Powdery Mildew Problem Week 5

Looking to get some advice. I have a grow that I desperately want to finish, however I have powdery mildew. I have heard a few solutions, but I like to get answers from more than one source.

I have two 240W tents with 9 plants in them each. 18 total. My RH is never above 25%, and the tempratures is usually in the 80's. I'm using a bucket system/ebb and grow system and using hydroton as a medium with 1000 watters in both with HPS. I water twice a day, and once or twice a day I am trimming off any signs of powdery mildew. I'm pretty sure that the problem occured after it went into flowering. I didn't had the finances to take care of it before flowering. I am trying to take as many effective measurements as possible without using chemicals, and whatever will decrease the amount of trimming that I am doing. I want the buds to get as much photosynthesis as possible.

I did however buy Ed Rosenthal's Zero Tolerance Fungicide, and have been spraying it on a paper towel and am dabbing/wiping off any powdery mildew that I find on the stalks and nodes. Today I took a few additional steps. 1. I made a 25% Bleach solution and sprayed it onto a paper towel, and wiped down the walls of the tent. I plan on doing this once or twice a week from here on out. 2. I went out and bought a HEPA filter. I'm alternating it between the two tents every couple of hours when the lights are on. I am also leaving it in whichever tent overnight, and I leave it on the whole time. I did turn off the fans in the tents however, as I have heard that this can exasperate the problem. I turned them off before wiping down the walls or buying the HEPA filter.

One thing that I did hear is to go out and buy Hydrogen Peroxide with a 3% solution, and add 6 to 8 ounces of it per 5 gallons, and to spray the plants in their current state. I also heard to do the same thing after harvest time, only to soak each cutting for up to 5 minutes each. Then to leave them in front of a fan to dry off the excess water so it will prevent new mold/bud rot. I am concerned with this method though. Would spraying the H2O2 solution on my plants affect the taste of the final product? Would it make it more susceptable to bod rot or new mildew? If I do decide to spray it with this solution, should I turn the fans on? Another thought...I heard that spraying the plants with Perrier will also greatly help as a foliar spray seeing as how it helps by also containing CO2...what if I was to mix the hydrogen peroxide with Perrier? I mean it's basically adding Carbon Dioxide with Hydrogen Peroxide. I don't know what kind of reaction my plants would have. If anyone has tried this, I'd love to hear back about results.

Any help would be much appreciated!!

I have completely eradicated Powdery mildew from my neighborhood using neem oil. Spray with neem and coat the leaves and it should hold it in check for now. The neem oil interferes with the spores germinating. So by using it as a prevetative you'll never see PM nor mites or thrips as long as you spray well every 2 weeks (upto the 3rd or 4th week of flowering) whether you see anything or not. In your case I would hit it once with neem really quik and then hope it keeps it away until harvest.

I have a mold susceptible strain, since i put in large fans running 24/7(all plants moving in airflow) i havn't had any mold or mildew.

...there aren't many things you can safely use in flower and neem is one you DON'T want to use in flower. ...it's VERY important that you do some research into the life cycle of powdery mildew because the best way to control it is to make sure you don't allow conditions in your grow to promote the growth of the mildew, ...the spores are EVERYWHERE so when the conditions are right, mildew appears.

my suggestion would be for you to dose all your vegging plants with Eagle 20 which should rid those plants of the mildew, which is systemic like an infection which is why it is so hard to control in flower because systemic treatments aren't safe for YOUR system.

...anyway, with the plants already in flower you could continue the H2O2, i've never used it myself but i've heard it's effective in a limited way and safe to use in flower, or you could spray your plants down with a milk solution as the milk not only kills the mildew an contact, it also boosts your plants immune system, ...it won't get rid of the pm permanently with only one spraying as i needed to spray every few days for nearly a month before the pm stopped coming back entirely, it DID eradicate the pm, just not instantly.

...i'd also suggest you do some defoliation as good air-flow within the grow is crucial as Buds suggests, if it's crowded in there and the air is semi-still, the pm will love it!

anyway, here is some information i dug up on the use of milk as an organic fungicide so you can read it and decide for yourself if you want to try it, ...there are a lot of haters who will tell you using milk is a stupid idea but all you need to do is try it once and you will be amazed at how the pm just disappears, ...read this info and give it a try (1 part milk to 10 parts water and spray the shit out of them) and i think you'll like the results.

...oh yeah, again, as Buds suggest, spraying in flower can lead to moldy buds so make an effort to not spray the buds, just spray the shit out of the leaves, and don't forget the undersides.

peace, bozo

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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.


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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).

heard a spray made of one part SKIM MILK to 5 parts water, sprayed on the affected area, kills powdery mildew

^^^and thats y u read before posting lol. already covered. well i second that ^^

justanotherbozo said:

...there aren't many things you can safely use in flower and neem is one you DON'T want to use in flower. .

Click to expand...

Would you please educate us as to why not?