If there was ever an indication that restoring natural areas is really horticulture, this is it. Even an artisanal project like ours would never be able to keep up with noxious weed growth and re-growth without a certain amount of pesticide application.
There is a difference between widely broadcasting pesticides that kill a lot of organisms and applying a small amount to a specific target at the right time in its life cycle. This is the time that my current target – scotch broom – is most vulnerable. And if there is poison oak adjacent, well, I might spend some time on that.
The two herbicides I use – glyphosate on(ingredient in Roundup®) and triclopyr (Garlon®) are the least toxic to me, and the assortment of creatures they’re likely to contact. (I prefer to use the ester formulation of Garlon because it is less poisonous to me, the applicator, than the amine). I occasionally use Poast®, an herbicide that kills grass but not broadleaf weeds.
Restorationists rely on spraying weeds to get native plants established. But they also are looking out for some of the organisms that can be damaged by overzealous use of chemicals. There is a growing conservation biology literature, for example, on pesticide effects on rare and endangered butterflies and their larvae.
Anyway, there are other ways to work on the weeds. One hand-weeding method developed by Joan Bradley and her sister relied on minimal disturbance, slow clearing, and fostering natural regeneration by working from the best, most intact areas outward. This method has a lot to recommend it. It requires discipline to not clear out all the weeds in the worst areas. It requires patience. But the good thing is, it doesn’t take a lot of intensive work – the two authors regenerated 40 acres in a public park in Australia by working just a few hours at a time.
I still aspire to mastering that technique. Meanwhile, the hybrid method of following machine-clearing with hand work, mowing, and spraying will have to do. I’m off to climb the hill with my 40 pounds of solution – 24 in the backpack sprayer, carrying a jug with the rest. Saves on the gym membership.
P.S. Scotch broom flowers make a pretty good yarn dye. I experiment with the many I haven’t killed yet.