Barley stripe rust is a fungal disease of

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...

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 paras ...

of ''

Puccinia striiformis ''Puccinia striiformis'' var. ''striiformis'' is a 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. Infection can cause losse ...

''. It was first detected in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

in 1991, in northern and eastern

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...

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

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

and western

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

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 pustules appear on

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

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

rye Rye (''Secale cereale'') is a grass grown extensively as a grain, a cover crop and a forage crop. It is a member of the wheat tribe (Triticeae) and is closely related to both wheat (''Triticum'') and barley (genus ''Hordeum''). Rye grain is u ...

, certain wild barleys such as '' Hordeum jubatum'' (foxtail barley),

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

, and numerous

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

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 (sometimes Cascadia, or simply abbreviated as 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 ...

where cool, wet weather greatly favors disease development.

Management

The disease can be managed by growing disease resistant

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...

s. Foliar

fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

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