Natural sprays often the best solution

By Dorothy Dobbie

Jan. 1, 2009

There are only a few commercial pesticides left for use in the garden today, and even these are mostly based on natural plant products readily available to any plant practitioners. So why not brew your own remedies?

Pyrethrum spray is effective against most chewing and sucking insects, including aphids, mites, leafhoppers, cabbageworms and many other insects.

Pyrethrum daisy, or Tanacetum cinerariaefolium, is a type of white chrysanthemum that grows from Zone 3 to Zone 7. The white variety is often called Dalmation daisy. Its cousin, and almost equally effective, pyrethrin source is the beautiful painted daisy (Chrysanthemum coccineum ), which rabbits seem to enjoy in our spring gardens. They may use it as a delouser. Pyrethrum daisies originated in China. The dried petals were traditionally used as a lice and flea repellent.

Pyrethrum breaks down quickly in the environment and will not harm mammals including people. As late as 1946 in Amsterdam, pyrethrins were added as an insecticide to the municipal water supply. Pyrethrins were also used to delouse troops from Napoleon’s time to the Second World War. Today, 70% of the world’s commercial pyrethrum crop comes from Kenya.

Pick pyrethrum daisies in full bloom and hang in a dry sheltered spot to dry.

When ready to make a spray, grind dried flowers to a find powder and mix the result with water and a few drops of liquid soap. Store the mixture in a closed jar because exposure to air will cause loss of effectiveness. The amount of water used will depend on the strength of the pyrethrum in the flower heads so you will have to experiment with concentrations.

Here are a few more equally effective solutions:

• Garlic oil spray: Garlic has long been used as an effective insecticide and repellent. Today, concentrated garlic products are even being used to repel mosquitoes. The following recipe is for use in the garden.

Soak three ounces of finely minced garlic cloves in two teaspoons of mineral oil for at least 24 hours. Slowly add one pint of water with one teaspoon of liquid soap. Stir thoroughly and strain into a glass jar for storage. Use at a rate of two tablespoons to a pint of water. If this is effective, try a more dilute solution in order to use as little as possible. Garlic is effective against leafhoppers, squash bugs, blister beetles, caterpillars, aphids, cabbage loopers, and white flies. Ensure thorough coverage and spray every few days.

Yarrow tea: One cup of yarrow plant pieces should be soaked in 16 ounces of water for 24 hours. Brew in the sun, then strain and mix the result with a gallon of water. Add two cups of strong coffee and one quarter teaspoon of dish detergent.

Spray on aphids, mealy bugs and all soft-bodied insects.

Apply in early evening when temperatures are lower. Spray twice, both upper and lower sides of flowers. Use caution around beneficial insects such as bees and ladybugs.

Spray in the early morning or evening when insects are about and do not spray when temperatures exceed 25 C. Be careful to avoid spraying yourself and wash carefully if you do.

One more caution: never use these sprays on blue spruce trees because they will interfere with the waxy coating on needles making the trees vulnerable to other attack.

Dorothy Dobbie is the publisher of Manitoba Gardener Living. For information or subscriptions call 940-2700.