Steve Kawaratani used to apply restricted synthetic pesticides to plants in his nursery. Then scientists discovered how damaging and far-reaching those chemicals could be, and like many in the horticultural field, Kawaratani took a closer look at the pesticides being sprayed so freely.
Kawaratani, who owns Laguna Nursery in Laguna Beach, began searching for organic, less toxic controls for pests and, in many cases, has found alternatives that promote a cleaner environment.
“I used to apply a strong synthetic fungicide on the roses,” he said. “But it bothered me to use a product that says on the label that it ‘causes permanent eye damage.’ That fungicide is toxic to customers and many species of birds, butterflies and ladybugs.”
Then he discovered a powerful yet virtually benign mixture that prevents and eliminates fungal diseases known to attack roses, such as rust, powdery mildew and black spot.
“It turns out that baking soda is a powerful fungicide,” said Kawaratani. “When this is combined with horticultural oil as a carrier, it inhibits and destroys fungus diseases.”
Over the past several years, many synthetic pesticides have been taken out of production and replaced by more natural means of eradicating pests from agriculture and the home garden.
“After years of using synthetic pesticides that are still causing problems long after they were applied, we’ve finally decided that nature knows best and have returned to concepts like mulching and biological means of destroying pests,” said Lili Singer, a Van Nuys horticultural consultant and editor of the Southern California Gardener, a Santa Monica-based publication.
Pest control measures that mimic nature are key, said John Kabashima, environmental horticulture advisor with the University of California Cooperative extension, who is based at the South Coast Research and Extension Center in Irvine.
“Nature produces a wide array of chemicals used, in many cases, to protect an animal or plant,” he said. “There are many new materials coming out that are naturally occurring and selective, rather than broad spectrum.”
Most insects in the garden are harmless, said Nick Nisson, entomologist with the agricultural commissioner’s office in Anaheim. “When you use general insecticides, you kill off all insects, including the beneficial ones that prey on harmful insects,” he said.
Organic pesticides are made up of carbon molecules, degrade quickly and disappear when exposed to sunlight and air, while synthetic chemical pesticides last much longer.
Organic methods include insect growth regulators, which inhibit development. Pheromones--compounds that female insects release to attract males for mating--are used to lure male insects into traps. A fungi spray controls whiteflies and other greenhouse pests, and studies are being done on antagonistic organisms that irritate certain plant pests.
Kabashima advocates integrated pest management, a program created 30 years ago for the agricultural community that doesn’t forbid the use of synthetic pesticides but employs them in controlled and limited amounts.
“One of our main problems in controlling pest damage is that every year several exotic species of pests are introduced into California from other areas of the United States and world,” he said. Pests originally from other areas often don’t have any natural predators, which enables them to multiply rapidly and do great damage.
Introducing a natural predator brings everything into balance. The ash whitefly that was devastating fruit trees a few years ago was eventually killed off by a stingless wasp brought in from northern Europe, the whitefly’s original home.
“Biological controls such as beneficial insects are self-perpetuating and will work year after year,” said Singer.
Home gardeners often misuse pesticides, said Kabashima. “There is no regulation in the home garden, and many people don’t even bother to measure out the product or thoroughly read the directions,” he said.
Singer agrees: “People are very cavalier about following directions on labels. If a product says to wear protective clothing and a mask, then that’s what you should do.”
Gardening organically is not an exact science, but it isn’t hard to do. To avoid using pesticides, especially the synthetic ones, keep the following tips in mind:
* Some bugs are OK. “People who have zero insect activity in their yards have a dead garden and are living in a toxic waste dump,” said Kawaratani. “Your yard is a small ecosystem, and insects fill every niche imaginable. Some feed on fungus, yeast and mold, others on decaying organic material, and some pollinate plants.” Killing off insects indiscriminately upsets this delicate balance.
Very often, pest problems will work themselves out in a couple of days, especially if your beneficial population is strong.
* Know when to take action. A little insect damage isn’t anything to worry about, but at times some kinds of pests, including aphids, whiteflies, scale insects and caterpillars, reach high population levels in the garden and must be dealt with before they destroy plants.
* Figure out the problem. “Before you start killing things, identify what it is you want to kill, because they could be beneficial insects,” said Nisson. “Many predators mimic their prey, which is true of the ladybird larvae, which looks like a mealybug.” A single ladybug larvae is a voracious aphid eater.
Singer suggests getting a 10-power magnifying glass to look closely at the damage and the suspected pest. If you can’t figure out the problem, talk to a nurseryman or horticultural consultant.
* Try mechanical controls. Large insects such as caterpillars can be easily picked off and destroyed, and small insects such as aphids can be smashed with your fingers, said Nisson.
Water is the universal solvent, said Kawaratani. “Once you’ve identified the problem, use a stream of water to get rid of many pests such as aphids, thrips and spider mites,” he said.
* Consider biological controls. There are a variety of beneficial insects and other organisms that will feed on pests. Ladybugs, praying mantises and lacewings are just a few. Beneficials can be found at nurseries and through mail-order companies. Make sure you buy and release them at the correct time of year.
Bacillus thuringiensis is the most widely used biological control in the world. It creates spores that paralyze caterpillars’ guts and cause them to stop eating and die.
* Use mulch. Recent studies show that using mulch prevents root rot in plants, said Singer. “The mulch keeps the plant roots at an even temperature, protected from extremes in weather, which prevents plant stress and susceptibility to illness,” she said.
* Spray insecticidal soap and horticultural oils. Both soap and oil clog the breathing apparatus of pests, interrupt other bodily functions and gum up their legs, said Kawaratani. “And pests don’t develop a resistance to these products,” he added.
Although horticultural oils aren’t organic, they are very fine and become inert almost instantly, he said.
* Use organic pest control solutions with caution. Organic solutions such as rotenone and pyrethrins may be derived from plant sources and don’t linger in the environment, but they are extremely toxic upon application. Follow package directions exactly.
* Let nature do the dirty work. “Nature’s plan is to keep things in balance,” said Kawaratani. “One of the most important counterbalances in nature is cold and rain. Pests will die during the winter’s cold, and rain often washes away fungal problems before they have a chance to spread.”