Blight
Encyclopedia
Blight refers to a specific symptom
affecting plant
s in response to infection by a pathogenic organism
. It is simply a rapid and complete chlorosis, browning, then death of plant tissue
s such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this symptom are called blights. Several notable examples are:
On leaf tissue, symptoms of blight are the initial appearance of lesions which rapidly engulf surrounding tissue. However, leaf spot
may, in advanced stages, expand to kill entire areas of leaf tissue and thus exhibit blight symptoms.
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
affecting plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s in response to infection by a pathogenic organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
. It is simply a rapid and complete chlorosis, browning, then death of plant tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
s 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 potatoPhytophthora infestansPhytophthora infestans is an oomycete that causes the serious potato disease known as late blight or potato blight. . Late blight was a major culprit in the 1840s European, the 1845 Irish and 1846 Highland potato famines...
, caused by the water mold Phytophthora infestansPhytophthora infestansPhytophthora infestans is an oomycete that causes the serious potato disease known as late blight or potato blight. . Late blight was a major culprit in the 1840s European, the 1845 Irish and 1846 Highland potato famines...
(Mont.) de Bary, the disease which led to the Great Irish Famine - Southern corn leaf blight, caused by the fungusFungusA fungus is a member of a large 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, Fungi, which is separate from plants, animals, and bacteria...
Cochliobolus heterostrophusCochliobolus heterostrophusCochliobolus heterostrophus is a fungal plant pathogen. It can cause Southern Corn Leaf Blight in Maize.Cochliobolus heterstrophus is found in many tropical regions and in the southern part of the US. Cochliobolus, although not currently the most economically serious disease, can be a very...
(Drechs.) Drechs, anamorph Bipolaris maydis (Nisikado & Miyake) by the bacterium Erwinia amylovora (Burrill) Winslow et al., is the most severe disease of pearPearThe pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
and also is found in appleAppleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
and raspberryRaspberryThe raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves...
, among others. - Bacterial leaf blight of riceRiceRice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
, caused by the bacterium Xanthomonas oryzaeXanthomonas oryzaeXanthomonas oryzae is a species of proteobacteria. The major host of the bacteria is rice .The species contains two pathovars which are non-European: Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv...
(Uyeda & Ishiyama) Dowson. - Early blight of potato and tomato, caused by species of the ubiquitous fungal genus AlternariaAlternariaAlternaria is a genus of ascomycete fungi. Alternaria 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...
- Leaf blight of the grasses
On leaf tissue, symptoms of blight are the initial appearance of lesions which rapidly engulf surrounding tissue. However, leaf spot
Leaf spot
Leaf spots are round blemishes found on the leaves of many species of plants, mostly caused by parasitic fungi or bacteria.A typical spot is "zonal", meaning it has a definite edge and often has a darker border. When lots of spots are present, they can grow together and become a blight or a blotch...
may, in advanced stages, expand to kill entire areas of leaf tissue and thus exhibit blight symptoms.