Green Pesticides

Now that the harmful effects of conventional pesticides are well known, a host of green alternatives are being developed. Among them are sprays containing essential oils; insecticidal soaps; and products that include edible ingredients.

One recently released insect spray contains spices and oils like wintergreen, cinnamon, coconut, clove, and safflower. Dr. Earth, the company that makes the spray, says it works by blocking the neurotransmitters of bugs like aphids, caterpillars and whiteflies, so that the pests die. It’s used on fruit and vegetable crops. Insecticidal soap, made by Espoma, is applied to produce, and dries out pests by breaking down their exoskeletons. It’s so safe, says the company, that it can be applied to crops right up to the day they’re harvested.

Bugs can also be used as natural pesticides, depending on what pests need to be controlled. Microscopic, water-soluble organisms called nematodes can be used on lawns to get rid of white grubs. Ladybugs are natural aphid predators, and can be bought to control marauding aphid populations.

New fungicides are being developed that kill fungi without damaging other, possibly beneficial plant organisms. Plant fungi breaks down the plant’s natural defensive chemicals, called phytoalexins, by releasing enzymes that destroy them. The new fungicides, called paldoxins, block the fungi’s ability to destroy phytoalexins. The plants resist the fungi and thrive.

Soledade Pedras, professor of chemistry at Canada’s University of Saskatchewan, explained why these fungicides, which she helped develop, are environmentally friendly: "Conventional fungicides kill constantly. Our products only attack the fungus when it's misbehaving or attacking the plant. And for that reason, they're much safer."

It’s important to note that organic pesticides may not always be green. A study from Canada’s University of Guelph measured synthetic pesticides against organic pesticides, and found that the organic substances also had negative effects on the environment. The study, which stretched over two years, was conducted on soybean crops and aphids. Two organic pesticides were examined – Superior 70 oil, a mineral oil that suffocates aphids, and Botanigard, a fungus that kills the flies.

Researchers measured these pesticides’ ecological impact and discovered that although organic pesticides were altogether less likely to leach into soil and water, harm the skin, cause problems when ingested, or be toxic to wildlife, they were still significantly harmful to the environment. Superior 70 was actually more damaging on a pounds-needed-per-acre basis than the conventional pesticides, and both organic pesticides also killed a great deal of the aphid’s natural predators. Scientists wanted consumers to take this message from the study: organic does not always translate to environmentally friendly.