Blight is a rapid and complete chlorosis, 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 Phytophthora infestans (Mont.) de Bary, the disease which led to the Great Irish Famine
- Southern corn leaf blight, caused by the fungus Cochliobolus heterostrophus (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, caused by an unknown agent, infects all citrus scions.
- Fire blight of pome fruits, caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., is the most severe disease of pear and also is found in apple and raspberry, among others.
- Bacterial leaf blight of rice, caused by the bacterium 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
- Leaf blight of the grasses e.g. Ascochyta species and Alternaria triticina that causes blight in wheat
- Bur oak blight, caused by the fungal pathogen Tubakia iowensis.
- South American leaf blight, caused by the ascomycete Pseudocercospora 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 spots 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, and Phytophthora blight is named after the water mold Phytophthora parasitica.
When blights have been particularly vast and consequential in their effects, they have become named historical events, such as the 19th Century Potato Blight, 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 during the 1940s and 1950s in the event described as The Blight or The Cedar Blight.
Three dead Bermuda cedars in 2019
- Agrios, George N. 2005. Plant Pathology. 5th ed, Burlington, MA: Elsevier Academic Press.
- Partridge, J.E. "Southern Corn Leaf Blight." 2003. 8 August 2006. "Plant Pathology 369 - Southern Corn Leaf Blight Key words: Plant Disease, Bipolaris maydis, Helminthosporium maydis, Cochliobolus heterostrophus,Corn, Sorghum, Teosinte". Archived from the original on 2010-07-23. Retrieved 2012-03-02.
- Oda, M., Sekizawa, Y., and Watanabe, T. 1966. "Phenazines as Disinfectants Against Bacterial Leaf Blight of the Rice Plant." Applied Microbiology 14(3):365-367.
- Tanaka, T.; Katoh, T.; Satoh, T. (2002). "Role of the rice seedlings [Oryza sativa] and Kouyawarabi (Onoclea sensibilis L.) infested with Burkholderia plantarii as the source of bacterial seedling blight of rice". Annals of the Phytopathological Society of Japan (in Japanese). 68 (3): 283–290. doi:10.3186/jjphytopath.68.283. ISSN 0031-9473. Retrieved 15 December 2021.
- Tisserat, N. "Ascochyta Leaf Blight of Turf". Colorado State University. Retrieved 11 September 2019.
- "Alternaria triticina (leaf blight of wheat)". www.cabi.org. 27 September 2018. Retrieved 11 September 2019.
- Guyot, Jean; Le Guen, Vincent (2018). "A Review of a Century of Studies on South American Leaf Blight of the Rubber Tree". Plant Disease. American Phytopathological Society. 102 (6): 1052–1065. doi:10.1094/pdis-04-17-0592-fe. ISSN 0191-2917. PMID 30673445.
- "Pseudocercospora ulei (MICCUL)[Overview]". Global Database. EPPO (European and Mediterranean Plant Protection Organization). 2002-04-09. Retrieved 2021-08-28.
- Erasing the Past: A New Identity for the Damoclean Pathogen Causing South American Leaf Blight of Rubber
- South American Leaf Blight of rubber (Microcyclus ulei), plantwise.org
- Chase, A. R. (1984). "Diseases of Foliage Plants - Revised List 1984". Agricultural Research Center - Apopka, University of Florida. Archived from the original on 30 October 2014.
- Undlin, Siri (2020-12-23). "13 Different Types of Cedar Trees (All Cedar Tree Varieties)". PlantSnap. PlantSnap Inc. Retrieved 2021-10-05.
This tree-covered much of the island, but the forest was decimated first by settlers, and then later by an infestation of scale. It is an event known today as "the blight." This caused a variety of pollinators to become extinct and is a harrowing example of how unchecked human development can cause a catastrophe in the natural world.
- "Speciation at Spittal Pond". Evolving Shores. Explorations in Biology, Bermuda College. Retrieved 2021-10-05.
in the 1940s, two species of scale were accidentally introduced, and, unable to deal with this foreign pest, 95% of Bermuda's cedar trees were killed. The 5% of trees who survived the blight were found to be resistant to the scale. These have been propagated since then, and the Bermuda cedar survives today. Unfortunately the cedar was Bermuda's main tree cover up until the blight, with little diversity to fill the void when the trees died off. Thus, some species who depended on and thrived in its branches, such as bluebirds and white-eyed vireo became critically endangered along with it. Others, such as the endemic cicada went extinct without it.
- Mastny, Lisa. "Bermuda". World Wildlife Fund. World Wildlife Fund. Retrieved 2021-10-05.
An estimated 95 percent of the surviving population of native Bermuda cedar (Juniperus bermudiana) was destroyed between 1946 and 1951 (Rueger and von Wallmenich 1996), following the accidental introduction of two coccoid scale insects (Sterrer 1998a). Only an estimated one percent of the original cedar forest survived the blight (BBP 1997).
- "Bermuda: The Best Places to Get Away from It All in Bermuda". Frommer's. FrommerMedia LLC. Retrieved 2021-10-05.
Seymour's Pond Nature Reserve. Under the management of the Bermuda Audubon Society, this 1-hectare (2 1/2-acre) site attracts the occasional birder as well as romantic couples looking for a little privacy. Just past the pond, you'll spot pepper trees and old cedars that escaped the blight;
- "Leader of fight against tree blight dies". The Royal Gazette. Bermuda. 2011-02-10. Retrieved 2021-10-05.
Mr. Groves, who was made an Officer of the Order of the British Empire for his services to Bermuda and agriculture, was Assistant Director of Agriculture in the late 1940s when a blight decimated the Island's cedar forests.
- Calnan, Patricia (2011-02-10). "Learning about the cedar tree". The Royal Gazette. Bermuda. Retrieved 2021-10-05.
The accidental introduction of the Oyster-shell Scale and the Juniper Scale caused the demise of at least 85 percent of the cedar population by 1951, with more than 100,000 being felled during and after the scale infestation.
- Hardy, Jessie Moniz (2020-10-14). "Dark Bottom, a 1950s haven and horror". The Royal Gazette. Bermuda. Retrieved 2021-10-05.
Dark Bottom, a dense forest of cedar trees just below the lighthouse where he and his friends played.
"It was not scary by day, but at night if you had to cross that going somewhere you made time," the 75-year-old said. "There was no stopping."
He thinks the story was made up to ensure the neighbourhood children were home on time.
"We thought it was extraordinary that the beast had five fingers," he said.
The trees were killed by the cedar blight in the late early 1950s
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- 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.