White Mold

How to Identify and Control White Mold

White Mold

Here are tips on how to identify, control, and prevent the fungal plant disease white mold.

What Is White Mold?

White mold, also known as sclerotinia, is a fungal disease that affects over 360 different plants, including beans, peas, lettuce, and members of the cabbage family. White mold is sometimes called timber rot when it affects tomatoes. Mold symptoms appear on blossoms, stems, leaves, and pods that have water-soaked spots. Leaves will wilt, yellow, and die; pods may rot.

Host crops are most susceptible during flowering, but young seedlings are also very vulnerable. White mold typically infects the plants early in the spring or summer and then develops unnoticed for a while. White mold fungus releases spores when the weather is cool, and these spores can be carried by the wind and infect other plants. This is why it is so important to catch white mold and destroy infected plants quickly.


    How to Identify White Mold Damage

    White mold symptoms vary depending on the environment and type of plant, but here are some common ones:

    • The stem might first appear to have a water-soaked part. At this point in the infection, the plant will look healthy from above.
    • Wilting of individual stems, especially at the base with tan discoloration.
    • Infected stems may appear to have tan to dark brown lesions on them. From these lesions, a dense, cotton-like growth will form under conditions of high humidity.


    Photo Credit: The Ohio State University. White mold takes over a bean plant with its dense cotton-like growth.

    Control and Prevention

    How to Control White Mold

    • As soon as you notice any diseased plants, destroy them immediately.
    • If your soil is infected, remove as much of it as you can and replace it with clean soil.
    • You can use a barrier, such as plastic or mulch, to cover the infected ground to prevent the spread of the disease.

    Prevent White Mold

    • Be sure to use well-drained soil and space your plants properly to avoid crowding. Also, remember to avoid areas with poor air circulation.
    • When watering your plants, try not to water the tops of them. Or water the plants early in the day so they have the chance to dry before nightfall.
    • You can also spray your plants with an approved fungicide to help prevent infection. Spray the plants right before they bud, then spray again a week later.
    • Control your weeds. Weeds can host this disease and spread it to your plants.
    • If possible, remove all crop residue after harvesting. If residue is left, this disease may develop in it. White mold spores are long-lasting, so they will survive the winter if given the chance.


    Reader Comments

    Leave a Comment

    It sounds as if you may be

    The Editors's picture

    It sounds as if you may be watering too frequently. Make sure that you aren't saturating the soil; let it dry out and then deeply water and then let it dry out again between waterings. Take the seedlings off any watering trays so they're not wet on the bottom; let them drain and put on a cloth. You can scrape off the white mold; if it gets too bad, you might need to replant the seedlings in clean soil. You could also consider an anti-fungal product; ask your garden center. Finally, some readers suggest adding a little sand and others say sprinkling with cinnamon helps!

    im scared that my lettuce

    im scared that my lettuce plants will get white mold what is the best pesticide for this mold i live in detroit michigan and im making a garden in my grandmothers back yard and im choosing a moist area in her back yard what am i supposed to do when my plant gets white mold do i throw it away or keep it please answer my qustion i would kindly like an answer

    To prevent white mold, avoid

    The Editors's picture

    To prevent white mold, avoid wet soil or overwatering. Just keep soil moist.
    Use raised beds.
    Create furrows in the soil for watering or irrigation so that the water doesn't just flow all over the bed surfaces.
    Do not water from overhead and get the plants wet; water at the soil line.
    Space plants extra far apart to allow good air circulation.
    Remove and destroy entire infected plants and crop residues as soon as you see any signs of mold.
    Hope this helps.

    Kathy Joyce, Try watering

    Kathy Joyce,

    Try watering early morning.
    When you water at night, a lot of water remains around the plant and its root. It facilitate rotting and development of diseases.

    The flowers on both my

    The flowers on both my petunia plants have polka dot-looking white spots on each bloom. They are separated from each other the length of the small patio. I did water each evening, they have drainage holes. What happened?

    Thanks for answer to petunia

    Thanks for answer to petunia white dots,

    On my sunflowers, there is a

    On my sunflowers, there is a sticky white drippy looking substance between the main stem and the leaf stem. What is this and how should I treat it? And, is it contagious to the garden generally?

    Every once in a while we

    The Editors's picture

    Every once in a while we don't have a clear and specific answer and this is one of those times, Lad. You do not indicate where you are but it seems that the sticky white substance may not be from the plant itself but from whiteflies or aphids.
    Now you wonder, what to do? If indeed this is the case, ideally, you would want to encourage "good bugs" (some wasps, predatory mites, black ladybird beetles, for example, depending on your area) into your garden to eliminate these pests rather than apply insecticides, which might destroy any good bugs that are present. A good bug welcome mat can not be put out in a day; it's often a gradual thing that can be accomplished by bringing in other plants.
    To have a better idea of what you're dealing with and how to eliminate it, we suggest that you contact your local agricultural extension service. They would be more familiar with specific conditions in your area. Hope this helps—Best wishes!



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