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26-08-2004, 09:21 AM

From: "Pam - gardengal"
1PfXc.236703$eM2.214651@attbi_s51

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.

pam - gardengal

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.