A wet spring brings early greenery to the towns and cities of the Chihuahuan Desert. No, not green lawns and leafing trees; before even those harbingers of spring. Instead, the green of a pesky invader, London Rocket. This introduced weed, a member of the mustard family, seems to be everywhere in a good year, right up to the time the weather turns hot. Then, the greenery fades and the weeds die, their over-enthusiastic production of seeds accomplished.
Most of us welcome the sweeps of color in the somewhat dismal months
between January and the leafing out of trees and shrubs. It's equally true, of
course, that we find less welcome the pulling of these weeds from unwanted places. But
this naturalized citizen has another unwanted gift for our Southwestern chile farmers.
The leaf hoppers that have fed so voraciously on the spicy weed carry the wilt disease
deadly to the chile fields. As the hotter days bake life from the mustard, the leaf
hoppers switch to chile, and the farmers feel the heat of failed crops.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Foliage, flowers, and fruit of London Rocket (Sisymbrium irio). Image by A.H. Harris.