You know … the unattractive white powdery-looking spots that seem to appear from nowhere during mid- to late-summer? These fungal spots begin on lower leaves and can quickly spread to cover leaf surfaces of entire plants. Lilacs, phlox, bee balm, asters, dahlias, cucumber and summer squash are all susceptible, particularly if the plants do not have good air circulation (a problem I plant to avoid). Not liking to spray fungicides, I’ve tolerated powdery mildew for years. But when cleaning up paperwork this past winter, I found a note I had jotted down, likely while watching any one of gardening shows I try to take in during cold weather months. The note said: powdery mildew; 1 part milk to 9 parts water; spray 2x weekly.
My guess is this tidbit of advice came from one of those shows HGTV deemed unworthy … probably Gardening by the Yard … but I can’t be sure. It also may have come from an old Victory Garden show on PBS. Anyway, I tried this concoction on all my phlox, one lilac (saving the others for comparison), and my cucumbers and summer squash. In previous years all had been covered by powdery mildew. The cucumbers and squash would simply succumb. The phlox would valiantly bloom on in spite of the truly unattractive appearance of its leaves. The photo at the top shows an unsprayed lilac … it just looks plain sad. The photos below show a nearby lilac two weeks after just one magic milk spray. The powdery mildew is not completely gone – you can see a few traces on the lower leaves – but is controlled. Just one spraying of magic milk stopped powdery mildew in its fuzzy little tracks on my cucumbers and squash leaves – though I will spray again for insurance. The phlox leaves look better than they ever have by this time of year … two weeks after the initial spray only small traces of powdery mildew appeared – I re-sprayed.
I’ve not yet figured out exactly why milk works to stem the spread of powdery mildew – there must be a substance in milk that holds fungus in check – but I’d love to hear from anyone who can explain milk’s effect. But the point is it works, it requires no special permit to use, and its nearly free.