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Erysiphe graminis f.sp. tritici is a plant pathogen that causes a fungal infection known as powdery mildew. It is most common in grains, and it can be identified by the characteristic white spots on leaves and stems that appear to be made of powder. Powdery mildew is one of the most widespread and easily recognizable plant diseases.
Life cycle of the black rot pathogen, the gram negative bacterium Xanthomonas campestris pathovar campestris. Plant pathology or phytopathology is the scientific study of plant diseases caused by pathogens (infectious organisms) and environmental conditions (physiological factors). [1]
Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). [1] Organisms that cause infectious disease include fungi , oomycetes , bacteria , viruses , viroids , virus -like organisms, phytoplasmas , protozoa , nematodes and parasitic plants . [ 2 ]
In 1961 Sanwal listed 33 species and provided a key. [3]The most important species of these are Aphelenchoides ritzemabosi, the chrysanthemum foliar nematode; Aphelenchoides fragariae, the spring crimp or spring dwarf nematode of strawberry, which also attacks many ornamentals; and Aphelenchoides besseyi, causing summer crimp or dwarf of strawberry and white tip of rice.
The plant disease triangle represents the factors necessary for disease to occur. Plant disease forecasting is a management system used to predict the occurrence or change in severity of plant diseases. At the field scale, these systems are used by growers to make economic decisions about disease treatments for control.
The pathogen only survives on infected plant debris, allowing this practice to hasten decomposition of the debris. [ 10 ] [ 13 ] [ 14 ] Crop rotation will allow the debris enough time to decompose. Recommendations vary depending on location, but 2 years is the minimum allowance for rotation.
Aphanomyces euteiches is a water mould, or oomycete, plant pathogen responsible for the disease Aphanomyces root rot. The species Aphanomyces euteiches can infect a variety of legumes. Symptoms of the disease can differ among hosts but generally include reduced root volume and function, leading to stunting and chlorotic foliage.
The risk of spreading the bacteria to healthy tomato plants is greatest during transplanting, tying, and suckering or any time when the host may be wounded. Once the bacteria enters the plant through a wound, it will move and multiply primarily in the xylem vessels. Once established, the bacteria may move into the phloem, pith, and cortex. [9]