by Celine Caron
People who live in wet climates are often all too familiar
with the effects of mildew on such plants as gooseberries,
currants, raspberries, grapes, phlox, and roses ... and if
the same individuals keep fruit trees, they're probably
acquainted with apple or pear scab (Venturia
inaequalis) as well. Many commonly used wholistic
controls aren't terribly effective against these fungi ...
while more potent fungicides—including lime
sulfur—do indeed destroy mildew and scab but,
unfortunately, also kill Anthocoris musculus, a
valuable predator of mites and aphids.
The dilemma does have a resolution, though ... and
it came about through the work of an English entomologist,
Dr. Peggy Ellis. Since commercial fruit growers commonly
spray a 5% solution of synthetic urea on fallen leaves to
control apple and pear scab, Dr. Ellis reasoned that human
urine—which contains 2 to 4% urea, depending on the
diet—could serve the same purpose.
The entomologist first tested her theory on a backyard
gooseberry patch ... and was pleased to find that the urine
was extremely effective in combating a mildew problem that
had afflicted the plants. Encouraged by this success, she
reported her discovery to the members of the Henry
Doubleday Research Association in the fall of 1978. As a
result of her report, I soon became aware of this
breakthrough in wholistic fungus control. And since my own
currant crop was plagued with a severe mildew problem at
the time, I was able to test the remedy immediately ... and
my results were every bit as good as those that Dr. Ellis
More work has been done—on both a formal and an
informal grower-to-grower level—over the past few
years, and the success record is impressive enough to make
me want to pass the news of this technique along to
MOTHER's fruit-growing readers.
UREA . . . I'LL NEVER STOP SAYING
Thanks to the research completed thus far, it's possible to
outline both preventive and curative urine treatments. In
either case, though, be aware that undiluted urine will
sometimes scorch leaves and could kill foliage, so the
substance should generally be used in its pure form only on
Step 1: Spray straight urine on trees and shrubs just
before the leaves fall in the autumn ... or soon thereafter
(in this case, of course, leaf burn won't be a problem).
Make sure, too, that the ground beneath the
plants—out to the drip line—is well covered
with the liquid ... as this precautionary measure will
destroy any spores present on the fallen leaves.
Step 2: Treat the trees and shrubs with undiluted urine
again in the spring, before the buds open. Be sure
to spray the earth beneath the plants, as well.
Step 3: Three weeks after the buds have opened, treat the
patch or orchard with a solution of four parts water to one
part urine. This procedure should be repeated whenever you
notice signs of a developing infection.
Spray the affected bushes or trees with a four-to-one
solution of water and urine as soon as signs of fungal
attack appear. (In critical cases, I've used a two-to-one
solution, and achieved excellent results with no evident
burning of leaves.)
Urine can be stored in plastic pails or tanks. When it's
kept in such containers over a period of time, occasional
stirring will render the liquid all but odorless. Some of
the nitrogen in the urine will escape during storage,
unless you add a small quantity of material that's rich in
carbon content (two excellent candidates are dry leaves and
chopped straw) to the pail before any fermentation takes
In short, human urine (which, if from a healthy individual,
is pretty much sterile) should be of real value to backyard
fruit and berry growers. To quote the Henry Double
day Research Association Newsletter, "This easiest
of all remedies ... should attack only the types of fungi
which produce ascospores or conidia, but it is worth using
it freely and observing results. . . ."
There's a readily accessible and effective solution to
the problems of orchard mildew and scab.
EDITOR'S NOTE. Celine Caron is the coauthor, with
lean Richard, of Fruits et petits fruits: Guide
pratique de production agriculture ecologique, a
fruit— and berry growing manual that was
published in Quebec, Canada in 1981.
We want to note that MOTHER's staffers have
not yet tested Caron's remedy ... and that it
should be considered an experimental treatment and used
sparingly on your crops until you're confident of its
safety and effectiveness.