Rusts are fungal plant pathogens of the order Pucciniales causing plant fungal diseases.
The Agricultural Research Service (ARS) is the principal in-house research agency of the United States Department of Agriculture (USDA). ARS is one of four agencies in USDA's Research, Education and Economics mission area. ARS is charged with extending the nation's scientific knowledge and solving agricultural problems through its four national program areas: nutrition, food safety and quality; animal production and protection; natural resources and sustainable agricultural systems; and crop production and protection. ARS research focuses on solving problems affecting Americans every day. The ARS Headquarters is located in the Jamie L. Whitten Building on Independence Avenue in Washington, D.C., and the headquarters staff is located at the George Washington Carver Center (GWCC) in Beltsville, Maryland. For 2018, its budget was $1.2 billion.
Stem rust, also known as cereal rust, black rust, red rust or red dust, is caused by the fungus Puccinia graminis, which causes significant disease in cereal crops. Crop species that are affected by the disease include bread wheat, durum wheat, barley and triticale. These diseases have affected cereal farming throughout history. The annual recurrence of stem rust of wheat in North Indian plains was discovered by K.C. Mehta. Since the 1950s, wheat strains bred to be resistant to stem rust have become available. Fungicides effective against stem rust are available as well.
Wheat leaf rust is a fungal disease that affects wheat, barley, rye stems, leaves and grains. In temperate zones it is destructive on winter wheat because the pathogen overwinters. Infections can lead up to 20% yield loss. The pathogen is a Puccinia rust fungus. It is the most prevalent of all the wheat rust diseases, occurring in most wheat-growing regions. It causes serious epidemics in North America, Mexico and South America and is a devastating seasonal disease in India. P. triticina is heteroecious, requiring two distinct hosts.
Leptosphaeria sacchari is a plant pathogenic fungus which causes a disease called ring spot on Saccharum officinarum. This species was originally described in 1890 by Kruger and in 1892 by Van Breda de Haan after it was discovered in the Dominican Republic. L. sacchari is the applied name, whereas Epicoccum sorghinum is the accepted name.
Puccinia cacabata is a fungal species and plant pathogen that causes rust on cotton. It was originally found on the leaves of Chloris ciliata in Bolivia.
Puccinia schedonnardii is a basidiomycete fungus that affects cotton. More commonly known as a “rust,” this pathogen typically affects cotton leaves, which can decrease the quality of the boll at time of harvest. As large percentages of cotton in the United States are resistant to various rust varieties, there is little economic importance to this disease. In places where rust is prevalent, however, growers could see up to a 50% reduction in yield due to rust infection.
Cochliobolus victoriae is a fungal plant pathogen. It caused the disease called "victoria blight" affecting oats and similar grains.
Puccinia asparagi is the causative agent of asparagus rust. It is an autoecious fungus, meaning that all stages of its life cycle – pycniospores, aeciospores, and teliospores – all develop upon the same host plant . Rust diseases are among the most destructive plant diseases, known to cause famine following destruction of grains, vegetables, and legumes. Asparagus rust occurs wherever the plant is grown and attacks asparagus plants during and after the cutting season. Asparagus spears are usually harvested before extensive rust symptoms appear. Symptoms are first noticeable on the growing shoots in early summer as light green, oval lesions, followed by tan blister spots and black, protruding blisters later in the season. The lesions are symptoms of Puccinia asparagi during early spring, mid-summer and later summer to fall, respectively. Severe rust infections stunt or kill young asparagus shoots, causing foliage to fall prematurely, and reduce the ability of the plant to store food reserves. The Puccinia asparagi fungus accomplishes this by rust lowering the amounts of root storage metabolites. The infected plant has reduced plant vigor and yield, often leading to death in severe cases. Most rust diseases have several stages, some of which may occur on different hosts; however, in asparagus rust all the life stages occur on asparagus. Because of this, many observers mistake the different stages of the Puccinia asparagi life cycle as the presence of different diseases. The effects of Puccinia asparagi are present worldwide wherever asparagus is being grown. Asparagus rust is a serious threat to the asparagus industry.
Puccinia coronata is a plant pathogen and causal agent of oat and barley crown rust. The pathogen occurs worldwide, infecting both wild and cultivated oats. Crown rust poses a threat to barley production, because the first infections in barley occur early in the season from local inoculum. Crown rusts have evolved many different physiological races within different species in response to host resistance. Each pathogenic race can attack a specific line of plants within the species typical host. For example, there are over 290 races of P. coronata. Crops with resistant phenotypes are often released, but within a few years virulent races have arisen and P. coronata can infect them.
Puccinia helianthi is a macrocyclic and autoecious fungal plant pathogen that causes rust on sunflower. It is also known as "common rust" and "red rust" of sunflower.
Puccinia melanocephala is a fungus and plant pathogen, it is the causal agent of sugarcane rust. It was originally found on the leaves of a species of Arundinaria (cane) in Assam, India.
Puccinia menthae is a fungal plant pathogen that causes rust on mint plants. It was originally found on the leaves of Mentha aquatica.
Puccinia erianthi is a species of fungus and a plant pathogen. It was originally found on the leaves of Erianthus fulvus in Punjab, India. It is a common cause of sugarcane rust.
Puccinia horiana is a species of fungus that causes chrysanthemum white rust, is a disease of plant species of the genus Chrysanthemum.
Puccinia jaceae var. solstitialis is a species of fungus in the Pucciniaceae family. It is a plant pathogen that causes rust. Native to Eurasia, it is the first fungal pathogen approved in the United States as a biological control agent to curb the growth of the invasive weed yellow starthistle.
Wheat yellow rust, also known as wheat stripe rust, is one of the three major wheat rust diseases, along with stem rust of wheat and leaf rust.
Puccinia poarum, a species of fungus, known as the coltsfoot gall rust, or meadow grass rust, is a plant pathogen. This fungal parasite forms a yellow to orange gall, 1–2 cm in diameter, on the underside of leaves of coltsfoot. It also infects but does not gall grasses of the family Poaceae. P. poarum is a genetically diverse species that has been reported on at least seventy plant hosts. It was originally found on Poa fertilis and Poa nemoralis in Denmark in 1877.
Ruth Florence Allen (1879–1963) was an American botanist and plant pathologist and the first woman to earn her Ph.D. in botany from the University of Wisconsin. Her doctorate research focused on the reproduction and cell biology of ferns, particularly the phenomenon of apogamy. Later in her career, Allen shifted her focus to plant pathology. Her major contribution to the field of mycology was furthering the understanding of rust fungi, a group of economically important plant pathogens. Allen completed many studies on Puccinia graminis, once considered a catastrophically damaging disease-causing agent in cereal crops before the discovery of current management measures.
Plant Protection and Quarantine (PPQ) is one of six operational program units within the Animal and Plant Health Inspection Service (APHIS) of the United States Department of Agriculture (USDA). The PPQ works to safeguard agriculture and natural resources in the U.S. against the entry, establishment, and spread of animal and plant pests, and noxious weeds in order to help ensure the protection of native flora and an abundant, high-quality, and varied food supply.
