Peronospora knautiae. [Descriptions of Fungi and Bacteria].

1994 ◽  
Author(s):  
G. Hall
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Leaf Spots ◽  
Rain Splash

Abstract A description is provided for Peronospora knautiae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Cephalaria transylvanica, Knautia arvensis, K. carpatica, K. caucasica, K. drymeia subsp. drymeia, K. integrifolia, K. godeti, K. montana, K. silvatica, Pterocephalus plumosus, Scabiosa columbaria, S. lucida, S. ochroleuca, Succisa pratensis. DISEASE: Downy mildew of Knautia and Scabiosa species. Leaf spots are violet or brown and sparse. GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Azerbaijan, Stavropol, Turkmenistan. Europe: Austria, Czechoslovakia, Denmark, Estonia, France, Germany, Italy, Latvia, Lithuania, Norway, Poland, Romania, Russia (Novgorod, Pskov, St. Petersburg, Yaroslavl), Sweden, Switzerland, Ukraine. TRANSMISSION: By conidia which are dispersed by wind or rain-splash.

Peronospora oerteliana. [Descriptions of Fungi and Bacteria].

1994 ◽  
Author(s):  
G. Hall
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Disease Transmission ◽  
Rain Splash

Abstract A description is provided for Peronospora oerteliana. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Primula acaulis, P. algida, P. elatior, P. juliae, P. officinalis, P. veris, P. vulgaris. DISEASE: Downy mildew of Primula species. GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Kazakhstan. Europe: Czechoslovakia, Denmark, Eire, France, Germany, Poland, Romania, Sweden, Switzerland, Yugoslavia, UK (England, Scotland). TRANSMISSION: By conidia which are dispersed by wind or rain-splash. The role of oospores in disease transmission is unknown, but they may have a perennating function.

Peronospora sordida. [Descriptions of Fungi and Bacteria].

1991 ◽  
Author(s):  
G. Hall
Keyword(s):  
New York ◽  
North America ◽  
Northern Ireland ◽  
Downy Mildew ◽  
Geographical Distribution ◽  
Plant Pathogen ◽  
Disease Transmission ◽  
Channel Islands ◽  
Rain Splash

Abstract A description is provided for Peronospora sordida. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Scrophularia altaica, S. aquatica, S. auriculata, S. bosniaca, S. californica, S. heterophylla, S. lanceolata, S. marylandica, S. nodosa, S. scopolii, S. umbrosa (=S. alata), Verbascum banaticum, V. blattaria, V. densiflorum (=V. thapsiforme), V. glabratum subsp. glabratum, V. lychnitis, V. nigrum, V. phlomoides, V. phoenicum, V. speciosum, V. thapsus, V. thapsus subsp. crassifolium (=V. montanum), V. virgatum. DISEASE: Downy mildew of Scrophularia and Verbascum, some species of which may be cultivated commercially for their medicinal or ornamental value; an obligately necrotrophic plant pathogen. GEOGRAPHICAL DISTRIBUTION: Asia; USSR (Kirghizia, Turkmenia, Uzbekistan). Europe; Austria, Belgium, France, Czechoslovakia, Denmark, Eire, Finland, Germany, Hungary, Italy, Netherlands, Norway, Poland, Rumania, USSR (Byelorussia, Estonia, Latvia, Lithuania, RSFSR, Ukraine), Sweden, Switzerland, UK (England, Channel Islands, Northern Ireland, Scotland, Wales), Yugoslavia. North America; USA (California, Illinois, Indiana, Iowa, Kansas, Kentucky, Missouri, Nebraska, New York, Ohio, Wisconsin, Virginia). TRANSMISSION: By spores ('conidia') dispersed by wind or rain-splash. The role of oospores (if they are usually formed) in disease transmission is unknown.

Peronospora digitalis. [Descriptions of Fungi and Bacteria].

1994 ◽  
Author(s):  
G. Hall
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Republic Of Georgia ◽  
Rain Splash

Abstract A description is provided for Peronospora digitalis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Digitalis ferruginea, D. grandiflora (= D. ambigua), D. lutea, D. purpurea. DISEASE: Downy mildew of Digitalis species. Leaf lesions are hypophyllous, dark brown, spherical, initially 1-2 cm diam., eventually coalescing. GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Azerbaijan, Republic of Georgia. Europe: Czechoslovakia, France, Germany, Lithuania, Norway, Poland, Romania, Switzerland, Ukraine, UK (England, Scotland, Wales). TRANSMISSION: By conidia dispersed by wind or rain-splash.

Botryosphaeria obtusa. [Descriptions of Fungi and Bacteria].

1973 ◽  
Author(s):  
E. Punithalingam
Keyword(s):  
New York ◽  
Geographical Distribution ◽  
Fruit Rot ◽  
Dark Spot ◽  
Black Rot ◽  
Night Time ◽  
Leaf Spots ◽  
Spore Release ◽  
Botryosphaeria Obtusa ◽  
Rain Splash

Abstract A description is provided for Botryosphaeria obtusa. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Malus and Vitis. Also on Acer, Alnus, Amygdalus, Artemisia, Betula, Citrus, Crataegus, Cupressus, Diospyros, Eriobotrya, Hicoria, Juniperus, Liquidambar, Liriodendron, Lucuma, Magnolia, Melia, Nannorrhops, Nerium, Pinus, Platanus, Prunus, Rhamnus, Ribes, Robinia, Rubus, Salix, Sassafras, Tectona, Ulmus, Viburnum, Yucca. DISEASE: Causes canker and dieback on pomaceous fruits and grapevine but can live saprophytically on dead wood and bark of many woody plants. On apple, B. obtusa is responsible for three diseases: a canker (New York apple tree canker or black-rot canker); frog-eye leaf spot; and black-rot of the fruit. Cankers start as small elliptical areas of discoloured wood, often with a peripheral crack; as they grow the bark becomes roughened and black pycnidial pustules protrude. Diseased branches and twigs can be girdled and killed. Leaf spots begin as small, circular, purple spots which increase in size, developing a light brown centre, the typical 'frog-eye' symptom. Extensive defoliation may result if this stage of the disease is severe. The fruit rot usually commences at a wound or at the calyx as a dark spot, which spreads to envelope the whole fruit. Diseased fruits are firm and black but eventually shrivel and become mummified. GEOGRAPHICAL DISTRIBUTION: Widespread in the temperate areas; Europe, Southern Africa, North and South America, India, Japan, New Guinea, Western Australia, Tasmania, New Zealand. TRANSMISSION: The fungus can over-winter on mummified fruit, cankers, dead twigs and secondary hosts. Conidia and ascospores are mostly dispersed by rain-splash and perhaps by insects. Spore release is affected by relative humidity and temperature and dispersal is stimulated by night-time rain (50, 735).

Phytophthora ilicis. [Descriptions of Fungi and Bacteria].

1991 ◽  
Author(s):  
G. Hall
Keyword(s):  
North America ◽  
Geographical Distribution ◽  
Lower Surface ◽  
Late Winter ◽  
Leaf Fall ◽  
Ilex Aquifolium ◽  
Leaf Spots ◽  
Twig Blight ◽  
Wet Weather ◽  
Rain Splash

Abstract A description is provided for Phytophthora ilicis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Ilex aquifolium, I. aquifolium f. aureo-marginata. DISEASE: Produces a severe die-back disease (leaf and twig blight) of young and mature holly plants; a facultatively necrotrophic plant pathogen. Symptoms consist of black leaf spots, defoliation, twig die-back and berry infection. Limb and trunk cankers develop inside tissues. Leaf fall begins from the lower branches and progresses upwards producing shafts or pyramids of defoliation. The disease develops well in cool, wet weather but is checked during hot, dry periods. GEOGRAPHICAL DISTRIBUTION: Europe; UK (England), Netherlands. North America; USA (OR, WA). TRANSMISSION: By sporangia borne on sporangiophores which emerge through stomata on the lower surface of leaves. Sporangia are dispersed by rain-splash or by wind and infect leaves via wounds, or twigs via leaf scars. Growth of the mycelium from twigs extends into branches. Berries are infected in late winter and spring. Oospores are formed in leaf spots and in the cortex of dead twigs. They may act as perennating structures, allowing the fungus to survive over the summer and then germinate in cooler weather.

Peronospora euphorbiae. [Descriptions of Fungi and Bacteria].

1994 ◽  
Author(s):  
G. Hall
Keyword(s):  
South Africa ◽  
North America ◽  
South Dakota ◽  
Downy Mildew ◽  
Geographical Distribution ◽  
Disease Transmission ◽  
Rain Splash

Abstract A description is provided for Peronospora euphorbiae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Euphorbia dulcis, E. paralias, E. peploides, E. peplus, E. platyphylla, E. prostrata, E. serpens, E. serpyllifolia, E. serratula (= E. stricta). DISEASE: Downy mildew of Euphorbia species. Leaf lesions are hypophyllous, but superficial in E. paralias, as it has stomata on the upper surface of its leaves, which curl upwards. GEOGRAPHICAL DISTRIBUTION: Africa: South Africa. Asia-Temperate: Japan. Europe: France, Italy, Majorca, Poland, Romania, Spain, Switzerland, UK (England). North America: USA (South Dakota, Texas). TRANSMISSION: By conidia which are dispersed by wind or rain-splash. The role of oospores in disease transmission is unknown, but they may serve as perennating structures.

Cercospora carbonacea. [Descriptions of Fungi and Bacteria].

1987 ◽  
Author(s):  
S. Little
Keyword(s):  
Puerto Rico ◽  
North America ◽  
South America ◽  
Sierra Leone ◽  
Geographical Distribution ◽  
Leaf Spot ◽  
West Indies ◽  
Lower Surface ◽  
Leaf Spots ◽  
Rain Splash

Abstract A description is provided for Cercospora carbonacea. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Dioscoria spp. DISEASE: Leaf spot of yams. Causes fairly large, 5-20 mm, angular leaf spots, which are usually delimited by the leaf veins. The dark brown to almost black leaf spots give an almost charred appearance to the leaves, while on the lower surface the spots are grey becoming brown with age. GEOGRAPHICAL DISTRIBUTION: Africa: Ethiopia, Ghana, Guinea, Nigeria, Sierra Leone, Tanzania, Togo, Asia: Burma, India, North America: Canada (Ontario), West Indies (Barbados, Grenada, Jamaica, St. Vincent, Puerto Rico, Trinidad); South America: Venezuela. TRANSMISSION: Presumably by wind-borne and rain-splash dispersed conidia, surviving adverse periods in crop debris.

Xanthomonas manihotis. [Descriptions of Fungi and Bacteria].

1977 ◽  
Author(s):  
J. F. Bradbury
Keyword(s):  
Geographical Distribution ◽  
Manihot Esculenta ◽  
Bacterial Blight ◽  
Vascular Tissue ◽  
Cassava Bacterial Blight ◽  
Progressive Die ◽  
Leaf Spots ◽  
Planting Material ◽  
Rain Splash ◽  
Infected Material

Abstract A description is provided for Xanthomonas manihotis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Manihot esculenta. DISEASE: Cassava bacterial blight. The symptoms are unusually diverse, and include spotting, blight and wilt of leaves, wilt and dieback of stems, necrosis of vascular tissue of stems and roots, and exudation of bacterial ooze. The disease may begin with water-soaked angular leaf spots that enlarge and coalesce, forming necrotic areas and eventually causing the leaf to dry and fall. In moist conditions ooze is formed on the lesions. Infection may travel back to the petioles and stems, young stems being particularly susceptible. A progressive die-back may follow. The roots usually remain healthy in appearance, but in some susceptible varieties dry, rotted spots may develop around necrosed vascular strands (Lozano, 1975). When infected material is planted the first symptoms are wilting and dieback of the young shoots soon after emergence. GEOGRAPHICAL DISTRIBUTION: Argentina, Brazil, Colombia, Venezuela, Nicaragua, Nigeria, Ghana, Togo, Cameroon, Zaire, Uganda, Malawi, Madagascar, Mauritius, India, Malaysia, Indonesia, Taiwan. CMI Map 521, ed. 1, 1977. TRANSMISSION: The disease is spread in the field mainly by rain-splash. Dissemination is, therefore, mainly downwind (53, 3724). Insects may also transmit the disease, as does Pseudotheraptus devastans in Zaire (Maraite & Meyer, 1975). The disease overwinters and travels from one area to another in infected planting material. Infested tools may also spread disease, especially as harvesting is accompanied by much cutting (Lozano, 1975).

Cercospora malayensis. [Descriptions of Fungi and Bacteria].

1987 ◽  
Author(s):  
S. Little
Keyword(s):  
Sierra Leone ◽  
Geographical Distribution ◽  
Leaf Spot ◽  
West Indies ◽  
Leaf Surface ◽  
Euphorbia Pulcherrima ◽  
Leaf Spots ◽  
Brown Leaf Spot ◽  
Brown Leaf ◽  
Rain Splash

Abstract A description is provided for Cercospora malayensis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Hibiscus abelmoschus (musk mallow), H. cannabinus (deccan hemp), H. esculentus (okra), H. fisculatus, H. mutabilis, H. sabdariffa, H. suranensis, Euphorbia pulcherrima, Sphaeralcea cisplaniina. DISEASE: Leaf spot or brown leaf spot of Hibiscus spp. The first symptoms are yellowish patches on the leaf surface. These then become necrotic and gradually expand into irregular greyish brown leaf spots with dark brown to purple borders, surrounded by a pale yellow halo. Ultimately the necrotic areas become shrivelled and crack (30, 445). GEOGRAPHICAL DISTRIBUTION: The fungus is found wherever Hibiscus is cultivated (Chupp & Sherf, 1960). Africa: Ethiopia, Ghana, Mauritius, Sierra Leone, South Africa, Sudan, Tanzania, Uganda, Zimbabwe; Asia: Borneo, India, Indonesia, Japan, Malaysia, Philippines; Australasia: Fiji, Papua New Guinea; North America: West Indies (Jamaica, Trinidad, Cuba); South America: Colombia, Venezuela. TRANSMISSION: Presumably by wind-borne and rain-splash dispersed conidia.

Peronospora jaapiana. [Descriptions of Fungi and Bacteria].

1981 ◽  
Author(s):  
S. M. Francis
Keyword(s):  
New Zealand ◽  
Downy Mildew ◽  
Geographical Distribution ◽  
Leaf Surface ◽  
Leaf Material ◽  
Leaf Spots

Abstract A description is provided for Peronospora jaapiana. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Rheum officinale, R. palmatum, R. rhaponticum, R. undulatum. DISEASE: Downy mildew of rhubarb. Seedlings in cold frames and plants in the field may be attacked and heavy losses caused in cold, wet seasons. The fungus causes a severe spotting and eventual destruction of the leaves. Plants may be almost completely defoliated. The earliest symptoms are conspicuous yellowish spots of 1 cm or more diameter which appear on the upper leaf surface. These areas are at first delimited by the veins but in severe attacks they soon spread causing the veins to break and the leaves then fall to pieces. With age the leaf spots become dry and brown and very brittle. The condiophores which may be seen on the under surface of the leaves beneath the yellow spots in the earlier phases of the disease were sparingly produced in the material seen (IMI 251354) and resembled the downy mildew of rose, Peronospora sparsa, in this respect. They are reported as forming a grey to fawn downy growth in Australia when conditions are moist. GEOGRAPHICAL DISTRIBUTION: Asia (USSR (Estonia, Latvia)); Australasia (Australia, New Zealand); Europe (Britain, Denmark, France, Germany, Norway, Poland, Switzerland); N. America (Canada, USA). TRANSMISSION: No oospores have been reported for this species and the pathogen is said to perennate as mycelium in the young shoots of propagating roots (Chupp & Sherf, 1960). The hyphae of P. jaapiana contain unusually large amounts of glycogen which enables them to overwinter in decaying leaf material on the ground (Magnus, 1910).

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