Dow AgroSciences has received U.S. Environmental Protection Agency and California Department of Pesticide Regulation approvals for Dithane F-45 Rainshield fungicide use in walnuts.

Dithane F-45 provides control of walnut blight.

The active ingredient in Dithane F-45 is mancozeb, an EBDC class of chemistry fungicide from the FRAC Group M3. When mixed with copper, Dithane F-45 provides control of walnut blight.

Dow says growers have relied on this combination for more than 20 years. University of California efficacy trials show the mancozeb and copper combination is an effective treatment for walnut blight.

Dithane F-45 is packaged as a liquid flowable formulation with an ultra-small particle size that rapidly disperses and quickly goes into solution. It is easy to pour with virtually no dust, and is non-abrasive to equipment.

The fungicide can be tank mixed with commonly-used copper products.

Dow says the “Rainshield” technology – a combination of surfactants and wetting agents built into the formulation – gives Dithane F-45 rain fastness, re-distribution qualities, and plant adhesion.

Applications stick to plants, and re-distribute on plant surfaces when moisture – sprinklers, rain, or dew – is present.

Applications of Dithane F-45 can be made to all commercial walnut varieties and at any time walnuts are susceptible to the disease.

Early-blooming varieties are typically more susceptible to walnut blight since bloom occurs closer to the rainy season. Late-blooming varieties, including Chandler, need protection from walnut blight.

The recommendation, Dow says, is to begin applications at pistillate flower emergence - sometimes called the ‘prayer stage.’