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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. * ''Xylella fastidiosa'' is known to cause BLS in a very wide range of plants. Each of its subspecies has have a different host range. ** The ''multiplex'' subspecies causes BLS of pecans. * Bacterial spot of peppers and tomatoes is caused by the bacteria Xanthomonas campestris pv. vesicatoria, ''Xanthomonas campestris'' pv. ''vesicatoria'', which has since been divided into four pathovars in three species. * Bacterial spot of peaches is caused by the bacteria Xanthomonas pruni, ''Xanthomonas arboricola'' pv. ''pruni''. It also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylella Fastidiosa
''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 ( xylem vessels) 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. ''Xylella fastidiosa'' can infect an extremely wide range of plants, many of which do not show any symptoms of disease. Disease occurs in plant species that are susceptible due to bloc ... [...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 Earth's atmosphere, 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 cloud, 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 reflection (physics), reflected and refraction, refracted by the ice cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterial Tree Pathogens And Diseases
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit the air, soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in mutualistic, commensal and para ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaf Scorch
Leaf scorch (also called leaf burn, leaf wilt, and sun scorch) is 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, herbicide injury, and disease injury.Treatment Affected plants may sometimes recover through watering and fertilization (if the cause is not over-fertilization). Light pruning may also help to reduce the water-pumping load on the roots and xylem.[...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 osmosis (the moveme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylem
Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts of the plants such as stems and leaves, but it also transports plant nutrition, nutrients. The word ''xylem'' is derived from the Ancient Greek word (), meaning "wood"; the best-known wood organism is plants, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858. Structure The most distinctive xylem cell (biology), 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''. Wood also contains two other type of cells: Ground tissue#Parenchyma, parenchyma and ground tissue#Fibres, fibers. Xylem can be found: * in vascular bundles, present in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree Crown
The crown of a plant is 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. These fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peach Scab
Peach scab, also known as peach freckles, is a disease of stone fruits caused by the fungi ''Cladosporium carpophilum''. The disease is most prevalent in wet and warm areas especially southern part of the U.S. as the fungi require rain and wind for dispersal. The fungus causes scabbing, lesions, and defoliating on twig, fruit, and leaf resulting in downgrade of peach quality or loss of fruits due to rotting in severe cases. Symptoms The disease affect most stone plants including peaches, apricots and plums. The symptoms can generally be found in three major parts of plant: fruits, twigs, and leaves. The symptoms on leaves and twigs are often considered as the least notable. Infected leaves initially show small and green colored lesions on under the leaves. They progress into yellowish brown and eventually appear as dark brown or black spots. Twig lesions start to form on green young stems. The lesions are about 3 up to 6.5 mm in diameter size. They usually first have redd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leafhopper
Leafhopper is the common name for any species from the family (biology), family Cicadellidae: based on the type genus ''Cicadella''. 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 Vector (epidemiology), 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 Auchenorrhy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthomonas Pruni
''Xanthomonas arboricola'' pv. ''pruni'' is a bacterial disease of almost all ''Prunus''. The first complete genome was submitted to NCBI in 2019. Available genomes place it as a member inside ''Xanthomonas arboricola''. Hosts Almost all ''Prunus'' spp. Distribution Unknown in stonefruit in California until detection in Sacramento and northern San Joaquin Valley in the spring of 2013. it is still restricted to those two areas. Also found in almond cultivation in Victoria, Australia. Detection Palacio-Bielsa ''et al.'', 2011 provides a SYBR Green I-based assay. Management Copper and mancozeb are recommended in California for almonds and have served well elsewhere. No pesticides are registered for almonds anywhere in Australia. Phage therapy has been heavily studied for ''X. pruni'' and some treatments have been very successful. Civerolo & Keil performed several experiments in the 1970s with ' showing that peach and apricot were protected by external applications of solution ... [...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 polymor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
