Committing to growing a vegetable garden organically is not difficult when you begin with good quality organic soil, seeds and seedlings. Just add water, sunshine and organic fertilizer, and in time, you will enjoy the harvest.
But what happens when you have problems like insect infestations and plant diseases? Growing an organic garden means treating pests and diseases differently than in a conventional garden. Instead of reaching for a chemical spray at the first sighting of an unwanted bug or a wilted leaf, take a deep breath, and follow simple, intuitive organic gardening principles to manage problems.
First, you need to think like nature, says Mark Highland, horticulturist and author of Practical Organic Gardening (Cool Springs Press). For example, aphids may attack your tomatoes. The solution can be as simple on waiting for nature to bring you ladybug larva to feed on the aphids. After all, for every bad bug, there is a good bug that will come along to eat it.
The next step is to consider your threshold for insect damage. Many insect populations, Japanese beetles, for instance, will visit your garden for a few weeks and then move on. You can easily pluck off offending beetles (or caterpillars) and drop them in a bucket of soapy water. Be sure to wear gardening gloves when handling insects, especially prickly caterpillars.
Aphids can be knocked off plants with a spray of water from a powerful watering wand, just set the nozzle to blast and watch the action.
If your pest problem is persistent, then proceed to consider the seriousness of the infestation.
“When you think about a pest or disease, you need a host, a pathogen and an environment that’s conducive to the disease or pest,” Highland says. To eliminate the pest, you just need to knock out one corner of this “disease triangle.”
Keys to Organic Gardening
You can deter insect damage by growing a diverse array of plants, managing the garden organically and monitoring for unwanted insects.
When you grow a limited variety of plants, you risk a monoculture that tips the ecological balance, making it vulnerable to pests and diseases. Think about commercial farming where pests sweep through groves and orchards.
Right plant, right place. Know your site: is it sunny or shady? Dry or wet? Know your hardiness zone and read plant tags. A shade-loving plant like hosta will not thrive in full sun, and unhealthy plants are more susceptible to insect and disease damage.
Attract beneficial insects. Make a home for good bugs by planting native plants and host plants. Learn the names of bugs in your garden, Highland advises. It could be that you have a beneficial insect, not a pest. Good bugs to attract to your garden include spiders, dragonflies, assassin bugs, praying mantises, wasps, lacewings, minute pirate bugs and aphid midges.
Build a healthy ecology. Nourish your plants with good quality organic soil and amendments. Start a compost pile for free “black gold” to build up the soil and provide nutrients during the growing season.
Organic Pest Management in the Home Garden
To fight pests naturally in the home garden, use the principles of Integrated Pest Management (IPM). “You need to get out there and look at your plants. See what’s chewing on the leaves,” Highland says. “Then you can see what pests might be out there and you can address it.”
Tip: When you inspect your plants, look for insect debris, rolled leaves or holes in foliage.
Sometimes, you can exclude pests from plants with barriers like a row cover. Netting protects berries from birds and chipmunks. You could build a cold frame that allows you to get a jump on the season and protects plants from predators and diseases.
Keep in mind that a good offense is often the best defense: Plant a lot of pollen-rich flowers in your garden to protect your plants from pests and diseases. Insects are brought in by pollen. When you plant flowers like asters, daisies and sunflowers, they will generate more pollen and attract more beneficial insects. And remember that native plants feed native pollinators.
Even in an organic garden, sometimes, the answer is a pesticide, and you always start with the least toxic option. When using any garden chemicals, carefully read and follow label directions and remember that twice as much does not mean twice as effective or results twice as fast. Highland recommends following a pesticide treatment with a probiotic, like a shot of organic fertilizer to the affected plant.
Two effective treatments in the organic gardener’s arsenal are Bt, Bacillus thuringiensis, and Neem oil. Neither will harm your edibles and are safe around humans and pets. Apply Bt before you have problems in the garden. It’s a bacteria that kills caterpillars from the inside out. For early spring corn, spray when it’s knee high to prevent corn borers. Reapply throughout the growing season for best results.
Neem oil is a strong and effective organic treatment that is a natural byproduct of the Neem tree. It’s available in different strengths, so make sure it’s rated for the problem in your garden. Neem oil is effective against aphids, mites, scale, leaf hoppers, white flies, caterpillars, mites, mealybugs and thrips. It’s excellent to use to control insects on indoor plants. As a fungicide, it can treat black spot, scab, rust, leaf spot, anthracnose and tip blight. It can also kill the bacterial disease fire blight that causes plant leaves to wilt and look like they have been burned.