As my CLM time here in Carlsbad winds down and I finish other tasks, one project still looms large. This deadly search for African rue, a noxious weed, is the story of this month. Inevitably I call it the Hunt for Rue: October.
Along with Malta star-thistle, African rue is the most hated weed in the Carlsbad Field Office. Even its scientific name, Peganum harmala, contains within it both “harm” and “mala,” Spanish for “bad.” Around Carlsbad, rue is found on oil pads, brought in as seeds stuck in truck tires. Though rue is toxic to people and livestock, the containment strategy is based mostly on concerns over rangeland health. Should this plant escape the oil pads and invade the open range, little could stop it. Rue’s massive, branching roots can reach 20 feet in depth, and the plant makes allelopathic chemicals to suppress competitors.
“WANTED-Dead, not Alive” flyers around the office advise staffers to report this weed, which I did as soon as I saw it. The herbicide period for rue runs for just a few weeks in the spring and the fall, so spraying had to wait. In the meantime, I returned and discovered rue on other pads in the neighborhood. I recorded them until I’d checked every pad on my aerial photo, returning over the next few weeks until eventually I had checked over 600 pads spread across over 100 square miles. I created a layer in GIS showing the pads I had checked and estimates of the rue present. There always seems to be even more rue lurking just over the edge of the map.
Finally, I’ve had a chance to strike back. This week was the start of open season on African rue, when several groups of BLM staffers and contractors drove out into the oilfields toting two ton tank trailers full of blue herbicide cocktail. I was among them.
A schism exists between two camps favoring two different delivery methods. One camp favors the wand, basically a giant manual squirt gun connected by a hose to the tank, and the other favors the booms, remote herbicide blasters appended on the back of the tank trailer controlled from the cab. The wand camp charges that the boomers waste expensive herbicide by shooting a band of spray twenty feet wide to hit one plant, in the process potentially killing other plants in the area, and that boomers waste hours returning to town so they can reload. The boom camp claims the wand folks waste hours by trying to cover acres – one plant at a time. Coverage from booms is spotty due to wind, say the wand folks. Well coverage from wands is spotty due to the users’ eyesight, say the boomers. It can get heated, reflecting two different worldviews more than anything. Neither may be superior, the best method varying from pad to pad depending on weed number and density, other plants, weather, labor, funding and many other factors. In the end, everybody agrees we want African rue dead, not alive.