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How to detect and control Powdery Mildew

Updated on November 14, 2011

Powdery Mildew

Powdery mildew is a plant disease/fungus. It can affect almost any type of plant and spreads easily. Virtually all plants can be affected but if caught early on, can be disposed of easily. When I first started my garden, my squash and zucchini plants all grew a white powdery substance on the leaves and after a few days the entire plant's leaves were covered. Since I was a novice I thought nothing of it until my leaves started to yellow and wilt. Thinking I had done something wrong(maybe my soil was not properly fertilized, not enough sun, or just underwatering) I resorted to the online media to help me with my problem. Rather quickly, I came across a site that helped me identify powdery mildew and because I had let it progress so long, I eventually had to dispose of the entire plant and begin anew. Since then, I have kept a watchful eye and am here to help others so as to not have my problem. Powdery mildew can be pretty easy to prevent and if a small case pops up, easy to fix as long as it is caught early.

If left to its own devices, powdery mildew can cause leaves to yellow and wilt. Leaving the plant weak and the leaves to affected to cling onto the plants. Leaves will break and fall and stunt the growth of the rest of the plant.


Plant Diseases

Plant diseases can come in all shapes and forms but they all harm your plants. Whether or not it can stunt your plant's growth like powdery mildew or destroy leaves completely like leaf scorch, plant diseases can wreak havoc on a garden and look awful on crops or flowers that you have spent hours bending your back for.

Plant diseases can be controlled and if you keep an eye out, they can be stopped before they even become a problem. Powdery mildew is one plant disease that can develop over quite some time so nipping it in the bud (pun intended) can stop it almost completely. A watchful gardner can learn from previous happenings of plant diseases but if you are a novice gardner, this lens can help you be watchful for powdery mildew. Chances are, if you run into this type of plant disease, it will take time to get it under control but future hapenings from powdery mildew will be noticed earlier and can be prevented easier.


What is Powdery Mildew

Wilted Leaves and White Spots

Powdery mildew is a very common plant disease and plant fungus and almost every gardener can come across it in certain conditions. It is a fungus that grows spores on the leaves of plants and if not kept under control, very easily spread to the rest of the plant and others of the same variety. Powdery mildew is host specific meaning that it usually grows on that certain plant or others of the same variety. However, this does not mean that you can have several different cases affecting different plants!

Powdery mildew isn't always fatal but can stunt the growth of the plant. Since it covers leaves and plants use their leaves for photosynthesis, it can be hard for a plant to grow hearty and strong. Newer leaves will grow and keep the plant alive but eventually will succumb to the mildew and the process repeats.

You can notice it via the white or gray splotches that appear on the leaves. It actually starts further down but may not be as detectable until the tops of the leaves are affected. Although it may not look good when your plants are affected by powdery mildew, do not stress, it can be eradicated and controlled and the rest of this lens is going to show you how to help prevent it from happening or if it has happened, how to save your plant!

What can cause Powdery Mildew - Below is an example of Overcrowding


Powdery mildew is a fungus that grows and attacts plants and can grow under the right conditions. Above I stated that my plants were also affected. Turns out that many of the conditions that cause it could have been my cause for the outbreak!

I live in an apartment complex and the area that my garden is in is small. I tried to make use with what I had and can say, I am happy with my produce now! I currently grow green beans, swiss chard, strawberries, and pumpkins. I stopped with the squash and zucchini as they became very affected and did not want a weak crop:(

Dampness or areas with high humidity = Fungi can grow in areas of the wet nature. Living in the southern states of the U.S.A, humidity is very high. Eyeglasses can fog up when you step outside. Well fungi can grow in these areas because they thrive in wet conditions. It does not need to rain for it to grow because so much moisture can be in the air!

Bad air flow = Since I live in an apartment complex, my garden is surrounded by a tall brick outlying. A few spaces are made where bricks were left out to make the design. On the outer edge of the bricks are hedges that my complex has. What this means is that the air flow was not good. The fungi could spread easily with just a small amount of wind and could thrive because of the humidity in the air.

Overcrowding = I am a novice gardener, I thought I knew what was best and planted a variety of plants in a small space. Most of the plants were vines and flourished! (I know better now and am doing great!) Plants were practically growing on top of each other and competing for the sun. Growing tall and quick, the mildew found it easy to spread to other leaves and eventually cause me to get rid of a few of them.

Certain things can cause powdery mildew and a combination of these can have it grow. I believe it was all three of these that caused a rampant growth of the fungi.

Powdery Mildew?!?!

Powdery Mildew is very common but easy enough to get rid of with proper control methods.


How to Control Powdery Mildew

How to Grow Healthy Vegetables

I hope that you found this page for information on controlling the situation and not fretting to much about it! It is common and very easy to work with so hopefully you aren't pulling your hair out:)

Powdery mildew can grow in crowded conditions so trimming and pruning back leaves and vines can reduce the fungi. or even the chance it grows. This helps with better over-crowding and air circulation. If the wind can blow through easier, it can help dry out the damp conditions.

If you see affected leaves, trim them at once and dispose of them. Do not add them to compost as the heat may not kill the spores and you run the risk of infecting others. Rather, throw them with the trash or burn them. You cold also just take them out the the yard and let them rot naturally because it doesn't grow well with grass.

Water below the leaves. Watering above creates backsplash and can be a waste of water for your plants. Rather, water at the base to make sure your plant is getting the full benefit.

I would invest in a spray bottle and lightly spray the leaves on top of the plants. Although they grow in damp conditions, it is difficult for the spores to grow on wet leaves. This is why you may notice it after rain has stopped and the leaves are dry. In humid conditions, the leaves being partially wet can reduce the effects of the mildew spreading.

Don't start a new plant because the mildew prefer younger plants. So contolling the problem with your older plants can stop it from growing to your smaller plants. Kind of like nipping the problem in the bud so to speak. (No pun intended :))

Organic mold Killer

Organic mold cleaner can be made with vinegar and lemon juice. This link is for shower mold but works great on plants!

How to prevent Powdery Mildew - Does not mean that it can't still happen!


Once you understand how the fungus works, limiting the cause can be fairly easy. Powdery mildew attacks certain types of plants such as lilacs, vine plants (Zucchini and Squash are my examples), grapes, and cucumbers. If you prefer to not have the outbreak happen so easily, Try a plant that has a high resistance to it. If you must have your plants that can be affected, try growing them in the sun as to cut down on the moisture. Make sure your air circulation is prominent and also try to keep the moisture down. To much watering can cause the damp conditions and if you live in a high humidity environment, overwatering can be common. Just don't let the plants get thirsty!

Fungicides - For another alternative

Although I do not condone the use of fungicides as I believe a little work is easy to do to help plants others may not be inclined to do so. You may need to apply fungicides every week or two or until you feel it is under control.

Dr. Earth 7004 Concentrate 3 Controls Organic Fungicide Hose End, 32-Ounce
Dr. Earth 7004 Concentrate 3 Controls Organic Fungicide Hose End, 32-Ounce

A little pricier but you get more bang for your buck! 2 Pints and a few extra dollars are worth it. Also organic

Garden SafeFungicide3(Ready-to-Use) (HG-10414X) (24 fl oz)
Garden SafeFungicide3(Ready-to-Use) (HG-10414X) (24 fl oz)

Safe for the garden but do not know if I would feel comfortable eating crops that have been sprayed with this since I support organic produce :) But hey, to each their own right?


What causes plant diseases?

There are many causes for plant diseases and powdery mildew is a very common one, but with proper knowledge, we can overcome them and produce bountiful flowers and crop. What do you think is the most important cause?

Which do you think is the common cause of plant diseases?

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Any questions or comments? - Ask and I will respond!

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    • profile image

      Karen 2 years ago

      Hi Sean - are we neighbors? :)Things that have woerkd well for me over the years: snap peas, lettuce, arugula, chard, all herbs, tomatillos (not sure why they are hardier than tomatoes but they do seem to be), green beans. My lettuce is in a partly shaded area and thus grows well without bolting through July or August as long as I water it enough.

    • profile image

      anonymous 4 years ago

      Can I eat the zucchini from my plant with a lot of mildew on the leaves?

      I have cut back the plant to nothing since the leaves all had the fungus. But

      I do not know if we should eat the zucchini from it and the tomatoes that are near it?

    • profile image

      anonymous 4 years ago

      @CatJGB: i have this white powdery mold on my black sofa black clothing in my apartment

    • profile image

      CatJGB 4 years ago

      I've read you can spray affected leaves/plants with a mix of milk and......water? I forget exactly, lol. But I've just put a zucchini plant in a pot today, seeing as it's spring so I'm curious to see how it goes. Last years zucchini in the garden can=me down with it badly towards the end of the season.

    • goo2eyes lm profile image

      goo2eyes lm 5 years ago

      i have green zucchini and cucumbers in my garden and towards late summer, the plants get powdery mildew. my garden is close to a creek.

    • profile image

      miaponzo 5 years ago

      Great plant mildew info! Blessed!

    • profile image

      BeyondRoses 5 years ago

      My ferns use to be green, and lush, then they would get mildew. Lots of good tips for controlling Powdery Mildew.

    • yourselfempowered profile image

      Odille Rault 5 years ago from Gloucester

      Just got my wings, so came back to bless :)

    • yourselfempowered profile image

      Odille Rault 5 years ago from Gloucester

      Wow, really comprehensive information here! Excellent lens! :)

    • lilymom24 profile image

      lilymom24 5 years ago

      Nice lens and as someone who has a garden for a hobby, I appreciate all the information I can get. =)

    • KokoTravel profile image

      KokoTravel 6 years ago

      Again, in the rainforest that the Pacific NW is, we are constantly on watch for the powdery mildew.

    • kingsrookie lm profile image

      kingsrookie lm 6 years ago

      thanks for the feedback:)

    • profile image

      ajsanders100 6 years ago

      A well put together website and a very good job about powdery mildew!