Brown Rot Blossom and Twig Blight

The blossom and twig blight phase begins with the death of young blossoms and their associated spurs and leaves. Infection moves from flowers into twigs to form small cankers. Gum exudes at the base of infected flowers. Cankers on blighted twigs have tan centers with dark margins. In high humidity gray brown spore masses form on diseased flower parts and twig cankers.

The fungus survives on diseased twigs and mummified fruits, either on the tree or on the ground. Brown rot fungus spores are airborne and are also spread by rain splash and insects. Moderate temperatures and moist weather during bloom favor blossom blight.

• Remove fruit mummies from the trees immediately after harvest or during the dormant season.
• Use soil cultivation to cover and breakup mummified fruit.
• Two to three bloom fungicide applications are necessary to control brown rot blossom and twig blight, depending on the weather. Because apricot sepals, in addition to other flower parts, are susceptible, the application at red bud is most important.
• Spray every 14 days to provide adequate continuing protection,. When continued heavy rainfall is occurring or other conditions are occurring that result in high susceptibility to infection, shorten this interval to 7 to 10 days.

Aerial applications are generally not as effective as properly applied ground sprays but may be necessary when the orchard floor is too wet.