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West Nile virus will change the very design of our outdoor spaces
West Nile virus will change the very design of our outdoor spaces
By MARJORIE HARRIS
Saturday, April 26, 2003 - Page L1
At a recent Toronto talk about water features in the garden, the speaker made no mention of West Nile virus. This was a surprise to many in the audience. Isn't this a topic that's just behind SARS in intensity? And isn't it going to make a huge difference to our gardening? The designers and horticulturists I've talked to certainly think so.
What was once a mere trend -- using stones, rock and gravel -- has now taken on a new meaning. "We expect to have more requests for hard surfaces in our designs," says Lisa Rapoport of Plant Architect Inc. in Toronto. "And we will look increasingly at organic and non-organic materials for their qualities of change."
Instead of meadowy drifts of plants, we'll be watching cedar turning grey and copper going from metallic to brown to verdigris. Instead of reflecting pools, we'll watch the play of light in mirrors and crushed glass. "It will be more Zen-like," says Rapoport, adding that desert plants will also be big.
Retailers such as Toronto's UpCountry Garden have already changed their ordering. "We've stopped buying birdbaths," manager Duncan Fanning says. "And we only stock those that can be turned into a fountain with little circulating pumps."
He's also selling a lot more garden torches with citronella oil to help to repel mosquitoes, as well as nifty netting made to go over a market umbrella.
But some people are going much further. Remember sitting around your grandmother's screened porch back in the last century? She had the right idea. At the recent Canada Blooms garden show in Toronto, screened gazebos were getting plenty of interest. At Belvedere Woodcraft, gazebos with both windows and screens were being touted as outdoor dining rooms or hot-tub enclosures.
Limestone Trail is a manufacturer of high-end gazebos based near Oakville, Ont., one of the areas that was hardest hit by West Nile virus last summer. "We had three orders on one street alone in Oakville," owner Stewart James says. "We hoped it was the great design of our gazebos, but it turned out there'd been so many birds found with West Nile virus that people were really worried."
Until this year, Canadian garden-tool distributor Rittenhouse Tools has been selling the Mosquito Magnet mainly to golf courses and professional grounds keepers. No more. Now, in addition to a professional version that costs about $2,000, there's a back-yard version retailing for about $500. "Sales have gone off the scale to the public," owner Mark Rittenhouse says of the U.S.-made line of mosquito traps, which lure biting insects with warm carbon dioxide that mimics human exhalations.
One of only a handful of Canadians to attend the American Mosquito Control Association meeting this year, Rittenhouse says there are many approaches to dealing with West Nile virus. "What we keep hearing over and over was it will take an Integrated Pest Management approach to get through this." This could mean using larvicides as the adults drop eggs, and insecticides when the new generation comes along.
How far are gardeners going to have to go? So far, there have been no cases of North American children getting really sick with the virus; it's healthy, middle-aged adults who need to worry. In other words, the gardening demographic. So it's going to change our practices. It means getting out there covered up in loose, light-coloured clothing, especially at dusk and dawn. It means using DEET (though there are organic mixes definitely worth experimenting with).
But maybe it also means taking a less-is-more approach: a single, stunning container in a bed of pea gravel filled with alpine plants rather than masses of shrubby privacy.
The cleanup
The main axiom with West Nile prevention: Don't get bitten. That means eliminating the kinds of places where they like to breed. Mosquito eggs can lie dormant in the soil for years. With a little bit of water and warmth, they can hatch in a half an hour. The larvae pupate in four days and in about 10 days there is a whole new generation of adults.
Rittenhouse horticulturist Bruce Zimmerman says the days are over when we can just let humus build up under evergreens as we instinctively want to. These are just the spots where the insects like to spend their down time out of the wind. Even compost could be a haven (though they don't breed there), so it should be turned every few days.
Make sure all the hedges and shrubs close to the house are pruned to let in lots of light. Weedy areas hold in dew and can be a breeding institute if you don't chop them back.
The plants
You've spent years cultivating a border of wonderful tall ornamental grasses; do you have to whack them all out now? Not necessarily, Zimmerman says. You need to divide them to make sure that there are no bare centres to hold moisture. Many Miscanthus species like damp clay soil, and the more mature the grass, the more likely they will be a mosquito haven. Try the smaller forms such as Panicum and Helictotrichon or the most ground covering types of Fescue.
Go for highly scented plants around any area where you spend time sitting or eating: a surround of herbs such as artemisias, lavender, sages (all of the salvia family), rosemary and thyme (none of which mosquitoes like) rather than a more blowsy concentration.
Xeriscaping is a gardening trend that was already taking root in response to recent droughts, but it is a smart approach to mosquito defence. To xeriscape means to place all plants with the same water needs together, emphasizing drought-tolerant plants. Consider sedums and optuntias (native cactus), which are now showing up in a huge number of exciting varieties. For a focal point use native prairie plants: liatris, rudbeckias, echinacea and gentians to light up the eye and bring in the beneficial bugs you need for a healthy garden.
The water features
Mosquito larvae hatch in still water, so your reflecting pool needs to have a bubbler or a fountain installed. There are larvicides that can be applied to water, but some provinces require a licensed operator to apply it, so check first. Look for products that use the naturally occurring Bacillus thuringiensis israelensis (Bti), which kills larvae when they consume it, but always check local regulations.
If you have a pond, it should be deep enough to hold fish, which will eat the larvae and keep the pond clean, according to Rittenhouse. But fountains and gushing geysers are fine, as long as they keep running. That means running it every day, or covering it when not in use. Plant Architect Inc. recently did a downtown Toronto garden that incorporates a tiny fountain in the top of a table: perfect for chilling wine and providing ambient sound, but easy to cover or drain.
Birdbaths are definitely on the questionable list, unless they are changed daily. But anything that can catch water is risky, from a puddle lying in the bottom of a chair to the top of your swimming pool cover (pools themselves aren't a problem because of the chlorine). Check that pile of leftover plastic pots and saucers. And make sure there isn't water remaining in saucers after watering containers.
Plastic play houses are an oasis for mosquitoes. Clean them out and make sure they are airy and haven't anything that will trap water inside. If you have a rain barrel, make sure that there's no way insects can get in. They should have intact screens inside and be stirred up every few days.
The dining area
Mosquitoes aren't a problem in the middle of a sunny day. But just about the time you want to come out and relax with a cocktail, they swarm around for a feed. So much for the idea, pushed so strenuously in recent years by the shelter mags, of dining by candlelight among the greenery. Romantic, yes, but not when you are dressed head to toe in bug gear.
This is why Rapoport is also predicting that outdoor dining rooms will have not only more hard surfaces but screening as well. And shrubby plants will be placed farther away.
We may be moving to a slightly simpler approach to our garden, a little more Zen and a little less zing in the way we plant. But if everyone has the common sense to follow some rules, this will not hamper the pleasure we take in our gardens.
Copyright Marjorie Harris, 2005
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