Walnut blight can take a hefty toll on production of walnuts, but growers in California have an option for combating the disease!

In a recent article published by Western Farm Press, Tips for better control of walnut blight shines the light on how well copper can help control walnut blight when mixed with Manzate. Specifically, we’d like to insert Magna-Bon CS 2005 here as this formula of copper sulfate pentahydrate in-solution is OMRI-listed with systemic capabilities and has proven results combating disease in copper-resistant strains. One unique trait to CS 2005 is utilizing less than an 1/8 lb per acre of metallic copper making it more environmentally friendly than competitors. While we had heard stories from growers using more than 3-5 lbs. per acre.

“Success in controlling walnut blight requires application of protective sprays to early shoots, flowers, and developing nuts, reports Rick Buchner, University of California Cooperative Extension farm advisor for Tehama County. In orchards with histories of walnut blight damage, protective treatments at seven to 10-day intervals during prolonged wet springs are necessary for adequate disease control. In areas or years with less intensive rainfall, spray intervals can be stretched, and weather forecasts can help with spray timing, he adds. “Blight treatments work by protecting walnuts from infection,” Buchner says. “They won’t control the disease if applied after infection has already occurred. Copper, tank-mixed with Manzate for each treatment, is currently the best available choice for walnut blight management.”

Alongside Buchner, research performed by Dr. Jim Adaskaveg – UC Riverside, inoculated walnut trees with copper resistant strains of Walnut Blight. With 4 applications during the trials in April through May: 4/6, 4/14, 4/23, and 5/1 of 27 ounces of Magna-Bon CS 2005 and 2.4 lbs. of Manzate DF, had 100% control of the disease! This solidifies the statement provided by Buchner, “Our experience still suggests that any good quality copper will provide good control, Spray rates vary by copper formulation.”

Click here to see the application rates for CS 2005 combating walnut blight.

In the diagrams, you will see the results by Dr. Jim Adaskaveg results from his trials of Walnut Blight!

Click Here to read the Information Sheet on Dr. Jim Adaskeveg research!

We also have additional research by Dr. Jim Adaskaveg with Walnut Blight. As you can see in the research information below, Magna-Bon CS 2005 had 94% Control of Walnut Blight with an infection rate of over 34%. Conventional copper hydroxides were even worse than the control!

We’re happy to hear that Dr. Jim Adaskaveg and Rick Buchner are on the same page.


Northcutt, Greg. “Tips for Better Control of Walnut Blight.” Farm Progress, 10 Dec. 2018, www.farmprogress.com/tree-nuts/tips-better-control-walnut-blight