Going Green in the Garden

Organic Treatments for Pests And Diseases Gain Ground In the Marketplace
A Guide to What Works

Adrian Higgins
Washington Post Staff Writer
Thursday, May 10, 2001
Page H01

Concerned about the health of his staff, Mitch Baker pulled virtually all the chemical pesticides from the shelves of his two Bethesda nurseries last spring.

Baker, vice president of American Plant Food, said he was bracing for the economic loss that would come from denying longtime customers the insecticides, fungicides and weedkillers that had become part and parcel of the bittersweet gardening experience.

The shelves at the two stores -- at 5258 and 7405 River Rd. -- were restocked with an array of organic treatments for pests and diseases. The result: Most customers were more than glad to replace their arsenals of Acephate, Malathion and Sevin with insecticidal soaps and oils. "It has not been a money-losing situation at all," said Baker.

Enthused by the experience, Baker now loads up plastic tubs with such products as neem oil, lime-sulfur spray and hot pepper wax for show-and-tell forays to local garden clubs, where he extols the virtues of a greener way to garden.

Baker's mission has been made much easier because of the development in the past five years of new products and significant advances in old ones. More gardeners, for example, are asking for a pesticide called neem oil, made from the seed of a tropical tree, and another made from refined canola oil. Improved products include paraffin oil, which once could be used only in winter when plants were dormant but now can be used safely year-round.

The growth of a more organic approach to gardening comes at a time when chemical options are diminishing. The federal Environmental Protection Agency last year reached agreement with the makers of two widely used pesticides -- diazinon and chlorpyrifos -- to phase them out because of health problems associated with overexposure. Popular brands of diazinon include Ortho and Spectracide; chlorpyrifos is marketed under the trade name Dursban and is included in numerous familiar products, including Ortho Lawn Insect Spray.

Organics are still just a fraction of the market -- $10 million to $15 million in annual sales in a $1 billion industry, according to an executive with the Scotts Co. in Marysville, Ohio. But the pace of research into organic and biological controls continues feverishly, and their use is bound to increase.

Scotts, a major producer of chemical fertilizers and pesticides, is considering its own launch of natural pesticides.

A major reason their appeal has remained limited, Baker says, is that they are made and sold by a plethora of small companies that don't have the large marketing and advertising budgets of the major chemical companies. They are also not as instantly effective and require a greater knowledge of which pests and diseases are being targeted.

The organics, said Baker, "take longer and may have to be applied more often," he said. "People don't understand that."

For example, spray the aphids on your roses with diazinon, and watch the bugs keel over. Spray them with neem oil, and you are likely to see the aphids still active the next day, said Baker.

In reality, the oil is slowly killing the insects, which have stopped feeding and harming the plant.

"Gardening organically makes you a more aware gardener," said Baker. "It requires closer monitoring and inspection, and therefore you get much more out of it."

In addition, fully one-half of all plant failures have nothing to do with pests and diseases, said Jon Traunfeld, of the Maryland Home & Garden Information Center. They are the victims of poor gardening practices, including improper plant selection and location, incorrect soil preparation and physical damage to tree trunks, he says. Fix those, and the reliance on chemical props diminishes.

Baker acknowledges that not everyone is interested in switching from synthetic pesticides. "For the guy who's got half an hour to take care of the problem before he goes to the golf course or tennis court, this may not be for him," said Baker. "That's a choice."

Some of the organic controls predate the chemical revolution of the 20th century, including Bordeaux mixture, used in French vineyards to combat fungal diseases; and pyrethrin, an insecticide derived from a species of chrysanthemum. But many are newly available, including neem oil, developed by James Locke, a scientist at the U.S. National Arboretum.

A separate market has developed for biological controls, including predatory insects, mites and nematodes as well as different strains of a naturally occurring bacterium, Bt, for infecting and killing young caterpillars of the gypsy moth, various leaf-eating worms and borers in the vegetable garden and the nymphs of mosquitoes.

Most people are aware today of the salutary effect of ladybugs and praying mantises in eating aphids and other bugs. In reality, scientists say, the two are among the least effective of the beneficial bugs available. A whole mail-order industry has emerged to supply professional horticulturists.

A Web site by the California Environmental Protection Agency lists 132 retail and wholesale suppliers selling 120 different organisms www.cdpr.ca.gov/docs/dprdocs/goodbug/benefic.htm

Among the most useful are various species of tiny, non-stinging wasps, each programmed to go after a specific pest. They must be purchased and released at the right time, often two releases within a few days of each other. Another recommended insect is a soft-bodied, lime-green flying creature with glasslike wings. About an inch or less in length, it is known as a lacewing and is found commonly in local gardens.

Another on the California list seeks out and destroys scale and mealybugs. It goes by the redoubtable name of mealy bug destroyer.

This may sound like a horror flick from the 1950s, but the use of these hired assassins is now mainstream in horticultural institutions around the country. Some advocates say buying these beneficial bugs is not necessary in the home garden: By not using pesticides indiscriminately, you will attract beneficials naturally.

Charles Reed took a more proactive approach. He lives at Redsdale, a 50-acre estate on the James River in Henrico County, Va., with extensive boxwood plantings, vegetable gardens, a formal garden designed by noted Richmond landscape architect Charles Gillette, and greenhouses where annuals and tender trees are raised for use around the estate and a restaurant owned by Reed.

Reed and his gardener, Norman Harvey, found themselves faced with a plague of whiteflies, a tenacious parasite of greenhouse plants, vegetables and certain ornamentals. Everything was covered in a sooty mold, one of the side effects of the pest. They gave up growing tomatoes. Harvey tried fumigants against the invaders. "They always seem to come back." He then sent off for a wasp named Encarsia formosa. "I started off in the greenhouse, and, to my surprise, it cleaned the whole place up," he said. The wasp then moved outside and annihilated the outdoor whitefly. Since then, the estate has been run organically with heavy emphasis on biological control. To get the leaf minor in the boxwood, Harvey buys a wasp named Diglyphys isaea, and makes three releases after spring temperatures reach 60 degrees. It is then the miner emerges from the leaf to pupate. The wasps are expensive -- $85 for 250 -- but the property has many boxwoods, and the cost is the same as having a professional in to spray, said Reed. But with one difference: Now the eggs laid by the songbirds and waterfowl will hatch.

Harvey also uses beneficial mites to hunt red spider mites on broadleaf evergreens.

One of the most creepy biologicals is a microscopic wormlike creature called a nematode. As with other organisms in this weird world, there are good nematodes and bad nematodes.

One species is effective against white grubs in lawns. Another can be used to go after borers, one of the most destructive pests of dogwoods, cherry trees and peach trees.

But applying them takes knowledge: The nematodes must be alive -- you have to check using a strong magnifying glass -- and then applied when humidity is high, the sun is low and, in the case of the borers, when the tree bark is moistened enough to prevent the nematodes from drying out.

Meet those conditions, and the critters will seek out and destroy borers, said Ed Lewis, assistant professor of entomology at Virginia Tech. Gordon Hecker, vice president of North America marketing for the Scotts Co., which owns Ortho and Miracle-Gro, says that organic products in the past "just haven't tended to move off the shelf very quickly, and that seems to be a result of the products being either less efficacious than their really very safe chemical equivalents or more expensive."

Still, there is increased public interest in these products, and the company is studying whether to introduce a line of natural pesticides, he said. Such a move would be good for gardeners, Baker says, by making more products available and, eventually, making them cheaper.

The chemical companies "are, or will be, losing market share as consumers turn to organics. It's only a matter of time before some of these big companies enter organics," he said.

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