Home Gardens Can Flourish Without Use of Strong Pesticides

Landscape designer Frank Perino used to routinely spray his clients’ gardens with conventional insecticides and fungicides whenever the first aphids or mildew spores appeared. Now he carries a small sprayer filled with nontoxic Basic H soap and sprays only when he sees a potentially damaging population of insects on a particular plant.

Bryce Martin, a garden hobbyist with more than 100 rose bushes in his collection, regularly sprayed his garden with chemicals, as advocated by rose experts.

“That didn’t last long because when I really read the labels on those products, they terrified me and I decided I didn’t want anything to do with them,” he said. “I don’t see the necessity for wearing a Darth Vader-like outfit of mask, protective clothing and the like just to combat some insects.”

Perino and Martin are among the growing number of professional and amateur gardeners who prefer to avoid toxic pesticides and have adopted other methods to combat insect pests in their gardens and homes.

Integrated pest management (IPM) is one such approach. Developed 30 years ago in California and Texas for the agriculture industry, it was initially regarded as controversial. In the last few years, IPM has grown in popularity and is now being adapted to home use.

The objective of IPM is not to eradicate pests but to control their populations. IPM is not a quick-fix solution to hordes of invading insects. Instead of using chemicals as the first line of defense, IPM consists of monitoring the site to identify the insect population, determining tolerable levels of damage to garden or house, applying least toxic strategies and tactics, and keeping records of what’s happening in the garden.

“IMP is an ecologically balanced philosophy of pest management,” said Sheila Daar, one of the authors of the authoritative book “Common Sense Pest Control” and a co-founder and executive director of the Bio-Integral Resource Center (BIRC) in Berkeley, regarded by experts as the foremost IPM group in the United States.

BIRC is a nonprofit organization founded in 1978 to research and provide practical information on least-toxic methods of pest management. It has a worldwide membership, provides consultation on pest management and publishes a technical bulletin for professionals and a quarterly newsletter for homeowners.

“In the last three years, there’s been an exponential increase in the number of consumers and professionals who are using IPM methods in their homes or farms,” Daar said.

“People are more aware of the negative effects of pesticides, especially relating to ground water contamination,” she said. “When farmers can’t drink their own well water, the pesticide issue really hits home.”

Recent studies by the Environmental Protection Agency revealed residue from 74 different pesticides in wells in 34 states, including California.

Insect resistance to pesticides is also increasing. Currently, 600 of the most significant pests, including insects, weeds and plant diseases, are resistant to one or more classes of chemicals that had been developed to control them.

In the 1940s, the U.S. Department of Agriculture estimated that 7% of the crops grown domestically were lost to insect damage. In 1974, that grew to a 13.5% crop loss despite a tenfold increase in the use of pesticides.

Many Los Angeles residents were alarmed by the 1989 aerial spraying of malathion to combat fruit flies. They were concerned at the side-effects of the pesticide, many without realizing that the average home gardener uses high concentrations and more toxic chemicals in their own back yards.

“It is not uncommon for a homeowner to apply more toxic amounts of pesticides to his or her own property than the aerial spraying,” said Bill Edwards, chief deputy with the Los Angeles County Agricultural Commission.

The malathion solution dropped from helicopters consisted of 2.8 ounces of 95% malathion mixed with 9.6 ounces of dry protein bait applied per acre. The recommended solution for homeowners to use is .5 ounce of 50% malathion per gallon of water. This solution covers plants within about 1,000 square feet.

Excessive use of toxic chemicals has also produced the unwanted result of creating pests out of species that had not previously caused any noticeable harm.

“Spider mites are now a problem worldwide as a direct result of the use of DDT, which killed their natural enemy,” Daar added.

Daar and others believe there’s a more effective solution for minimizing insect damage to human gardens and habitations.

She and co-authors William and Helga Olkowski have written a 715-page book explaining IPM. It details how to determine if an organism is really a pest, and if so, how to control it. Chapters include pests of the garden, pests of indoor plants, pests of the house structure and pests inside the house.

“IPM is a numbers game,” Olkowski said. “If you can keep the number of pest organisms below the level that causes intolerable economic, aesthetic or medical damage then there’s no problem.”

Daar practices what she preaches, and in her own garden she grows roses and other ornamentals the IPM way.

“Unfortunately, people growing roses are told that they’re so disease-prone that they must be sprayed every two weeks or so to protect them. But that’s not true,” she said.

“I combat powdery mildew on my roses by spraying them with water to drown the mildew spores or by pruning off the leaves that are diseased. Occasionally, I use an anti-transpirant, which acts as a barrier to the disease. Good cultural practices and elimination of any plants that are real problems will effectively solve most situations.”

The first two steps in implementing IPM are to be aware of what’s happening in the garden and then deciding how much plant damage you can tolerate.

A person growing roses for exhibition doesn’t want a single insect on the flower, whereas someone growing flowers for garden display or bouquets may not mind knocking a few clinging aphids off the blooms. A plant with a few holes chewed from the foliage may appear unattractive, but the plant’s health isn’t affected.

“Some people have insect-phobia and won’t tolerate any insects in their gardens,” said Tim Payne, assistant professor of entomology at UC Riverside. “A few aphids on a rose don’t cause any damage, but I can’t convince my family to tolerate a worm in the broccoli.”

But in reality, insects are as much a part of a garden as the plants in it.

“There are no pests in nature. There is no waste in nature,” said Mike Atkins, Ph.D., professor of entomology at San Diego State University, author of three textbooks and a longtime proponent of IPM.

Atkins was also a founder of Safer Inc., the maker of nontoxic products to combat garden insect and disease problems.

“ ‘Pest’ is only a human concept when they get in our way, and nature provides regulatory forces in an ecosystem. The problem with using a nuclear-bomb approach to insect control is that the beneficial insects like ladybugs, spiders, lacewings and parasitic wasps are also destroyed, leaving the problem insects like aphids, scale, thrips and mites to resume their attack,” Atkins added. “The idea of eliminating all insects from a garden is absolutely ridiculous.”

A certain number of the so-called pests must remain in a garden as a food source for the beneficial insects. If a garden has been subjected to regular spraying of chemicals, it can take up to one year to attain a garden with a balance of harmful and beneficial insects.

According to Daar, the first step is to watch what’s actually happening in your garden.

“When you spot insects moving, don’t just freak out and run for the nearest spray can. Identify the insects, learn if they are attacking the plants or if they are being eaten themselves,” she cautioned.

For example, while many people can spot ladybugs and welcome them in their yards, they fail to recognize their larval stage, when they look like tiny dragons. The black-bodied, red-spotted creature has a voracious appetite and is more effective at consuming aphids than its mature form.

Atkins suggests placing sticky yellow traps at the garden perimeter to act as warning signals.

“They’ll attract winged aphids, winged psyllids, whitefly and scale and can alert the gardener to potential problems,” Atkins said.

The third step in an IPM program is spot treatment. It may not be necessary to spray the entire garden if an insect outbreak is limited to a specific plant. Try the least toxic method, such as a blast of water from the hose, effective in combatting aphids and spider mites. Only resort to the chemical means of attack if all else has failed.

Finally, the fourth step, keeping accurate records, helps pinpoint what works and under what circumstances, such as weather conditions or types of fertilizer used.

Some garden professionals, however, don’t agree that IPM is the definitive answer to pest control.

Andy Lopez, a landscape design and maintenance professional for 20 years, believes IPM doesn’t go far enough.

“I practice AIPM, what I term ‘advanced integrated pest management,’ because I believe in completely nontoxic methods of pest control,” Lopez said.

The author of “How to Heal the Earth in Your Spare Time,” Lopez advocates relying on nontoxic soaps (he favors a concoction including Tabasco sauce), liberal use of compost and strong reliance on beneficial insects.

“Healthy plants can withstand insects and disease, and one of the best ways to accomplish that is to provide them with fertile soil complete with microorganisms,” he said.

He also discourages the use of fertilizers with high amounts of nitrogen.

“The high nitrogen fertilizers act on plants like steroids do on humans. It pumps them up to produce lots of lush green growth, and makes them an insect target.”

Lopez said that ant control is a key to reducing harmful insect and disease attacks. Ants herd aphids like cows and cultivate them for their sweet, sticky secretions. But in the process, they spread fungal diseases from plant to plant.

Lopez believes ants are an important part of the ecosystem. “It’s easy to kill them, and a lot harder to figure out what’s going on and cooperate with them.”

Since ants invade human space as they seek food and water, Lopez sets up “ant cafes” around his garden. By feeding the ants as well as setting barriers like sticky tape around his plants, he keeps most of them out of his own territory.

“If you control the ants, you control 90% of the problems in a garden,” he said.

With patience, and practice of these and other IPM techniques, the garden hobbyist can expect to see significant changes in their gardens.

“In the first season, you can see a tremendous change,” Daar said, “and by the second growing season there can be dramatic results.”

Resources

“Common-Sense Pest Control: Least Toxic Solutions for Your Home, Garden, Pets and Community” by William Olkowski, Ph.D., Sheila Daar and Helga Olkowski, published in 1991 by the Taunton Press, $39.95, hardback.

“How to Heal the Earth in Your Spare Time” by Andy Lopez, published by the Invisible Gardener of Malibu, paperback, $10.

Bio-Integral Resource

Center

P.O. Box 7414

Berkeley, Calif. 94707

(510) 524-2567

The Invisible Gardener

29169 Heathercliff Road

Suite 216-408

Malibu, Calif. 90265

(302) 457-6658