Saturday, July 7, 2012

Friday Flora Late edition

Late indeed:
This is the withered remains of one of many honey locust suckers that have been sprouting up in front of the house. There were at least three honey locust trees there, and though we cut them out, their roots have been sending up suckers like mad. Honey locust trees are something nice to have elsewhere: the perfume of the flowers of a grove of them, a quarter-mile up the road from us, sweetened the air at our house this spring. However, we don't really want big trees this close to the house, and these can be quite nasty: they have vicious thorns that love to dig in deep and break off inside of you. Worse, trying to dig up the suckers is an exercise for, well, suckers: the roots are just too deep.

So, I put down the shovel and shears and picked up my crossbow. Crossbow is a mix of 2,4-Dichlorooxyaceticacid (2,4-D):
and 2,4,5-Trichloro-2-pyridinyloxyacetic acid (Triclopyr):
both of which have some similarity to indole-acetic acid (IAA)

and Phenylacetic acid
These last two are examples of auxins, perhaps the most significant naturally occuring plant hormones. Deprive a plant of the ability to produce or respond to auxins, and everything goes wrong--stunted growth, no blooming, no apical dominance, no ripening, and worse. However, zap a plant with a huge overdose of auxin-analogs, like I just did...well, anyone who has gone through puberty knows how rough an overdose of hormones can be. This is a few orders of magnitude worse--the plant is overwhelmed, activates genetic programs for development and senescence at the same time, and keels over dead in short order. Interestingly, these synthetic auxins don't do much to monocots (grasses, lilies and their ilk)--once absorbed into the plant, they are chemically modified into an inactive form.

It was not without misgivings that I strapped on the backpack sprayer. Both 2,4-D and triclopyr are considered relatively benign, as herbicides go--they have been shown to decay with a half-life in the range of a month or so, and not to bioaccumulate significantly. However, they do persist enough that we are discouraged from using them wherever we're going to have lactating animals grazing for a year. This is an issue, since we want to have milch goats roaming around the property.

Worse, like political candidates who hung out with a bad crowd in their youth, both 2,4-D and triclopyr have a historical association with 2,4,5-T. 2,4,5-T was part of Agent Orange--and it turns out that it's basically impossible to synthesize 2,4,5-T without having some of it undergo a spontaneous reaction with itself. That reaction makes 2,3,7,8-tetrachlorodibenzodioxin, a deadly poison, a carcinogen in any dose, and a molecule that is essentially immortal in the environment--one of the more evil chemicals humans have made since we started mashing together carbon atoms in the lab. Like politicians who have done their best to expunge certain historical facts from their record, triclopyr even underwent a name change--if you stuck to IUPAC naming conventions, you could also abbreviate its name as 2,4,5-T.

Also, I would love to have this property be organic*, and the Real Doctor and I are working to that end. Right now, though (WARNING! self-justification alert!) we are facing several years' worth of neglect all at once. We are figuring that for the next year or two, we will be using some herbicides, when necessary. But, tree-huggers that we are, we're going to do as much as possible in other ways. Consider the effect of the "natural" herbicides "Painted Lady" and "Ash":
It's kind of amazing to watch them go after blackberry brambles. They'll eat every leaf they can reach, and the effect is not too different from Agent Orange. Here's a picnic table that we didn't even know existed a week earlier:
two days' of nibbling by the goats revealed it, and all that is left of the once-enveloping bramble is the stems.

*I know 2,4-D is organic. I mean in the colloquial, not chemical sense.

No comments:

Post a Comment