Hector the Injector, Pacific Gas & Electric Co.’s reliable pesticide sprayer, may visit your doorstep with his jackhammer injector and his port-a-pack of Cambistat, a chemical that stops tree growth.

For the record, Cambistat is a wood-preservative-turned-growth-regulator that retards the growth of mature trees, thereby reducing the trimming needed to keep power lines free of sparking branches.

The formulation of Cambistat contains antifreeze – like what’s in your car – and it’s injected into the soil on all four sides of a tree to stunt its branches. In technical terms, Cambistat is a “triazole” compound which is taken up into the woody parts of the plant, leaving the leaves to green-up normally, resulting in a window of manikin “green” trees in the utility’s corridor.

Cambistat works its magic by messing up the tree’s hormones that make it grow and by killing off the threads of soil fungi attached to the tree’s roots that scavenge for nutrients. Without the mycorrhizal means to draw water and nutrients into the roots, with the tree’s green chlorophyll engine running smoothly, yet the tree looks green, needs less water, and doesn’t grow. In the words of PG&E’s contractor, the retardant has “the benefit of improving the tree’s health,” another miracle of fungicidal chemistry!

Cambistat is a member of the chemical tribe of pesticides known as “triazoles” – not unlike the tribes we know such as OP’s or pyrethroids. All triazoles are fungicidal, and a few are pharmaceuticals that doctors prescribe for nail fungus or fungal brain infections. Some azoles preserve wood. Still others inhibit “nitrification” of fertilizers – nitrification converts ammonium-based fertilizers into ammonia gases that leak into the sky from the field. Farmers use nitrification inhibiters to keep N-rich fertilizers in the ground where they belong.

Although Cambistat stunts the growth of trees, PG&E admits it can mean smaller tulips. Backers of Cambistat’s use claim that the formulation is immobile, doesn’t follow gravity water into groundwater, and doesn’t harm creeks, streams and rivers. In fact, at a SETAC conference the other year, Bayer Crop Science claimed to have found a drift-free, pure and pristine forest in Germany, and when they tested the soil, they found natural triazole compounds made by Mother Nature, thereby creating a theoretical, if not mythical, “natural triazole” that nature made.

Last year the Danish government evaluated triazoles and concluded “the gradual release of triazole fungicides … [from wood] becomes potentially relevant in terms of risk of groundwater contamination.” These big words express a concern over damage to ground and surface water over time.

The EPA has rejected growth retardants like Cambistat, all of them except for Cambistat itself, though the perfect retardant has not been found. California’s Department of Pesticide Regulation did a mouse study, found that it injured mice, but not enough to restrict its registration – get this euphemism – as a “growth regulator.” The European Union sets the trigger concentration for it in drinking water at one-tenth of a microgram per liter (regulation 1107 – 2009). That’s very low, but the U.S. EPA has no drinking water standard at all, but the EPA still regards it as highly toxic to earthworms and moderately toxic to fish. The EPA allows its use on cut flowers, but not on food crops or fruit and nut trees.

It’s perfectly safe – yes – if we don’t get it on our skin, in our eyes or on our clothes, says the EPA. PG&E’s contract from Utah says it makes trees healthier and more drought-tolerant, and in the soil, it read the detour signs and goes into trees and not into water. We have holes in our doughnuts, why shouldn’t we have holes in our water laws? According to Duke Energy, each tree gets only four to 203 grams of the active ingredient, and in our drinking water, well maybe it stops us from growing old. PG&E isn’t injecting around its poles, it’s injecting trees between poles, unless your trees yield nuts or fruits. The message from PG&E is to open your door to that fellow Hector the Injector, and let Hector make your trees trim and healthy. And don’t! Don’t worry about your wells – PG&E is on the job!


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