It's been several months since this column has taken a hard look
at prevalent garden myths, meaning I've let quite a few easy ones go
by. But here's a dangerous one I encountered just a few days ago
while on plant geek duty at a local nursery center, and it makes as
good a Myth of the Week as any:
"Organic pesticides don't harm the environment."
We're talking pesticides, and on the organic side of the
equation, this means things like insecticidal soaps, Bt (Bacillus
thuringiensis), pyrethrum (from African mums), and rotenone (pea
family). You'll see these listed as the active ingredients in all
sorts of organic pesticides.
What is important to remember is that a pesticide contains a
poison, whether organic or synthetic. "Organic" means the poison is
derived from the earth, its deposits, or its plants. "Synthetic"
means the poison is made by evil Republicans in lab coats. Either
way, it kills bugs.
All poisons used in pesticides are rated on a scale called EIQ,
or Environmental Impact Quotient. They are tested for range of
toxicity, or what it is they will harm or kill. Let's say the poison
doesn't harm people in anything short of beer-chugging amounts; that
might merit a 2. If an ounce of the stuff in a stretch of stream
kills all the fish; give it a 10. The poisons are tested for how
long they stay in the soil, in plants, if they kill bees, if they
kill worms, etc.
Here are some interesting EIQs:
can see that some organic poisons—and all of these are in use—have a
higher Environmental Impact Quotient than some synthetics, notably
the synthetic Carbaryl (Sevin), one of the most commonly used
synthetic pesticides in the world.
My point is not to knock organics. I try not to use any
pesticides in my garden. The best way to avoid using pesticides is
to keep a clean and tidy garden, keep your plants watered, and keep
them healthy. I've had stretches close to ten years without having
to spritz anything that's a poison. But once in a while an
infestation can get pretty ugly. I'll first use an organic
insecticide, usually a soap, in moderation and exactly according to
instructions. A very limited use, and most often the job is done.
But organic pesticides have very real drawbacks. Most of them are
broad spectrum, meaning they kill beneficial insects (just like
those dangerous synthetic chemicals). They are not as thoroughly
tested as synthetics. Batch strength can vary. And, perhaps most
dangerous of all, they are perceived by the gardening public as
safe. Nothing could be farther from the truth.
Pyrethrum is an organic poison used by organic vegetable growers
and used by commercial industries as the toxin in sprays designed to
kill everything from wasps to asparagus beetles. It's also a nerve
toxin, and extremely dangerous to infants. Never use wasp spray
around an infant, or you will learn just how dangerous some of
Mother Earth's little secrets can be.
Safe/dangerous are always relative, anyway. One hundred years
ago, there were no synthetic pesticides in use, not in gardening,
not in agriculture, not anywhere. The big pesticide used across the
land was 100 percent organic. It was lead-based.