Celery (Apium graveolens var. dulce)-Early Blight (Cercospora Blight)

Cause Cercospora apii is a fungus that probably lives in infected celery refuse from previous years. Early blight is seldom a problem in Oregon. Wet weather favors spore production.

Symptoms Disease appears on leaves as circular, yellowish spots enlarging to 0.5 inch in diameter and becoming darker. In wet weather, the dark, scorched centers of older spots become gray. Infections on fleshy celery petioles elongate with growth. The disease may appear during summer or early autumn, often preceding celery late blight.

Cultural control

  • Treat 1- or 2-year-old seed in water at 118°F for 30 min, as for bacterial blight. Do not treat older seed; it is less able to withstand treatment, and besides, fungal propagules on seed lose viability after 3 years.
  • Grow seedlings in soilless or pasteurized media in clean trays. Check regularly for signs of disease, and discard any plants with symptoms.
  • Incorporate crop refuse promptly after harvest to encourage rapid breakdown in soil.

Chemical control Use a good spreader-sticker at 1 or 2 oz/100 gal water with all materials. Make the first field application when plants have started growing and are well established after transplanting. Apply later at 10-day intervals.

  • Chlorothalonil formulations (Group M5) are labeled.
    • Bonide Fung-onil is available for home gardens. H
    • Bravo WeatherStik at 2 to 3 pints/A starting when transplants are set in field and repeat on 7-day intervals. Do not apply within 7 days of harvest. 12-hr reentry.
    • Echo 720 at 1 to 1.5 pints/A on 3- to 5-day intervals or at 2 to 3 pints/A on 7-day intervals. Preharvest interval is 7 days. 12-hr reentry.
  • Copper products (Group M1) are not recommended as stand-alone materials.
    • Badge SC at 1 to 4 pints/A on 7-day intervals. Preharvest interval is 0 days. 24-hr reentry for greenhouse use; 48-hr reentry for all other applications.
    • Bordeaux 8-8-100.
    • Champ Formula 2 at 1.33 pints/A. 48-hr reentry.
    • Champ WG at 2 lb/A on 7- day intervals. 48-hr reentry. O
    • C-O-C-S WDG at 1 to 1.9 lb/A. 48-hr reentry.
    • Cueva at 0.5 to 2 gal/100 gal water on 7- to 10-day intervals. May be applied on the day of harvest. 4-hr reentry. O
    • Cuprofix Ultra 40 Disperss at 1.25 lb/A on 7- to 14-day intervals. 48-hr reentry.
    • Kocide 2000 at 1.5 lb/A or Kocide 3000 at 0.75 to 1.5 lb/A on 7-day intervals. 48-hr reentry. O
    • Liqui-Cop at 2 to 3 teaspoons/gal water. H
    • Nu-Cop DF at 2 lb/A on 7-day intervals. 48-hr reentry. O
    • Previsto at 1 to 2 quarts/A on 7-day intervals. 48-hr reentry. O
  • Demethylation-inhibiting (DMI) Fungicides (Group 3) are labeled for use.
    • Bumper 41.8 EC at 4 fl oz/A on 7-day intervals. Preharvest interval is 14 days. 12-hr reentry.
    • PropiMax EC at 4 fl oz/A on 7-day intervals. Do not apply within 14 days of harvest. 12-hr reentry.
    • Tilt at 4 fl oz/A on 7-day intervals. Do not apply within 14 days of harvest. 12-hr reentry.
    • Topaz at 4 fl oz/A on 7-day intervals. Preharvest interval is 14 days. 12-hr reentry.
  • Merivon Xemium (Group 7 + 11) at 5.5 fl oz/A on 7- to 14-day intervals. Do not make more than two (2) applications before alternating to a fungicide in different FRAC groups (non-Group 7 and non-Group 11). Preharvest interval is 1 day. 12-hr reentry.
  • Miravis Prime (Group 7 + 12) at 9.2 to 13.4 fl oz./A on 7- to 10- day intervals. Do not make more than two (2) applications before alternating to a fungicide in different FRAC groups (non-Group 7 and non-Group 12). Preharvest interval is 0 days. 12-hr reentry.
  • Regalia (Group P5) at 0.5 to 4 quarts/A plus another fungicide on 5- to 10-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
  • Strobilurin fungicides (Group 11) are labeled for use. Do not make more than one (1) application of a Group 11 fungicide before alternating to a labeled fungicide with a different mode of action.
    • Aftershock at 5.7 fl oz/A on 7- to 10- day intervals. Do not apply within 3 days of harvest. 12-hr reentry.
    • Cabrio EG at 12 to 16 oz/A on 7- to 14-day intervals. Preharvest interval is 0 days. 12-hr reentry.
    • Evito 480 SC at 5.7 fl oz/A on 7- to 10-day intervals. Preharvest interval is 3 days. 12-hr reentry.
    • Quadris Flowable at 9 to 15.5 fl oz/A or Quadris Opti at 2.4 to 3.7 pints/A on 7- to 14-day intervals. Quadris Flowable may be applied the day of harvest. Preharvest interval is 7 days for Quadris Opti. 4-hr reentry for Quadris Flowable, 12-hr reentry for Quadris Opti.
    • Quilt or Quilt Xcel at 14 fl oz/A on a 7- to 10-day interval. Do not apply within 14 days of harvest. 12-hr reentry.
  • Trilogy at 0.5% to 1%. Not labeled for use in Oregon.. Do not use above 90°F or when plants are under heat or moisture stress. Do not use when foliage is wet as good coverage is essential. Poor control as a stand-alone product. Preharvest interval is 0 days. 4-hr reentry. O

Reference Berger, R.D. 1975. Disease incidence and infection rates of Cercospora apii in plant spacing plots. Phytopathology 65:485-487.