Floating Row Cover
In our trial garden, our premier method of pest protection is to simply exclude them with a soft but effective barrier. We use sheets of white "floating row cover," a multi-purpose, ultra-lightweight spun fabric that can be readily purchased at most good independent garden centers and is readily available online. (Online sources include: Peaceful Valley Farm Supply, Harmony Farm Supply, Gardener's Supply Co.)
These thin row covers are simply laid loosely over the top of the plants in the beds, then fastened down at the sides of the beds so nothing can crawl under. Row covers work by effectively blocking pests out as the plants grow, while still letting ample sunlight and water in through the porous fabric. When the plants are near maturity or begin to flower and need pollination, the row cover is removed. Row cover works wonderfully well to protect against otherwise hard to treat pests such as leaf miners and cabbage moths.
Newer Organic Controls
Actinovate is a relatively new organic product containing beneficial bacteria in a soluble powder that will control a wide range of diseases including powdery and downey mildew, botrytis, alternaria and other air borne pathogens on plant surfaces. It also works as a soil drench to control root decay diseases such as pythium, phytophthora, fusarium, rhizoctonia, verticillium, and other root decay fungi.
Serenade is an organic product the controls bacterial diseases like powdery mildew, rust, and black spot that affect many plants including squash, cucumber, roses, hollyhocks, and zinnias, just to name a few.
Wherever slugs and snails are abundant, bi-weekly applications of organic Sluggo Plus around garden beds and surrounding garden spaces will definitely control them. Sluggo Plus is also effective against earwigs and sow bugs, which are notorious eaters of seedlings.
Safers Soap is a great product made from naturally occurring fatty acids. At the first sign of damage, a weekly spray with Safers Soap is very effective in controlling common aphids, mealy bugs and white flies and other damaging pests like mites and thrips on vegetables herbs and flowers and fruit trees of all kinds.
Bacillus thuringensis (a.k.a. BT) is an effective organic treatment for all caterpillars pests that particularly enjoy eating leafy vegetables and Brassica family members like broccoli, cauliflower, napa cabbage and kohlrabi. As with most of the organic pest products, an application at regular intervals for about 2 to 3 weeks usually provides adequate control.
Not all insects that you see in the garden are harmful for plants and many are actually quite helpful, distributing pollen between flowers or providing food for beneficial insects. A garden of diverse plant varieties also creates an ecosystem that attracts lots of beneficials. Even if you are strictly a vegetable gardener, it's important to plant some flowers and/or flowering herbs to attract pollinating bees of all kinds. Sunflowers, poppies, cosmos, tithonia, monarda, zinnias, marigolds and herbs like lavender, catmint, dill, borage and basil are favorite bee destinations.
Yarrow and alyssum are good too, and their flowers will attract lacewings and ladybugs. The larvae of these insects dine on aphids, mites and other small insects and their eggs. Alyssum, bishops lace, chamomile, cosmos, fennel, and monarda are just a few plants that will attract hover flies (aka syrphid fly). The adults look like little bees that hover over and dart quickly away, but they don't sting. They lay white, oval eggs singly or in groups on leaves, which hatch into green, yellow, brown, orange, or white half-inch maggots that look like caterpillars. They raise up on their hind legs to catch and feed on aphids, mealy bugs and other pests.
When we grow parsley, cutting celery, dill or cilantro we let some of the plants mature and blossom. Their flowers, along with those of marigolds and zinnias are wonderful for attracting parasitic mini wasps, which are parasites of a variety of insects. They have stingers that have been adapted to allow the females to lay their eggs in the bodies of insect pests. The eggs then hatch, and the young feed on the pests from the inside, killing them. After they have killed the pests, they leave hollow "mummies" which we see regularly here in the garden, especially on aphids. It’s wild!
Having an organic garden doesn’t have to be tricky; what you put into it, you will get right back out of it. Building healthy soil will give you healthy plants. Creating biodiversity in the garden will help to have an ecosystem that can sustain itself. And for those times when you do need a little extra help with those pesky critters, there are safe products on the market that will do the trick. With some simple garden planning, you can avoid inviting situations that encourage pests and diseases.