Organic Gardening Basics: Organic Pest and Weed Control

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Planting seedlings makes identifying weeds easy—they're whatever you didn't plant.

Anyone can grow plants. There’s lots of information out there, more than you could possibly ever read, more than you would want to, and many of the sources contradict each other. Don’t worry! Start however you can, find mentors, and let your experience with the plants be your guide. If you stick with it, each year will bring you greater abundance.

Pest Patrol

Every vegetable garden hosts a wide range of insects, the majority of which are harmless or beneficial. Plant diversity helps naturally “balance” insect life in a garden, so plant easy-to-grow herbs and summer flowers­–try Greek oregano, catnip, sweet alyssum and calendula–alongside produce. Tall sunflowers serve as perches for bug-eating birds.

Spend the first year in your garden learning about insect life. The more you know about your insect foes, the better you can defend your crops. You’ll know pest species from beneficial bugs because they will gather in scary numbers on specific plants. Check plants twice a week for unusual insect activity. When you notice insects damaging a crop, capture a few in a jar and study them until you can make a positive identification (see “What’s Buggin’ You?” below). Pick troublemakers off by hand and drop them into soapy water (none of the common garden pests bite or sting). Most infestations can be controlled with simple methods such as hand picking and encouraging beneficial insects. And don’t forget our feathered friends–birds and poultry feast on all kinds of garden pests.

Bug Battle

For insect battles you can’t win with hand-to-hand combat, you may need to call in reinforcements. Fortunately, an organic control product exists for nearly every type of pest.

1. Fire ants, leaf-eating caterpillars and beetles: Try biological pesticides based on naturally occurring soil bacteria. The oldest, Bt (Bacillus thuringiensis ssp. kurstaki), works well on caterpillars. Spinosad is useful for fire ants and beetles. If pests require repeated treatment, alternate the two to keep insects from becoming resistant.

2. Aphids, leafhoppers, snails and slugs: Diatomaceous earth is a natural material that kills pests by dehydration. The effects are short-lived because it seeps into soil after rain, but a thorough, well-timed dusting can work wonders. You can also make leaves less tempting by painting them with a paste of kaolin clay and water. Organic produce that has traces of a dusty, off-white residue was probably treated with kaolin clay.

3. Aphids, mites and other small sucking insects: Control these bugs with two applications of insecticidal soap (available at garden stores) five to seven days apart. Blast infested plants with a strong spray of water to dislodge offenders, then apply soap to kill any left. (Once insects are washed to the ground, few make it back up to growing tips.) Use soap sparingly: It can reduce yields of some crops and damage leaves if applied on a hot, sunny day.

4. Whiteflies, squash bugs and Mexican bean beetles: Try horticultural oils made from soybean or neem oil. Neem seldom eliminates pests, but it often reduces them to levels that can be managed by handpicking.
— Barbara Pleasant, garden writer

What’s Buggin’ You?

A variety of resources will help you identify the pests in your garden. Whitney Cranshaw’s indispensable book Garden Insects of North America covers hundreds of bugs. Every gardener should have a copy! You can also rely on online sources: Kansas State University’s Research and Extension office offers an online pest identification resource (search “insect problems”). The Integrated Pest Management guides from Penn State are remarkably easy to use, too.

Weed Warrior

Weeds are part of life in the garden, but with a little care and observation, you can keep them at bay naturally. Most novice gardeners start their gardens with seedlings. This makes it easy to identify weeds–they’re whatever you didn’t plant!

It’s easiest to eradicate weeds when they are seedlings. Pull or hoe them before they go to seed. A good hoe should be item No. 1 on your garden essentials list. A push-pull scuffle hoe slices weed seedlings with little effort and lets you cover large unmulched areas quickly. For hoeing out weeds in tight spaces, a circle hoe or small Winged Weeder are top choices.

Mulch with herbicide-free grass clippings or other organic mulch such as leaves or straw everywhere you can. The clippings prevent weed seeds from sprouting, and conserve moisture and release nutrients as they decompose.

If you don’t have mulch, consider corn gluten (available at garden stores). This nontoxic, plant-based herbicide is a byproduct of corn processing that kills germinating seeds and provides nitrogen. You can’t use corn gluten with direct-seeded crops, because it may kill seeds, but it’s a good option for transplants. Organic growers should be aware that corn gluten may contain genetically modified corn.
— Cheryl Long, editor in chief, Mother Earth News magazine

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