New fungicides combat almond diseases

New fungicides, registered or slated for registration, will give California Almond growers more choices to manage springtime foliar diseases.

In a presentation at the 2009 Almond Industry Conference, researcher Jim Adaskaveg, University of California-Riverside, described the new products and each fits in the management of foliar diseases.

Some of the products may not be registered in time for the 2010 season. Check with a crop protection professional.

The new products are PhD, a polyoxin and a reduced-risk fungicide; Inspire and Quash, sterol inhibitors with a single-site mode of action; Luna Privilege, a carboximide with a single-site mode of action; and the natural products Regalia, Actinovate, and Cerebrocide.

Adaskaveg revealed results from 2009 trials throughout the state showing that the pre-mixtures Adament, Luna Sensation, Inspire Super, Quilt Xcel, and Inspire XT gave the best overall control of brown rot blossom blight.

Luna Privilege, a single treatment, showed comparable performance to the premixtures.

In each case, three back-to-back applications of the products were made from late February to late March.

The most effective natural product for brown rot was Regalia.

In the same trials, the most effective new fungicide for shot hole was Syllit, with Quash and high rates of Inspire Super and Quilt Xcel providing very efficacious treatments.

The best performing new treatments for Botrytis blossom blight were Adament, Inspire Super, Inspire XT, Luna Privilege, Luna Sensation, and Quilt Xcel. Combining scores for disease incidence and severity, Luna Privilege came out on top.

UC Farm Advisor Brent Holtz, Madera County, reported on a powdery mildew–like disease. The symptoms are similar to a disease called rusty spot in peach, but the causative agent is thought to be the apple powdery mildew fungus.

The disease occurs from petal fall to pit hardening. The number of diseased fruit does not appear to be influenced by the weather. Growers in his area are reporting a 10-15 percent loss in production where symptoms of this disease are observed, Holtz said.

Holtz has conducted trials with Carmel and Nonpareil varieties to determine the best control options. The fungicides Laredo, Topsin+Microthiol, and Gem were the most effective, using similar timing to scab treatments - three applications two to five weeks after petal fall.

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