By Mike Donahue
Moapa Valley Progress
The Nevada Department of Agriculture (NDOA) is in the midst an intensive campaign designed to search out and destroy three noxious weed species that are attempting to gain a foothold in the Silver State.
The three invasive weeds, Purple Loosestrife, Lythrum salicaria L. (Lythraceae); Yellow Star Thistle, Centaurea solstitialis L., and medusahead grass, Taeniatherum caput-medusae (L.) Nevski, can be found in many Nevada and Clark County locations, depending on the species, including in and around Moapa Valley, according to Jamie Greer, NDOA assistant program coordinator.
The campaign to control or eradicate these weeds, called “early detection, rapid response,” is part of Nevada’s Coordinated Invasive Weed Strategy. Its purpose is to identify and destroy specific noxious weeds found growing in the state.
“Noxious weeds are different species of non-native plants that are injurious to agriculture, horticulture crops, natural habitats and/or ecosystems and humans and/or livestock,” Greer said recently in an Elko workshop. “Historically the plants were most likely introduced accidentally through mismanagement and/or ignorance.”
Once introduced into specific areas in the U.S., many species of invasive and noxious weeds were spread throughout the country in contaminated shipments of produce, forage crops and seeds and even intentionally as ornamental plants for home gardens.
Believe it or not, because many noxious weeds are quite beautiful, it’s possible to actually purchase them at some home improvement and big box stores to plant in your garden.
Although there are a considerable number of noxious weeds in Nevada including camelthorn, knapweed, several varieties of thistle, salt cedar, perennial pepperweed, hemlock, toadflax, and leafy spurge, NDOA has targeted purple loosestrife, star thistle and medusahead grass because of their horrible impacts once established.
Purple loosestrife infects wetlands and can choke out native species and forever change the areas’ function and structure. Heavy plant beds have actually stopped the flow of water through a wetland area. Purple loosestrife or purple lythrum is a member of the Lythraceae or loosestrife family. The plant often sends up multiple stems that can range in height from 6 to 8 feet. The stems are four to eight sided and can either be smooth or pubescent. The erect stems are tough and often appear o be woody at the base of the plant. Leaves are simple, entire, and can be opposite or whorled. Purple loosestrife flowers are arranged on a spike that is from 2 inches to 3 feet long. Individual flowers have five to seven petals that arise from a cylindrical green tube. Petals of the flower are typically purple but can range from white, to pink, or to red.
Medusahead grass crowds out native grasses and plants, and drastically reduces the grazing capacity of rangeland. It is an aggressive winter annual 1/2 to 2 feet tall with leaf blades generally 1/8 inch wide or less. It has an inflorescence long-awned spike nearly as wide as long. Mature awns or beards are twisted, one to four inches long, stiff, finely barbed. It is sometimes confused with foxtail or squirreltail, however, the spike head does not break apart as seeds mature.
The yellow starthistle stops native species from growing, degrading natural habitats and ecosystems completely. Yellow star-thistle is a plant toxic to horses causing chewing disease, Nigropallidal encephalomalacia. It is a member of the sunflower or daisy family and is characterized by a yellow thistle-like flower with 3/8 – ¾-inch yellowish spines in a star-like arrangement at the base of the flower head. The flower heads occur singly at the ends of branched stems 18-36 inches high which arise from a basal rosette of leaves. The stem and leaves are a dull green color and covered with fine woolly hairs. As leaves ascend the stem they become shorter and narrower with pointed tips. S tarthistle flower heads consist of tubular yellow florets in a discoid head about one inch in diameter. The marginal flowers produce nonplumed seeds and the central flowers plumed seeds. The root is a taproot extending deeper than the annuals it may compete with for moisture and nutrients.
Federal, state and county authorities have declared war on these plants and are using a variety of means to fight them including burning, herbicides, pulling and bio controls such as insect introductions.
“It’s really everyone’s duty to protect the landscape from noxious weeds,” Greer said. “It’s actually against the law to have these plants are your property and not do anything about them.”
