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Citrus

Septoria Spot

Pathogen: Septoria spp.

(Reviewed 7/03, updated 7/03)

In this Guideline:

Symptoms
Comments on the disease
Management

SYMPTOMS
Symptoms of Septoria spot appear as small, light tan to reddish brown pits on fruit, 0.04 to 0.08 inch (1-2 mm) in diameter. Dark brown to black fruiting bodies often grow in the small depressions, which usually do not extend beyond the oil-bearing tissue. The spots are much more conspicuous after the fruit has changed from green to yellow or orange. A tearstaining often accompanies the spotting. On lemon, the small spots develop into large, brown blotches during storage. Septoria may cause similar spotting on leaves or twigs that are weakened by frost or pests.

COMMENTS ON THE DISEASE
The Septoria fungus causes spotting of Valencia oranges and occasionally of lemons and grapefruit. It occurs in the San Joaquin Valley and interior districts of southern California during cool, moist weather.

Infections begin when Septoria spores are spread throughout the tree in dew or rain water. The damage to the rind lowers the grade of the fruit and results in culling.

Septoria spot may be confused with copper injury, except that the pits caused by copper do not have fungal fruiting bodies.

MANAGEMENT
Apply a preventative copper spray in late fall or early winter, just after the first rain. In years with heavy rainfall, respraying may be necessary.

Common name

(trade name) Amount to Use

A. ZINC SULFATE-COPPER SULFATE-HYDRATED LIME#

(3-2-6-100) 10-25 gal/tree

COMMENTS: For use on grapefruit, oranges, and lemons. Apply in 100 gal water from Oct-Dec or just after first rain. In the Central Valley increase the amount of hydrated lime to 20 lb for the control of leafhoppers, if populations of this pest are high; if populations are low, use the 6 lb rate. Hydrated lime helps prevent copper toxicity under certain environmental conditions.

# Acceptable for use on organically grown produce.

PUBLICATION

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Diseases
H. D. Ohr, Plant Pathology, UC Riverside
J. A. Menge, Plant Pathology, UC Riverside

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