Of all the challenges I face in my attempt to grow my own food sustainably, grasshoppers have proven the most difficult. As the temperatures climb to three digits, the infestation sets in. Every year, the damage is the same.
Once-perfect tomatoes and bell peppers, just about to ripen, are missing bite-sized chunks. Beautiful leaves of Swiss chard that I've nurtured through drought sprout holes as large as a fist. Fruit trees are defoliated, with strips of bark eaten off from around their limbs, threatening their very existence.
One might be tempted to blame this on organic gardening practices, but I believe the opposite: that it demonstrates how aspects of industrial agriculture are unsustainable. By converting millions of acres of native land into farmland, we've ruined the natural habitat for skunks, foxes, road runners, coyotes, toads and every other grasshopper eater.
When mixed with water and sprayed onto plants, kaolin clay forms a mineral film that repels grasshoppers, beetles and other insects.
Then we plant corn, wheat or sorghum from horizon to horizon, a grasshopper buffet. This boosts their population to an unnatural proportion that not even our strongest chemical insecticides can abate.
In my efforts to mitigate grasshopper problems, I've found a variety of sustainable practices that don't require toxic chemicals. But each has had its limitations.
Last year, I used an insect barrier to protect small beds of lettuce and a row of six pumpkins. Covering these crops with a gauzy cloth kept grasshoppers at a safe distance. Later in the season, I was assisted by a large family of skunks that took up residence nearby. Each evening, they emerged and roamed my garden, eating any insect they could pounce on.
This year, I've seen not a trace of my fragrant friends, despite my effort to build homes out of tree limbs to attract them. And the insect barrier won't suffice. My fruit trees are too large, and the expanse of land that 60 mounds of pumpkins require is too vast to cover with rolls of fabric.
But I've found another option that's nontoxic and inexpensive to apply: kaolin clay. When mixed with water and sprayed onto plants, it forms a mineral film that repels grasshoppers, beetles and other insects that can be difficult to control.
This is not the kaolin clay used in ceramics that can be purchased from an art supply store. Called Surround WP, it contains a form of kaolin clay that has been purified and processed for application on food crops. This fluffy white powder is sold in 25-pound bags for $50 at farm supply stores.
To apply Surround WP, you'll need a sprayer. The one I use has a hand-held nozzle connected by a hose to a 2-gallon tank, with a lid-mounted pump that works like a bicycle air pump to add pressure. I fill the tank with water, add one pound of Surround WP and shake the tank until the powder is mixed in; sometimes, I add a drop of liquid soap to break up the water tension for easier mixing.
With the nozzle set to "mist," I spray the plant's foliage and stems. At first, the plants look wet. But as the water evaporates, the plant is left with a white film that's a little spotty. Following up with a second application and sometimes a third, I coat the plant in an even film of white powder. That's the barrier that grasshoppers won't chew into.
The solution is suitable for any plant. I use it on okra, pumpkins, squash, watermelons, cantaloupes, tomatoes, peppers, fruit trees and even landscaping plants. Each application lasts until the next rain or until new growth crops up. Although you can use it any time, it's better to use it earlier in the season, especially for fragile, leafy crops such as Swiss chard; a fresh coat is a chore to wash off.
The coating not only repels pests, it also reduces the intensity of the sunlight, thus shading the plant a little and lowering its water requirements. I've never noticed it affect the amount of a harvest, other than by how it keeps a plant from being totally consumed.
Surround WP is one of the most effective defenses against grasshoppers, used not only by organic farmers but conventional farmers too. It seems to pose no danger to other insects or wildlife, and it doesn't even harm grasshoppers; it repels them. My father has used it for eight years with no plant casualties, and it has allowed us to save crops that are just coming to maturity when grasshoppers strike.
A watermelon vine treated with one application of kaolin clay shows spotty coverage that can be filled in with additional treatments.
