Franz Niederholzer, UCCE Farm Advisor, Colusa and Sutter/Yuba Counties

Fruit brown rot infection results in off-grade fruit and, in worst cases, may result in a sub-standard grade for the entire crop. The most effective programs for fruit brown rot control in UC research include effective fungicide selection (include a FRAC 3 fungicide at a labeled rate), higher spray volume (for example, 130-150 gallons per acre compared to 75-100 gallons per acre) for better spray coverage throughout the tree and including light summer (415) oil or an adjuvant such as Nufilm-P in the spray tank to improve spray deposition on the fruit.

For best control, fungicides must be applied ahead of major infection event (for example, rain or extended high humidity producing long, overnight dew events). Fruit brown rot can be very difficult to control, so growers should not expect miracle control under high-risk conditions of damaged, clustered fruit, and/or high levels of moisture in the orchard (rain or dew). Consult with your PCA and processor regarding fruit brown rot infection risk and, if a spray is needed, proper materials, preharvest intervals, rates, and timing.