I'm giving a talk on vegetable gardening soon and therefore am reviewing some of my notes on Integrated Pest Management (IPM), which BTW is not as complicated as it sounds. Basically it refers to traditional, common sense methods of maintaining a healthy garden with minimal pesticide use (as a last resort, or not at all depending on your own beliefs.) The "integrated" part of IPM is so-called because it involves using many strategies together: cultural methods, plant selection, and physical and biological controls.
Most gardeners have become more and more aware these days that pesticides can kill beneficial organisms in the garden as well as pests, and thus create an imbalance in an ecosystem. In many cases, an outbreak of pests is a result of an unhealthy landscape. That said, a garden is a manipulated environment and sometimes requires more help than the checks and balances that nature can provide. Here are some quick pointers on things you can do to prevent problems:
- Healthy soil is the most practical way to prevent problems.
- Pair plants with the soil conditions they require to prevent stress and increase disease-resistance. For most plants including vegetables, quality soil rich in organic matter is usually ideal (some mediterranean and desert plants prefer lean soil)
- Rotating food crops will help balance soil nutrient demands and prevent reoccurring crop-specific problems and pests. Alternating heavy feeders (such as brassicas) with light feeders (such as onions and root crops) will also help keep soil nutrients balanced.
- Replenish your soil regularly with nutritious organic material (compost)
- Weeds will compete for sunlight, water and nutrients with desirable plants, and should be hand-pulled as soon as possible. Preventing them from going to seed and applying an organic mulch will minimize future work. Avoid disturbing and exposing the soil as much as possible as this brings new weed seeds to the surface where they will germinate. This means no tilling!
- Preventing over-crowding and nighttime or excessive watering can help discourage fungus and mildew problems (see my previous post notes from Square Foot Gardening for plant spacing for common vegetables.)
Know your friends (Biological Controls)
- Many insects are harmless or beneficial to the garden
- Tolerate a few pests to maintain a healthy ecosystem - otherwise what will their natural predators have to eat?
- Attract birds to the garden with water, fruit and nesting places - flickers, wrens, chickadees and warblers are all desirable birds which nest in cavities or shrubs
- Ladybugs and their larvae, dragonflies, ground beetles and lacewing larvae are all useful predators in the garden
- Parasites, nematodes and micro-organisms can be purchased and unleashed against certain pests; there are specific ones for each pest and their residues break down quickly making them relatively safe. Do your research - yes, you may actually have to learn something to be a gardener!
Know your enemies
- Inspect the garden regularly before pests become an overwhelming problem
- When you discover damage to plants, identify the pest and consider its life cycle before deciding whether it needs to be dealt with. If you catch it early, you can probably just physically remove the pest (wash or pick it off.)
- A strong spray of water repeated several days in a row can knock down aphid populations
- Slugs love damp places so can be trapped under a board laid in the garden and collected in the early mornings
- Soaps and oils such as neem oil and dormant oils are considered safe if used properly; use insecticidal soap not just any household soap against aphids, spider mites, mealy bugs and whiteflies; dormant oil gets sprayed on trees during the winter to kill eggs of pests but can damage trees after they have leafed out
- Diatomaceous earth can be sprinkled on the ground to deter aphids, slugs and spider mites but may also harm worms.
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