Organic Disease Control
Here are some organic sprays with which
we've had experience. As always, treat a small section of the
plant first, and check in a day or two to make sure the spray
has done no harm. Only then treat the entire plant. And be sure
to treat both the top and the underside of the leaves, where
many disease organisms may be present.
Baking Soda I
Treats damping-off. Mix 1 tsp. baking soda
per one quart of water. Mist on soil surface weekly.
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Baking Soda II
Effective at treating powdery mildew and
black spot. Powdery mildew has become quite a problem in warm,
humid climates (like ours). The leaves of susceptible plants -
lilac, squash, and pumpkins among them - become coated with a
white mold, on both sides. Early action will stop the spread of
the disease. Mix 1 quart water, 1 tsp. baking soda, 1 tsp.
cooking oil, and a few drops of dish soap (DO NOT use
anti-bacterial soap). Shake well and spray. You will greatly
improve the effectiveness of the spray in treating powdery
mildew if you hose the leaves off thoroughly first. For black
spot, treat every 3-4 days. Cornell University research shows
this spray also may be effective at treating Urocladium leaf
spot in cucumber, Alternaria leaf blight and gummy stem blight
in muskmelon, late blight in potatoes, and several other
diseases, including suppressing anthracnose in curcurbits, rust
dollar spot and pythium blight in turf, rust in wheat, and
diseases affecting peanuts, banana, and alfalfa. It may also be
effective in treating phoma, phytophthora, scab, brown patch,
botrytis, and fungus gnats. Back to Top
Broccoli
It has been suggested that cultivating with
chopped broccoli around the roots of infected plants will
prevent wilting due to the Verticillium fungus. More research
needs to be presented before we promote this as a cure. But if
you have such a problem, it may be worth a try. We also
understand tilling in broccoli plants may help rid the soil of
the fungus. (Broccoli - tilled-in - is also a recommended
treatment for nematode problems, and used in cultivation can
help eliminate problems with root rot.) Back to Top
Chamomille Tea
Works great for treating damping-off and
other fungal diseases (we used it to treat damping-off disease
on 300-400 of our pepper seedlings last year.) Mix 1 tsp.
flowers per cup of hot water. Let steep 10 minutes and remove.
Let cool, then spray seedlings and soil surface. To avoid fungal
problems altogether, try mixing the tea in a 1:10 ratio into
your standard watering solution. Back to Top
Compost Tea
Treats foliar diseases such as leaf spots,
blights, damping-off, gray mold, downy and powdery mildew, and
apple scab. Compost tea also works as an effective innoculant to
restore or enhance soil microflora. Mix one part manure-based
compost to five parts water. Stir, steep for one week at 59 - 68
degrees F, and strain (through cheesecloth or another similar
medium; alternatively, one can start by putting the compost in a
burlap sack, thereby eliminating or reducing the need to
strain). Spray as needed. In areas where left spots or blights
are common problems, watering the foliage with compost tea is
reported to have preventative effects. Back to Top
Copper Fungicide
Treats left spots and blights. As copper is
barely tolerated in an organic garden, due to its persistent
presence in soil tests, copper should be used as a last resort.
See instructions on bottle. Back to Top
Garlic I
Treats damping-off. Mince one clove of
garlic, and let steep overnight in one quart of water. Strain
the next day. Mist on soil surface weekly. Back to Top
Garlic II
Treats fungal and other foliar diseases. Also
good as a bug spray. Soak 3 ounces of finely minced garlic
cloves in 2 tsp. of mineral oil for 24 hours. Stir well and
strain into a glass jar for storage. Combine 1-2 T of this
concentrate with 1 pint of water and spray. Back to Top
Hot Pepper Spray
Cause: Fusarium Wilt in solanaceous crops is
caused by several different types of the fungus Fusarium
oxysporum. All of Not recommended for diseases - at least we
haven't used it that way. But it makes a wonderful general
purpose spray for leaf-eating insects. Just be sure and test
this, as overuse may cause the leaves of sensitive plants to
curl up and dry. Liquefy 1 garlic bulb and 1 small onion in 1
quart of water. Stir in 1 tsp. of powdered hot pepper. Steep one
hour, strain, then add a few drops of liquid dish soap (DO NOT
use anti-bacterial soap) and mix well. Spray your plants
thoroughly. Keeps best in the refrigerator. Back to Top
Leaf Mold
A seed-starting soil of sand and leaf mold is
reported to control the damping-off fungus. We have no
experience with this method - having always used sterile mixes -
but will experiment with it this year. Back to Top
Skim Milk
A 50-50 mix of skim milk and water is
reported to be very effective at treating powdery mildew and
black spot. Back to Top
Spaghnum Moss
Helps prevent damping-off. Sprinkle a layer
of milled spaghnum moss on the soil surface. Back to Top
Uritica Dioica
Treats damping-off and other fungal diseases.
Take a 5 gallon pail and fill it 2/3 full of nettles. Add water
at 100 degrees F and steep for 3 weeks. Spray seedlings and soil
surface. If you don't have fresh nettles, try using dried. Back to Top
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