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Tuesday August 27, 2013 MYT 6:00:00 AM
Tuesday August 27, 2013 MYT 7:41:50 AM
by mary beth breckenridge
Nature's way: Joe Kovach promotes polyculture, a growing method that imitates the plant diversity found in nature. He says varying plant height – such as by planting in containers attached to fences at different heights – creates different layers of habitat, resulting in a more inviting environment for a variety of beneficial insects. – MCT photos
YOU might be working harder in the garden than you have to. By taking cues from nature, you can cut down on insect damage, diseases and other problems that often plague food gardens. Add a little human ingenuity, and you can even extend the growing season and skip much of the weeding and watering that make gardening a chore.
Joe Kovach preached those methods as an expert in integrated pest management with the Ohio State University Extension, and he put them to work in research plots where he studied the best ways to grow food on urban land. Now that he’s retired from the university’s Agricultural Research and Development Centre, he is using his methods at Wooster’s GreenPoint Garden, a plot on the north side of Akron city that grows food for Wooster Community Hospital.
Kovach, who holds a doctorate in entomology, designed the garden and volunteers as its director of operations. Although GreenPoint is large – about 0.3ha – he said the methods used there can improve even the smallest backyard garden.
At the centre of his strategy is polyculture, a growing method that imitates the plant diversity found in nature. In a natural setting, plants of different sizes, genetic make-ups, and flowering and fruiting times all co-exist in the same area, Kovach explained. That natural variety creates a system of checks and balances, keeping diseases and insects from spreading out of control.
“No matter what garden system you have, it’s an ecosystem,” he said. “We want ecosystem stability.”
Polyculture isn’t a perfect system. As Kovach likes to say, “Nature bats last.” But while it’s impossible to eliminate problems entirely, an ecologically stable garden will be better able to fight off trouble and bounce back when it occurs, he said. Here’s what he recommends:
> Plant a variety of foods
Plants belong to different families, or groups that share a similar genetic make-up. Broccoli and cabbage belong to one plant family, for example; tomatoes and peppers belong to another. Certain plant families are prone to certain pests, so mixing things up in the garden decreases the chance of one insect or disease wiping out your entire crop.
Kovach said most backyard gardeners achieve that diversity without even trying, just because they like to grow and eat a variety of foods. Still, it’s helpful to keep plant families in mind as you’re plotting your garden, he said. If you can keep plants in one family in the same row, it’s easier to rotate crops each year, a pro–cess that improves soil fertility and mitigates disease problems.
> Mix up plant heights
Just as insects differ in what they like to eat, they also differ in where they prefer to hang out. Planting tall and short crops in close proximity creates different layers of habitat, resulting in a more inviting environment for a variety of beneficial insects. And because bugs tend to stay put once they find plants they like, a spatially diverse habitat does a better job at confining pest damage, Kovach said. It makes it harder for undesirable insects to find other plants to feed on.
Kovach suggests varying plant height row by row – for example, planting a row of short plants such as strawberries, then a row of tall plants such as tomatoes, then another row of short plants like broccoli. He said you can also create plant height artificially by using vertical gardening – that is, planting in containers attached to fences or other upright structures.
At GreenPoint Garden, for example, beets and onions grow in long trays hung in two rows from heavy wire fencing called cattle panels. Peas are planted in the ground at the base of the fence. Even though those plants are all fairly short, the mass of plant material extends all the way from the ground to 2m or so above it.
> Plant at different times
Forget about planting your garden all at one time. Kovach recommends succession planting, or planting in stages so a crop matures at different times. By doing that, you reduce the likelihood of an entire crop being wiped out by a disease or insect, he said. An insect that attacks your early beans, for example, might be gone by the time the next wave matures. Besides, spreading out the harvest means you’ll have things to eat over a longer period.
> Be gentle on the soil
It used to be common practice to till a garden each year before planting and to continue tilling during the growing season to control weeds. But newer research shows excessive tilling disturbs the structure that allows air and water to move through soil, and it kills or disrupts the earthworms, insects, micro-organisms and other beneficial beings that live in the soil and support plant life. Kovach avoids the need to disrupt the soil by covering his planting rows with landscape cloth to prevent weed growth. He uses a propane torch to burn holes in it just large enough to plant through and accommodate the stems of the mature plants, but not so big that weeds seeds can get in easily.
The landscape cloth needs to be swept periodically to remove weed seeds, so there’s less chance they’ll find their way into the openings, he said. Not only does the landscape cloth virtually eliminate weeding, it also protects the plants from disease-causing organisms that can splash up from the soil when it rains. He recommends buying good-quality landscaping cloth so it will hold up over time.
> Cover up
Kovach likes to use low tunnels and row covers to protect plants from the cold, allowing him to plant earlier. Row covers are the simplest to use. They’re pieces of non-woven fabric that are laid over the plants and act as blankets, capturing warmth from the soil but still allowing rain to penetrate. Kovach said row covers provide enough protection to allow planting a few weeks early and can be kept in place most of the season to protect the plants against destructive insects.
Low tunnels are more like miniature, unheated greenhouses that cover rows of plants. They’re made from metal arches or similar frames a metre high, covered with sheets of plastic. The low tunnels at GreenPoint were created by bending metal conduit into arches and slipping the ends of the pipes over rebar posts driven into the ground. Plastic is draped over the arches and held in place with spring clips.
The plastic raises the temperature inside the low tunnels enough to change the growing conditions by an entire hardiness zone, he said. The plants have to be watered under the plastic until it’s removed when the weather warms. GreenPoint Garden also uses high tunnels, which are similar to low tunnels but large enough to walk in. They’re more common in large-scale growing perations than backyard gardens.
> Other tips
Kovach also recommends planting grass pathways between garden rows instead of just leaving them as bare soil. The grass sucks up moisture so the paths don’t get so muddy during wet spells, and it keeps dust down in dryer periods. You’ll need to mow the grass periodically,
Consider adding a drip irrigation system. It requires a little plumbing know-how, but it eliminates the need to water and also keeps foliage dry, cutting down on disease. Compost makes great fertiliser, but Kovach isn’t opposed to using some chemical products. If you do use chemical fertilisers, choose a liquid type. It won’t burn plants the way granular fertilisers can, he said. – Akron Beacon Journal/McClatchy-Tribune Information Services
Mimicking Mother Nature
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Environment, Environment, Ecowatch, gardening, polyculture
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