Didymella pinodes | |
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Necrotic lesions caused by Didymella pinodes on field pea leaves two weeks after infection | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Dothideomycetes |
Order: | Pleosporales |
Family: | Didymellaceae |
Genus: | Didymella |
Species: | D. pinodes |
Binomial name | |
Didymella pinodes (Berk. & A. Bloxam) Petr., (1924) | |
Synonyms | |
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Didymella pinodes (syn. Mycosphaerella pinodes) [1] is a hemibiotrophic [2] fungal plant pathogen and the causal agent of ascochyta blight on pea plants. It is infective on several species such as Lathyrus sativus , Lupinus albus , Medicago spp., Trifolium spp., Vicia sativa , and Vicia articulata, and is thus defined as broadrange pathogen. [3]
Symptoms include lesions on leaves, stem and pods of plants. The disease is difficult to distinguish from blight caused by Ascochyta pisi , though D. pinodes is the more aggressive of the two pathogens. [4]
The disease cycle starts with dissemination of ascospores after which germination pycnidia rapidly develop. [5] Pycnidiaspores quickly disperse by rain splashes are responsible for reinfection over short distances. Consequently, production of pseudothecia is initiated on senescent tissues. After rainfall, ascospores are released from the pseudothecia and disperse by wind over long distances. [6]
Useful levels of resistance remain to be determined and the application of fungicidal sprays was reported to be uneconomical. [7] [8] Furthermore, reports showed that insensitivity arises against chemicals such as strobilurons after continuous application. [9] Thus, cultural management is the preliminary option to control the disease progress by minimizing inoculum carry over as well as survival of inoculum on crop residues and in soil, and avoiding initial infection from arial inoculum. [10] Furthermore, burying of infected residues declines pathogen survival, [11] however, crop rotation and tillage regimes have little influence on disease severity. [12] Delayed sowing by 3–4 weeks reduces ascochyta blight severity by more than 50%, [13] however, such measures are not feasible at higher latitudes, because of a shorter growing season.
So far, only incomplete resistance is available in the pea germplasm and quantitative differences are highly influenced by environmental conditions, plant age and physiological characteristics of plants. [14] [15] Tall cultivars with more erect growth suffer lower D. pinodes infection. [16] Susceptibility increases with earliness [17] and along with maturity of plants. [18]
Besides morphological traits, a proteomic and metabolomic study pinpointed molecular markers contributing to resistance. [19] Disease severity of leaves was also reported to be lower when pea plants are associated with rhizobial bacteria that presumably provoke so called induced systemic resistance. [20]
Take-all is a plant disease affecting the roots of grass and cereal plants in temperate climates caused by the fungus Gaeumannomyces tritici. All varieties of wheat and barley are susceptible. It is an important disease in winter wheat in Western Europe particularly, and is favoured by conditions of intensive production and monoculture.
Fusarium culmorum is a fungal plant pathogen and the causal agent of seedling blight, foot rot, ear blight, stalk rot, common root rot and other diseases of cereals, grasses, and a wide variety of monocots and dicots. In coastal dunegrass, F. culmorum is a nonpathogenic symbiont conferring both salt and drought tolerance to the plant.
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. Aphanomyces root rot is an important agricultural disease in the United States, Europe, Australia, New Zealand, and Japan. Management includes using resistant crop varieties and having good soil drainage, as well as testing soil for the pathogen to avoid infected fields.
Pseudocercosporella capsellae is a plant pathogen infecting crucifers. P. capsellae is the causal pathogen of white leaf spot disease, which is an economically significant disease in global agriculture. P. capsellae has a significant affect on crop yields on agricultural products, such as canola seed and rapeseed. Researchers are working hard to find effective methods of controlling this plant pathogen, using cultural control, genetic resistance, and chemical control practices. Due to its rapidly changing genome, P. capsellae is a rapidly emerging plant pathogen that is beginning to spread globally and affect farmers around the world.
Mycosphaerella brassicicola is a plant pathogen. The pathogen is the teleomorph phase of an ascomycete fungus, which causes the ring spot disease of brassicas. The supplementary anamorph phase Asteromella brassicae produces conidia through its asexual reproduction, however these spores are not confirmed to cause disease in host plants.
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Zymoseptoria tritici, synonyms Septoria tritici, Mycosphaerella graminicola, is a species of filamentous fungus, an ascomycete in the family Mycosphaerellaceae. It is a wheat plant pathogen causing septoria leaf blotch that is difficult to control due to resistance to multiple fungicides. The pathogen today causes one of the most important diseases of wheat.
Stemphylium solani is a plant pathogen fungus in the phylum Ascomycota. It is the causal pathogen for grey leaf spot in tomatoes and leaf blight in alliums and cotton, though a wide range of additional species can serve as hosts. Symptoms include white spots on leaves and stems that progress to sunken red or purple lesions and finally leaf necrosis. S. solani reproduces and spreads through the formation of conidia on conidiophores. The teleomorph name of Stemphyllium is Pleospora though there are no naturally known occurrences of sexual reproduction. Resistant varieties of tomato and cotton are common, though the pathogen remains an important disease in Chinese garlic cultivation.
Choanephora cucurbitarum is a fungal plant pathogen that causes fruit and blossom rot of various cucurbits. It can also affect okra, snap bean, and southern pea, and may cause a stem and leaf rot of Withania somnifera. Recently Das et al. 2017 added few more patho-index on aubergine, teasle gourd (Momordica subangulata Blume subsp. renigera de Wilde, hyacinth bean, green pea from India. Wet weather, high temperature and high humidity favor disease development from inoculum that is typically soil-borne. Signs of infection on fruits or leaves include water-soaked, necrotic lesions, which progress rapidly under ideal conditions. As the fungus begins to produce spores, affected tissues become dark grey-brown and hairy as a result of the superficial sporangia.
Ascochyta is a genus of ascomycete fungi, containing several species that are pathogenic to plants, particularly cereal crops. The taxonomy of this genus is still incomplete. The genus was first described in 1830 by Marie-Anne Libert, who regarded the spores as minute asci and the cell contents as spherical spores. Numerous revisions to the members of the genus and its description were made for the next several years. Species that are plant pathogenic on cereals include, A. hordei, A. graminea, A. sorghi, A. tritici. Symptoms are usually elliptical spots that are initially chlorotic and later become a necrotic brown. Management includes fungicide applications and sanitation of diseased plant tissue debris.
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Didymella rabiei, commonly called chickpea ascochyta blight fungus, is a fungal plant pathogen of chickpea. Didymella rabiei is the teleomorph of Ascochyta rabiei, which is the anamorph, but both names are the same species.
Alternaria solani is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato. Despite the name "early," foliar symptoms usually occur on older leaves. If uncontrolled, early blight can cause significant yield reductions. Primary methods of controlling this disease include preventing long periods of wetness on leaf surfaces and applying fungicides. Early blight can also be caused by Alternaria tomatophila, which is more virulent on stems and leaves of tomato plants than Alternaria solani.
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Xanthomonas axonopodis pv. manihotis is the pathogen that causes bacterial blight of cassava. Originally discovered in Brazil in 1912, the disease has followed the cultivation of cassava across the world. Among diseases which afflict cassava worldwide, bacterial blight causes the largest losses in terms of yield.
Pisatin (3-hydroxy-7-methoxy-4′,5′-methylenedioxy-chromanocoumarane) is the major phytoalexin made by the pea plant Pisum sativum. It was the first phytoalexin to be purified and chemically identified. The molecular formula is C17H14O6.
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