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How to Identify and Control Gray Mold Fungus or Botrytis

Gray mold has compromised these Riesling grapes.

Photo Credit
Photo by Rob & Lisa Meehan, Wikimedia Commons
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Prevent Gray Mold in Your Garden!

Catherine Boeckmann
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Pest Type
Plant Diseases

Do you ever look at your beautiful plants and see something fuzzy and gray? It might be gray mold, a common but nasty fungus that loves to infect gardens. This post will equip you with the knowledge to identify, control, and prevent gray mold or botrytis, so your garden can thrive!

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 leading 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.

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Identification

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. This webbing contains structures that contain fuzzy spores. Spores become active and are released with no 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.
identify-gray-mold-botrytis.jpg
The fuzzy gray spores characteristic of botrytis infect an impatiens plant.
Photo Credit: Francesca Peduto Hand, The Ohio State University. 

 

Gardening Products
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.
Garden Pests
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann

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Comments

jennifer (not verified)

2 years 12 months ago

what spray do I have to get to kill gray mold in my plant soil? I've tried all natural ways to get rid of it but nothing working. I believe I need a chemical spray now and I have it in some herd plants too. Its still growing in soil this is dry, I even bleached my whole house and still got it back. please help me.

S. Eberhardt (not verified)

2 years 5 months ago

Also want to know how to rid gray mold from soil.

jon (not verified)

2 years 11 months ago

I think you need to get new soil and put it somewhere else.

jim (not verified)

6 years ago

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 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.

Connie (not verified)

2 years 8 months ago

We had a beautiful willow tree die of this. An elderly neighbor told us to put a black tarp over the entire area after we removed the dying tree for as many days as we could with the sun beating on it. We left it on for several weeks just to make sure. It worked! We planted a new willow about 6 months later and it’s been about 4 years and it’s doing great. I think the heat all day killed it.

ANN (not verified)

8 years 2 months ago

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

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.

Kathee (not verified)

8 years 3 months ago

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?