Pyrenophora tritici-repentis. [Descriptions of Fungi and Bacteria].

Author(s):  
M. B. Ellis

Abstract A description is provided for Pyrenophora tritici-repentis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Wheat, rye, barley, Agropyrons repens, Cynodon dactylon, Elymus glaucus. DISEASES: Causes yellow leaf spot of cereals and grasses; oval to lanceolate. yellow to grey brown lesions often with a yellow halo. The lesions can be distinguished from those caused by Cochliobolus sativus because of their lighter colour. The disease results in premature death of leaves. It can also cause a seedling blight and root rot. Common and widespread on Agropyron repens[Elymus repens] and wheat, occasionally on barley and rye and recorded on many other grasses. Sometimes causes severe leaf wilt and spotting especially on durum wheat. Leaves of Agropyron repens[Elymus repens] when attacked gradually lose their colour and wither from the tips backwards; they become at first pale yellow, later grey. On wheat fusiform, oval or lanceolate spots, 0.5-2 cm long, 2-4 mm wide are formed. These are at first yellow but later turn brown or greyish brown often with a yellow halo. The leaves die prematurely from the tip backwards. GEOGRAPHICAL DISTRIBUTION: Australia; Asia (Japan, India, Nepal); Africa (Uganda, Kenya, Tanzania, Ethiopia); Europe (Britain, Germany, Czechoslovakia, Sweden, Cyprus); S. America (Bolivia); and N. America (Canada, USA). TRANSMISSION: Air-borne spores (51, 1045p), seed-borne by both external contamination and internal infection (34, 24), secondary grass weed hosts (11, 695), carryover on stubble and other crop debris (43, 1225f; 52, 685).

Author(s):  
A. Sivanesan

Abstract A description is provided for Cochliobolus cynodontis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Cynodon dactylon (very common on this host), other Cynodon spp., Agropyron, Ammi, Arecastrum, Axonopus, Calathea, Chamaedorea, Chrysalidocarpus, Dactyloctenium, Eleusine, Hordeum, Ipomoea, Lycopersicon, Muhlenbergia, Oryza, Panicum, Pennisetum, Poa, Rhapis, Secale and Zea. DISEASE: Leafspot of Bermuda grass end other crops, leaf blight end brown patches of turf, lawns end golflinks. GEOGRAPHICAL DISTRIBUTION: Argentina, Australia, Bangladesh, Brazil, Brunei, Egypt, Ghana, Guinea, India, Israel, Iraq, Italy, Japan, Kenya, Malaysia, New Zealand, Pakistan, Papua New Guinea, Puerto Rico, Spain, South Africa, Sudan, Tanzania, Trinidad, Turkey, USA, USSR, Venezuela, Yugoslavia and Zambia. TRANSMISSION: By wind-borne conidia and seed-borne.


Author(s):  

Abstract A new distribution map is provided for Candidatus Phytoplasma prunorum Seemüller & Schneider. Phytoplasma. Hosts: Prunus spp., including peach, apricot, cherry, almond and plum. Wild hosts include bindweed (Convolvulus arvensis) and Bermuda grass (Cynodon dactylon). Information is given on the geographical distribution in Europe (Albania, Austria, Belgium, Bosnia-Herzegovina, Bulgaria, Cyprus, Czech Republic, France, Mainland France, Germany, Greece, Mainland Greece, Hungary, Italy, Mainland Italy, Poland, Romania, Serbia, Slovenia, Spain, Mainland Spain, Switzerland), Asia (Azerbaijan, Turkey).


Author(s):  
J. F. Bradbury

Abstract A description is provided for Xanthomonas oryzae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Oryza sativa. Natural infection of Leersia oryzaides, Leersia oryzaides var. japonica and Zizania latifolia[Zizania aquatica] is known (Mizukami & Wakimoto, 1959). Natural infection of Cyperus rotundus and C. difformis was reported in India (48, 460), but inoculation of these hosts in the Philippines failed (48, 1689). By inoculation many wild species of Oryza (45, 1789), Leptochloa filiformis (48, 1689), L. chinensis, L. panacea and Zizania aquatica (48, 1683) have all been found susceptible. DISEASE: Bacterial blight of rice and kresek disease of rice. Blight most commonly appears on leaves of young plants, after planting out, as water-soaked stripes at the margins. These enlarge and coalesce to give the characteristic yellowish lesions with wavy edges that occur mainly along the margins of the upper parts of the leaves. These lesions may later expand to cover much of the leaf, which turns whitish or greyish and dies. Leaf sheaths of the more susceptible varieties may be affected. Kresek, which occurs in tropical regions, is a strong systemic infection in which leaves or whole young plants wither and die. In older plants the leaves become pale yellow. GEOGRAPHICAL DISTRIBUTION: Limited to Asia (CMI Map 304, ed. 2, 1964). Occurrences not shown on this map include Korea, Taiwan and Indonesia (Mizukami & Wakimoto, 1969). TRANSMISSION: Spread locally by wind and rain and also by flood and irrigation waters; gains entry to the field in infected planting material, to the nursery in seed, and to both nursery and field from volunteer rice plants and weed hosts usually via the irrigation water. Overwintering may occur on volunteers, on or in the rhizospheres of weed hosts, in stored infected straw and in seed, but it is unlikely in soil and plant debris exposed to the weather, at least under Japanese conditions (Mizukami & Wakimoto, 1969). Infection is through hydathodes and wounds. Penetration through stomata results in a build-up of bacteria in the intercellular spaces, but it is not until they have been exuded on to the leaf surface and re-admitted through the hydathodes and thence into the vascular system, that symptoms of the disease appear (46, 2720).


Author(s):  
J. L. Mulder

Abstract A description is provided for Puccinia cynodontis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Aecial stage on species of Plantago. Uredial and telial stages on species of Cynodon, particularly C. dactylon. DISEASE: Leaf rust of Bermuda grass (Cynodon dactylon). GEOGRAPHICAL DISTRIBUTION: Widespread. Africa: Ethiopia, Ghana, Kenya, Libya, Malawi, Mauritius Morocco, Nigeria, Sierra Leone, South Africa, Sudan, Tunisia and Zambia. Americas: Argentina, Barbados, Bermuda, Colombia, Dominica, Dominican Republic, Jamaica, Mexico, Nicaragua, Panama, Puerto Rieo, Salvador, Trinidad, USA (South) and Venezuela. Asia: Cambodia, Ceylon, China, India, Iraq, Pakistan, Turkey and USSR. Australasia & Oceania: Australia, Hawaii, New Caledonia, New Zealand and Papua & New Guinea. Europe: Cyprus, France, Malta and Rumania. TRANSMISSION: No studies appear to have been reported. Since the aecial stage has not been found in USA the urediospores presumably survive during the dormant periods of the tdial host.


Author(s):  
E. Punithalingam

Abstract A description is provided for Phoma sorghina. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Gramineae and all kinds of plants. Also isolated from soil, air and various animal sources. DISEASE: A minor leaf spot of cereals and grasses. The visible symptoms vary considerably; on sorghum leaves spots are usually irregular or rounded, yellowish-brown or grey with definite reddish-purple margins or indefinite in outline, reaching 1 cm or more in width. Pycnidia develop within spots on leaves, glumes and seeds. Also the fungus has been implicated with pre- and post-emergence death of seedlings of Macroptilium and Sylosanthes species (54, 1779) crown rot of bananas (61, 3556), leaf spot of Agave americana and stem rot of Euphorbia tirucalli (63, 3383), brown stem canker of Leucosperum cordifolium (56, 253). GEOGRAPHICAL DISTRIBUTION: A ubiquitous fungus occurring in tropical and subtropical regions. Africa (Botswana, Cameroon, Egypt, Ethiopia, Gambia, Kenya, Malawi, Mauritius, Mozambique, Nigeria, Senegal, Sierra Leone, South Africa, Sudan, Tanzania, Togo, Uganda, Zaire, Zambia, Zimbabwe); Asia (Bangladesh, Brunei, Burma, China, Hong Kong, India, Indonesia (Irian Jaya), Laos, Malaysia, Nepal, Pakistan, Saudi Arabia, Sri Lanka, Taiwan, USSR); Australasia and Oceania (Australia, Hawaii, New Zealand, Papua New Guinea, Solomon Islands); Europe (Germany, Portugal, Italy, UK); North America (Canada, USA); Central America and West Indies (Antigua, Guatemala, Honduras, Jamaica, Nicaragua, Puerto Rico, Trinidad); South America (Argentina, Bolivia, Brazil, Colombia). TRANSMISSION: Probably by contaminated seed; the fungus has been found on or isolated from several seed samples (1, 289; 33, 599; 47, 2153; 54, 1779; 60, 367; 61, 4102). In Taiwan P. sorghina has been found to be transmitted from seed to seedlings (62, 4281). The fungus has also been claimed to persist on trash and weed hosts and remain viable up to 1 yr but lose its viability after 2 yr storage on dry infected leaves (Koch & Rumbold, 1921).


2018 ◽  
Vol 28 (3) ◽  
pp. 137-146 ◽  
Author(s):  
Adam Kuzdraliński ◽  
Hubert Szczerba ◽  
Anna Kot ◽  
Agnieszka Ostrowska ◽  
Michał Nowak ◽  
...  

We developed new PCR assays that target beta-tubulin (<i>TUB2</i>) and 14 alpha-demethylase (<i>CYP51</i>) genes and used them for the species-specific detection of <i>Blumeria graminis</i> f. sp. <i>tritici</i> (<i>Bgt</i>). Based on fungi DNA sequences available in the NCBI (National Center for Biotechnology Information) GenBank database we developed simplex and duplex PCR assays. The specificities of the primer sets were evaluated using environmental samples of wheat leaves collected during the 2015/2016 growing season across Poland. Primer sets<i></i> LidBg17/18 and LidBg21/22 strongly amplified fragments of the expected length for all 67 tested samples. Primer specificity was confirmed using field samples of <i>Zymoseptoria tri­tici</i>, <i>Puccinia triticina</i> (syn.<i> P. recondita</i> f. sp.<i> tritici</i>), <i>P. striiformis</i> f. sp.<i> tritici</i>, and <i>Pyrenophora tritici-repentis</i>.


2019 ◽  
Author(s):  
Nina V. Mironenko ◽  
Alexandra S. Orina ◽  
Nadezhda M. Kovalenko

This study shows that the necrotrophic effector gene ToxA is differentially expressed in isolates of P. tritici-repentis fungus at different time periods after inoculation of the wheat variety Glenlea which has the gene Tsn1 controlling sensitivity to the necrosis inducing toxin Ptr ToxA. Two P. tritici-repentis isolates with different ability to cause necrosis on the leaves of Glenlea variety (nec + and nec-) and with different expression level of ToxA and gene of factor transcription PtrPf2 in vitro were used for analysis. Isolates of P. tritici-repentis are characterized by the differential expression of ToxA in planta. The expression of the ToxA gene in P. tritici-repentis ToxA+ isolates significantly increased when infected the wheat leaves compared to ToxA expression results obtained in vitro. The levels of ToxA expression in both isolates differed significantly after 24, 48 and 96 hours after inoculation, however, the dynamics of the trait change over time were similar. However, the highest ToxA expression in the virulent (nec+) isolate in contrast with the avirulent (nec-) isolate was observed at a point of 48 hours. Whereas the expression of regulating transcription factor PtrPf2 in planta differed imperceptibly from expression in vitro throughout the observation period. Obviously, the role of the fungal transcription factor in regulating the effector gene expression weakens in planta, and other mechanisms regulating the expression of pathogen genes at the biotrophic stage of the disease develop.


Author(s):  
J. F. Bradbury

Abstract A description is provided for Clavibacter XYLI subsp. cynodontis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOST: Cynodon dactylon, where it is limited to the xylem. It also multiplies in the xylem of sugar cane and a Sudan grass-sorghum hybrid when artificially inoculated, but symptoms are not produced (61, 4328). Further host range not yet recorded. DISEASE: Bermuda grass stunting disease. Natural occurrences so far discovered have been in combination with mycoplasma-like organisms thought to cause white leaf and witches' broom symptoms. The presence of the bacterium causes considerably more severe symptoms. The full ecological significance of this bacterium has not yet been evaluated, but a further stress is usually required to produce noticeable symptoms. GEOGRAPHICAL DISTRIBUTION: Taiwan, USA (Florida). TRANSMISSION: So far only mechanical transmission, by artificial inoculation, is known. Cutting blades and possibly grazing animals are likely to spread the infection.


Author(s):  
G. F. Laundon

Abstract A description is provided for Puccinia polysora. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Erianthus divaricatus, E. alopecuroides, Euchlaena mexicana, Tripsacum dactyloides (= T. monastachyum), T. lanceolatum, T. latifolium. T. laxum, T. pilosum, Zea mays. DISEASE: Rust of maize causing chlorosis and premature death of leaves and leaf-sheaths. GEOGRAPHICAL DISTRIBUTION: Africa (Tropical, South, and Madagascar), Asia (S.E.), Australia (Queensland), Australasia, N. America (S. and E.), Central America and W. Indies, S. America (N.) (CMI Map 237). TRANSMISSION: By air over relatively short distances (37: 657) and by infected or contaminated material via air transport over long distances (38: 591).


Author(s):  
C. Booth

Abstract A description is provided for Pleospora herbarum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a wide range of hosts including apple, ash, broad bean, clover, endive, gladiolus, gramineae, lettuce, lupin, muskmelon, onion, Onobrychis, Medicago sativa, mangold, tomato, Trifolium, Vicia (40: 230). DISEASES: Leaf spot of mangold, clover (Trifolium), lucerne (Medicago sativa), endive, lettuce, onion seedlings and gladiolus, net blotch of field and broad bean (Vicia), ring spot of sanfoin (Onobrychis) foot rot of tomato. Severe leaf spot on muskmelon may cause leaf fall and sun scald of fruit (37: 625). Lesions caused by other fungi may also be colonized as on lucerne (38: 11) or be associated with some other disease complex such as Pseudomonas savastanoi on ash (36: 144). GEOGRAPHICAL DISTRIBUTION: World-wide; very common in temperate and sub-tropical regions. TRANSMISSION: Generally air-borne as ascospores or conidia. These penetrate the leaf or petiole via stomata (37: 365). May also occur on seeds (38: 146) and in soil.


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