WHERE DO NOXIOUS AND INVASIVE WEEDS COME FROM AND WHY DO THEY SPREAD?
Many of Nevada’s noxious and invasive weeds came from regions with comparable climates in eastern Europe and western and central Asia. They were introduced through human activity, both accidentally and intentionally. Cheatgrass is believed to have come to the west as a wheat seed contaminant. Salt cedar was planted along streams for erosion control. Purple loosestrife was planted in gardens for its pretty purple flowers. In the intervening 100 years they have become noxious and invasive weeds. Noxious and invasive weeds have a combination of traits that make them more competitive than natives. Tall whitetop, for example, produces thousands of seeds each year. Some of which can survive in the soil seed bank for 5 to 10 years. Plus it is rhizomatous. Rhizomes are underground stems with buds that can form new plants. Its roots can reach 20 feet deep in the soil. This combination of traits means that successful tall whitetop control requires years of treatment followed by decades of vigila
