New fungicides tackle brown rot in almonds

05/26/2011 01:31:00 PM
Vicky Boyd

With recent registrations of a handful of new active ingredients, almond growers have some additional highly effective tools in their arsenal to manage common diseases.

That was the message delivered to almond growers and consultants attending the recent Nickel's Field Day near Arbuckle, Calif., by Jim Adaskaveg, a University of California, Riverside, plant pathology professor.

Every year, Adaskaveg and his colleagues conduct trials looking at "a plethora" of fungicides against several common diseases on stone fruit, strawberries, almonds and grapes.

They issue a report card, using a system where ++++ indicates the highest efficacy, + is the lowest efficacy and - is ineffective.

Several chemical manufactures have introduced new active ingredients or new premixes in the past few years against brown rot. And Adaskaveg says they all seem to provide excellent control of the fungal disease, which also infects stone fruit.

A number of others, which he referred to as 7-11 premixes, will be registered in the coming years.

The 7-11 refers to the Fungicide Resistance Action Committee groups to which the components belong.

Group 7 includes triazoles. Group 11 is the QoI fungicides, also known as strobilurins.

Quadris Top from Syngenta Crop Protection was probably the first of the 7-11 premixes to be registered.

Among the ones awaiting registration are Merivan from BASF and Luna Sensation from Bayer CropScience.

They provide broader spectrum disease control than a single active ingredient, Adaskaveg says.

Because they contain two modes of action, they also have a type of built-in resistance management, he says.

Last season, Adaskaveg says he also looked at spray timing for brown rot control in almonds. He applied a single spray at pink bud, full bloom or petal fall.

"Eighty percent of the disease is controlled with the full-bloom spray with these newer materials," he says. "Some even have reach-back of five to six days."

Nevertheless, the fungicides work best when applied as a protectant spray.

The take-home message from the research, Adaskaveg says, is "a full-bloom spray is critical for managing brown rot."

To view updated ratings for brown rot control in almonds as well as jacket rot, anthracnose, shot hole, scab, rust, leaf blight, alternaria leaf spot, powder-mildew-like and silver leaf, visit UC IPM and scroll down to page 21.



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