Emulating Nature to Control Plant Pests

Growing things without using synthetic fertilizers or insecticides is gaining new attention, but it is a very old concept.

In the years before chemicals were introduced, there was no way to garden but organically.

“It’s ridiculous to say that crops won’t thrive without chemicals,” said Mike McGrath, editor in chief of Organic Gardening magazine.

“True gardening is growing without the use of chemicals. People who go out and soak the garden with chemicals aren’t gardeners, they’re mad scientists.”

Organic gardening lost popularity in the late 1940s when using petroleum-based chemical fertilizers and pesticides became the “new and better way” to farm and garden.

Farmers and home gardeners began using tons of chemical fertilizers and pesticides without much thought until the 1960s and early 1970s, when scientists began discovering how these chemicals harm the Earth.

Since then, scientists have found that much of the ground water in the United States is contaminated with pesticides and chemical fertilizers, including California’s, which is in “pretty bad shape,” said entomologist Michael Atkins, one of the founders of Safer Inc., a company that produces organic pesticides.

Research has shown for years that chemical pesticide use has led to a decline in the numbers and health of many animals. And now there is alarming evidence that artificial pesticides and industrial chemicals are causing sexual confusion and an inability to reproduce in some animals.

Unlike organic fertilizers and pesticides, which quickly degrade to harmless compounds when exposed to sunlight and air, synthetic chemical fertilizers and insecticides last much longer. A case in point is DDT. The pesticide was used throughout the United States until it was banned in 1970. Now, nearly 25 years later, it continues to be a problem.

“DDT is still showing up in ground water and soil samples in many agricultural regions,” Atkins said.

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“We’re finally beginning to understand the total costs of our habits when it comes to chemicals,” said Bill Roley, who is director of the Laguna Beach-based Permaculture Institute of Southern California, which is an educational nonprofit organization that deals with the relationship between water, waste and soil.

“Using chemical fertilizers does produce a lot quickly, but you don’t feed the soil,” Roley said. “If you add up the costs in terms of health and depletion of natural resources, chemical fertilizers aren’t such a bargain.”

In recent years, many home gardeners have given up chemicals.

“In the second half of the 1980s we saw an organic gardening boom,” Atkins said. He noted that Safer, which was started in 1981, was doing $10 million a year in business by 1991.

Big business has even started to grow produce organically in response to customer demands and because many chemicals are being restricted.

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Southern California is a leader in the production of organic produce.

In north San Diego County, there are about 400 organic farms, the highest concentration in the state and probably the country, said Faustino Munoz, farm adviser for UC Cooperative Extension in the county. He regularly advises small farmers, many of whom choose the organic route for health reasons and because they are interested in long-term viability of their farms.

“I farm organically because I can’t in good conscience cheat the Earth,” said Jerry Weiss, owner of Rocky Peak Farms in Fallbrook, a farm and a retail store. “Studies show organic foods are three to four times higher in minerals than non-organically grown foods.”

Prolonged use of chemical fertilizers and pesticides can eventually sterilize soil. There is also the danger of overfertilizing with chemicals, which quickly enter the plant’s system and can burn roots.

Organic fertilizers work differently than chemical fertilizers. Organic ones usually require soil bacteria to break them down before they are taken up by plant roots, so plants are fed slowly over a long period of time, said Roger Aguinaga, owner of Aguinaga Fertilizer Inc. in Irvine, which provides organic fertilizers and soil amendments to homeowners and farmers.

“Organic fertilizers also don’t become soluble and leach into ground water like their synthetic counterparts,” he said.

Margret Wagner of Orange is among gardeners who have embraced the organic concept. She has been gardening organically for five years at the Fullerton Arboretum, where she is chairwoman of the demonstration garden for the California Organic Gardening Club. She also has a private garden on the arboretum grounds.

“I garden organically because I feel it’s important not to poison the soil with chemicals that have a long life,” she said. “I also don’t want to kill beneficial insects. And organic gardening is cheaper; I fertilize with compost, and mulching keeps watering down.”

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To successfully garden organically, you must emulate nature, rather than fight it. If you’ve been using chemical methods, take heart. It’s never too late to rebuild your soil.

Organic gardening is best understood through the principles of “integrated pest management,” or IPM, which include selecting appropriate plants, using compost and not worrying about bugs.

This method was developed 30 years ago in California and Texas for the agricultural community, and although IPM doesn’t forbid the use of chemical fertilizers and pesticides, most of its methods are organic. With IPM, only as a last resort are chemicals to be used, and then in controlled and limited amounts.

IPM involves a combination of strategies to keep pest populations at a tolerable level and plants healthy, said Lili Singer, a Los Angeles horticultural consultant, publisher of the Southern California Gardener and host of a weekly radio gardening program.

The first rule of IPM is proper plant selection, Singer said. “Get a plant that will be happy in our Mediterranean climate. Then take proper care of the plant so it remains strong against pests and disease.”

One vital aspect of plant health is the soil condition. “Plants grown in rich, organic soil are easy to spot,” said Erik Katzmaier, a landscape architect with Katzmaier Newell Kehr in Corona del Mar. “Organically grown plants are deep green, lush and thick and have few pest problems.”

A good organic soil is built with compost, said Katzmaier, who regularly uses homemade compost in his own garden. “An organic garden sustains itself just like nature. You compost all of your kitchen scraps (except meat products), grass clippings, leaves and branches and return them to your soil.”

When you feed the soil with compost, you build the humisphere, said Roley of the Permaculture Institute.

“The humisphere is that crucial 12-inch layer of earth below your feet where 90% of biological life is found,” he said. “If you feed that layer with compost, you greatly reduce plant needs for fertilizer and pesticides.”

Feeding the soil with compost also does the important job of releasing helpful bacteria, which will keep in check harmful bacteria and soil-borne disease such as that caused by nematodes, said Aguinaga, whose company has a green waste recycling program. Every day it receives an average of 125 tons of plant materials from individuals and companies, which it uses to make compost.

“Compost also helps encourage drainage in clay soils, where plants suffer root disease because of excessive moisture, and compost bulks up fast-draining, sandy soil,” he said.

Another must of organic gardening is learning to live with a few bugs.

“The idea of eliminating all insects from the garden is ridiculous,” said entomologist Atkins. “The truth is, people who use insecticides on a routine basis are destroying beneficial insects, of which there are many. There are no pests in nature. Everything has a purpose. Only about 10% of insects are true pests. The other 90% are beneficial insects that actually prey on pests and survive because of them.”

Beneficial insects such as ladybug larvae may look frightening, but they are actually voracious eaters of harmful pests such as aphids.

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Ironically, it is true pests such as aphids and whiteflies that are resistant to pesticides. When you use chemicals, you knock out beneficial populations and can make a problem worse, Atkins said.

“I know people get frustrated with pests, but they must discipline themselves not to run to the garden center for the strongest chemical and nuke everything.”

“The key is tolerance,” Singer said. “Who cares if a tomato hornworm eats a couple of tomatoes? There’s usually enough left for you and your neighbors.”

If you do have an infestation of a certain pest, there are nontoxic ways to control them that won’t annihilate beneficial populations.

Two completely benign yet deadly weapons everyone has at their disposal are fingers and water. Organic gardener Wagner thinks nothing of handpicking worms or large bugs from her plants. Soft-bodied aphids can also be easily squished between the fingers. A strong spray of water will dislodge many pests and may even kill aphids without harming larger beneficial insects.

In recent years, many biological controls have also been introduced, such as insects, bacteria, fungi, viruses and nematodes that are predators or parasites of plant pests. The most widely used of these, Bacillus thuringiensis (BT) is widely available. This causes caterpillars to stop eating and poisons their blood. It is not harmful to humans or most other insects.

Other biological controls include ladybugs and lacewings, which feast on aphids. Beneficial nematodes clean up harmful nematodes in the ground. There are also parasitic wasps, which burrow into the bodies of various pesky insects and lay eggs.

The ash whitefly that was devastating fruit trees a few years ago was killed off by a stingless wasp brought in from northern Europe, the whitefly’s original home, Singer said.

When all else fails, some organic gardeners believe that the use of organic pesticides in limited amounts is warranted, as long as they are used with care. Organic pesticides are preferable to chemicals because they quickly break down when exposed to sun and air and leave no harmful residuals. They are, however, toxic during application, and some can be lethal to humans and wildlife.

Perhaps the most important rule of organic gardening is patience. It takes time to build up soil and lure beneficial insects into your garden.

Those who have made the commitment to garden without chemicals say that each season the garden gets better and better.

“Organic growing builds the soil,” Weiss said. “When the soil is healthy, so is the food you produce.”