How to Manage Pests

UC Pest Management Guidelines

Almond

Phomopsis Fruit Rot And Branch Dieback

Pathogen: Phomopsis amygdali

(Reviewed 3/09, updated 3/09)

In this Guideline:


SYMPTOMS AND SIGNS

Fruit symptoms of Phomopsis fruit rot include extensive grayish brown discolored and shriveled hulls that often have clear gum secretions and shriveled kernels. Affected fruit frequently abscise. Second-year symptoms include twig and branch dieback (see LOWER LIMB DIEBACK). Leaf lesions are round to irregular in shape with red-brown margins; in later stages they are dry and brown. Lesions are generally isolated but may occur on grouped leaves along a branch. Leaf lesions may abscise causing a shot hole symptom.

COMMENTS ON THE DISEASE

The disease is uncommon under California growing conditions and has only occasionally been reported in late spring and early summer when unusual high rainfall occurs in mid- to late spring. Sonora and Carmel are very susceptible; whereas Nonpareil and Mission are less susceptible to the disease.

MANAGEMENT

Generally, chemical control measures are not needed. If necessary, make one to two applications of Captan before late spring rains. Cultural control practices are ineffective.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431

Diseases

J. E. Adaskaveg, Plant Pathology, UC Riverside
W. D. Gubler, Plant Pathology, UC Davis
Roger Duncan, UC Cooperative Extension, Stanislaus County
J. J. Stapleton, UC IPM Program, Kearney Agricultural Center, Parlier
B. A. Holtz, UC Cooperative Extension, San Joaquin County

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