White Mold

How to Identify and Control White Mold

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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.

Identification

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.

Topics

- Gardening
- Pests & Diseases

Reader Comments

roses

i got a like a cotton white fugus on my roses what do i need to get rid of it

Powdery Mildew on Roses

It sounds like your roses may have powdery mildew. If possible, remove the infected leaves and treat the rest of the plant with a fungicide, which you can find in your local hardware store, garden center, or online. Powdery mildew forms when conditions are warm and humid, so if you happen to be watering your roses from overhead, try watering at the base of the plant instead to reduce moisture around the leaves.

Moldy plant food

I purchased a Sour Sop tree about 2 months ago, shortly after buying the tree the leaves started to get brown spots. I removed the leaves and it looked like the tree was doing ok now some leaves are spotting again. I did not have food for it so I used raised bed food for vegetables which ended up molding. I replaced the food with citrus tree food as well as a thin layer of cedar chips to keep the bugs off and again it molded. I did have a raised bed garden and was using compost tea to water the plants. Out of about 30 plants I have 3 left. The soil did mold is that because of the compost tea? I also have a mite problem which may have aided in the plants dying, I had them inside a lot of the winter which is where the mites are.

Sour sop problems

Have you contacted the source from which you purchased the plant? It may have been diseased or at least your vendor may have been able to provide some guidance. These are tropical plants that are vulnerable to a number of pests. That said, it is not a plant with which we have any experience, and would advise you to read up on it here: https://hort.purdue.edu/newcrop/morton/soursop.html (Perdue is an excellent resource). We would also suggest that you contact the cooperative extension nearest you (chick on your state here: http://www.almanac.com/content/cooperative-extension-services ) If the folks at the extension do not have an answer they may very well refer you to a colleague at a service that is knowledgeable.

"White Mold Mildew"

Barnstable Co. Ext. Serv. gave me a bad diagnosis, since your article does not seem to correspond to my situation. The "white mold" I have is NOT on the plants, but on the soil surface. There is nothing growing on plants, but I was worried about it's effect on my plants. It is ONLY on clear soil. It fades to gray color and disappears, but returns with moisture. It's spotty, in many areas, but only on clear soil. It's like fuzzy white ground cover.
Can you give me some better advice?

White Mold on Soil Surface

If you are talking about potted plants, it could be a harmless (and common) fungus called saprophytic fungus. It usually results from a combination of over watering, poor drainage, and old or contaminated potting soil. If any or all of those conditions ring true, repot the plant with new soil (and possibly a pot that drains better) and water less frequently.

My moon flowers started

My moon flowers started wilting and the leaves curled one section at a time, I checked around the roots and see white substance just below the soil surface . Now the entire plant has wilted, this is a well established plant I've had for 3 yrs. what could this be?

Wilting Moon Flowers

Hi Shirley,

There are a number of plant species with the common name of moon flower, but I am going to guess you have a Datura plant, in which case you may be looking at any one of the following viruses: Datura wilt virus, Datura distortion mosaic virus, Datura rugose leaf curl virus, or Datura quercina virus–all exhibit the wilting symptom. It is important to know if it is a virus and which one it is before treating it. I suggest taking some tissue cuttings (leaves and stem) and sending the sample to your local Cooperative Extension Office for testing. They will tell you a course of action to take.

White Mold

I have what looks like it could be white mold on the branch of a 4 foot tree that I received from the National Arbor Day site. It's just at the top of the tree, about an inch or two long area on a branch. Can it be washed off or is there a way I can get rid of it without killing the tree? The leaves have started to wilt, so I need to do something quickly. I live in Missouri, so humidity is high and there's not much we can do about that...

Powdery Mildew

It’s hard to say for sure, but what you describe sounds like powdery mildew fungus, which won’t kill the tree, but can be unsightly and might compromise the tree’s long-term health, if allowed to spread. Go ahead and remove that branch, then monitor to see if the spores are spreading. There are a number of non-toxic products on the market for treating it, and even a few home remedies!

It's spring time planting in

It's spring time planting in Michigan once again and tilling a second time before planting vegetables. Many gardeners had mold issues last year including me. What can I put in the soil as I till as a preventive to mold? Baking soda?

If you notice mold turn the

If you notice mold turn the soil over and bury the mold. Keep the soil as dry as possible and only water the individual plants not the entire garden. It also helps to add new fresh soil to the garden if the mold issue doesn't go away.

If I have what looks like

If I have what looks like white mold only on the soil, not the plants, can I just remove effected soil and apply a ground cover? Do I have to remove the soil? Can I just apply wood shavings? It appeared after we added chicken manure mixture to our garden. Is it related?

Hi, Jennifer: Just to be on

Hi, Jennifer: Just to be on the safe side, sure, go ahead and remove the affected soil, then proceed as usual. Mold is everywhere, though, and usually doesn't pose a problem in soil, as it will dissipate once its growing conditions (organic food, a lot of moisture) deteriorate. Mold on plants is another matter, as you recognize, as is nonwhite mold. Thanks for asking!

I have some indoor potted

I have some indoor potted plants. Some had begun to get "rootbound" being out of new soil I baked a lot of it to sterilize it. It was too late for the transplant for most and they died anyways. When removing from their pots for discard, I noticed white mold growing specifically where the inside of the pot meets the soil. I have one that survived and its pot has the mold in the same manner as well. So I watered around the edges with a peroxide solution. What else should I do? Can this kill my plant? Should I simply repeat the peroxide treatment and keep the problem at bay until I can harvest and discard the soil? This plant is 3-4 weeks from being ready to harvest

Hi Branden, We suggest that

Hi Branden,
We suggest that you remove the plant from the pot. Discard any soil that has mold on it and replant in a new bigger pot with light potting soil for containers.

can you eat the veggies after

can you eat the veggies after you remove the mold from the plants ?

Hi, P.J.: Excellent question!

Hi, P.J.: Excellent question! From a technical standpoint, the answer is yes. Assuming that you mean a leafy veggie, and not something that you would peel or de-pod anyway, it is indeed possible to wash them thoroughly enough to eat (say, with a very weak bleach solution, then assiduous rinsings), especially since some might end up being boiled anyway. From a practical and 100% safety standpoint, though, we wouldn't do it.

I can see there are white

I can see there are white powdery spots on some of the leaves of my yellow
zucchini. Do I have to remove and destroy the plant or will spraying these leaves with a fungicide help save the spread?

Hi, Lea: Meet powdery mildew.

Hi, Lea: Meet powdery mildew. Before doing anything drastic, just try washing it off with a water spray. (Some folks say plus milk, and/or plus baking soda, etc.; we say keep it simple, at least to start.) Do it in the morning so that the leaves have time to dry out before the humid part of the day, humidity being the main culprit, not water itself.

hello, your site and info has

hello, your site and info has been super helpful to me. I am growing quite a few things from seed right now inside and everything seems to be going great, only problem is white mold in some soil and on the containers I'm growing them in. Its not on the actual sprouts though. Any idea what I can do or if I leave it will it ruin all my plants? I'm growing veggies, fruit and herbs. Like I said though, they seem to be growing like crazy.

It sounds as if you may be

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

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

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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