Dithane® F-45 Rainshield® Fungicide Registered for Walnuts

Taylor Hillman General

Dow AgroSciences received U.S. EPA and California Department of Pesticide Regulation approval for Dithane® F-45 Rainshield® fungicide 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 (FRAC Group M3). “Dithane F-45, when mixed with copper, provides unsurpassed control of walnut blight,” says Jim Mueller, Dow AgroSciences field scientist.  “In fact, growers have relied on this combination for more than 20 years.  University of California efficacy trials continue to show the mancozeb + copper combination is the most 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.  Dithane F-45 can be tank mixed with commonly-used copper products.

Additionally, the “Rainshield” technology – a combination of surfactants and wetting agents built into the formulation – gives Dithane F-45 exceptional rainfastness, re-distribution qualities and plant adhesion. Applications not only stick to plants, but re-distribute on plant surfaces when moisture – sprinklers, rain, 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 simply because they bloom closer to the rainy season,” Mueller says.  “But even late-blooming varieties like Chandler need protection from walnut blight.  The recommendation is to begin applications at pistillate flower emergence, sometimes called the ‘prayer stage’.”