Blight refers to a specific symptom 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 exclu ...

s in response to infection by a pathogenic

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 "p ...

'' (Mont.) de Bary, the disease which led to the Great Irish Famine * 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 t ...

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 '' Bipolaris maydis'' (Nisikado & Miyake) Shoemaker, incited a severe loss of corn in the United States in 1970. * Chestnut blight, caused by the fungus ''Cryphonectria parasitica'' (Murrill) Barr, has nearly completely eradicated mature American chestnuts 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 amon ...

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 po ...

and also is found in

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

and raspberry, among others. * Bacterial leaf blight of

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...

, 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'' * 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 ''

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 tr ...

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

External links

{{Wiktionary *Berg A. 1926. Tomato Late Blight and its Relation to Late Blight of Potato. *Bonn WG, Zwet TVD. Distribution and economic importance of fire blight. Fire blight: the disease and its causative agent, Erwinia amylovora.:37–53. *Erskine JM. 1973. Characteristics of Erwinia amylovora bacteriophage and its possible role in the epidemiology of fire blight. Canadian Journal of Microbiology; 19(7):837–845. *Johnson KB, Stockwell VO. 1998. MANAGEMENT OF FIRE BLIGHT: A Case Study in Microbial Ecology. Annual Review of Phytopathology 36:227–248. *M. N. Schroth, S. V. Thomson, D. C. Hildebrand, W. J. Moller. 1974. Epidemiology and Control of Fire Blight. Annual Review of Phytopathology, 12:1, 389-412. *Mcmanus PS. 1994. Role of Wind-Driven Rain, Aerosols, and Contaminated Budwood in Incidence and Spatial Pattern of Fire Blight in an Apple Nursery. Plant Disease 78:1059. *Puławska J, Sobiczewski P. 2011. Phenotypic and genetic diversity of Erwinia amylovora: the causal agent of fire blight. Trees 26:3–12. *Rico A, Ortiz-Barredo A, Ritter E, Murillo J. 2004. Genetic characterization of Erwinia amylovora strains by amplified fragment length polymorphism. Journal of Applied Microbiology; 96(2):302–310. *Ritchie DF. 1977. Isolation of Erwinia amylovora Bacteriophage from Aerial Parts of Apple Trees. Phytopathology 77:101. *Steiner PW. 1996. What We Don’t Know About Fire Blight. Acta Horticulture; (411):3–6. *Thomas TM. 1992. Severity of Fire Blight on Apple Cultivars and Strains in Michigan. Plant Disease 76:1049. *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. Mycology Plant pathogens and diseases