – or more expensive – for farmers than spraying a fungicide or any other pesticide, for that matter, that doesn’t provide the level of disease control that was intended.

Rice growers, hopefully, will keep that in mind as they begin scouting their fields for symptoms of Rhizoctonia solani or sheath blight and preparing to spray Sercadis, a new fungicide product from BASF, that provides control of strobilurin-resistant sheath blight.

“Sheath blight is usually considered the No. 1 foliar disease in rice, particularly in fields that have a history of sheath blight,” says Alvin Rhodes, technical service specialist in Mississippi for BASF. “It’s the same disease as aerial blight in soybeans so we typically put more selection pressure on our fungicides for this disease.”

Rhodes said that’s why BASF and rice disease specialists are recommending that growers use a full rate of Sercadis when they begin observing symptoms of sheath blight. In South Louisiana, that will be 6.8 fluid ounces of active ingredient; farther north, 6 ounces may suffice.

“Our research indicates it’s better to use a high rate of Sercadis on the first application and then not have to spray again, if possible,” said Rhodes. “We believe that will mean reduced risk of developing resistance in sheath blight to this new compound.”

Sercadis, which contains the new active ingredient, Xemium, was first applied under a Section 18 special use exemption to control strobilurin-resistant sheath in South Louisiana two years ago. Growers have been relying on the strobilurin class of fungicides for years.

“Originally, we were recommending two sequential applications of a 4.5-ounce rate of Sercadis,” said Rhodes. “Now we’re recommending 6.8 ounces because it gives you longer residual control of sheath blight which may mean you won’t have to spray again. Further north, growers typically don’t spray as high rates as they do in the southern part of the region.”

Trials comparing other products with Sercadis in Louisiana resulted in a 33.2 percent incidence of sheath blight for Sercadis compared to 35.4 percent for the competing product and 58.5 percent where no fungicide was sprayed. Rice yields averaged 182 bushels per acre for Sercadis, 179.4 bushels for the competing product and 156.8 bushels for the untreated.

In Mississippi State University research trials, the plots sprayed with Sercadis averaged 239.7 bushels per acre, with a competing product, 235.7 bushels per acre and with no fungicide, 209.1 bushels per acre.

Sercadis should be applied with a 0.25-percent non-ionic surfactant solution or a crop oil concentrate at 1 percent by volume in a minimum of seven to 10 gallons per acre for aerial applications. Based on disease development, apply from panicle differentiation to late boot. Sercadis can be tank-mixed with another fungicide if needed for control of other diseases.

BASF also has these recommendations for preventing the spread of resistant sheath blight:

  • Use conventional tillage practices in the fall or spring.
  • Pull levees and hold water on field during the fall and winter.
  • Select the most resistant or tolerant varieties and hybrids.
  • Use recommended seeding rates and fertility practices.
  • Clean equipment before transporting to another field.
  • Make timely fungicide applications using multiple modes of action.
  • Use the full labeled rate of the respective fungicides. Do no reduce fungicide rates.

Sercadis provides both preventive and post-infection sheath blight control with long-lasting residual, BASF says. To read more about Sercadis, visit www.agproducts.basf.com>