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Bacterial Leaf Scorch
Bacterial leaf scorch (commonly abbreviated BLS, also called bacterial leaf spot) is a disease state affecting many crops, caused mainly by the xylem-plugging bacterium ''Xylella fastidiosa''. It can be mistaken for ordinary ''leaf scorch'' caused by cultural practices such as over-fertilization. Hosts BLS can be found on a wide variety of hosts, ranging from ornamental trees (elm, maple, oak) and shrubs, to crop species including blueberry and almond. Bacterial spot of peppers and tomatoes Bacterial spot of peppers and tomatoes is caused by the bacteria ''Xanthomonas campestris'' pv. ''vesicatoria''. Bacterial spot of peaches Bacterial spot of peaches is caused by the bacteria ''Xanthomonas campestris'' pv. ''pruni''. Spots may form on the leaves and they can be mistaken for ''peach scab'', which is caused by a fungus. Bacterial spot of pecans Symptoms An irregular browning leaf margin which may or may not be bordered by a pale halo.http://www.usna.usda.gov/Rese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylella Fastidiosa
''Xylella fastidiosa'' is an aerobic, Gram-negative bacterium, Gram-negative bacterium of the genus ''Xylella''. It is a plant pathogen, that grows in the water transport tissues of plants (Xylem, xylem vessels) and is transmitted exclusively by xylem sap-feeding insects such as Sharpshooter (insect), sharpshooters and Aphrophoridae, 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. ''Xylella fastidiosa'' can infect an extremely wide range of plants, many of which do not show any symptoms of disease. Dise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leafhopper
A leafhopper is the common name for any species from the family Cicadellidae. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or trees. Their hind legs are modified for jumping, and are covered with hairs that facilitate the spreading of a secretion over their bodies that acts as a water repellent and carrier of pheromones. They undergo a partial metamorphosis, and have various host associations, varying from very generalized to very specific. Some species have a cosmopolitan distribution, or occur throughout the temperate and tropical regions. Some are pests or vectors of plant viruses and phytoplasmas. The family is distributed all over the world, and constitutes the second-largest hemipteran family, with at least 20,000 described species. They belong to a lineage traditionally treated as infraorder Cicadomorpha in the suborder Auchenorrhyncha, but as the latter taxon is probably not monophyletic, many modern au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylem
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from the Ancient Greek word (''xylon''), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858. Structure The most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called ''vessels''. Xylem also contains two other type of cells: parenchyma and fibers. Xylem can be found: * in vascular bundles, present in non-woody plants and non-woody parts of woody plants * in secondary xylem, laid down by a meristem called the vascular cambium in woody plants * as part of a stelar arrangement n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaf Scorch
Leaf scorch (also called leaf burn, leaf wilt, and sun scorch) is defined as a browning of plant tissues, including leaf margins and tips, and yellowing or darkening of veins which may lead to eventual wilting and abscission of the leaf. Causes Leaf scorch can be caused by soil compaction (agriculture), soil compaction, transplant shock, nutrient deficiency, nutrient excess, drought, salt toxicity, injury, and disease injury.[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maple
''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http://www.mobot.org/MOBOT/research/APweb/. There are approximately 132 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America. Only one species, ''Acer laurinum'', extends to the Southern Hemisphere.Gibbs, D. & Chen, Y. (2009The Red List of Maples Botanic Gardens Conservation International (BGCI) The type species of the genus is the sycamore maple, '' Acer pseudoplatanus'', the most common maple species in Europe.van Gelderen, C. J. & van Gelderen, D. M. (1999). ''Maples for Gardens: A Color Encyclopedia'' Maples usually have easily recognizable palmate leaves ('' Acer negundo'' is an exception) and distinctive winged fruits. The closest relatives of the maples are the horse c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blueberry
Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section ''Cyanococcus'' within the genus ''Vaccinium''. ''Vaccinium'' also includes cranberries, bilberries, huckleberries and Madeira blueberries. Commercial blueberries—both wild (lowbush) and cultivated (highbush)—are all native to North America. The highbush varieties were introduced into Europe during the 1930s. Blueberries are usually prostrate shrubs that can vary in size from to in height. In commercial production of blueberries, the species with small, pea-size berries growing on low-level bushes are known as "lowbush blueberries" (synonymous with "wild"), while the species with larger berries growing on taller, cultivated bushes are known as "highbush blueberries". Canada is the leading producer of lowbush blueberries, while the United States produces some 40% of the world supply of highbush blueberries. Origin and h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Almond
The almond (''Prunus amygdalus'', syn. ''Prunus dulcis'') is a species of tree native to Iran and surrounding countries, including the Levant. The almond is also the name of the edible and widely cultivated seed of this tree. Within the genus ''Prunus'', it is classified with the peach in the subgenus ''Amygdalus'', distinguished from the other subgenera by corrugations on the shell (endocarp) surrounding the seed. The fruit of the almond is a drupe, consisting of an outer hull and a hard shell with the seed, which is not a true nut. ''Shelling'' almonds refers to removing the shell to reveal the seed. Almonds are sold shelled or unshelled. Blanched almonds are shelled almonds that have been treated with hot water to soften the seedcoat, which is then removed to reveal the white embryo. Once almonds are cleaned and processed, they can be stored over time. Almonds are used in many food cuisines, often featuring prominently in desserts, such as marzipan. The almond tree p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthomonas Campestris Pv
''Xanthomonas'' (from greek: ''xanthos'' – “yellow”; ''monas'' – “entity”) is a genus of bacteria, many of which cause plant diseases. There are at least 27 plant associated ''Xanthomonas spp.'', that all together infect at least 400 plant species. Different species typically have specific host and/or tissue range and colonization strategies. Taxonomy The genus ''Xanthomonas'' has been subject of numerous taxonomic and phylogenetic studies and was first described as ''Bacterium vesicatorium'' as a pathogen of pepper and tomato in 1921. Dowson later reclassified the bacterium as ''Xanthomonas campestris'' and proposed the genus ''Xanthomonas''.''Xanthomonas'' was first described as a monotypic genus and further research resulted in the division into two groups, A and B. Later work using DNA:DNA hybridization has served as a framework for the general ''Xanthomonas'' species classification. Other tools, including multilocus sequence analysis and amplified fragment-length ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halo (optical Phenomenon)
A halo is an optical phenomenon produced by light (typically from the Sun or Moon) interacting with ice crystals suspended in the atmosphere. Halos can have many forms, ranging from colored or white rings to arcs and spots in the sky. Many of these appear near the Sun or Moon, but others occur elsewhere or even in the opposite part of the sky. Among the best known halo types are the circular halo (properly called the 22° halo), light pillars, and sun dogs, but many others occur; some are fairly common while others are extremely rare. The ice crystals responsible for halos are typically suspended in cirrus or cirrostratus clouds in the upper troposphere (), but in cold weather they can also float near the ground, in which case they are referred to as diamond dust. The particular shape and orientation of the crystals are responsible for the type of halo observed. Light is reflected and refracted by the ice crystals and may split into colors because of dispersion. The crystals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree Crown
The crown of a plant refers to the total of an individual plant's aboveground parts, including stems, leaves, and reproductive structures. A plant community canopy consists of one or more plant crowns growing in a given area. The crown of a woody plant (tree, shrub, liana) is the branches, leaves, and reproductive structures extending from the trunk or main stems. Shapes of crowns are highly variable. The major types for trees are the excurrent branching habit resulting in conoid shapes and decurrent (deliquescent) branching habit, resulting in round shapes. Crowns are also characterized by their width, depth, surface area, volume, and density. Measurements of crowns are important in quantifying and qualifying plant health, growth stage, and efficiency. Major functions of the crown include light energy assimilation, carbon dioxide absorption and release of oxygen via photosynthesis, energy release by respiration, and movement of water to the atmosphere by transpiration. Thes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylem
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from the Ancient Greek word (''xylon''), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858. Structure The most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called ''vessels''. Xylem also contains two other type of cells: parenchyma and fibers. Xylem can be found: * in vascular bundles, present in non-woody plants and non-woody parts of woody plants * in secondary xylem, laid down by a meristem called the vascular cambium in woody plants * as part of a stelar arrangement n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilizer Burn
Fertilizer burns occur when the use of too much fertilizer, the wrong type of fertilizer, or too little water with a fertilizer causes damage to a plant. Although fertilizer is used to help a plant grow by providing nutrients, too much will result in excess salt, nitrogen, or ammonia which have adverse effects on a plant. An excess of these nutrients can damage the plant's ability to photosynthesize and cellularly respire, causing visible burns. The intensity of burns determine the strategy for recovery. Background Fertilizers contain nutrients that increase plant growth by increasing the rate of photosynthesis (the process in which plants uptake water and nutrients to create sugar) and cellular respiration (the process in which carbon dioxide and sugar is broken down to be used as energy, releasing oxygen). Nutrients and water enter the plant through the plants’ root cell membranes (the barrier separating the inside of the root cells from the outside) via of osmosis (the movem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
