Powder mildew on plants
Less than 3 years ago, researchers in South America discovered
alternative to controlling powdery mildew. Wagner Bettiol,
Brazil, found that weekly sprays of milk controlled powdery
zucchini just as effectively as synthetic fungicides such
benomyl. Not only was milk found to be effective at controlling
it also acted as a foliar fertilizer, boosting the plant's
Powdery mildew in the cucurbit family is caused by the organism
fuliginea. It is a serious disease that occurs worldwide.
organic gardeners had to rely on making a spray from baking
the disease. Now, instead of measuring out the baking soda
with a surfactant (a "sticking" substance) of either
oil or soap,
need only head for their refrigerators.
In his experiments with zucchini plants, Bettiol found that
of milk at a concentration of at least 10% (1 part milk to
significantly reduced the severity of powdery mildew infection
by 90%. While some gardeners may be tempted to increase the
milk for more control, Bettiol found that once concentrations
30%, an innoccuous fungus began to grow on the plants.
How does milk control powdery mildew?
Scientist aren't 100% sure how milk works to control this
that milk is a natural germicide. In addition, it contains
occurring salts and amino acids that are taken up by the plant.
previous experiments using sodium bicarbonate, potassium phosphate,
other salts, researchers have found that the disease is sensitive
salts. It is possible then, that milk boosts the plant's immune
prevent the disease.
Milk used around the world
The benefits of using milk to control powdery mildew haven't
to Brazil. Melon growers in New Zealand are saving thousands
every year by spraying their crops with milk instead of synthetic
fungicides. The melon growers in New Zealand have been so
the wine industry is taking notice and beginning experiments
control powdery mildew in grapes.
What kind of milk should be used?
In Bettiol's original experiment, fresh milk was used, straight
cow. However, this is obviously not feasible to most home
research work in New Zealand actually found that using skim
effective. Not only was it cheaper, but the fact that the
milk had no
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: http://188.8.131.52/journal/sej/full/c12_199908_180801.pdf (no more I assume)
Arzeena Hamir is an agronomist and writer for Organic Living
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