Apricot (Prunus armeniaca)-Shothole

Cause Wilsonomyces carpophilus, a fungus that overwinters on infected buds and twigs. Spores spread primarily by splashing water and can remain viable several months when dry. Most cultivars appear to be very susceptible.

Symptoms Leaves develop small, round, tan to purplish spots that are seldom larger than 0.25 inch wide. Tissue becomes somewhat raised and scurfy and often drops out in dry, warm weather, producing a shothole effect. Fruit symptoms are similar and can be accompanied by a clear, gummy exudate. Small red fruit spots may be numerous and slightly sunken. On dormant shoots, buds often are killed, but very few twig infections occur. Twig symptoms include small necrotic spots that become larger and sunken. Defoliation and fruit drop can occur when the disease is severe.

Chemical control To reduce the possibility of resistant fungal strains, alternate or tank-mix fungicides from different groups that have different modes of action.

  • Apply fungicides in October before heavy rains.
    • Bordeaux 8-8-100. O
    • Bravo Weather Stik at 3.1 to 4.1 pints/A. Group M5 fungicide. 12-hr reentry.
    • Champ WG at 8 to 16 lb/A. 48-hr reentry.
    • C-O-C-S WDG at 5 to 15.5 lb/A. 48-hr reentry.
    • Copper-Count-N at 8 to 12 quarts/A. At leaf fall. 48-hr reentry.
    • Cuprofix Ultra 40 Disperss at 5 to 8 lb/A. 48-hr reentry.
    • Cueva at 0.5 to 1 gal/100 gal water/A. May be used on day of harvest. Group M1 fungicide. 4-hr reentry. O
    • Echo 720 at 3.1 to 4.1 pints/A. Group M5 fungicide. 12-hr reentry.
    • Monterey Liqui-Cop at 3 to 4 Tbsp/gal water. H
    • Nordox 75 WG at 5 to 13 lb/A. 12-hr reentry. O
    • Ortho MAX Garden Disease Control at 3.75 teaspoons/4gal water. H
  • Apply again at shuck split.
    • Abound at 12 to 15.5 fl oz/A. Do not apply with silicone-based surfactants. May be applied the day of harvest. Sprayers used for Abound should not be used on apples. Group 11 fungicide. 4-hr reentry.
    • Bonide Captan 50 WP may be used in home gardens at 1 to 1.5 Tbsp/gal water. H
    • Bravo Weather Stik at 3.1 to 4.1 pints/A. Do not use past shuck split. Group M5 fungicide. 12-hr reentry.
    • Captan 80 WDG at 1.9 to 3 lb/A. May be applied up to the day of harvest. Group M4 fungicide. 24-hr reentry.
    • Cevya at 4 to 5 fl oz/A. May be used day of harvest. Group 3 fungicide. 12-hr reentry.
    • Echo 720 at 3 to 4.1 pints/A. Do not use past shuck split. Group M5 fungicide. 12-hr reentry.
    • Flint Extra at 3 to 3.8 oz/A. Do not use within 1 day of harvest. Group 11 fungicide. 12-hr reentry.
    • Inspire Super at 16 to 20 fl oz/A. Do not apply within 2 days of harvest. Group 3 + 9 fungicide. 12-hr reentry.
    • Luna Experience at 6 to 10 fl oz/A. May be used day of harvest. Group 3 + 7 fungicide. 12-hr reentry.
    • Luna Sensation at 5 to 7.6 fl oz/A. Do not use within 1 day of harvest. Group 7 + 11 fungicide. 12-hr reentry.
    • Miravis at 5.1 fl oz/A. Can be used up to the day of harvest. Group 7 fungicide. 12-hr reentry.
    • Miravis Duo at 13.6 fl oz/A. Can be used up to the day of harvest. Group 3 + 7 fungicide. 12-hr reentry.
    • Ortho MAX Garden Disease Control at 3.75 teaspoons/4gal water. H
    • Pristine at 10.5 to 14.5 oz/A. Can be used day of harvest. Group 7 + 11 fungicide. 12-hr reentry.
    • Quadris Top at 12 to 14 fl oz/A. May be applied on the day of harvest. Group 3 + 11 fungicide. 12-hr reentry.
    • QuiltXcel at 14 fl oz/A. May be applied the day of harvest. Sprayers should not be used on apples. Group 3 + 11 fungicide. 12-hr reentry.
    • Quash at 2.5 to 3.5 oz/A. Do not use within 14 days of harvest. Group 3 fungicide. 12-hr reentry.
    • Spectracide Immunox Multi-Purpose Fungicide Spray Concentrate for Gardens at 0.5 fl oz/gal water. May be applied up to the day of harvest. Do not apply more than seven (7) times per season. Group 3 fungicide. H
    • Topguard EQ at 6 to 8 fl oz/A. Do not use with silicone surfactants or within 7 days of harvest. Sprayers should not be used on apples. Group 3 + 11 fungicide. 12-hr reentry.
    • Ziram 76 DF at 6 to 8 lb/A. Do not apply within 30 days of harvest. Group M3 fungicide. 48-hr reentry.

Reference Tovar-Pedraza, J.M., Ayala-Escobar, V., and Segura-León, O.L. 2013. Thyrostroma carpophilum causing apricot shot-hole in Mexico. Australasian Plant Disease Notes 8:31-33.