By Aneurin Bosley
Some call it a chore to spray their lawns and gardens for those pesky insects and weeds, but not Peggy Land.
“I don’t think it’s an exaggeration to call chemical lawn care biological warfare.”
And the fight is against the many species of plant and insect life.
Land is a physiotherapist, a “green” gardening advocate and a member of a City of Ottawa advisory group called Health Dangers of Urban Use of Pesticides. The group’s mission is to get the city to limit the use of pesticides and to educate people on eco-friendly alternatives.
Land says there are many reasons to avoid using chemicals on your lawn and garden.
For one thing, many chemicals are “broad spectrum,” meaning they kill most creatures they reach.
This is a big problem, according to Lindy Ranger, a greenhouse technician with the National Capital Commission.
“In North America, there are about 640,000 species of insects, but only about 500 of those are what we would call pests,” she says.
“So when people spray indiscriminately, they kill off a lot of good insects that are helpful to a lawn or garden.”
When the helpful insects, worms and other creatures have been killed off, the soil in a garden will lose nitrogen and other nutrients, resulting in what Land calls chemical dependence.
“Chemical-dependent lawns are more vulnerable to insect attacks,” she says.
“It’s like a person who’s been on antibiotics for a long time. Their natural immune system is weakened.”
Ranger says it’s the same thing for plants.
Once their immune systems have been weakened, they become more susceptible to attacks by insects.
But then more chemicals are needed to get rid of the attacking insects. The irony is you’re probably better off leaving the plants alone.
“If your plants are in good health, they generally won’t be attacked by pests,” says Ranger.
At the same time, insects can build up immunities to chemicals, a particular concern for closed environments like greenhouses.
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“Say you’ve sprayed for white flies in a greenhouse,” says Ed Lawrence, head of greenhouse operations for the NCC. “If you kill off all but 50, those 50 may already have some natural immunities to the spray, or will build up those immunities.” Lawrence says you can end up creating a strain of chemical-resistant bugs.
Not that this is an issue for the greenhouses at the Governor General’s residence. They haven’t used poisonous pesticides for over ten years.
“There’s a motivating force when you have high-profile guests coming through here,” says Lawrence, pointing to the lush and colourful plant life that fills the greenhouse. He says he wouldn’t want to see foreign ministers getting poison on themselves by touching freshly-sprayed plants.
The key to keeping pests at bay in the Governor General’s greenhouse, apart from ensuring the plants and flowers are healthy, is striking a balance between pests and their predators. To control aphids, the technicians share the greenhouse with small hover flies, so called because they fly like helicopters. Their larvae feed on the aphid eggs, and keep the aphid populations down.
Some other alternatives to chemicals sound pretty wacky. Mark Dabrowski, who works with Ranger in the greenhouse at Rideau Hall, has one solution for people who really want to get rid of ants and ear wigs.
“Mix one teaspoon of boric acid with one tablespoon of sugar and spread it around,” he says. “Apparently ants and ear wigs can’t get rid of gas, so when they eat the boric acid with the sugar, they basically blow up.”
Dabrowski says rhubarb leaves can also be used against pests. “Boil a pound of rhubarb leaves for half an hour, let it cool, strain out the water and add a teaspoon or so of dish soap,” he says. The dish soap helps the liquid stick to the plants when you spray it.
For a truly “green” lawn, Land recommends planting white dutch clover, which she says doesn’t need much water and crowds out weeds.
“On Parliament Hill, which has been chemical free for five or six years, the parts of the lawn that are still green after droughts are clover.”
But overall, Land says people have to be realistic about their gardens. You can’t expect a lawn in northern Ontario to look like the eighteenth green at Augusta. So Land suggests growing things that thrive in the conditions you have in your yard.
She admits it takes some legwork to find a good balance, but adds this is a small price to pay for a healthy, balanced ecosystem. Besides, Land says getting an education should be part of the point.
“Our backyards can be such learning environments, instead of dangerous ones.”