The Enemy: Austrian filedcress (Rippa austriaca)
Strategy: This introduced invasive plant was found in the Jackson, Wyo., area and is a listed noxious weed in many states. Its closest relative to our area is perennial pepperweed. This perennial mustard grows to about 3 feet tall. It has a unique leaf for a mustard in that it clasps the stem with an additional leaf that grows from the base of a larger leaf. It has an aggressive rhizomatous root system that allows it to grow in thick patches, which is its major way of spreading. Although it produces thousands of seeds from the yellow cluster of flowers that grow at the tip of each branched stem, it rarely germinates from these seeds.
Attack: It is thought to have come into the western Wyoming area on either contaminated construction equipment or in soil that was brought in to build a raised landscape project along a roadside. Once established, it aggressively competes for the root zone of desirable plants, as well as creeps into adjacent areas. It has no forage value to livestock nor wildlife and will become a problem along ditches, canals, waterways and other disturbed sites such as roadsides.
Defense: Keep equipment clean. Know what this plant looks like and notify your county weed department if you find it. Mechanical control can be considered, but remember that plants that spread by roots are spread by aggressively tilling the soil. Once established, a Bayer product such as Escort XP or Telar XP at 1 to 1.5 ounces with surfactant is great. Along a ditch bank use Opensight (3.3 ounces per acre), which will control other weeds without harming the grasses. There are no biological control agents available other than possibly grasshoppers, but that’s another problem.