Organic
Diseas e and Pest Control
I garden on eight acres and
grow and tens of thousands of plants. We use no pesticides
in the greenhouses, on the plants, or on the land. And guess what?
None are needed.
Pesticides are toxic chemicals,
and it is my belief that no plant is worth poisoning my environment,
or the creatures that inhabit it. I strongly believe that the
need to use pesticides is a myth, quite similar to the old notion that
smoking had no ill effect on health. Extensive advertising,
and relentless promotion (even through our government and educational
institutions), has taught us to believe that gardening successfully
without pesticides is impossible. This is untrue.
There are many natural methods of dealing with insects
and plant diseases. Sometimes called organic methods of gardening,
these approaches are safe, non-toxic, frequently passive, and preventative.
They are easily implemented and generally much cheaper than chemical
alternatives. Organic methods use the natural elements of the environment
to maintain a healthy balance in the garden. One of the very unfortunate
effects of pesticide use is that it destroys the natural balance, and
frequently, more and more pesticides are required in order to rectify
a perceived problem.
My approach to disease and insect control is passive
and preventative. If a problem becomes persistent or particularly
annoying, I may take a more defensive tact.
Preventative Measures
Strong, healthy plants are much more able to resist disease
and insect infestations. Healthy plants are also, of course, essential
to a beautiful garden. To promote and maintain vigorous plants:
o grow them in the situation to which they are best suited. (Shade
plants in the shade, sun loving
plants in the sun.)
o provide fertile, well drained soil.
o drought-proof plants.
o provide adequate water, but avoid frequent sprinkling
or over-watering.
o weed regularly to eliminate plant competition and possible
carriers of disease and insects.
Insects and disease thrive in decaying plant material. Keep a tidy
garden. Deadhead regularly. Prune away dead or dying foliage. Clean
up fallen leaves. If possible, it is best to perform a complete
clean up of the garden in late fall, or alternatively perform this chore
very early in the spring before new growth begins. Use only thoroughly
composted organic material. Never compost foliage with a disease or insect
problem -- put it out with the trash. Good garden hygiene goes a long
way to discouraging insects and disease.
Once you have abandoned pesticides, many natural bug
fighters will move in to fight the battle for you. One of the greatest
pleasures in my garden is to encourage birds, frogs, toads, snakes
and specialized insects. Birds are easily enticed with houses, baths,
and through winter feeding. If there are shrubs or trees in the yard,
many birds will become permanent residents. Frogs, toads, and other
interesting aquatic life may be drawn into the garden by providing a
source of water, such as a small pond. Specialized bug fighting insects
(such as ladybugs) may be purchased or invited into the garden by growing
appropriate food plants.
Cultivate the true
Canadian attitude of 'Live and Let Live'. There are many
beneficial creatures (including insects) in the garden. Encourage
them to work for you. (It's free labour!!)
Improper watering is one (if not THE) major reason
why plants perform poorly, do not overwinter well and are constantly prone
to insect infestations and disease. Learn to use proper watering techniques
on all plants including perennials, annuals, vegetables and grasses (ie
lawn). Water deeply and less
frequently.
In order to be of use to the plant
the moisture must penetrate deep into the soil -- at least 6-8".
Deeper is better. Water your plants and test the soil to see how
deep the moisture has penetrated. You will be amazed at how much
watering is necessary in order to be effective. Avoid shallow,
frequent watering which creates a humid, moist atmosphere around the plant
and promotes fungal diseases, rot and attracts insects. Frequently
watering also encourages the germination of weed seeds. Allow the
top 1-2 inches of soil to dry out completely between waterings. By
watering deeply and less frequently you will be growing plants with deeper
roots which are then more able to withstand drought, winter temperatures
and also diseases and pests.
Defensive Alternatives
Sometimes despite best efforts, insects or disease attacks
a perennial, and it may be necessary to take some type of action.
Slugs
Slugs are perhaps the most persistent
and despised garden pest. Slugs prefer moist shady situations, but
can retreat underground when the weather is hot. Most frequently,
they emerge at night to feast on succulent foliage. Slugs can be controlled
in a variety of ways. Barriers utilizing copper or aluminum strips,
crushed egg shells, wood ash or lime can be laid to surround vulnerable
plants. Slugs with soft mushy bodies find these materials offensive
and even deadly. Barriers are less effective than some other methods
because the slug may be able to tunnel under the obstacle and still
reach the plant.
Traps are reasonably effective for catching and
killing slugs. Fill a small plastic margarine container with beer, or a mixture
of water and a few pieces of dry dog food, and sink it into the ground to
its lip. Slugs are attracted to the "drinking hole", fall in, and drown.
Depending on the number of slugs, the traps should be emptied and refilled
regularly. (Note that commercially prepared slug bait is very attractive
to dogs, birds, and even children. It is, however, also highly toxic!)
Diatomaceous Earth (DE) is a purchased product that
works well at repelling slugs. This powder-like substance is actually
tiny, almost microscopic silica which has been mined and milled from
fossil remains. It kills slugs and many other bugs (including fleas)
by mechanically cutting their body, thereby causing dehydration. "Natural"
grades of DE are nontoxic to mammals, however DE may kill beneficial
insects and therefore should be used with care in only localized problem
areas. Apply a liberal dusting of DE to wet foliage, paying particular
attention to the underside of leaves.
Safer's has a new non-toxic Slug & Snail Bait
which is easy to use and quite effective.
Essential Slug-fighting Equipment
One of the most effective alternatives
for eliminating slugs (and the most gruesome perhaps) is the collect
and kill method. This means handpicking and killing the creatures
by stomping on them, or drowning them in a sealed container. Slugs
can be collected late evening, early morning, and during or just after
a rain shower. They can usually be found on the underside of leaves, and
under logs or pieces of wood. A useful lure can be created by placing
a board in the garden and collecting the slugs underneath it on a regular
basis. If you are squeamish (as I am), don gloves, and using a butter
knife or other blunt flat tool, knock the slugs into a container for subsequent
final extermination.
Applied very early in the season, an ammonia
soak can be very effective, particularly around Hosta. Combine 1
part ammonia with 20 parts water. Soak the soil surrounding Hosta
and/or other perennials. This must be applied before plants have emerged
from the ground and NEVER directly onto a plant.
Caterpillars, Aphids and Other Undesirable Insects
Some larger insects such as caterpillars
may be also be controlled by hand picking, but usually they are too
small and too numerous. A similar but more effective alternative is
the shake and destroy method. Spread newspaper or scrap cloth under
the plant. Then shake the plant vigorously, dislodging the bugs and hopefully
dashing them to the ground. Carefully gather up the groundcover and burn,
soak in water, or dispose of in a tightly sealed garbage bag.
Sometimes bugs can be blasted away with a steady
stream of water. If using this method, make sure the spray is hitting
the underside of the leaves. The water jet method works best if used
on a regular basis -- even daily -- during periods of high infestation.
The most popular methods for controlling bugs
are sprays, and there are many effective home remedies. Most are
cheap, safe, and easy and convenient to use. Following are some recipes
that I use on persistent bugs. If one recipe does not appear to be effective,
try another or slightly change the ingredients.
Basic Soap Spray
Quart hand sprayer filled with warm water
Add a squirt of non-detergent soap such as Ivory
or baby shampoo
Do not use detergent as this could harm your plants.
Additions to the Basic Soap Spray
It is most convenient to prepare
additives in larger quantities and store the mixture for future
use in a glass container, such as a small jam jar. When using the mixture,
just add a teaspoon to your quart container of basic soap spray. It
is best to test the mixture on one or two leaves before sraying the entire
plant, to ensure that no leaf damage will result.
1. Oil Additive
Add a teaspoon of vegetable oil to the basic soap spray to improve
adherence.
2. Garlic Spray
Combine about 1/2 cup of mineral oil with a dozen or so
crushed cloves of garlic. Allow to stand for 48 hours. Strain. Start
by using roughly 1 tsp in your quart sprayer.
3. Hot Spray
In a food processor, liquify
a small onion and an entire bulb of garlic. Seep this mixture in a
cup of olive oil. After 48 hours, strain the olive oil and discard
the pulp. Add a half teaspoon of cayenne pepper. Store in a glass jar.
To use, add a teaspoon to basic soap spray.
Nicotine Spray
Soak an old broken up cigar in
a quart of water for 48 hours. Strain and use. If this "tobacco
tea" is very dark, it can likely be diluted.
"Safe" sprays are available commercially, the most
popular being insecticidal soaps. When buying these products, carefully
read the ingredients on the label to ensure that no toxic ingredients
have been included. Do not rely on the product name alone. A name like
"Green" or "Environmentally Safe" does not mean that the product is
non-toxic.
Generally, studies have shown that home remedies
are as effective as commercial spray. However, home remedies may
damage plants if used in high concentrations. Cautious experimentation
is advisable. It is also helpful to keep some notes documenting mixtures
and their effectiveness for future reference, and to share with fellow
gardeners. (Just like cooks share recipes.)
Plant Diseases
Well-maintained, vigorous, perennials
are generally disease free. However, certain popular varieties
are prone to persistent fungal conditions such as powdery mildew,
rust, and botrytis.
Mildew is a white, powdery fungus that covers the
leaves and stems of infected plants. Although rarely fatal, it does rob
the plant of its beauty. Plants most routinely affected are Summer Phlox,
Monarda, and Asters.
Rust is another type of fungal infliction that disfigures
the plant's beauty but rarely kills. Members of the Mallow Family, in particular,
Hollyhocks, seem most prone to this disease. Rust usually attacks
the leaves, causing conspicuous red-orange blemishes.
Botrytis is a very serious fungus disease which
may destroy the entire plant if not treated early. It is most frequently
seen in Peony and is characterized by brownish-gray mould on the foliage,
which subsequently wilts and turns black. At the first sign of this
disease, remove infected parts and burn them.
Many fungal diseases can be discouraged by good
garden sanitation. It also helps to locate susceptible plants in moist, fertile
soil, in a spot with good air circulation. Water-stressed, or crowded,
plants are more prone to fungus infections. Excessive moisture on the
plant's foliage is also a factor that contributes to the spread of fungal
spores. Watering the plant is therefore best done at ground level,
rather than spraying water over the plant.
There are several home remedies available that will
control and act as a preventative for many fungal diseases:
Baking Soda Spray
1 quart of water
1 teaspoon of baking soda
1 squirt of liquid, non-detergent soap
Spray infected leaves thoroughly,
including undersides and stems. In damp weather repeat regularly.
This is an effective mixture to help prevent botrytis, black spot,
rust, and powdery mildew.
Potato Starch Spray
1 quart of water
2 to 4 tablespoons of potato flour
1 squirt of liquid, non-detergent soap
In addition to fungal diseases, this blend is also an
effective insect spray.
Sulfur
Sulfur has been used as a natural
fungicide for thousands of years. It can be purchased as a liquid
or a powder. Sulfur acts as a preventative, and should therefore be
applied before the disease is evident. It is useless to spray after
the blight is already visible.
Bordeaux Mix
Bordeaux mix is a very powerful,
organic fungicide that has been in use for centuries. It is available
commercially as a powder which can be dusted onto plants, or mixed
with water and sprayed. Read the directions very carefully, and if
in doubt, use a solution that has been severely diluted. In excessively
high concentrations, Bordeaux Mix can kill the plant.
This only scratches the surface of organic
gardening. An excellent, easy to read and follow reference text
is Rodale's Chemical-Free Yard & Garden. Another
favourite is Marjorie Harris' delightful and very informative Ecological
Gardening.
In our modern,
high tech, fast moving world, it seems impossible that a single individual
could effect meaningful change. And most of us, puttering in our
gardens, will never be world revolutionaries. But we are each masters,
kings and queens, of our own plot of soil, and change comes with
a single step or a single spray.
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