Natural Insecticides
Garden Clippings for July 10, 2021
At one time it was simple. We saw a bug on a plant, and we grabbed a bottle of insecticide and we sprayed it. We saw dandelions or crabgrass on the lawn, and we sprayed that too.
It was the Ontario Liberals under Premier Dalton McGuinty who in 2009 introduced the Cosmetic Insecticide Act, who put an end to the indiscriminate use of hundreds of insecticides, fungicides and herbicides. The lawn care industry cried foul and many turf grass specialists’ businesses went for a downward spiral.
Since then, we’ve learned a thing or two. We’ve learned that a well-fed lawn will ward off most weeds. We’ve learned to tolerate a few weeds. And the lawn care companies are busier than ever before, keeping grass healthy.
In the insect world, we’ve learned that not all bugs are bad bugs. We’ve learned that a few aphids won’t harm a plant. We’ve learned to use pesticides as a last resort rather than first resort.
We have Google to thank for an unlimited gardening reference book, giving hundreds of home-made solutions for whatever bug is ailing any plant. Many will start with a soap and water solution, often followed by mixes of garlic, pepper, or a myriad of concoctions that can often be put together from your own pantry.
Hint: When looking on the web for a plant pest problem, be sure to include the word “Ontario or Canada” on the search line, because solutions from south of the border will more than likely include old fashioned chemical-based insecticides which are not available to us.
Unfortunately, there are a few insect pests that make life miserable, and for which there is no home-made remedy. Gypsy Moth is a relatively recent invader that is currently threatening the health of many trees including our precious original Oaks in sections along Lake Huron. To date, Btk (Bacillis thuringiensis kurstaki) is the only safe, effective and selective control for gypsy moth.
Btk is a bacterium that occurs naturally on decaying matter in the soil. It effectively controls many caterpillars while not harming flying insects, birds or mammals. Btk can be commercially sprayed by helicopter over large areas or used by homeowners for individual plants. Btk is considered a class 7 pesticide meaning nurseries and other retailers need to keep it under lock and key or behind the service desk out of shopper’s reach.
Insecticidal Soap is a safe broad spectrum natural insecticide used to control a wide variety of insects. A liquid application of insecticidal soap serves to coat the leaves of plants, making them less edible for insects. It may need to be reapplied after a rain. Insecticidal soap is readily available for gardeners without restriction. Buy it in a ready to use spray bottle or save a few dollars and buy it in concentrated form.
Diatomaceous earth is a powder or dust that resembles flour. Sourced from tiny, fossilized sea creatures, it will not harm, people, pets, birds or wildlife. Diatomaceous earth can be compared to tiny particles of glass that, when crawled over, will cut the soft bodies of crawling insects. It will need to be reapplied after a rain.
Pyrethrins are pesticides made from chrysanthemum flowers, and will effectively control many flying insects including mosquitos, fleas, moths and ants. Pyrethrins are found in many pesticide products and sprays under many brands, names and formulas.
