Gardening Articles: Edibles :: Fruit & Nut Trees
High-tech Dust Foils Pests
by Barbara Richardson
Surround on an apple tree in our test garden two weeks after application.
Beginning in spring of 2001, gardeners have an important new tool to protect their plants from pests. Best of all, it's a familiar and completely safe material, kaolin clay, a common ingredient of both toothpaste and aspirin as well as a host of common products such as ceramics, paints, and papers. Most Americans probably know kaolin best as one of the key ingredients of the medicine Kaopectate. So how did such a familiar material become the lastest hot item in pest control?
In the early 1990s, the USDA's Agricultural Research Service scientists Drs. Michael Glenn and Gary Puterka, Kearneysville, West Virginia, were charged with finding less toxic alternatives to the chemicals used in orchards. They knew that using dusts to repel insects has an ancient history, and that talcum, mica, and kaolin dusts had been studied for agriculture as far back as 1928.
But unlike researchers of 70 years ago, Glenn and Puterka had the help of New Jersey-based Engelhard Corporation, a company with expertise in surface chemistry and materials science. Engelhard developed a new material, a type of particle film using "engineered microscopic particulates to form a semicontinuous, porous barrier." They've trademarked the technology as HPF Technology, and the first product produced using it is Surround Crop Protectant. Engineered kaolin was chosen as the active ingredient because it meets size and shape specifications, is essentially non-toxic, and has specific light-reflecting qualities.
Surround works by coating plant surfaces with a powdery film. Some pests are repelled by the light reflected from the coated plant's surface; others simply don't recognize the host because it feels different. Further, the particles stick to pests and become a powerful enough irritant to make it leave. Finally, some pests simply can't hold onto the coated surface and fall to the ground.
Much of the initial field research involved apples and pears. Apple pests controlled by Surround include leafrollers and leafhoppers; codling moth, plum curculio, apple sucker, stink bugs, apple maggot, and thrips are suppressed. On pears, the difficult to manage pear psylla is controlled; thrips, leafhoppers, codling moth, stink bug, and mites are suppressed.
Among vegetable garden pests, use Surround against Japanese beetles, tarnished plant bugs, and Colorado potato beetles.
Because the material doesn't have an insecticidal effect, pest resistance is not a concern. It can be applied right up to the day of harvest, and simply washes or rubs off.