Hi -- I have been trying to control mildew in my garden with a spray of Sodium bicarbonate (Baking Soda) and dishwashing liquid. Have had no success. I started with a teaspoon of BS to a quart of water with a few drops of the liquid soap every four days. I then increased it to 1 tablespoon of BS per quart with the same 4-day interval and can't seem to stem the spread of mildew (NJ, Z6). It started on the Peony, then the Black-Eyed Susans, then Lilacs and then the Pumpkin vines. (Not yet on Phlox which is unusual). Since it's on both the Pumpkins and the flowers I might have both Downy and Powdery Mildew. Anyone have a different home remedy that works? Or a different mixture of the BS and soap that works? Thanks (NJ,Z6)
A 1999 Brazilian study found that a spray of dilute MILK worked better than any fungicide for controlling powdery mildew. Dilutions as weak as
10% milk were AT LEAST as effective as conventional fungicides, & at 20%, much better than fungicides. Milk outperformed sulfer, baking soda, horticultural oils, or any other remedy. What was formerly a serious problem with an array of treatments that had hardly any effect, is now easily controlled.
Here's an article on the first field study:
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one of several follow-up field studies:
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milk in the areas surrounding the infection so it will not spread to new plants. You can spray the presently infected plants to keep the fungus from increasing, though nothing will reverse the appearance at this stage
Then at the end of this year, you should sweep up the fallen lilac leaves, & cut back all the remnant pumpkin vines & any other infected perennial, bag & discard, rather than compost. This will limit the amount of spoors harbored in the soil for next year. Then at the start of next spring, use dilute milk to keep it from getting going again.
It may seem quite a wonder that this should be such a recent discovery, but really it isn't so new, it is only newly field-tested -- the Brazllian study with zuchinnis was first, with follow-up research in Australia & the US duplicating the good results for grape vines & other plants. Greenhouse workers have for a long time used milk as a tool disinfectant. And it is a very old practice to "wash" houseplants with milk to keep the leaves bright & shiny. These folk practices have been proven even more useful than was previoiusly known.
It is still also important to water from the ground instead of frp, overhead, & keep plants far apart & airy, as crowding & over-wetting helps excite the disease.
David Ross wrote in news: snipped-for-privacy@nowhere.not:
I don't know where you got that idea. Regular household bleach (alkaline) has labeled instructions for killing (non-powdery) mildew. On the other hand, milk and consumer grade hydrogen peroxide probably have below neutral pH despite being slippery.
At any rate, I've been lead to believe (or maybe it's just my pet theory) that merely changing the pH of the leaf surface is enough to inhibit powdery mildew.
For home remedies, I've heard more people using potassium bicarbonate (than sodium) and the milk. For non-home remedies I was surprised that Neem is labeled as useful against powdery mildew. There is also something called "Remedy" or R-something which is just potassium bi/mono? carbonate. There are also some cultural things you can do to curb the spread (control moisture, cut down on water splash, others I forget, water the soil, not the foliage like paggers said).
IIRC, some say potassium in general in important for disease resistance in plants.
Powdery mildew tends to be a topical rather than systemic fungal infection and spraying affected foliage with water will actually remove a portion of the mycelia rather than encouraging the problem. You can in fact wash off a good portion of the obvious signs of the disease. It tends to be a seasonal problem as well, most often appearing in late season when climatic and temperature conditions are conducive to its spread - cooler nights with high humidity levels from dew and condensation and warm dry days and soils.
Cultural controls are your best bet - avoid watering late in the day when the foliage does not have sufficient time to dry before the cool and dew of night sets in; water deeply at the root zone when you do water, so that you reduce the discrepancy between atmospheric humidity and soil humidity and water often enough so that the soil does not dry out; and provide sufficient spacing around plants to provide adequate air circulation. Practice good garden sanitation by removing weeds, fallen leaves and other debris that may harbor spores and allow reinfection. And whenever possible, chose mildew resistant selections of plants that are particularly prone to PM. With most woody plants and hardy perennials, PM is unlikely to do any significant permanent damage, being mostly cosmetic in nature, but with annuals, it can cause defoliation and the death of the plant - severely affected plants are best removed.
As is the case with most fungal problems, once you visibly see signs of the disease it is often too late for much control and certainly for cure. Fungicides of any type, chemical or home remedy, will be prophylactic at best, only retarding the spread of the disease but not eliminating the problem.. Pretty much any standard home remedy will be effective in this regard - milk (as paghat indicates), the tried and true Cornell University formula of baking soda (bicarbonate of soda) and water with a few drops of cooking oil or dishwashing soap as a surfactant, Neem oil, and aerated compost tea will all serve to control the spread to new or unaffected foliage. Chemical fungicides will not provide any better cure, but can be equally effective in controlling the spread. To be truly effective, any of these remedies should be started long before you see any physical signs of the problem and repeated at regular intervals throughout the growing season. And since most fungal diseases are extremely adaptable and can develop resistance to fungicides very rapidly, rotating through a series of control measures will provide the most effective results.
Thanks for your reply in re mildew. As to your comment above about potassium: One of my daughters works in an office building in NYC that hires a service to tend to the plants in the various offices. She has notices that the person that waters the plants always has bananas floating in the watering can. She/I have no idea why. Could it be that potassium leaches from the bananas?
Thank you for your reply. I think that's a good point you made about rotating control measures. So instead of stopping my remedy I will continue it and add the milk spray as well.
snipped-for-privacy@aol.company.net (Twobtold) wrote in news: snipped-for-privacy@mb-m26.aol.com:
I've heard of people burying bananas and banana peels near rose bushes for the potassium. I've done that myself (peels) but just because I had some handy. You might want to rinse them first to get rid of some of the pesticide residue on the skin.
Either that or the cleaning service is run by some very sloppy monkeys. ("Dear company president, would you please ask Urooahah the equipment guy to stop leaving his lunch in the watering cans? Thank you. P.S. FYI, Those weren't chocolate chip cookies at the company picnic")
I missed the original post but it seems to have something to do with mildew forming on indoor plants.
FWIW, I have had some success with powdery mildew (outdoors) control on Zucchini using Oxidate, a commercial preparation of hydrogen peroxide. Sprayed on the plants at a concentration of 0.1 to 0.3% it kills powdery mildew if it hasn't completely covered the plant. Heavy infestations may take two applications. Grocery store hydrogen peroxide is generally around 3% concentration, so dilute it 10:1.
I've tried it on shower curtains also, but with less success. However at the 0.1-0.3% level I haven't observed any harm to plants.
Actually mildew is very adverse to an alkaline environment. That is why both Baking soda and milk work on this disease and why acid rain increases its prominence. Fot sodium bicarbonate users, forget the soap and use a small box of Arm and Hammer to a gallon of water. It doesn't work any better than the milk treatment but avoids the sour milk smell.
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