We as Americans are constantly bombarded with marketing to be ‘green’. Use compact fluorescent bulbs to save energy, use compost instead of chemical fertilizers, or use electronic billing to ‘save trees’. The list is endless. But, what about when in comes to pesticides? There is so much confusion when it comes to the terms ‘organic’, natural, botanical etc. What does it mean to go green for pest control? Does ‘green ‘ pest control mean non-toxic?

Lots of folks think they’re doing ‘organic’ pest control by sprinkling boric acid all over their countertops or around the perimeter of the kitchen to control ants! First off, the active ingredient in boric acid is boron which is a mineral that is mined. It contains no carbon (the only real benchmark to be called organic) and is therefore inorganic. It is however a natural material that IS toxic, so the example I just described is a misuse and potentially harmful. Boron based compounds act as stomach poisons and as such are often formulated into baits for insect control. Timbor and Bora care are borate (sodium octaborate tetrahydrate) based wood preservative products that are effective at controlling fungus, and powder post beetles. Other natural mineral based pesticides are diatomaceous earth, silica gel, sodium fluoaluminate and sulfur. These low to non-toxic dusts kill insects by ‘physical’ means like abrading away the insect’s protective wax cuticle causing them to dry up or by damaging the lining of the gut. Once again these low toxicity products are not without their hazards and must be used with caution because the ‘active ingredient’ in some of them is silica that can be irritating to the skin and lungs. (Silica is basically ground glass dust.)

The ‘botanical’ insecticides are both natural and organic (carbon containing) and because they are derived from plants must be completely safe correct? Well, one of them, (a novel termiticide/insecticde compound derived from the bark of Ryania sp.) you could literally drink (though I wouldn’t recommend it!) with no ill effects while another, nicotine, is one of the most toxic compounds known requiring extreme caution when handling. It is interesting that two ancient plant derived insecticides (nicotine and pyrethrum) are permitted to be used in organic gardening. (I thought organic meant NO pesticides! Just kidding!) They are on opposite ends of the spectrum when it comes to user safety with nicotine being a highly toxic nerve agent while pyrethrum has very low toxicity to warm-blooded animals. In my industry, we have many synthesized versions of pyrethrum called pyrethroids and also a few versions of synthetic nicotine. The compounds are classified as neonicotinoids, and although they are moderately toxic in their pure technical grade, products for both professionals and consumers alike are formulated for safe handling. I’ll bet you’ve used at least one of the neonicotinoid active ingredients (imidicloprid) to control grubs in your lawn or fleas on your pet (AdvantageII). While nicotine and pyrethrum have been around for centuries, several new low toxicity plant based pesticides have been discovered in recent years, and many have shown promising results. One of them is an extract from the seeds of the Neem tree that can act as an insecticide (growth regulator) or fungicide. It primarily works on insects that attack plants, so it’s great for gardeners.

Several commercial named products are available for use on ornamental shrubs, trees, and also food crops. Limonene is a citrus oil extract that has been used in flea control shampoos, animal repellants and also has contact insecticidal activity against many household insects. Capsaicin (the stuff that makes chili peppers hot) is yet another natural substance that will control mostly soft bodied plant-feeding insect by repelling them and has made its way into nuisance wildlife repellants too (Caution! Handle with care.) Finally, the essential oils extracted from plants like cedar, clove, cinnamon, various types of mint, rosemary, etc mostly all work as a contact kill only with no residual activity and may need to be re-applied often. One other class of ‘green pesticide’ is the biopesticides made up of viruses, bacteria, nematodes, fungi, and others. While toxicity to non-target animals and humans is extremely low, they’re not broad-spectrum in their effectiveness, and many are species specific!

There is your round up of ‘green pesticide’ technology. While many of these products are effective, they do have their drawbacks (quickly break down..no residual action, slow acting) and they all are toxic to one degree or another, so they must be handled and applied with safety in mind.