United States Department of Agriculture Field Guide for Managing Rabbitbrush in the Southwest Forest Southwestern Service Region TP-R3-16-31 February 2015 Cover Photos Top left: Green rabbitbrush, USDA Forest Service Top right: Green rabbitbrush flowers, Mary Ellen Harte, Bugwood.org Bottom left: Rubber rabbitbrush flowers, USDA Forest Service Bottom right: Rubber rabbitbrush, USDA Forest Service The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TTY). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TTY). USDA is an equal opportunity provider and employer. Printed on recycled paper Green Rabbitbrush (Chrysothamnus viscidiflorus) Rubber Rabbitbrush (Chrysothamnus nauseosus, syn. Ericameria nauseosa) Sunflower family (Asteraceae) Green and rubber rabbitbrush are native shrubs that grow Some species are widespread geographically, and some are widely across western U.S. rangelands. Though they can restricted to a limited area. The specific rabbitbrush species appear as a weedy monoculture (especially following of concern should always be known before proceeding with disturbance), they are early colonizers and their presence management. In this guide, suggestions for management are can be reduced under improved management regimes. directed mostly toward green and rubber rabbitbrush, but This field guide serves as the U.S. Forest Service’s control methods may be applicable to other species as well. recommendations for management of green rabbitbrush and rubber rabbitbrush in woodlands, rangelands, and deserts Growth Characteristics associated with its Southwestern Region. The Southwestern Both species of rabbitbrush are perennial, warm season, Region covers Arizona and New Mexico, which together native shrubs with rounded or pyramidal-shaped canopies. have 11 national forests. The Region also includes four Characteristics for both species are summarized in table 1. national grasslands located in northeastern New Mexico, In addition to the growth characteristics shown in table 1, western Oklahoma, and the Texas panhandle. both species exhibit the following: Description • A deep root system with a taproot and less developed lateral roots. Green rabbitbrush (synonyms: yellow rabbitbrush, Douglas • Flowers are perfect, meaning both male and female rabbitbrush, chamisa) and rubber rabbitbrush (synonyms: structures are present within each flower. gray (also grey) rabbitbrush, golden rabbitbrush, chamiso blanco) are native shrubs and, while often unwanted, • Reproduce vegetatively and via seed; seeds are are usually not considered to be invasive. The genus wind disseminated achenes with a pappus; seed Chrysothamnus is very complex with as many as 16 ripens in autumn, but may germinate in either the species and 41 subspecies described in the literature. spring or fall with available soil moisture. Though Table 1. Growth characteristics Species Vegetative Appearance Stems Leaves Flowers Green Grows 12–48 inches tall Smooth, greenish-yellow Green rabbitbrush leaves Green rabbitbrush subspecies tend rabbitbrush with a more compacted stems. are linear similar to rubber to have smooth, papery, layered crown width. rabbitbrush but lack a involucres and appear sticky at the felt-like layer. Instead, base of the flower clusters. they have a bright green dotted appearance and are arranged in a slight spiral at the stem. Rubber Open, wide-spreading Upright, yellowish-green, Rubber rabbitbrush leaves Though appearance varies rabbitbrush crown; grows to 12–90 flexible stems from are linear, less than 0.04- between rubber rabbitbrush inches tall and are typically base with a grayish- inch wide, and covered by subspecies, flowers tend to be 0.2- to 3-feet wide, but may white appearance due to a felt-like layer that serves yellow in color, tubular shaped, grow as wide as tall. the presence of dense, to insulate and reduce and occur in clusters at the tips tangled, felt-like white evapotranspiration. of upright stems. The grayish hairs. subspecies tend to have tangle- haired bracts (involucres) below the flower. 1 abundantly produced, seeds do not persist in the maintenance equipment. seed bank; typically, seed is viable for less than Invasive Features 3 years. Germination occurs over a broad range of temperatures, requires at least 13 percent soil Although not invasive, rabbitbrush can increase moisture, and may be inhibited by soil conditions of substantially, particularly in disturbed areas such as high salinity. Vegetative sprouts emerge from buds abandoned crop fields, overgrazed areas, or rangeland that located on lower stems and the root crown at or has been replanted. While rabbitbrush rapidly expands slightly below the soil surface. following a disturbance, it is not overly competitive and may actually serve to (1) build soil stability and structure, (2) Ecology prevent other more detrimental species from establishing, Impacts/Threats and (3) create a favorable microclimate for more desirable Green and rubber rabbitbrush are well suited for restoration plants to establish. and are commonly planted on damaged sites, especially strip mines, road cuts, and severely deteriorated rangeland. When Management intentionally planted, these shrubs establish easily and grow rapidly into uniform stands. On undisturbed rangelands, Early detection, control, and followup monitoring of green and rubber rabbitbrush will increase in cover and rabbitbrush coupled with efforts that improve range density after fire or heavy disturbance. With time and condition are important for long-term rabbitbrush improved management, they usually become less noticeable management. Due to copious seed production and a tendency as sagebrush and other associated species return. to vegetatively reproduce following surface disturbance, rabbitbrush populations can quickly become a dense Location monoculture. If a localized population needs to be removed These shrubs favor sunny, dry, open sites and tend to grow to meet a particular land use goal, it is highly recommended on medium to coarse-textured soils such as sandy, gravelly, to treat rabbitbrush and reseed simultaneously in the fall or loam soils. Rubber rabbitbrush tolerates a wide range (single entry approach) to prevent other weedy species from of pH values, from moderately acidic to basic or strongly establishing. The following actions should be considered alkaline. It is often one of the first plants to colonize an area when planning an overall management approach: following extreme disturbance and can even establish and • Healthy plant communities should be encouraged and grow in harsh soil conditions such as mine spoils. Green maintained to limit rabbitbrush infestations. rabbitbrush is somewhat tolerant of saline soil and is used as an indicator species for degraded sites. Both rabbitbrush • Detect, map, and eradicate new populations of species span a wide range of elevations from sea level to rabbitbrush as early as possible. Keep annual records 10,500 feet. of reported infestations. • Implement monitoring and a followup treatment plan Spread for missed plants and seedlings. Rabbitbrush propagates vegetatively and by seed; all species of rabbitbrush are very prolific seed producers. Table 2 summarizes some management options for Seed is easily dispersed via wind, water, humans, birds, and controlling rabbitbrush under various situations. Choice rodents. Seed is also spread over long distances by adhering of method(s) taken for rabbitbrush control depends on to surfaces and undercarriages of road vehicles and road numerous factors including current land use and site condition, accessibility, terrain, climate, density and 2 Table 2. Management options* Site Physical Methods Cultural Methods Biological Methods Chemical Methods Roadsides, Mowing alone will Clean machinery following Leaf beetle (Trirhabda For ground application, use ATV, fencelines, suppress top growth activity in infested areas. nitidicollis) has shown truck mounted, or tractor pulled or noncrop but will not control the potential for control; spraying equipment. Train road crews to identify areas plants. Consider mowing however, USDA has and report infestations. Wash under vehicle after in combination with not given approval as a application to prevent spread. herbicide control. biological control agent. Rangelands, Physical methods Avoid driving directly Same as above. For widespread infestations, pastures, (including prescribed through infestation; limit use ground or aerial broadcast or riparian burning) are usually disturbance. spraying. corridors unsuccessful and tend to Reseed with plants that are For sparse infestations, use increase density. desirable and will compete. backpack spraying. Wilderness, Remove localized After passing through Same as above. Use backpack or hand-held other natural populations