Controlling Pest and Disease Naturally

With the good weather and the pleasures of gardening come the annoyances of pests and diseases.  Controlling pests and diseases on plants - both indoor and outdoor -  is a complex subject, but there are some simple guidelines that most home gardeners can follow that will help to avoid and/or control these problems.

Pest and Disease Controls
The best insect pest and disease control is prevention, if that fails  - you will need to take action -  use some sort of control - chemical or natural. Some pests - such as Whitefly  and Aphids multiply so quickly that if you don't deal with them right away, you will find it really hard to get rid of them.

Natural Pest Controls
Although there are various chemical controls available for controlling insect pests, you may not want to use strong chemicals to keep your plants pest-free. Instead you can try various different methods to avoid  and control problems, and control chemically them only as a last resort.

Many insects have natural enemies which provide some control. A diligent home gardener may find that this and other natural controls used together may be sufficient to control garden pests.

Predacious insects such as lady beetles and their larvae, syrphid flies, lacewing larvae, assassin bugs and many other beetles - prey upon other insects - aphids especially.

Parasites insects such as the ichneumon wasp and tachinid flies lay their eggs on or in caterpillars. The larvae or young of the fly,  then eat the host caterpillar.

Spiders, snakes, birds, frogs and mice also help to reduce the insect population, but unfortunately may catch beneficial insects along with the harmful ones.

To create a good environment in your garden for beneficial predatory and parasitic insects and other organisms, follow these guidelines:

1.          Plant a variety of flowering plants which provide pollen and nectar food sources for many adult insects such as parasitic wasps and flies.

2.          Use pesticides sparing, confining the application to the plants affected by the pest.

3.          Avoid pesticide drift to neighbouring plants which may harbour beneficial insects. (Never apply sprays on a windy day)

4.          Hand-pick larger insects such as Tomato hornworms, snails, slugs, or Colorado potato beetles, and wash off spittle bugs, aphids and mites with a strong, fine jet of water.

5.          Plant French and African Marigolds  and Tansy around the garden. These plants have a fatal attraction for certain pests and they will rush to gobble these plants up, leaving others alone.

Disease Control
Some of the same guidelines apply to disease control -  good sanitation, early detection and good cultural practices are all part of prevention.

In some cases, disease not only causes damage, but also spreads quickly from plant to plant. (Some insect pests, such as Leafhoppers, spread certain types of disease between plants;  Diseases such as Black Spot of Roses is easily transmitted by your own efforts to remove the diseased leaves, or by watering, and can quickly affect all  your rose bushes.). Powdery Mildew if not dealt with at the onset of an infestation can also quickly spread.

Sanitation
Good air circulation (don't crowd your plants) is important. Air circulation deters fungus from taking hold and spreading.  Maintain your plant beds weed free and use some sort of mulch to help keep them clear (shredded Cedar mulch; crushed stone; wood chips; coco shells  are all possible mulch choices). Good watering habits are important also -  water early in the morning so that the leaves dry off in the sun; preferably use drip hoses, or at least water the plants from underneath to avoid wetting the leaves.  Remember, damp leaves are an invitation to fungus. If you have a diseased plant in the bed, remove all the damaged foliage, put it in a garbage bag and wash your hands (or change gloves) before handling the healthy plants.  Any tools used to cut diseased branches or leaves should be cleaned in a 10% bleach solution before the next cut.  A few other pointers include:

If re-using pots - always wash them out with a strong soap and water solution, then rinse them in a 10% solution of bleach;  if you have a plant that is infested with a pest or a disease, keep it away from your other plants.
Examine your plants closely for any sign of pest or disease. This should be done frequently - and a good opportunity is when you are strolling around the garden admiring or watering your plants.

If you find something that looks suspicious but aren't sure about it, take a sample to your local garden centre and ask someone there.


FAQ

Q.           My birch tree has tiny holes in the trunk and branches and looks sickly, what could the problem be?

A.          Birch trees are among the many trees attacked by borer insects, if the problem is widespread it may eventually destroy the tree. The best plan is to have a tree expert come and have a look to assess the damage.

Q.           I notice a sticky substance on some of my plant leaves. What is it?

A.          This is called "Honeydew ' and is left behind by aphids.

Q.          How can I get rid of an aphid infestation?

A.          Lady beetles can be purchased at many garden supply centres and you can then set them free around the affected plants. You can also use an insecticidal soap spray on the aphids.
Q.          I notice my rose leaves have big, ragged holes chewed in them, what causes this?

A.          Caterpillars can cause a lot of damage to various plant leaves.

Q.          What causes the leaves on some plants to be rolled up on the edges?

A.          An insect called a Leafroller.

Q.          I have a lot of earwigs in my garden, how can I get rid of them?

A.          Earwigs like dark, damp places. Cut a short piece of hose, block up one end, spray a little water in and put it in a dark nook.  In the morning bring a pail with a strong bleach solution in  and  shake out the piece of hose over the bucket. The Earwigs who gathered there will fall into the water and be destroyed.

Q.          I seem to have White Grubs in my flower beds,  aren't they just grass pests?

A.          White grubs are found mainly in lawns, but they may migrate to flower beds, where they can attack the roots of young bedding plants and seedlings.

Q.          What can I do to get rid of slugs and snails?

A.          Put on rubber gloves and remove them manually either early in the morning or in the evening, dumping them into a bucket with a strong bleach solution. You can also make your own slug and snail bait with beer or brewers yeast.


Bibliography
The following texts and authorities were used to support information provided in this article.

Barrons, Keith C. Ph.D.          Are Pesticides Really Necessary?
                                       Regnery Gateway, Inc. Chicago, Ill. 1981

Burrows, William.                    Textbook of Bacteriology, 15th Ed.
W.B. Saunders Co., Philadelphia. 1950

Cravens, Richard H.          Pests and Diseases.
Time Life Books. Virginia. 1977

Davidson, Ralph H.
Lyon, William F.                    Insect Pests of Farm, Garden & Orchard.
                                                 John Wiley and Sons. Toronto. 1979.
Ellis, Barbara W.   
Bradley, Fern Marshall) Editors          The Encyclopedia of Natural Insect and Disease Control.
                                                 Rodale Press. P.A. 1984.

Haines, John
Bakaitis, Bill                    "Fungus". Sept-Oct 1991. Viruses, Microflora and Plants. 
Published in the Biology Digest as an abstract. Vol 18, 91/92 - 0001 - 91/92 - 1172.
Pirone, P.P.                    Diseases and Pests of Ornamental Plants.

Shurtleff, Malcolm C.          How to Control Plant Diseases in the Home and Garden. 2nd Ed.
Iowa State University Press. Iowa. 1966
Ware, George W.                    Pesticides, Theory and Application.
W.H. Freeman & Company. San Francisco. 1993
Wellman, Frederick L.                    Plant Diseases, An Introduction for the Layman.
                                                 Natural History Press. New York. 1971
Westcott, Cynthia                    Plant Disease Handbook. 3rd Ed.
                                                 Van Nostrand Reinhold Co. New York. 1971.

                   Controlling Lawn and Garden Insects.
                                                 Ortho Books. San Francisco. 1987.

Insect and Disease Control in the Home Garden. 1993-1994
The Ontario Ministry of Agriculture and Food. Toronto. 1994.