Gray Mold or Botrytis

How to Identify and Control Gray Mold Fungus or Botrytis

Gray mold-on Riesling grapes-Rob and Lisa Meehan-Wikimedia Commons

Gray mold has compromised these Riesling grapes.

Photo by Rob & Lisa Meehan, Wikimedia Commons

Here are tips for how to identify, control, and prevent gray mold, or botrytis.

What is Gray Mold?

Gray mold is a fungus otherwise known as Botrytis cinerea that can affect any part of a plant and is one of the most common diseases found among bedding plants. This disease will easily infect plants that are already damaged or beginning to die. It then spreads quickly and can cause extensive damage to healthy parts of plants.

Moisture is one of the main causes of gray mold. The wetter your plants are, the more susceptible they are to becoming infected. Your plants also must be injured before they can become infected. Be careful around your plants to prevent this.


    How to Identify Gray Mold Damage

    • The symptoms of gray mold depend on the type of plant and environmental conditions, but generally spots that appear water-soaked will form on the leaves. These might appear white at first.
    • These spots will then change color from gray to brown, eventually covering most of the leaf and causing it to wilt. The brown coloration is what often causes people to confuse gray mold with brown mold.
    • Under really humid conditions, grayish webbing may appear on the leaves. In this webbing are structures that contain fuzzy spores. Spores become active and are released with any activity at all.
    • Petals, stems, and buds can also be infected.
    • Eventually, all of the infected parts of the plant will be covered by a fuzzy gray growth, causing you to seemingly have gray flowers.


    Photo Credit: Francesca Peduto Hand, The Ohio State University. The fuzzy gray spores characteristic of botrytis infect an impatiens plant.

    Control and Prevention

    How to Control Gray Mold

    • Remove the infected plants and destroy them.
    • Clean thoroughly between your plants so that the disease cannot infect your other plants.
    • You can try using sprays with cultural controls on your plants to prevent further infections.

    Prevent Gray Mold

    • Handle your plants carefully when transplanting and pruning. Gray mold usually attacks wounded plants, so avoid harming your plants.
    • Keep your plants dry. Avoid overhead watering and watering late in the day. Give your plants time to dry off after watering them during the day.
    • Space your plants properly to encourage good air circulation.
    • Remember to clean between your plants. Remove any debris, including cuttings and dead leaves.


    Reader Comments

    Leave a Comment


    all plants in my greenhouse are finished but whats left is heavily infested with botritis. when i remove the plants, spores are going to fill the air. the soil will be covered with spores. my question is; can i use that soil again? can i take the soil outside and add alot of nitrogen to start it composting?

    Botrytis Spores

    The Editors's picture

    Botrytis spores can be cooked away in a compost pile, but only if the pile reaches upwards of 131°F (55°C) and stays at that temperature for several days. That being said, we wouldn’t recommend using the soil in your greenhouse again, just in case the composting didn’t do the job completely. 


    thanks for the recommendation. what do you think i can add to the 5 yards of soil to get it hot enough to kill the botritis spores.
    i'm thinking, cottonseed meal & straw. i want to be organic & economical.

    black rot on concord grapes

    is there a natural remedy to correct this problem without using chemical sprays?

    Natural Remedies for Gray Mold

    The Editors's picture

    Unfortunately, it can be difficult to get rid of gray mold without chemical sprays. We would recommend following our tips like destroying all plants that are infected and making sure that your plants are not in an overly moist environment. The article provides some natural and easy prevention methods that might be able to keep you from having to use a chemical spray.

    Hydrangea with shiny white patches on the leaves.

    I just planted some hydrangea. Two days later when I went to water them they have large shiny white patches on most of the leaves. What is the problem?

    Powdery Mildew on Hydrangeas

    The Editors's picture

    It appears that the problem might be powdery mildew. To find out how to prevent and control this fungal disease, go to our powdery mildew page.

    I have a petunia in a hanging

    I have a petunia in a hanging pot and I noticed it has black spots on leaves and around small blooms. I don't know if they are bugs of some kind also found a small green worm or maggot on another bloom. Any suggestions on what to put on my plant? Some of my plant leaf ends are a pale light green is this not enough water?

    Black specs might be

    The Editors's picture

    Black specs might be "frass"...caterpillar poop. You  may have a worm eating your plants. Blast the leaves with insecticide spray.

    I have a hydrangea plant has

    I have a hydrangea plant has brown leaves and are falling off.We think it may have over watered.Is there any way I can save plant?

    Are the hydrangea leaves

    The Editors's picture

    Are the hydrangea leaves turning brown around the edges? Usually, this is a moisture issue. Sometimes, the plant can be root-bound, too.
    Gently dig the plants early in the morning to check for both conditions. If needed, lightly loosen the roots with your hand. You can also soak the root ball in water until it's moistened through. Make sure you maintain uniform moisture for your hydrangeas.
    Location can also be an issue. If they're getting sun burnt, they'd do better with light shade.

    I bought a spider plant all

    I bought a spider plant all of the leaves are yellow and the tips are black and appear to be bent like an edge.
    Could you please help?

    It sounds like your plant may

    The Editors's picture

    It sounds like your plant may be getting too much sun. Move it to a cooler spot in the house; be sure it is not close to heat vents or on top of the television.

    I have peonies that seem to

    I have peonies that seem to have this gray mold on the leaves. It hasn't turned brown or wilted the leaves, but I've noticed that my hydrangea that is next to it doesn't look too good. I have 3 others in my gardens and they all look great still. Could whatever is on the peonies have affected my hydrangea too? Its not as green and lush as it should be and the edges of the leaves look like their browning. I live in zone 7 and my peonies are well passed bloomed. I usually wait til fall to cut the foliage down. Should I have cut that down sooner? And do you think I should move the peony because it is rather close to the hydrangea? When I put the hydrangea there it wasn't as big as it is now.

    It's probably powdery mildew

    The Editors's picture

    It's probably powdery mildew from humid conditions. It isn't pretty but it won't hurt the peony this late in the year. Cut it back in the fall and dispose of the leaves. Make sure your peony has good air circulation next year. It may be a good idea to move it away from the hydrangea. Go to our peony page for more information.

    I have a question about my

    I have a question about my garden and I think it is probably related to this article about gray mold. I recently moved to a northern California coastal town. Long growing season, very temperate climate. I'm living in my RV and am surrounded by asphalt, so I container garden, allot. I'm trying to keep the pots wet enough so that the plants don't wilt from the heat, but its humid here.
    My sage plants turn yellow and get brown spots. My squash gets spots, turn brown and die. The gray webbing takes over. yuck,but the plant keeps trying. I have tomatoes near the squash, one looks like it rotted from too much water, but I don't water until the top few inches are dry. That's every other day here.
    Any suggestions? I thought the plants were getting sunburned, maybe that's the damaged entry point for the gray mold. Some one suggested shade cloth. But doesn't that seem weird with tomatoes?

    Vegetables and herbs can

    The Editors's picture

    Vegetables and herbs can suffer from various problems due to high humidity, high heat, too much/too little water, etc. Too much water can cause sage leaves to yellow and form brown spots, but so can high temperatuers, etc. Sometimes squash gets downy mildew, powdery mildew, or white mold. Tomatoes can also get white mold, powdery mildew, root rot, etc. For some disease information, see:
    In general, make sure not to waterlog the soil, and check the drainage at the bottom of the containers--be sure the drainage hole(s) are not blocked. Temperatures might get very hot if your containers are on asphalt, so a shade cloth during hot afternoons might be helpful, or positioning them to get partial shade in the afternoon. You can also add a little mulch on the soil surface--but keep the mulch from directly contacting the main stem of the plant, in case the humid air might encourage disease. Avoid overhead watering, which can encourage disease--water the plants at the base, or use self-watering containers.
    If you could set up a fan to blow gently on the plants for a few hours each day, that might help to avoid diseases in humid weather. The more (gentle) air circulation, the better.

    Some of my gladiola's florets

    Some of my gladiola's florets did not open/ bloom on the top found them empty from indside. Is it a disece or under fed? Thanx.

    It sounds like your gladiolus

    The Editors's picture

    It sounds like your gladiolus may have had thrips. They feed on the shoots and flowers.


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