Powdery mildew is a fungal disease that is one of the more common plant diseases that many home vegetable gardeners will experience. Powdery mildew is in the order of Erysiphales which contains one family named Erysiphaceae of which many cause powdery mildew.
Powdery mildew begins on a host plant, in this case one of your
vegetable plants, when the sexual ascospores, or the asexual conidia
germinating on the surface of the plants leaf or stem, resulting in
septate mycelium of uninucleate cells.
Powdery mildew is one of the easier plant diseases to spot. If your
plants are affected, what you will see are white powdery spots on the
leaves and stems. Powdery mildew is most prominent on the lower leaves
although powdery mildew will appear on the upper leaves as it
progresses. If left untreated, the spots will get larger and more dense
as more spores form.
Do you live in an area or environment where you will experience high
humidity and moderate temperatures? If so, then you are more likely to
experience Powdery mildew.
So what will powdery mildew do to your plants if not addressed? Chances
are it won’t kill your plants, but will contribute to the reduction of
fruit and vegetable yields.
While many home vegetable gardeners are looking for a cure for powdery
mildew, one simply does not exist. So what you need to do is take steps
to preventing and controlling powdery mildew. Two good things to make
sure your plants are receiving in helping with prevention is air
circulation and direct sunlight. Both have shown to inhibit powdery
But, let's say that powdery mildew already exists on your plants. What
you have to do now is move into "control" mode. According to Organic Gardening,
"Research studies in 1999 and 2003 on infected zucchini and winter
wheat (respectively) indicated that spraying cow's milk slowed the
spread of the disease."
By mixing 1 part milk and 9 parts water (by volume), you will create a
spray that can then be applied to your affected plants. Also you can
try a mix of 1 teaspoon of baking soda with 1 quart of water as a spray.
This helps raise the pH, which is not a suitable environment for
At the end of the season, remove all plants that were affected with
powdery mildew, bag them up and throw them away. While some sources say
they are ok to add to your compost pile, I take a more cautious stand
and do not do so.