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Cercospora Blight

Many types of blight strike edible gardens, typically with specific plants in sight. Cercospora blight commonly affects carrots and celery with leaf-disfiguring and crop-reducing results. Referred to as early blight for these two vegetables, Cercospora blight hits young carrot and celery plants during early periods of rapid growth.

As with many fungal plant diseases, long periods of wet leaves provide ideal conditions for Cercospora blight infections. The fungal spores spread by wind and water. Gardeners also spread the disease on tools and hands when working in infected gardens while leaves and stalks are wet.

Cercospora Blight Identification/Symptoms: Primarily a leaf-spotting disease, Cercospora blight's first symptoms arrive as small leaf spots. As the disease progresses, leaf spots multiply, enlarge, and merge together, until blight-encompassed leaves shrivel and die. Though early blight doesn't directly affect carrot roots, the loss of leaves diminishes growth and harvests.

In carrots, Cercospora blight starts with small, irregular, purple-green to purple-black leaf spots. In celery, early blight symptoms begin as small, circular yellow or brown leaf spots. When conditions support this disease, it spreads rapidly across leaves and through crops. On leaf undersides, spot centers turn gray and fuzzy with fungi. Close examination reveals Cercospora blight's characteristic threadlike, silvery spores.

How to Control Cercospora Blight: Once Cercospora blight infects plants, control becomes more difficult. Prevention is key to protecting your crops from this disease. Daconil® fungicides from GardenTech® brand offer highly effective protection to prevent, stop, and control Cercospora blight in carrots and celery. These products treat celery up to seven days before harvest and treat carrots right up to harvest day:

  • Daconil® Fungicide Ready-to-Use simplifies targeted treatments for small areas, including container gardens and individual plants. Simply shake the grab-and-go sprayer bottle, and then spray all upper and lower plant surfaces to the point of runoff.
  • Daconil® Fungicide Concentrate offers an economical option for larger areas and simplifies measuring and mixing with its convenient measuring cap. Use with a hand-held, hose-end or tank-style sprayer, and treat all plant surfaces until thoroughly wet.

Cercospora Blight Tips: Cercospora blight fungi overwinter in garden debris, and spring into action year after year unless you intervene. Take time to clear your garden of fallen leaves and infected plants, and dispose of the debris before you hang up your tools for winter.

Always read product labels thoroughly and follow instructions, including guidelines for treatable plants, application rates and frequencies, and pre-harvest intervals (PHI) for edible crops.

GardenTech is a registered trademark of Gulfstream Home and Garden, Inc.

Daconil is a registered trademark of GB Biosciences Corp.

Photo Credit:

David B. Langston, University of Georgia, Bugwood.org (CC BY 3.0 US)

Brenda Kennedy, University of Kentucky, Bugwood.org (CC BY 3.0 US)

Brenda Kennedy, University of Kentucky, Bugwood.org (CC BY 3.0 US)

Brenda Kennedy, University of Kentucky, Bugwood.org (CC BY 3.0 US)