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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. The archaeological record suggests that wheat was first cultivated in the regions of the Fertile Crescent around 9600 BC. Botanically, the wheat kernel is a caryopsis, a type of fruit.
Rusts are fungal plant pathogens of the order Pucciniales causing plant fungal diseases.
Triticale is a hybrid of wheat (Triticum) and rye (Secale) first bred in laboratories during the late 19th century in Scotland and Germany. Commercially available triticale is almost always a second-generation hybrid, i.e., a cross between two kinds of primary (first-cross) triticales. As a rule, triticale combines the yield potential and grain quality of wheat with the disease and environmental tolerance of rye. Only recently has it been developed into a commercially viable crop. Depending on the cultivar, triticale can more or less resemble either of its parents. It is grown mostly for forage or fodder, although some triticale-based foods can be purchased at health food stores and can be found in some breakfast cereals.
Fusarium ear blight (FEB), is a fungal disease of cereals, including wheat, barley, oats, rye and triticale. FEB is caused by a range of Fusarium fungi, which infects the heads of the crop, reducing grain yield. The disease is often associated with contamination by mycotoxins produced by the fungi already when the crop is growing in the field. The disease can cause severe economic losses as mycotoxin-contaminated grain cannot be sold for food or feed.
Oryza sativa, also known as rice, is the plant species most commonly referred to in English as rice. It is the type of farmed rice whose cultivars are most common globally, and was first domesticated in the Yangtze River basin in China 13,500 to 8,200 years ago.
Magnaporthe grisea, also known as rice blast fungus, rice rotten neck, rice seedling blight, blast of rice, oval leaf spot of graminea, pitting disease, ryegrass blast, Johnson spot, neck blast, wheat blast and Imochi (稲熱), is a plant-pathogenic fungus and model organism that causes a serious disease affecting rice. It is now known that M. grisea consists of a cryptic species complex containing at least two biological species that have clear genetic differences and do not interbreed. Complex members isolated from Digitaria have been more narrowly defined as M. grisea. The remaining members of the complex isolated from rice and a variety of other hosts have been renamed Magnaporthe oryzae, within the same M. grisea complex. Confusion on which of these two names to use for the rice blast pathogen remains, as both are now used by different authors.
Avena sterilis is a species of grass weed whose seeds are edible. Many common names of this plant refer to the movement of its panicle in the wind.
The cereal grain wheat is subject to numerous wheat diseases, including bacterial, viral and fungal diseases, as well as parasitic infestations.
Stem rust, also known as cereal rust, black rust, red rust or red dust, is caused by the fungus Puccinia graminis, which causes significant disease in cereal crops. Crop species that are affected by the disease include bread wheat, durum wheat, barley and triticale. These diseases have affected cereal farming throughout history. The annual recurrence of stem rust of wheat in North Indian plains was discovered by Prof. K.C. Mehta. Since the 1950s, wheat strains bred to be resistant to stem rust have become available. Fungicides effective against stem rust are available as well.
Wheat leaf rust is a fungal disease that affects wheat, barley, rye stems, leaves and grains. In temperate zones it is destructive on winter wheat because the pathogen overwinters. Infections can lead up to 20% yield loss. The pathogen is a Puccinia rust fungus. It is the most prevalent of all the wheat rust diseases, occurring in most wheat-growing regions. It causes serious epidemics in North America, Mexico and South America and is a devastating seasonal disease in India. P. triticina is heteroecious, requiring two distinct hosts.
The Russian wheat aphid is an aphid that can cause significant losses in cereal crops. The species was introduced to the United States in 1986 and is considered an invasive species there. This aphid is pale green and up to 2 mm long. Cornicles are very short, rounded, and appear to be lacking. There is an appendage above the cauda giving the aphid the appearance of having two tails. The saliva of this aphid is toxic to the plant and causes whitish striping on cereal leaves. Feeding by this aphid will also cause the flag leaf to turn white and curl around the head causing incomplete head emergence. Its host plants are cereal grain crops including wheat and barley and to a lesser extent, wild grasses such as wheatgrasses, brome-grasses, ryegrasses and anything in the grass family.
Blumeria graminis is a fungus that causes powdery mildew on grasses, including cereals. It is the only species in the genus Blumeria. It has also been called Erysiphe graminis and Oidium monilioides or Oidium tritici.
Eyespot is an important fungal disease of wheat caused by the necrotrophic fungus Tapesia yallundae and Tapesia acuformis. It is also called Strawbreaker. Eyespot is more severe where wheat is grown continuously and when the weather is cool and moist. Treating crops against eyespot with fungicide costs millions to farmers and is complicated by the pathogen becoming resistant to the more commonly used fungicides. Severe cases of the disease can reduce yield by up to 40%. It is most common in temperate regions such as North and South America, Europe, Australia, New Zealand and Africa.
Tapesia yallundae is the causal agent for a variety of cereal and forage grass diseases. The anamorph of T. yallundae is the W-type strain of Pseudocercosporella herpotrichoides. The R-type strain of Pseudocercosporella herpotrichoides is now known as Tapesia acuformis.
Ug99 is a lineage of wheat stem rust, which is present in wheat fields in several countries in Africa and the Middle East and is predicted to spread rapidly through these regions and possibly further afield, potentially causing a wheat production disaster that would affect food security worldwide. In 2005 the noted green revolution pioneer Norman Borlaug brought great attention to the problem, and most subsequent efforts can be traced to his advocacy. It can cause up to 100% crop losses and is virulent against many resistance genes which have previously protected wheat against stem rust.
Barley, 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 production is used as animal fodder, while 30% as a source of fermentable material for beer and certain distilled beverages, and as a component of various foods. It is used in soups and stews, and in barley bread of various cultures. Barley grains are commonly made into malt in a traditional and ancient method of preparation.
Thinopyrum intermedium, known commonly as intermediate wheatgrass, is a sod-forming perennial grass in the Triticeae tribe of Pooideae native to Europe and Western Asia. It is part of a group of plants commonly called wheatgrasses because of the similarity of their seed heads or ears to common wheat. However, wheatgrasses generally are perennial, while wheat is an annual. It has gained the Royal Horticultural Society's Award of Garden Merit as an ornamental.
Plant disease resistance protects plants from pathogens in two ways: by pre-formed structures and chemicals, and by infection-induced responses of the immune system. Relative to a susceptible plant, disease resistance is the reduction of pathogen growth on or in the plant, while the term disease tolerance describes plants that exhibit little disease damage despite substantial pathogen levels. Disease outcome is determined by the three-way interaction of the pathogen, the plant and the environmental conditions.
Wheat yellow rust, also known as wheat stripe rust, is one of the three major wheat rust diseases, along with stem rust of wheat and leaf rust.
Mary Dilys Glynne was a British plant pathologist and mountaineer.
References
- ↑ Albertini, Catherine; Gredt, Michel; Leroux, Pierre (1999-05-01). "Mutations of the β-Tubulin Gene Associated with Different Phenotypes of Benzimidazole Resistance in the Cereal Eyespot Fungi Tapesia yallundae and Tapesia acuformis". Pesticide Biochemistry and Physiology . 64 (1): 17–31. doi:10.1006/pest.1999.2406. ISSN 0048-3575.
- ↑ Uslu, Emel; Miller, Terry E.; Rezanoor, Navideh H.; Nicholson, Paul (1998-09-01). "Resistance of Dasypyrum villosum to the cereal eyespot pathogens, Tapesia yallundae and Tapesia acuformis". Euphytica . 103 (2): 203. doi:10.1023/A:1018340018838. ISSN 1573-5060. S2CID 37989082.
- ↑ Jones, Stephen; Murray, Timothy; Allan, Robert (1995). "Use of Alien Genes for the Development of Disease Resistance in Wheat". Annual Review of Phytopathology . Annual Reviews. 33 (1): 429–443. doi:10.1146/annurev.py.33.090195.002241. ISSN 0066-4286.