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Salix alba, the white willow, is a species of willow native to Europe and western and central Asia. The name derives from the white tone to the undersides of the leaves.
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 often have a centre of necrosis. Symptoms can overlap across causal agents, however differing signs and symptoms of certain pathogens can lead to the diagnosis of the type of leaf spot disease. Prolonged wet and humid conditions promote leaf spot disease and most pathogens are spread by wind, splashing rain or irrigation that carry the disease to other leaves.
Stewart's wilt is a bacterial disease of corn caused by the bacterium Pantoea stewartii. The disease is also known as bacterial wilt or bacterial leaf blight and has been shown to be quite problematic in sweet corn. The causal organism is a facultatively anaerobic, gram-negative, rod-shaped bacterium. The disease is endemic in the mid-Atlantic and Ohio River Valley regions and in the southern portion of the Corn Belt. Stewart's Wilt causes minor reductions in field corn yield, despite common occurrence, because most hybrids grown in the Midwest have adequate resistance. However, the disease can be problematic in seed production because many countries have restrictions on maize seed from areas where the Stewart's Wilt occurs.
Salix pentandra, the bay willow, is a species of willow native to northern Europe and northern Asia. The scientific name refers to the male flowers having five stamens. The English name derives from the resemblance of the leaves to those of the bay laurel; other common names include bay-leaved willow and laurel willow. Its glossy leaves make it more decorative than many other willows, so it is often planted as an ornamental tree.
Dickeya dadantii is a gram-negative bacillus that belongs to the family Pectobacteriaceae. It was formerly known as Erwinia chrysanthemi but was reassigned as Dickeya dadantii in 2005. Members of this family are facultative anaerobes, able to ferment sugars to lactic acid, have nitrate reductase, but lack oxidases. Even though many clinical pathogens are part of the order Enterobacterales, most members of this family are plant pathogens. D. dadantii is a motile, nonsporing, straight rod-shaped cell with rounded ends, much like the other members of the genus, Dickeya. Cells range in size from 0.8 to 3.2 μm by 0.5 to 0.8 μm and are surrounded by numerous flagella (peritrichous).
Xylella fastidiosa is an aerobic, Gram-negative bacterium of the genus Xylella. It is a plant pathogen, that grows in the water transport tissues of plants and is transmitted exclusively by xylem sap-feeding insects such as sharpshooters and spittlebugs. Many plant diseases are due to infections of X. fastidiosa, including bacterial leaf scorch, oleander leaf scorch, coffee leaf scorch (CLS), alfalfa dwarf, phony peach disease, and the economically important Pierce's disease of grapes (PD), olive quick decline syndrome (OQDS), and citrus variegated chlorosis (CVC). While the largest outbreaks of X. fastidiosa–related diseases have occurred in the Americas and Europe, this pathogen has also been found in Taiwan, Israel, and a few other countries worldwide.
Pseudomonas viridiflava is a fluorescent, Gram-negative, soil bacterium that is pathogenic to plants. It was originally isolated from the dwarf or runner bean, in Switzerland. Based on 16S rRNA analysis, P. viridiflava has been placed in the P. syringae group. Following ribotypical analysis misidentified strains of Pseudomonas syringae pv. ribicola and Pseudomonas syringae pv. primulae were incorporated into this species. This pathogen causes bacterial blight of Kiwifruit.
Ralstonia solanacearum is an aerobic non-spore-forming, Gram-negative, plant pathogenic bacterium. R. solanacearum is soil-borne and motile with a polar flagellar tuft. It colonises the xylem, causing bacterial wilt in a very wide range of potential host plants. It is known as Granville wilt when it occurs in tobacco. Bacterial wilts of tomato, pepper, eggplant, and Irish potato caused by R. solanacearum were among the first diseases that Erwin Frink Smith proved to be caused by a bacterial pathogen. Because of its devastating lethality, R. solanacearum is now one of the more intensively studied phytopathogenic bacteria, and bacterial wilt of tomato is a model system for investigating mechanisms of pathogenesis. Ralstonia was until recently classified as Pseudomonas, with similarity in most aspects, except that it does not produce fluorescent pigment like Pseudomonas. The genomes from different strains vary from 5.5 Mb up to 6 Mb, roughly being 3.5 Mb of a chromosome and 2 Mb of a megaplasmid. While the strain GMI1000 was one of the first phytopathogenic bacteria to have its genome completed, the strain UY031 was the first R. solanacearum to have its methylome reported. Within the R. solanacearum species complex, the four major monophyletic clusters of strains are termed phylotypes, that are geographically distinct: phylotypes I-IV are found in Asia, the Americas, Africa, and Oceania, respectively.
Brenneria is a genus of Pectobacteriaceae, containing mostly pathogens of woody plants. This genus is named after the microbiologist Don J. Brenner.
Clavibacter michiganensis is an aerobic non-sporulating Gram-positive plant pathogenic actinomycete of the genus Clavibacter. Clavibacter michiganensis has several subspecies. Clavibacter michiganensis subsp. michiganensis causes substantial economic losses worldwide by damaging tomatoes and potatoes.
Curtobacterium flaccumfaciens is a Gram-positive bacterium that causes disease on a variety of plants. Gram-positive bacteria characteristics include small irregular rods, lateral flagella, the ability to persist in aerobic environments, and cells containing catalase. In the interest of studying pathogenicity in plants, this species is broken down further into pathovars, which help to better describe the pathogen.
A wilt disease is any number of diseases that affect the vascular system of plants. Attacks by fungi, bacteria, and nematodes can cause rapid killing of plants, large tree branches or even entire trees.
Black rot, caused by the bacterium Xanthomonas campestris pv. campestris (Xcc), is considered the most important and most destructive disease of crucifers, infecting all cultivated varieties of brassicas worldwide. This disease was first described by botanist and entomologist Harrison Garman in Lexington, Kentucky, US in 1889. Since then, it has been found in nearly every country in which vegetable brassicas are commercially cultivated.
Dickeya solani is a bacterium that causes blackleg and soft rot in potato crops. Its symptoms are often indistinguishable from those caused by Pectobacterium but is more virulent, causing disease from lower levels of inoculum and spreading through the plant more effectively.
Bacterial wilt of turfgrass is the only known bacterial disease of turf. The causal agent is the Gram negative bacterium Xanthomonas translucens pv. graminis. The first case of bacterial wilt of turf was reported in a cultivar of creeping bentgrass known as Toronto or C-15, which is found throughout the midwestern United States. Until the causal agent was identified in 1984, the disease was referred to simply as C-15 decline. This disease is almost exclusively found on putting greens at golf courses where extensive mowing creates wounds in the grass which the pathogen uses in order to enter the host and cause disease.
Bacterial wilt of carnations is a bacterial disease caused by the plant pathogen Paraburkholderia caryophylli. Previously named Pseudomonas caryophilli, the pathogen is an aerobic gram negative bacteria known for only being capable of entering its host through wounds. Once inside the host, it colonizes the vascular system and roots causing symptoms such as, internal stem cracking, yellowing of the leaves, wilting, and the development of cankers. As a bacterial disease, bacterial wilt of carnations can also be characterized by signs such as bacterial streaming, and bacterial ooze.
Xanthomonas oryzae pv. oryzae is a bacterial pathovar that causes a serious blight of rice, other grasses, and sedges.
Melampsora amygdalinae is a fungal pathogen and part of the division Basidiomycota. It is known as a rust fungus that is host specific. M. amygdalinae commonly infects willows of the genus Salix. This fungus was first discovered in 1909 by Heinrich Klebahn who was a professor of soil biology in Hamburg. Neimi at el. explain how the pathogen occurs throughout the whole distribution of the host, and the small natural populations are an area of interest. This rust fungus is annual and autoecious, which references the fungus spending its entire life in a single host.
Clavibacter insidiosus is a species of Clavibacter. It causes bacterial wilt, with its most notable host being Medicago sativa (alfalfa). Other species in the Medicago genus are also known to be hosts such as Medicago falcata. Additionally, Lotus corniculatus, Melilotus alba, Onobrychis viciifolia, and Trifolium sp. are known hosts.
Clavibacter sepedonicus is a species of bacteria in the genus Clavibacter. C. sepedonicus is a high-profile alien plant pathogen of A2 Quarantine status affecting only potatoes. It causes a disease in potatoes known as 'ring rot' due to the way it rots vascular tissue inside potato tubers It is present in parts of Europe but is under statutory control under 'Council Directive 93/85/EEC' of 4 October 1993 on the control of potato ring rot. This means that if an outbreak occurs, the outbreak must be controlled and if possible the disease has to be eradicated. If necessary, prohibitions are put into place to prevent further spread.
References
- ↑ PCR-Based Detection of the Causal Agent of Watermark Disease in Willows, authors: L. Hauben, M. Steenackers, and J. Swings; Applied and Environmental Microbiology, October 1998, p.3966-3971, Vol.64, No.10
- 1 2 Willow Resistance to the Watermark Disease, author: M. Steenackers. "Research Institute for Nature and Forest". Archived from the original on 2011-07-19. Retrieved 2009-02-18.
- 1 2 Turner, J. G.; Davis, J. M. L.; Guven, K. (January 1992). "Watermark disease of tree willows". Proceedings of the Royal Society of Edinburgh, Section B. 98: 105–117. doi:10.1017/S026972700000748X. ISSN 2053-5910.
- ↑ "Brenneria salicis (watermark)". www.cabi.org. Retrieved 2017-10-24.
- ↑ Gremmen, J.; Kam, M. de (1981-10-01). "New developments in research into the Watermark disease of White willow (Salix alba) in the Netherlands". European Journal of Forest Pathology. 11 (5–6): 334–339. doi:10.1111/j.1439-0329.1981.tb00103.x. ISSN 1439-0329.
- ↑ Sakamoto; Takikawa; Sasaki (1999-10-01). "Occurrence of watermark disease of willows in Japan". Plant Pathology. 48 (5): 613–619. doi:10.1046/j.1365-3059.1999.00368.x. ISSN 1365-3059.
- ↑ Maes, Martine; Huvenne, Hanneke; Messens, Eric (June 2009). "Brenneria salicis, the bacterium causing watermark disease in willow, resides as an endophyte in wood". Environmental Microbiology. 11 (6): 1453–1462. doi:10.1111/j.1462-2920.2009.01873.x. ISSN 1462-2920. PMID 19220404.
- ↑ Patrick, K.N. (January 1991). "Watermark Disease of Cricket Bat Willow: Guidelines for Growers" (PDF). Archived from the original (PDF) on 2017-10-24. Retrieved 2017-10-24.