Barley stripe rust is a fungal disease of

barley Barley (), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains; it was domesticated in the Fertile Crescent around 9000 BC, giving it nonshattering spikele ...

caused by ''Puccinia striiformis'' f. sp. ''hordei''. a

forma specialis ''Forma specialis'' (plural: ''formae speciales''), abbreviated f. sp. (plural ff. spp.) without italics, is an informal taxonomic grouping allowed by the International Code of Nomenclature for algae, fungi, and plants, that is applied to a para ...

of ''

Puccinia striiformis ''Puccinia striiformis'' is a fungal species and plant pathogen. It causes stripe rust on wheat, but has other hosts as well. The species is common in Europe and in more recent years has become a problem in Australia. Crop infections can cause ...

''. It was first detected in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

in 1991, in northern and eastern

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

in 1993, In 1995 it was detected for the first time in western

Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...

and western

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

and is currently considered to be well established there.http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=116 Extension publication - US: Oregon The disease initially develops at a small loci within a field and spreads rapidly and has caused significant losses in areas where climatic conditions are cool and wet.

Symptoms

Infections produce linear, orange-yellow

pustule A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this ...

s appear on

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

and/or heads. As the disease progresses, pustules coalesce to form long stripes between

leaf vein A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...

s. On susceptible cultivars, entire leaf blades may be covered with pustules. The black spore stage develops as linear black pustules covered by the leaf epidermis.

Disease cycle

''Puccinia striiformis'' f. sp. ''hordei'', is an

obligate parasite An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, ...

that overseasons on

volunteer Volunteering is an elective and freely chosen act of an individual or group giving their time and labor, often for community service. Many volunteers are specifically trained in the areas they work, such as medicine, education, or emergency ...

barley or

rye Rye (''Secale cereale'') is a grass grown extensively as a grain, a cover crop and a forage crop. It is grown principally in an area from Eastern and Northern Europe into Russia. It is much more tolerant of cold weather and poor soil than o ...

, certain wild barleys such as ''

Hordeum jubatum ''Hordeum jubatum'', with common names foxtail barley, bobtail barley, squirreltail barley, and intermediate barley, is a perennial plant species in the grass family Poaceae. It occurs wild mainly in northern North America and adjacent northeast ...

'' (foxtail barley),

wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...

, and numerous

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

grass species.http://www.dpi.vic.gov.au/dpi/nreninf.nsf/childdocs/-22C871BE2A0105794A2568B30004D413-3C5B474B480825C8CA256BC700824574-78F1BBD6496F89034A256DEA00274EEC-FC12E4D8B8736B23CA256CF7000B0281?open Extension publication - Australia The disease begins from a very small number of infections that are difficult or impossible to detect in the field. Spread of the pathogen can be explosive and cause significant losses, especially in the

Pacific Northwest The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...

where cool, wet weather greatly favors disease development.

Management

The disease can be managed by growing disease resistant

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s. Foliar

fungicide Fungicides are pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in losses of yield and quality. Fungicides are used both in agriculture and to fight fungal infections in animals, ...

s may be required when growing a susceptible cultivars.

External links

References

{{Authority control Fungal plant pathogens and diseases Barley diseases Puccinia Forma specialis taxa