Gooseberry and Currant (Ribes spp.)-Powdery Mildew

Cause Podosphaera mors-uvae (formerly Sphaerotheca mors-uvae) has been reported on Ribes spp. in the Pacific Northwest. Erysiphe grossulariae and Phyllactinia ribes have also been found on Ribes spp. in California. The black overwintering structures, called chasmothecia, form on canes and twigs. Ascospores are released around bloom. Conidia can be produced within 10 days on infected leaves and contribute to multiple infections during the growing season. The black currant cultivars Ben Nevis, Magnus, and Tsema were very susceptible to this disease at Mt. Vernon, WA.

Symptoms The fungus appears as a white powdery growth on the leaf surface, green shoots, and particularly fruit. Infected plants often are stunted. As fruit matures, the mildew changes to a dark brown coating with tiny black specks (chasmothecia) that render the berries unmarketable. Infected fruit often crack open and rot.

Cultural control

  • Plant resistant cultivars. The red currant cultivars Minn 69 and Viking, the white currant cultivars Blanka, Mason's, and Primus and the black currant cultivars Ben Alder, Titania, and Ben Tirran have shown little, if any, symptoms at Mt. Vernon, WA.
  • Prune and thin bushes to provide better air circulation and drying conditions. Better fungicide coverage will also aid in disease management.

Chemical control

  • Delayed dormant (green-tip stage)
    • Lime Sulfur Ultra (27% lime sulfur) at 3 gal/100 gal water. 48-hr reentry. O
    • Rex lime sulfur (28%) at 3 gal/100 gal water. 48-hr reentry. O
  • Apply at prebloom as blossoms are ready to open, at full bloom, and 2 weeks later. Alternate or tank-mix products from different groups that have different modes of action. Limit the use of any one group during the growing season.
    • Abound at 6 to 15.5 fl oz/A. Do not apply with silicone-based surfactants. May be applied on the day of harvest. Group 11 fungicide. 4-hr reentry.
    • Aprovia at 8.6 to 10.5 fl oz/A plus an adjuvant. Labeled only for Gooseberry. Do not use within 21 days of harvest. Group 7 fungicide. 12-hr reentry.
    • Aprovia Top at 8.5 to 13.5 fl oz/A. Do not apply within 21 days of harvest. Group 3 + 7 fungicide. 12-hr reentry.
    • Cabrio EG at 14 oz/A. Use before symptoms are anticipated. May be used at harvest. Group 11 fungicide. 12-hr reentry.
    • Flint Extra at 3 to 3.5 fl oz/A. Do not use on 'Concord' grapes. Do not use within 14 days of harvest. Group 11 fungicide. 12-hr reentry.
    • Gatten at 6.4 fl oz/A. Do not use within 14 days of harvest. Group U13 fungicide. 12-hr reentry.
    • Inspire Super at 16 to 20 fl oz/A. Do not apply within 7 days of harvest. Group 3 + 9 fungicide. 12-hr reentry.
    • Kaligreen (82% potassium bicarbonate) at 2 to 3 lb/A is labeled for currant. Might supplement a normal program when powdery mildew is first observed. Do not mix with other pesticides. Thorough coverage and frequent applications are essential. 4-hr reentry. O
    • Luna Sensation at 4 to 7.6 fl oz/A. Do not use within 14 days of harvest. Group 7 + 11 fungicide. 12-hr reentry.
    • Luna Tranquility at 13.6 to 27 fl oz/A. May be used day of harvest. Group 7 + 9 fungicide. 12-hr reentry.
    • Mettle 125 ME at 3 to 5 fl oz/A. Do not within 14 days of harvest. Group 3 fungicide. 12-hr reentry.
    • Miravis Prime at 9.2 to 13.4 fl oz/A. Do not use within 14 days of harvest. Group 7 + 12 fungicide. 12-hr reentry.
    • Monterey Bi-Carb Old Fashioned Fungicide at 4 teaspoons/2 gal water only for currant. H
    • M-Pede at 1 to 2 gal/100 gal water is registered for currant. Good coverage is essential. Do not use within 3 days of applying sulfur. Do not mix with hard water. 12-hr reentry. O
    • Oso SC at 3.75 to 13 fl oz/A. May be applied on the day of harvest. Group 19 fungicide. 4-hr reentry. O
    • Ph-D WDG at 6.2 oz/A plus an adjuvant. May be applied on the day of harvest. Group 19 fungicide. 4-hr reentry.
    • Prev-Am at 50 fl oz/100 gal water. Do not use above 90°F or when plants are under heat or moisture stress. 24-hr reentry.
    • Prolivo 300 SC at 4 to 5 fl oz/A. Can be used day of harvest. Group 50 fungicide. 4-hr reentry.
    • Pristine at 18.5 to 23 oz/A. Do not use with any other tank additive. Can be used day of harvest. Group 7 + 11 fungicide. 12-hr reentry.
    • Proline 480 SC at 5.7 fl oz/A. Do not use within 7 days of harvest. Group 3 fungicide. 12-hr reentry.
    • Propiconazole-based fungicides are registered. Do not use within 30 days of harvest. Group 3 fungicides. 12-hr reentry.
      • Bumper 41.8 EC at 6 fl oz/A.
      • PropiMax EC at 6 fl oz/A.
      • Tilt at 6 fl oz/A.
    • Quadris Top at 12 to 14 fl oz/A. Do not apply within 7 days of harvest. Group 3 + 11 fungicide. 12-hr reentry.
    • Quash at 2.5 oz/A. Do not use within 7 days of harvest. Group 3 fungicide. 12-hr reentry.
    • QuiltXcel at 14 to 21 fl oz/A. Do not use within 30 days of harvest. Sprayers should not be used on apples. Group 3 + 11 fungicide. 12-hr reentry.
    • Rally 40 WSP at 5 oz/A. Applications may be made up to the day of harvest. Group 3 fungicide. 24-hr reentry.
    • Regalia at 1 to 4 quarts/A. Use on 7-day intervals. May be used day of harvest. Group P5 fungicide. 4-hr reentry. O
    • Spectracide Immunox Multi-Purpose Fungicide Spray Concentrate for Gardens at 1.25 fl oz/gal water. May be applied up to the day of harvest. Group 3 fungicide. H
    • Sulfur-based products have good efficacy. Do not use within 2 weeks of an oil spray. Group M2 fungicides. 24-hr reentry. O
      • Cosavet-DF (80% sulfur) at 6 to 15 lb/A.
      • Kumulus DF (80% sulfur) at 6 to 15 lb/A.
      • Microthiol Disperss (80% sulfur) at 6 to 15 lb/A. Do not use a spreader-sticker.
      • Lilly Miller Sulfur Dust at 1 Tbl/gal water. H
    • Torino at 3.4 oz/A. Do not use within 3 days of harvest. Group U6 fungicide. 4-hr reentry.
    • Trilogy at 1% of spray volume. Do not use near sulfur applications, below 45°F, above 90°F, or when plants are under heat or moisture stress. Do not use when foliage is wet as good coverage is essential. Not registered in Oregon. 4-hr reentry. O
    • Trionic 4 SC at 8 to 16 fl oz/A. Do not apply within 14 days of harvest. Group 3 fungicide. 12-hr reentry.

Biological control

  • Aviv (Bacillus subtilis strain IAB/BS03) at 10 to 30 fl oz/100 gal water. Do not tank mix with more than one product. Unknown efficacy. Preharvest interval not specified. 4-hr reentry. O
  • Serenade ASO (Bacillus subtilis strain QST 713) at 2 to 4 quarts/A. Active ingredient is a small protein. May be applied up to and including the day of harvest. 4-hr reentry. O
  • Serenade Garden Disease Control Concentrate at 2 to 4 fl oz/gal water. H O
  • Sonata (Bacillus pumilis strain QST 2808) at 2 to 4 quarts/A plus an adjuvant. May be applied up to and including the day of harvest. 4-hr reentry. O

Reference Purnell, T.J. and Sivanesan, A. 1970. Sphaerotheca mors-uvae. CMI Descriptions of Plant Pathogenic Fungi and Bacteria, No. 254. Surrey, England: Commonwealth Mycological Institute.