Conidiobolus obscurus. [Descriptions of Fungi and Bacteria].

Author(s):  
N. Wilding

Abstract A description is provided for Conidiobolus obscurus. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Aphids (Homoptera: Aphididae); one record also from Philaenus spurnarius (Homoptera: Cercopidae). GEOGRAPHICAL DISTRIBUTION: Europe, N. America, Asia, Australia. DISEASE: Infection is by germ tubes issuing from the conidia and penetrating the integument of the aphid. Dead insects characteristically hang from stems and leaves of the host plant by the proboscis inserted in the plant tissues. They are clothed in conidiophores bearing the large conidia that sparkle in bright light. In N. Europe C. obscurus occurs most frequently in the autumn and spring in relatively cool, moist weather.

Author(s):  
N. Wilding

Abstract A description is provided for Neozygites fresenii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Aphids (Homoptera: Aphididae) especially species of the genus Aphis. GEOGRAPHICAL DISTRIBUTION: Very widespread, including Europe, N. & S. America, Asia, Africa, Polynesia. DISEASE: Capilloconidia adhere to the aphid by the sticky apical droplet. A germ tube is produced which forms an appressorium on the insect cuticle and a tube from the appressorium then penetrates it. Aphids killed by N. fresenii characteristically hang from the stems and the underside of leaves of the host plant by the proboscis inserted in the plant tissues. Aphis fabae killed by this species are orange in colour when dry and grey in moist conditions as the fungus begins to sporulate. This fungus is most frequently associated with dense populations of aphids in warm seasons and is unusual in attacking aphid populations in the tropics.


1995 ◽  
Vol 73 (S1) ◽  
pp. 1275-1283 ◽  
Author(s):  
Shigehito Takenaka

To develop efficient control measures against fungal plant pathogens, the dynamics of host plant colonization during disease development and the interactions among fungi within host plant tissues need to be clarified. These studies require accurate quantitative estimation of specific fungal biomass in plant tissues. This has been approached by direct-microscopic methods, cultural methods, chemical determinations of fungal components, serological methods, and molecular methods. Among these methods, serological and molecular methods provide rapid, specific, and sensitive quantitative measures of fungal biomass in host plant tissues. Therefore, studies on fungal dynamics of host plant colonization using these two methods are presented. Some examples of species interactions among pathogenic fungi within host plants, such as synergism and competition, are reviewed and the usefulness of serological and molecular methods for studies on these interactions is presented. These quantitative methods will provide helpful information for understanding the ecology of plant pathogenic fungi, such as the dynamics of host plant colonization and species interactions. Key words: quantitative methods, fungal biomass, ELISA, PCR, fungal colonization, species interaction.


Author(s):  
J. Walker

Abstract A description is provided for Gaeumannomyces graminis var. tritici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Gramineae, especially Triticum, Hordeum, Secale, Agropyron and several other grass genera and, more rarely, Sorghum and Zea; also recorded from the roots of plants in other families. DISEASE: Take-all of cereals and grasses (also referred to as deadheads or whiteheads, pietin and pied noir (France), Schwarzbeinigkeit and Ophiobolus Fusskrankheit (Germany), Ophiobolusvoetziekt (Netherlands) and others). Root infection is favoured by soil temperature from 12-20°C (Butler, 1961). Ascospore germ tubes penetrate root hairs and the epidermis in the meristematic region (Weste, 1972) leading to plugging of xylem and root death. GEOGRAPHICAL DISTRIBUTION: (CMI Map 334, ed. 3, 1972). Widespread, especially in temperate zones. Africa; Asia (India, Iran, Japan, USSR): Australasia and Oceania; Europe; North America (Canada, USA); South America (Argentina, Brazil, Chile, Colombia, Uruguay). TRANSMISSION: In soil on infected organic fragments, as runner hyphae on roots of cereals and grasses and, under special conditions, by ascospores. Seed transmission very doubtful (47, 3058).


Author(s):  
S. M. Khairi

Abstract A description is provided for Podosphaera clandestina. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Crataegus monogyna, C. pentagyna, C. punctata, Mespilus germanica, Cratoegomespilus grandiflora, C. dardari, Pyrus communis, Cydonia vulgaris, Pyrocydonia winkleri and P. danieli. DISEASE: Hawthorn mildew. Severe attacks cause defoliation and death of terminal buds on young seedlings and on soft shoots on hedges and trees. The disease has been recorded on hawthorn fruits. The host plant can be grown only from seeds. GEOGRAPHICAL DISTRIBUTION: Worldwide (Salmon, 1900; 45, 3081). Cleistothecia play no part in the disease in England. The overwintering mycelium, inside infected buds, survives until the following spring. These infected buds are the primary infections found each year. Secondary infection is by air-borne conidia.


Author(s):  
P. F. Cannon

Abstract A description is provided for Puccinia levis var. brachiariae comb. nov., which causes small lesions on young stems and leaf lamina of the host plant and, where present in quantity, could significantly reduce vigour. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (Malawi, Uganda, Zambia and Brazil) and hosts (Brachiaria brizantha [Urochloa brizantha], B. decumbens [Urochloa decumbens], B. humidicola [Urochloa humidicola] and an unnamed Brachiaria sp.).


Author(s):  
P. F. Cannon

Abstract A description is provided for Lophiostoma semiliberum, which is considered to be a saprobic fungus, colonizing dead plant tissues. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (North America (Canada, Ontario), Asia (Japan), Europe (Belgium, Czech Republic, Denmark, Finland, France, Germany, Italy, Ireland, Netherlands, Poland, Portugal, Sweden, Switzerland, Ukraine, UK)). L. semiliberum is reported most typically from dead culms of Phragmites australis, and from a range of other grass hosts.


Author(s):  
J. C. Walker

Abstract A description is provided for Synchytrium endobioticum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Solanaceae (potato, Solanum tuberosum). Other plants infected experimentally include several species of Solanum (Karling, 1964), Petunia and Nicotiana spp. (53, 4566), Lycopersicon esculentum, Physalis and Capsicastrum spp. (59, 416). DISEASE: Potato wart disease, causing dark brown warty cauliflower-like excrescences of infected tubers, which decay to release golden-brown resting spores. On aerial shoots green galls may develop, composed of convoluted masses of tissue. GEOGRAPHICAL DISTRIBUTION: Africa, Asia, Europe, North America, South America (CMI Map 1, ed. 5, 1972). TRANSMISSION: By the movement of infected soil or plant tissues. Local dispersal by zoospores swimming in water films may also occur.


1991 ◽  
Vol 69 (7) ◽  
pp. 1483-1490 ◽  
Author(s):  
G. Bagatto ◽  
J. D. Shorthouse

The accumulation of copper and nickel in plant tissues and galls of Hemadas nubilipennis on lowbush blueberry near an ore smelter at Sudbury, Ontario, was investigated. Concentrations of these metals in the root, stem, and leaf tissue decline logarithmically with increasing distance from the Sudbury smelter. The pattern of accumulation for copper and nickel in the various tissues was root > stem > leaf > berry; however, metal differences in these tissues were not as great in plants farther from the smelter. The root tissue is the primary site of accumulation of these metals when environmental levels of copper and nickel are high. The highest concentrations of copper and nickel were found in the galls, indicating that gall tissues act as a strong physiological sink for micronutrients and redirect nutrients from the host plant. Key words: Vaccinium angustifolium, copper, nickel, gall, Sudbury.


2016 ◽  
Vol 84 ◽  
pp. 128-136 ◽  
Author(s):  
Nancy Calderón-Cortés ◽  
Claudia A. Uribe-Mú ◽  
A. Karen Martínez-Méndez ◽  
Luis H. Escalera-Vázquez ◽  
E. Jacob Cristobal-Pérez ◽  
...  

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