A beautiful lawn that could be certified organic, and is pest-free. Is it possible?

Anyone calling their lawn “organic” will need organic means to repel lawn pests. That means synthetic chemical pesticides are out, due to their negative effects on wildlife and water quality.

Folklore Pesticide Recipes: Organic, but Unproven

If mainstream insecticides are out, what’s in?

When looking up the best natural, nonharmful pesticides (also called biopesticides), you will find a wealth of homemade pesticide remedies.

No doubt: Many plants have insecticidal qualities. That has led to a host of popular concoctions of dish soap, vegetable oil, cayenne pepper and essential oils, passed around enthusiastically on the internet. They sound like eco-friendly ways to deal with garden pests and avoid chemical pesticides. But there’s one problem: Little evidence says they work well in pest management.

Claims of effectiveness tend to be anecdotal. For every gardener who says liquid soap slew the spider mites on the begonias, you’ll find another who confesses the neighborhood lizards found croton leaves even more delicious after a garlic spray.

Luckily for homeowner and newbie organic gardeners, there are recommended organic, natural insecticides professionals rely on. They’re used by organic lawn care specialists and organic farmers who must get their fields certified as organic.

If you do have that dream of a stunning lawn that you could certify organic, know that it’s possible with two provably effective organic pesticides that even the USDA would accept under organic certification standards: neem oil and diatomaceous earth. And yes— they work.

Neem Oil

Extracted from a tree native to India (Azadirachta indica), neem oil could be dubbed the ultimate organic pest preventive. It slowly kills insects and gradually prevents them from reestablishing.

Because the USDA certified the oil as organic, it can be approved for use under organic certification, including for lawns.

Neem’s active compound, azadiractin, has been a popular ingredient in some natural pesticides bug sprays as a “growth regulator” — meaning it interrupts insect growing phases and eventually leads to the death of even the most-hated lawn pests. It may not just interrupt their growth and maturity, but also stop them from reproducing and outright repel them, according to Penn State University.

There are some studies showing it could negatively affect some beneficial insects, too, (though it’s not shown to always kill them). This tends to be the case only if these beneficials are soft-bodied and feed on neem-treated plants in your lawn. If neither is the case, there should be no worries.

The Colorado State University Extension lists neem oil as recommended alternative natural pest control for target insects including thrips, mealy bugs, and even some fungal diseases, all of which can be a pain to lawn owners. Application involves diluting about 2-4 tablespoons in one gallon of water, mixing it well, and spraying your lawn from multiple angles every 7 (curatively) to 14 (preventively) days to ensure thorough coverage.

Doug Sheldon, the CEO of Dirt Doctor, Inc. (and point person at the Texas Organic Research Center), had a few comments about neem oil from his experience. “Neem can be effective, but it has to be used within hours of mixing in a liquid,” he said. “The effectiveness is reduced dramatically within hours of mixing and the dry powder is expensive to purchase.”

Diatomaceous Earth

With neem oil spray in your arsenal as a good organic preventive, diatomaceous earth steps in as an excellent curative option when for rough turfgrass pest problems. It will also keep your lawn in that environmentally friendly “organic” category, no questions asked.

According to David Curtis and George Serrill, co-owners and partners at EnviroTech Soil Solutions Inc. — a company specializing in diatomaceous earth products — diatomaceous earth is virtually harmless (to nonpests, that is) and easy to certify organic. It also poses incredibly limited dangers to beneficial pollinators, and most living things for that matter, making it even more appealing to those who are both lawn and nature lovers.

How can diatomaceous earth kill lawn pests while sparing most everything else? Curtis and Serrill say diatomaceous earth acts at a microscopic level: It acts like shards of glass for pests when applied to plants, or directly on the pests themselves.

Only hard-bodied pests with exoskeletons — and even among those, only those that spend a good amount of time creeping and crawling in your lawn— will be affected. Soft-bodied insects and flying insects won’t be harmed, however, and neither will widely-loved beneficial pollinators including butterflies and bees.

Curtis and Serrill say diatomaceous earth will affect grasshoppers, fleas, mites, ticks, crickets, and even Japanese beetles. To apply, mix one pound of diatomaceous earth with one gallon of water. Get out the spray bottle and spray your lawn with it from multiple angles. If pest problems persist, reapply it again in one week.

What Natural Pesticides Should You Avoid?

To make this question more specific: Which organic pesticides don’t work as well as people claim? Sheldon at Dirt Doctor has a bone to pick with one widely used (and internet-recommended) pesticide in particular: insecticidal soap.

When asked if insecticidal soaps work, Sheldon said, “Yes, but there are much better products today that target specific pests.” He mentioned research in 2017 showing that insecticidal soaps simply don’t work well as a broad-spectrum pest repellant (and maybe not as many as diatomaceous earth or neem oil might target).

Insecticidal soaps can help decimate soft-bodied pests (or the larval stages of hard-bodied pests) when applied occasionally. They aren’t as good against hard-bodied ones.

The real scoop from the research: The more you apply insecticidal soaps against the same population of lawn interlopers, the more resistant they will get to the applications. With repeated use, you’ll have to switch to something else.

What to do? Save the hot-pepper-cooking-oil-garlic spray for your pizza. Experts say it’s best to try more-vetted biopesticides, including neem oil and diatomaceous earth.

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