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
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?
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
Here's an article on the first field study:
And one of several follow-up field studies:
Spray 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.
-paghat the ratgirl
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
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
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
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?
firstname.lastname@example.org (Twobtold) wrote in
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.
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
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.
pam - gardengal
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