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  • Battling Tomato Blight

    Created by olinga Moses on

    How is tomato early and late blight controlled?

  • Author
  • #221137

    Eric Vinje

    Hello Olinga –

    Please find our recommendations for treating early and late blight in tomatoes:

    • Plant resistant cultivars when available.
    • Remove volunteers from the garden prior to planting and space plants far enough apart to allow for plenty of air circulation.
    • Water in the early morning hours, or use soaker hoses, to give plants time to dry out during the day — avoid overhead irrigation.
    • Destroy all tomato and potato debris after harvest.

    If disease symptoms are observed, apply a copper based fungicide (2 oz/ gallon of water) every 7 days or less, following heavy rain or when the amount of disease is increasing rapidly. If possible, time applications so that at least 12 hours of dry weather follows application.

    Early Blight

    Late Blight

    Hope it helps!



    Tomato blight is easily controlled by environmental factors. Keeping a clean, sterile growing environment is essential to prevention.
    1. Eliminate infected plant material. This is key to preventing future infestations. Any infected plant material or soil must be removed and either sterilized or destroyed. One diseased leaf or root left to overwinter in the soil may cause disease problems the following year. Do not compost the infected plant material, as compost does not get hot enough to kill the blight spores. If no green waste collection is available, burning the material is recommended.
    2. Sanitize your grow space. After ridding yourself of infected material, a deep cleaning of the space is a must. All planters and pots should be thoroughly disinfected. If indoors, make sure to clean and sort of filters, vents, and light fixtures you may have.
    3. Keep plant foliage dry. Once you’ve disinfected your space, its important to practice proper blight prevention techniques. Always water below the plant and refrain from getting any water on plant leaves. Make sure your plants have ample space to prevent crowding and prune your plants to remove any leaves that may be touching the soil. Keep in mind, spores must be released into a water film before they are able to penetrate plant tissue. By reducing or eliminating moisture from plant leaves, you will effectively stop the blight’s ability to sicken your plants. Decreasing relatively humidity will also help in creating an inhospitable environment for blight. A dehumidifier has potential to work wonders.
    4. Avoid overwatering. Excessively wet soil can prolong an outbreak of blight. Allow soil to dry as much as possible before watering. When you do water, make sure to water thoroughly without saturating your plants. Good drainage is key, 10-20 percent of the total water added should be coming out of the bottle of the pot or planter. A thick layer of straw or even plastic mulch will help create a buffer between a wet soil and foliage that must be kept dry. Mulching is key to a cleaner grow space and keeping plants off the soil if overwatering does occur.
    5. Develop a crop rotation. Crop rotation is key to preventing future blight infestations. Fours years is a good number to shoot for. Only solanaceae plants are affected by early and late blight. By avoiding plants in the nightshade family (potatoes, eggplant, pepper or tomatoes) you can help curb the diseases’ lifecycle. Stick to the cucurbitaceae, brassicaceae, maize, legumes and amaranthacea families of vegetables for at least three growing seasons. The longer you can avoid planting solanaceae vegetables, the better off you are likely to be.

    Blight infestations can be tricky, picking ripe or almost ripe vegetables early can sometimes be the only way to salvage a severely blighted garden. Regular use of fungicide spray can be helpful if applied at the recommended rate on a weekly or bi-weekly basis. Remove any infected leaves or material immediately and dispose of it to prevent spread of the disease. Healthy plants will fare better in the face of an infestation, proper care and fertilization is key. Good luck!!

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