How does milk control powdery
Scientist aren't 100% sure how
milk works to control this disease. It seems that milk is a natural
germicide. In addition, it contains several naturally occurring
salts and amino acids that are taken up by the plant. From previous
experiments using sodium bicarbonate, potassium phosphate, and
other salts, researchers have found that the disease is sensitive
to these salts. It is possible then, that milk boosts the plant's
immune system to prevent the disease.
Milk used around the world
The benefits of using milk to
control powdery mildew haven't been isolated to Brazil. Melon
growers in New Zealand are saving thousands of dollars every
year by spraying their crops with milk instead of synthetic fungicides.
The melon growers in New Zealand have been so successful that
the wine industry is taking notice and beginning experiments
using milk to control powdery mildew in grapes.
What kind of milk should be
In Bettiol's original experiment,
fresh milk was used, straight from the cow. However, this is
obviously not feasible to most home gardeners. The research work
in New Zealand actually found that using skim milk was just as
effective. Not only was it cheaper, but the fact that the milk
had no fat content meant that there was less chance of any odours.
Wagner Bettiol's original article
was published in the journal Crop Science (Vol. 18, 1999, pp.
489-92). It can be found on-line at: