Fine-tuning Bloom Disease Programs

February 1, 2013

A number of excellent fungicide treatments have been registered to protect against brown rot, shot hole, gray mold and jacket/green fruit rot, according to UC plant pathologist Jim Adaskaveg, who spoke at the 2012 Almond Conference in December. Newly registered fungicides include Fontelis and Luna Sensation. Many of the new products are pre-mixtures of two active ingredients to boost effectiveness, activity spectrum and resistance management.Apply bloom sprays late in the day to minimize bee exposure.

Growers must determine what combination of fungicides and timings best fit their individual bloom-time disease management programs. The Conference poster (Adaskaveg 2012 p path4) presented by Dr. Adaskaveg provides field results and timing for a number of newly registered fungicides.

The UC IPM website is also a comprehensive resource. Documents of particular relevance include “General Properties of Fungicides Used in Almonds” and “Fungicide Efficacy for Almond Diseases.”

In addition to treatment efficacy and timing, there are other key considerations for a sound bloom fungicide program. One is resistance management. Dr. Adaskaveg reported emerging resistance of the brown rot pathogen (Monilinia laxa) to the anilinopyrimidines in FRAC resistance group 9 (e.g., Vanguard and Scala). Background on resistance management and sample spray programs are found on the UC IPM site in the “General Properties” and “Fungicide Resistance Management” documents. Also see the document “2012 Efficacy and Timing of Fungicides, Bactericides and Biologicals for Deciduous Tree Fruit, Nut, Strawberry and Vine Crops.”

Another key consideration is minimizing exposure of bees to sprays by avoiding applications when pollen is available and bees are foraging. This normally is best accomplished by spraying after mid-afternoon and at night. Information and guidelines can be found in the “Efficacy and Timing” document.

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