H2O2 & Powdery Mildew

A big misconception of PM is that water helps it spread but water actually kills the spores! I've sprayed my plants that had signs of PM caused from a root aphids attack with plain tap water ......it's been working just as good or better than the GreenCure I'd been using!!

Just make sure you do this with the lights on and be mindful that soaking the buds too much may potentially lead to bud mold or some other kind of pathogen(s).
I don't see how that could be true. the spores would need water to germinate...maybe it's the chlorine in the tap water you're using??


Living dead girl
No, it's true. PM lives in/on living plant tissue, and while it requires moisture, washing the leaves down with water kills the fruiting bodies, which are the only thing we can see with the naked eye (after they've grown to large enough proportions). It's true.
Do you turn lights on or off when you apply milk and do you rinse after
...yeah man, it's been quite a while since i posted here but i saw your thread and thought i'd stop in and see if i could offer any help.

...anyway, pm spores are everywhere so if you provide the conditions it likes, it will appear so do yourself a favor and do some studying on the life cycle of powdery mildew so you become aware or just exactly what those conditions are.

...that being said here is some information i found back a few years ago when i had my own battle with pm, fortunately the milk worked like a charm, with the caveat that milk won't cure your pm in one spray, you'll need to spray every 3 or 4 days for at least a few weeks before you finally get rid of it. ...you'll also need to figure out what your doing wrong so you can stop doing that so you no longer provide pm friendly conditions.

peace, bozo


Milk is a useful fungicide in the garden, and is more effective than standard chemical brands.

Researchers believe the potassium phosphate in milk boosts a plant's immune system to fight the fungi.

Where most organic gardeners use a baking soda, soap and oil solution, milk may be substituted to combat the unwanted fungus.

Preparing a Milk Solution and Spraying Schedule

The correct dilution and spraying schedule for garden plants depends on the situation and takes some trial and error.

A milk fungicide solution can range from 1 part milk to 9 parts water, to a strong, milk-only solution. A 1:1 dilution may work for a week, but a 1:8 solution requires spraying every 3 or 4 days.

Skim milk may work better than whole milk, as the higher fat milk may clog a sprayer; even reconstituted powdered milk works.

Uses for Milk Fungicide

Milk was originally used in the garden to treat powdery mildew on squash plants. It is now also commonly used on flowers such as rudebekia (Black-eyed Susans) and Begonias to cure powdery mildew.

Milk has also been used to cure Botrytis on a Cyclamen houseplant. This was applied full strength every morning (leftover breakfast milk). Rotten leaves were picked away and the plant pulled through with no more Botrytis.

Black spots and rust on roses can be controlled but not cured with milk. Fortunately, milk can prevent the spread of these fungi to other plants and new leaves. This can be very useful when bringing home a plant from the nursery and finding a black spot.

The copyright of the article Milk as a Garden Fungicide for Powdery Mildew, Botrytis, and Black Spots in Organic Gardening is owned by Deborah Turton. Permission to republish Milk as a Garden Fungicide for Powdery Mildew, Botrytis, and Black Spots in print or online must be granted by the author in writing.


by Arzeena Hamir
Powdery Mildew

Less than 3 years ago, researchers in South America discovered a new alternative to controlling powdery mildew. Wagner Bettiol, a scientist from Brazil, found that weekly sprays of milk controlled powdery mildew in zucchini just as effectively as synthetic fungicides such as fenarimol or benomyl. Not only was milk found to be effective at controlling the disease, it also acted as a foliar fertilizer, boosting the plant's immune system.

Powdery mildew in the cucurbit family is caused by the organism Sphaerotheca Fuliginea. It is a serious disease that occurs worldwide. For decades, organic gardeners had to rely on making a spray from baking soda to control the disease. Now, instead of measuring out the baking soda and combining it with a surfactant (a "sticking" substance) of either oil or soap, gardeners need only head for their refrigerators.

In his experiments with zucchini plants, Bettiol found that a weekly spray of milk at a concentration of at least 10% (1 part milk to 9 parts water) significantly reduced the severity of powdery mildew infection on the plants by 90%. While some gardeners may be tempted to increase the concentration of milk for more control, Bettiol found that once concentrations rose above 30%, an innoccuous fungus began to grow on the plants. How does milk control powdery mildew?

Scientist aren't 100% sure how milk works to control this disease. It seems that milk is a natural germicide. In addition, it contains several naturally occurring salts and amino acids that are taken up by the plant. From previous experiments using sodium bicarbonate, potassium phosphate, and other salts, researchers have found that the disease is sensitive to these salts. It is possible then, that milk boosts the plant's immune system to prevent the disease.

Milk used around the world
The benefits of using milk to control powdery mildew haven't been isolated to Brazil. Melon growers in New Zealand are saving thousands of dollars every year by spraying their crops with milk instead of synthetic fungicides. The melon growers in New Zealand have been so successful that the wine industry is taking notice and beginning experiments using milk to control powdery mildew in grapes.

What kind of milk should be used?
In Bettiol's original experiment, fresh milk was used, straight from the cow. However, this is obviously not feasible to most home gardeners. The research work in New Zealand actually found that using skim milk was just as effective. Not only was it cheaper, but the fact that the milk had no fat content meant that there was less chance of any odours.

Wagner Bettiol's original article was published in the journal Crop Science (Vol. 18, 1999, pp. 489-92).
Lights on or off
Do you turn lights on or off when you apply milk and do you rinse after
That post was from 4 years ago, but I would at least turn your lights down so they don’t burn your plants after sprayin. I always just spray at lights out. But if you’re fighting pm it might not be good to have that high rh with light out.
I don't know a lot about UV sterilization of air, but in water you need slow flow so that there is sufficient contact time between the water and the UV. Pushed through a tube. Tubular.
Typically UV is designed with certain peak flow rate so definitely need sufficient contact otherwise UV won't be super effective
I have been infected for the first time. Damn! I have decide to try the H2O2 fix first. BEFORE everyone tells me to use Eagle 20; I would like to give this route a try for organic purposes...

I am going to use a 3% solution of H2O2 and mix 1 Cup to 1 Gallon of water. My current PH level is 6.3-6.8%. I lowered my RH level to 4o%. [normally 55-65%]. Since I can't change my heat, I am at the mercy of whatever my lights and CO2 burner can generate. I raised my A/C temperature so my indoor temps should run between 70-82 degrees. [normally shoot for 68-74]. I plan on sraying my mixture.

Could someone please provide some advice to my questions:
1. How oftern can I spray in both bloom and veg rooms?
2. Is my PH level good for this mixture?
Sorry a bit late in the reply but I would like to say this for other growers who share the same problems stumbling upon here.
1. H2O2 works for a wide range of pH, would say between 5-9 is totally fine so there is no need add pH adjustment.
2. Powdery mildew belongs to a group of microorganisms called water molds (sci name oomycetes). Simply means water is key route for infection, either through irrigation water or overhead spraying, or travelling through humid air. Therefore, the irrigation water and overhead spraying water should be proper disinfected with sanitizer. Heard from a grower that a new peroxide product (silver stabilized hydrogen peroxide, SHP) works great at 50ppm when there is PM infection. When there is no PM, keep a residual of 20ppm SHP in the water works like charm and fend off water molds including PM, phytophtora, pythium.
I'd try to raise the pH on top of that peroxide mixture, get it to 10 and it's a PM treatment by itself. I would spray as often as I'm seeing fruiting bodies.

Consider a horticultural oil that also acts as a physical blocker, such as Storch or, my own preferred, JMS Stylet.
Peroxide in itself is enough and have less harm for the plants, with adding benefit of providing O2 to the root zone. However, water with pH @ 10 is the optimal for plant growth tho. Hows your experience with this?
currently testing home hobby uv-c light to rid pm. u tube---

UV is a great way to kill in the pm in the water going through the UV however it won't help with PM on the leaf and plants, and the PM that are swimming in the water pipe. Only a water sanitizer like chlorine, chlorine dioxide and H2O2. But chlorine products dont work well with plants. Some concerns about chlorate and chorite residual build up in the plants when using chlorine dioxide.
Do you turn lights on or off when you apply milk and do you rinse after
I read somewhere else that you need the lights on for at least 5 hours after you spray or sunlight because the milk needs to dry and when it does it makes an antiseptic, good luck bud girl!
Can you spray the milk solution directly on the buds? I keep reading that most of these preparations you have to keep it off the buds, is this true with milk?