Blight refers to a specific

symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

affecting

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

s in response to infection by a

pathogenic In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

Description

Blight is a rapid and complete

chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...

, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this symptom are called blights. Several notable examples are: * Late blight of potato, caused by the

water mold Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result ...

Phytophthora infestans ''Phytophthora infestans'' is an oomycete or water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight. Early blight, caused by ''Alternaria solani'', is also often called "pot ...

'' (Mont.) de Bary, the disease which led to the

Great Irish Famine The Great Famine ( ga, an Gorta Mór ), also known within Ireland as the Great Hunger or simply the Famine and outside Ireland as the Irish Potato Famine, was a period of starvation and disease in Ireland from 1845 to 1852 that constituted a ...

* Southern corn leaf blight, caused by the

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

Cochliobolus heterostrophus ''Cochliobolus heterostrophus'' is a fungal plant pathogen. It can cause southern corn leaf blight in maize. ''Cochliobolus heterostrophus'' is found in many tropical regions and in the southern part of the US. ''Cochliobolus'', although not ...

'' (Drechs.) Drechs,

anamorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

Bipolaris maydis ''Cochliobolus heterostrophus'' is a fungal plant pathogen. It can cause southern corn leaf blight in maize. ''Cochliobolus heterostrophus'' is found in many tropical regions and in the southern part of the US. ''Cochliobolus'', although not c ...

'' (Nisikado & Miyake) Shoemaker, incited a severe loss of corn in the United States in 1970. *

Chestnut blight The pathogenic fungus ''Cryphonectria parasitica'' (formerly ''Endothia parasitica'') is a member of the Ascomycota (sac fungi). This necrotrophic fungus is native to East Asia and South East Asia and was introduced into Europe and North America ...

, caused by the fungus ''Cryphonectria parasitica'' (Murrill) Barr, has nearly completely eradicated mature

American chestnut The American chestnut (''Castanea dentata'') is a large, fast-growing deciduous tree of the beech family native to eastern North America. As is true of all species in genus Castanea, the American chestnut produces burred fruit with edible nuts. ...

s in North America. *

Citrus blight Citrus blight is a type of blight that occurs in tropical and semi-tropical regions. Specializing in infecting citrus trees, the blight is found in North America, the Caribbean, South America, South Africa and Australia. The blight injures plants ...

, caused by an unknown agent, infects all citrus scions. * Fire blight of pome fruits, caused by the

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

Erwinia amylovora Fire blight, also written fireblight, is a contagious disease affecting apples, pears, and some other members of the family Rosaceae. It is a serious concern to apple and pear producers. Under optimal conditions, it can destroy an entire orchard ...

'' (Burrill) Winslow et al., is the most severe disease of

pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the family Rosaceae, bearing the p ...

and also is found in

apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...

and

raspberry The raspberry is the edible fruit of a multitude of plant species in the genus ''Rubus'' of the rose family, most of which are in the subgenus '' Idaeobatus''. The name also applies to these plants themselves. Raspberries are perennial with w ...

, among others. * Bacterial leaf blight of

rice Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima ''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...

, caused by the bacterium ''

Xanthomonas oryzae ''Xanthomonas oryzae'' is a species of bacteria. The major host of the bacterium is rice. The species contains two pathovars, neither of which is native to Europe: ''X. o.'' pv. ''oryzae'' and ''X. o.'' pv. ''oryzicola''. ''Xanthomonas oryzae ...

'' (Uyeda & Ishiyama) Dowson. * Bacterial seedling blight of rice (''Oryza sativa''), caused by pathogen ''

Burkholderia plantarii ''Burkholderia plantarii'' is a Gram-negative soil bacterium. Its specific name comes from the Latin ''plantarium'' (seedbed).Garrity, George M.; Brenner, Don J.; Krieg, Noel R.; Staley, James T. (eds.) (2005). Bergey's Manual of Systematic Bacte ...

'' * Early blight of potato and tomato, caused by species of the ubiquitous fungal genus ''

Alternaria ''Alternaria'' is a genus of Deuteromycetes fungi. All species are known as major plant pathogens. They are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead to asthma. They ...

'' * Leaf blight of the grasses e.g. ''

Ascochyta ''Ascochyta'' is a genus of ascomycete fungi, containing several species that are pathogenic to plants, particularly cereal crops. The taxonomy of this genus is still incomplete. The genus was first described in 1830 by Marie-Anne Libert, w ...

'' species and ''

Alternaria triticina ''Alternaria triticina'' is a fungal plant pathogen that causes leaf blight on wheat. ''A. triticina'' is responsible for the largest leaf blight issue in wheat and also causes disease in other major cereal grain crops. It was first identified ...

'' that causes blight in wheat *

Bur oak blight Bur oak blight (BOB) is a fungal disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are ...

, caused by the fungal pathogen ''Tubakia iowensis''. * South American leaf blight, caused by the

ascomycete Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...

Pseudocercospora ''Pseudocercospora'' is a genus of ascomycete fungi. An anamorphic version of the genus ''Mycosphaerella'', ''Pseudocercospora'' species are plant pathogens, including the causal agent of the so-called South American leaf blight of the rubber tre ...

ulei'', also called ''Microcyclus ulei'', ended the cultivation of the rubber tree (''

Hevea brasiliensis ''Hevea brasiliensis'', the Pará rubber tree, ''sharinga'' tree, seringueira, or most commonly, rubber tree or rubber plant, is a flowering plant belonging to the spurge family Euphorbiaceae Euphorbiaceae, the spurge family, is a large fami ...

'') in South America. On leaf tissue, symptoms of blight are the initial appearance of lesions which rapidly engulf surrounding tissue. However,

leaf spot A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions ...

s may, in advanced stages, expand to kill entire areas of leaf tissue and thus exhibit blight symptoms. Blights are often named after their causative agent. For example, ''Colletotrichum'' blight is named after the fungus ''

Colletotrichum capsici ''Colletotrichum capsici'' is a species of fungus and plant pathogen which causes leaf blight on ''Chlorophytum borivilianum'', basil, chickpea and pepper as well as dieback in pigeonpea and anthracnose in poinsettia The poinsettia ( or ) ...

'', and ''Phytophthora'' blight is named after the water mold ''

Phytophthora parasitica ''Phytophthora nicotianae'' or black shank is an oomycete belonging to the order Peronosprales and family Peronosporaceae. Hosts and symptoms ''Phytophthora nicotianae'' has a broad host range comprising 255 genera from 90 families. Hosts incl ...

''. When blights have been particularly vast and consequential in their effects, they have become named historical events, such as the 19th Century

Potato Blight ''Phytophthora infestans'' is an oomycete or water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight. Early blight, caused by ''Alternaria solani'', is also often called "po ...

, also known locally from its primary consequence as the ''Great famine'', the Great Famine of Ireland, and Highland Potato Famine, and the near extinction of the

Bermuda cedar ''Juniperus bermudiana'' is a species of juniper endemic to Bermuda. This species is most commonly known as Bermuda cedar, but is also referred to as Bermuda juniper (Bermudians refer to it simply as ''cedar''). Historically, this tree formed wo ...

during the 1940s and 1950s in the event described as ''The Blight'' or ''The Cedar Blight''.

Gallery

File:Chestnut blight.jpg, Chestnut blight File:Brown Felt Blight.jpg, Brown felt blight File:Late blight on potato leaf 2.jpg, Potato late blight File:Fire blight appletree fruit closeup.JPG, Fire blight appletree fruit File:Three dead Bermuda cedars (Juniperus bermudiana) at Prospect Camp, Bermuda in 2019.jpg, Three dead Bermuda cedars in 2019

References

Vanneste JL. What is fire blight? Who is Erwinia amylovora? How to control it? Fire blight: the disease and its causative agent, Erwinia amylovora.:1–6.

External links

* * {{Wiktionary-inline Plant pathogens and diseases Mycology