Alternatives to Chemical Pesticides

Wondering what to do about pests in your yard? There are many things that homeowners can do to reduce pest populations on their properties. You need to learn some basic biology and learn how to recognize small problems before they become large problems. Anyone can reduce pest insect and disease populations below levels where they cause noticeable damage without resorting to using chemical pesticides.

Step 1. Identify the Pest!
Step 2. Learn the Life Cycle and then Break It!
Step 3. Other Ways to "Break" a Life Cycle
Step 4. Prevent the Problem in the First Place

Step 1. Identify The Pest!

Determine which type of organism has caused the problem. Many different organisms may cause damage on plants.

Insects:

Often remain on the damaged plants

• Adult insects may possess wings
• Most insects possess three pairs of legs (They may appear to have more)

'Make a mess'.
They may:

• chew plant tissues, leaving holes or tunnels
• leave droppings (frass)
• produce 'sucking damage'
• produce honeydew (which may lead to sooty mould)
• produce webbing
• produce galls

Diseases (E.g. Bacteria, Fungi, Viruses):

• Cause plant tissue to rot; 'ooze' may be present during wet weather.
• Form small or large spots on leaves, stems, fruits, and/or roots.
• Produce white or grey 'hair like' growth on plants.
• Cause sudden wilting of plants.
• Produce bright orange pustules on undersides of leaves.
• Produce mosaic patterns on leaves.
• Cause excessive branching or deformed flowers.

You may need to collect a specimen (insects and/or damaged plant material), and take it to your local garden centre, or to a master gardener, to be positively identified. It is impossible to treat any problem without a proper diagnosis.

Once the pest is identified.....

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Step 2. Learn The Life Cycle, And Then Break It!

Good sources of information include: horticultural professionals and master gardeners, government publications, university and government Web sites. Note: you will probably be searching for information on local pest problems. Choose information from sites with a similar climate to Ottawa's. You will need to know:

When and where does the pest occur?

• Which season of the year?
• On which host plant(s)?

Look for the pest and take management action before it has a chance to reproduce and spread to other plants.

Remove preferred host plants if practical.

When are pests most susceptible to management actions?

• small, soft insects are an easier target that large soft ones
• some insects may spend part of their life cycle protected within or beneath something
• diseases often have resistant resting stages
• diseases are limited by environmental conditions

Target the stage that is easiest to manage

Where and how does the pest spend the winter?

• In the soil?
• On bark?
• In dead leaves?

Remove the overwintering pest during garden clean up!

Make your garden less hospitable by removing or damaging overwintering sites.

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Step 3. Other Ways To 'Break' A Life Cycle

Prune out and destroy infested plant material. If the material is diseased make sure that you sterilize pruners between cuts using rubbing alcohol, or 10 per cent bleach solution. Do not compost infected plant material in home composters.

Prune around plants to allow for adequate air circulation.

Hand pick larger insects from infested plants and drown them in soapy water.

Use traps to catch pests (E.g. sticky bands, earwig traps, slug traps etc.).

Use barriers to exclude pest insects (E.g. collars, row covers).

Apply registered 'alternative' products according to label directions (Note: while these products do not persist in the environment, some are non-selective, and will damage all organisms that are exposed to them).

Apply dormant oil to branches of woody plants, when a susceptible stage spends the winter there.

Spray Insecticidal Soap on small, exposed, soft bodied insects or earwigs. More than one application of soap will be necessary to manage pest populations.

Use biological insecticides

• Bacillus thuringiensis (B.t) - to kill larvae of moths. Note: this product must be eaten by the caterpillar to be effective.

Use organically derived pesticides

• Rotenone
• Pyrethrum

Apply diatomaceous earth where insects will crawl through it.

Apply Sulphur or Lime sulphur to dormant plants to kill over wintering diseases.

Apply Baking Soda solutions, or milk to control powdery mildew.

Note: when applying any of these products, make sure that they cover all surfaces of the plants being treated. Many products must be reapplied following rain.

Use biological controls. They will help to establish a balanced ecosystem on your property.

• Apply parasitic nematodes
• Encourage birds and/or bats on your property
• Recognize and encourage invertebrate predators and parasites on your property.

Common beneficials in the Ottawa area include:

• Ladybird beetles
• Ground beetles
• Rove Beetles
• Tiger Beetles
• Parasitic Wasps
• Syrphid fly larvae
• Parasitic Flies
• Lacewing and Antlion larvae

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Step 4. Prevent The Problem In The First Place

Insects are less likely to infest healthy plants, and vigorous plants are able to tolerate more pest damage.

• Ensure that plants receive adequate light and moisture. When watering, use drip or soaker irrigation instead of overhead irrigation.
• Ensure that plants receive adequate (not excessive) nutrients. Amend soil with organic material (compost, screened topsoil).
• Maintain proper soil pH and tilth.
• Provide winter protection for plants where necessary.
• Practice proper garden sanitation.

Select plants for your yard that have few pest problems.

• Plants such as Roses, Lilies, Viburnum, Birch, Elm, etc. are known to have many troublesome pests. Choose alternatives or expect to do more work maintaining them to avoid infestations.

Select resistant varieties.

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