WSU Extension


Carrot : Leaf spot
(revision date: 4/11/2018)

Leaf spot of carrot is also known as early blight. It is a fungal disease. The disease produces leaf and stem spots, primarily attacking young leaves. Initially the spots are small, with yellow halos or margins. Older lesions may become tan or light gray as the fungus produces spores on the infected tissues. Severe infections may result in death of leaves. Disease spores can be spread by wind. The fungus primarily overwinters in diseased plant material. Leaf spot may be confused with leaf blight, which generally attacks older foliage.
Management Options

Non-Chemical Management
  • Rotate crops. Allow two or three years between carrot crops in a given location.
  • Plant in well-drained soils.
  • Schedule watering so that carrots are dry by night.
  • Remove plant debris from the garden. Destroy or discard (do not compost) diseased materials.
Select non-chemical management options as your first choice!

Chemical Management

Apply when plants are 6 inches tall or when disease threatens. Repeat at weekly intervals if necessary.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Copper Fungicide Spray or Dust RTU [Organic]
    Active ingredient: basic copper sulfate  |  EPA reg no: 4-58
  • Bonide Liquid Copper Fungicide Conc/Organic Gardening
    Active ingredient: copper octanoate  |  EPA reg no: 67702-2-4
  • GardenTech Daconil Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 67572-82-71004
  • Monterey Liqui-Cop Copper Fungicidal Garden Spray
    Active ingredient: copper-ammonia complex  |  EPA reg no: 54705-7
  • Ortho Max Garden Disease Control Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 239-2522
  • Soap-Shield Flowable Liquid Copper Fungicide [Organic]
    Active ingredient: copper octanoate  |  EPA reg no: 67702-2-56872
  • This list may not include all products registered for this use.
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Caption: Cercospora leaf spot on carrot
Photo by: R.S. Byther