Weed Science Commons^™

Black Medic (Medicago Lupulina) Identification And Control In Residential Landscapes, Michael Caron, Taun Beddes, Corey Ransom

All Current Publications

Black medic (Medicago lupulina) is an herbaceous winter or summer annual broadleaf landscape weed. This fact sheet provides a weed description and describes suppression and control options.

A Case Study Of Suspected Sheep Losses Due To Chokecherry Not Death Camas, Kevin D. Welch, Clint A. Stonecipher, Stephen T. Lee, Daniel Cook, Benedict T. Green

Poisonous Plant Research (PPR)

Death camas (Zigadenus paniculatus) is a toxic plant often associated with poisoning cases in livestock, especially in sheep, in the spring on mountain foothills. Consequently, when sheep are found dead in mountain foothills, and death camas is present, it is often implicated as the potential cause of death. However, this may be over simplistic as there may be other plants that may also contribute to, or are the cause of, death in sheep. In this study, we present a case of approximately 200 sheep out of a band of 400 that died within 24 hours of beginning to …

White Bryony (Bryonia Alba), Taun Beddes, Michael Caron, Jacob Hadfield, Cory Ransom

All Current Publications

White bryony is more than just a nuisance plant. It is an aggressive, perennial vine that threatens riparian ecosystems, agricultural lands, and residential landscapes by destructively smothering vegetation. Additionally, its toxicity poses risks to people, livestock, and pets. Early detection and consistent management are critical to reducing its spread in Utah.

Canada Thistle (Cirsium Arvense) Identification And Control, Caitlin Henderson, Robert Nelson Schaeffer, Corey Ransom

All Current Publications

Cirsium arvense is an invasive perennial weed adaptable to a wide range of habitats. Since its arrival in North America in the 1600s, it has spread throughout much of the country. It has become prevalent in rangelands and disturbed areas in the Intermountain West, displacing native plant species, reducing crop yields, and affecting pasture quality. This fact sheet outlines how to identify Canada thistle, its life cycle, and how to manage it through cultural, mechanical, biological, and chemical control.

Wild Licorice (Glycyrrhiza Lepidota) Identification And Management In Pastures, Jacob Hadfield, Taun Beddes, Michael Caron, Corey Ransom

All Current Publications

Wild licorice, also known as American licorice, is a perennial legume native to North America, commonly found in the western United States. Wild licorice reproduces rapidly through seeds and rhizomes, leading to large infestations, particularly in pastures. The low preference of livestock for wild licorice results in overgrazing of other plant species, leaving them at a competitive disadvantage, further promoting the spread of wild licorice and contributing to pasture infestations. This fact sheet reviews the identification and management of wild licorice in pastures.

Weed Incursion Of Irrigated Forage–Forb Mixtures Under Mob Grazing Or Mowing In The Mountain West Usa, Jennifer Macadam, Jared Gibbons, Xin Dai

Browse all Datasets

Improving the quality of irrigated pastures can increase the profitability of ruminant production systems. Increasing pasture plant biodiversity is beneficial for ruminants, pollinators, and soil health, but it is challenging to manage weed incursion in seeded mixed-species pastures. This study assessed the weed incursion that resulted when forage legumes or grasses were seeded as binary mixtures with one of four non-legume forbs. Defoliation occurred at 6-week intervals as either mowing or mob grazing. Forbs were chicory, plantain, Lewis flax, or small burnet and forages were alfalfa, birdsfoot trefoil, creeping foxtail, intermediate wheatgrass, kura clover, meadow bromegrass, orchardgrass, perennial ryegrass, reed …

Parrotfeather (Myriophyllum Aquaticum) Identification And Management In Waterways, Jacob Hadfield, Cody Zesiger, Michael Pace, Mirella Ortiz, Corey Ransom

All Current Publications

Parrotfeather (Myriophyllum aquaticum) is an invasive aquatic plant species that grows in ditches, ponds, lakes, and other freshwater habitats. Due to its aggressive nature, parrotfeather will often take over freshwater settings by creating a thick mat covering that prevents sunlight for native aquatic organisms and inhibits regular water flow. This fact sheet discusses identification and management options.

Wild Parsnip (Pastinaca Sativa) Identification And Control In Residential Landscapes, Michael Caron, Taun Beddes, Corey Ransom

All Current Publications

Wild parsnip is a weed that can potentially cause serious injury to gardeners. This fact sheet describes this weed, its lifecycle, and suppression and control options.

Environmental Physiology Of Medical Cannabis, F. Mitchell Westmoreland

All Graduate Theses and Dissertations, Fall 2023 to Present

Cannabis (Cannabis sativa L.) is increasingly being cultivated for industrial and medical uses. Medical cannabis is grown for cannabinoids and terpenes, compounds that continue to show promising therapeutic potential. Cannabidiol (CBD) and delta-9- tetrahydrocannabinol (Δ9-THC) are the two most common cannabinoids, but more than 150 have been identified in cannabis. The 2018 Farm Bill federally legalized cannabis containing less than 0.3% THC and high-THC medical cannabis is legal in 38 states. There is a need to understand environmental effects on yield and quality to ensure safety and quality for medical use.

The cultivation of medical cannabis is centered around …

Cattle Toxicity From Woolly Locoweed (Astragalus Mollissimus): A Case Study In Central New Mexico, Casey N. Spackman, Clint A. Stonecipher, Daniel Cook

Poisonous Plant Research (PPR)

Livestock toxicity resulting from poisonous plants poses a significant challenge for ranchers, particularly concerning locoweeds (Astragalus spp. or Oxytropis spp.). This study investigated a case of cattle poisoning in central New Mexico, where clinical signs were consistent with locoweed toxicity. Rangeland conditions were hot and dry following earlier spring rains, promoting advantageous environmental conditions for a locoweed outbreak. Analysis of Woolly locoweed (Astragalus mollissimus) and animal samples from the ranch confirmed the presence of swainsonine, a key toxin in locoweeds. It can be concluded that the likely cause of cattle losses was locoweed toxicity, highlighting the …

Whitetop (Hoary Cress) Control In Residential Situations, Taun Beddes, Michael Caron, Jacob Hadfield, Corey Ransom

All Current Publications

Whitetop (Lepidium draba, formerly Cardaria draba) is a persistent, perennial weed that grows in open, sunny areas. It spreads by seeds and rhizomes, enabling it to spread by several feet in a single season. It is common in wildlands, agricultural, and residential areas. It rapidly spreads into unhealthy lawns, landscape beds, and vegetable gardens. This fact sheet provides information on identification, lifecycle, landscape damage, and suppression and control options.

Furthering Indaziflam-Based Management Strategies Of Three Invasive Annual Grasses In Northern Utah, Peter Weston Maughan

All Graduate Theses and Dissertations, Fall 2023 to Present

Indaziflam is an herbicide highly recognized for its potential to effectively control weedy, winter germinating grasses, such as downy brome, as the herbicides prevents seed germination for several years. Unfortunately, most of these studies only capture the first 2-3 years of indaziflam’s 3-5 years soil activity. This thesis sought to better understand indaziflam’s long-term effects by monitoring both a healthy ecosystem and a degraded ecosystem for up to 5 years after indaziflam application. A secondary study was also conducted to better understand the potential of revegetation via reseeding in indaziflam treated soils. The study concluded that indaziflam very little long-term …

Demonstration Farm Provides Educational Opportunity For Ipm, Nick Volesky, Mair Murray

Outcomes and Impact Quarterly

The mission of USU Extension’s Integrated Pest Management (IPM) program is to increase the use of sustainable pest management practices within urban and rural landscapes to provide economic, human, and environmental health in Utah. In the spring of 2022, the IPM program established a vegetable farm to test and demonstrate IPM practices. The farm served as an experiential learning classroom for almost 50 farmers and home gardeners.

Helping Utah Landowners Reduce Pesticide Use Through A Statewide Ipm Program, Nick Volesky, Mair Murray

Outcomes and Impact Quarterly

The Utah Integrated Pest Management (IPM) program provides outreach and education to Utahns to reduce pesticide use and ultimately protect human and environmental health. In 2022, the IPM program responded to stakeholders’ needs by partnering with county Extension offices to deliver eight (8) in-person workshops across the state. The workshops connected Extension specialists and county faculty with managers of home landscapes and farms. The objective of the workshops was to provide participants with IPM skills to identify, monitor, and manage pest problems in preparation for the upcoming growing season.

Identification And Management Of Scotch Thistle (Onopordum Acanthium L.) In Pastures, Rangelands, And Non-Crop Settings, Cody Zesiger, Jacob Hadfield, Kalen Taylor, Corey Ransom

All Current Publications

Scotch thistle (Onopordum acanthium) is an invasive species native to Eurasia. It was likely introduced into North America during the late 19th century (Young & Evans, 1969). Due to the plant’s size and prickles, a stand can damage pasture productivity, ruin campsites, or make trails nearly impassable. The thistle also outcompetes desirable plants and greatly reduces forage use by large animals. Since not all thistles are related or alike, it is essential to correctly identify Scotch thistle before making management decisions. This fact sheet provides information about identification, lifecycle and distribution, and management.

Identifying And Managing Dyer's Woad (Isatis Tinctoria) In Pastures, Rangelands, And Non-Crop Settings, Cody Zesiger, Jacob Hadfield, Corey Ransom

All Current Publications

Dyer's woad (Isatis tinctoria) was introduced into Utah during the mid-nineteenth century as a source of indigo dye. The plant escaped cultivation and has spread across rangelands, foothills, and other sites throughout the Intermountain West. This fact sheet provides information about identifying dyer's woad and its lifecycle, distribution, and management in pastures, rangelands, and non-crop settings. It includes information about using appropriate herbicides to control dyer's woad and how to apply them.

An Evaluation Of The Susceptibility Of Goats To Larkspur Toxicosis, Kevin D. Welch, Clint A. Stonecipher, Dale R. Gardner, Benedict T. Green, Daniel Cook

Poisonous Plant Research (PPR)

Larkspurs (Delphinium spp.) are a major cause of cattle losses in western North America, whereas sheep have been shown to be resistant to larkspur toxicosis. Goats are often used as a small ruminant model to study poisonous plants, even though they can be more resistant to some poisonous plants. It is not known how susceptible goats are to the adverse effects of larkspurs. In this study, we evaluated the susceptibility of goats to larkspur toxicosis by performing a dose-response study. We dosed goats with D. barbeyi collected near Cedar City, Utah at 3.3, 4.4, 6.6, 8.8 and 10.0 g …

Molecular Differentiation Of Astragalus Species And Varieties From The Western United States: The Chloroplast Dna Bridge Between Evolution And Molecular Systematics, Marwa Neyaz, Daniel Cook, Rebecca Creamer

Poisonous Plant Research (PPR)

Locoweeds are the most widespread poisonous plant problem in the world and have been reported in the Western United States since the 1800s, causing tremendous losses in livestock. Consumption of locoweeds by grazing animals stimulates the neurological disease, locoism, characterized by weight loss, ataxia, and lack of muscular coordination. The name locoweed is used for Astragalus and Oxytropis species known to contain swainsonine, the toxic principle produced by the plant endophytic fungus Undifilum. Astragalus includes 2,500-3,000 species and many varieties that have almost identical morphological characteristics that overlap among species, leading to improper identification. Therefore, the aim of this study …

The Influence Of Adjacent Weed Populations On Thrips And Iysv In Onion, S. Andrew Swain

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Onion thrips (Thrips tabaci) and Iris Yellow Spot Virus (IYSV) constitute a pest complex of global concern for allium growers. Yield losses due to onion thrips alone can be heavy, and in tandem with IYSV, these losses can be complete.

This study was one phase of a multi-phase research project intent on exploring the potential drivers of thrips and virus infestation in onion. Preliminary observations in participating growers’ fields in northern Utah pointed towards a potential link between weedy field borders and thrips/IYSV infestation in onion. Field work was carried out at the Kaysville experiment station examining the …

Responses Of Canada Thistle To Defoliation And To Damage From A Stem-Mining Weevil In Utah, Wendy Sue Halsey

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The responses of Canada thistle stems to damage by two types of herbivores were investigated to determine the potential role of these herbivores as biological control agents. Canada thistle stems at a cattle exclosure in Rich County, Utah were cut at one to two centimeters aboveground in June, 1991, to mimic grazing by cattle. Neighboring stems within 30 centimeters were also cut in some treatments to investigate the effects of physiologically connected ramets on the growth and reproductive responses of individual focal stems. I measured plant height, stem diameter, and number of flowerheads for each of the focal stems during …