Peronospora hariotii. [Descriptions of Fungi and Bacteria].

1983 ◽  
Author(s):  
S. M. Francis
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Weather Conditions ◽  
Lower Surface ◽  
Buddleja Davidii ◽  
Nursery Stock ◽  
Terminal Bud

Abstract A description is provided for Peronospora hariotii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Buddleja davidii cv. White Profusion, B. globosa and cultivars, especially cv. Lemon Ball. DISEASE: Downy mildew of Buddleja. This is a disease of nursery stock and there are no reports of the fungus infecting mature plants. Young plants 1-2 ft. high bear conspicuous brown lesions on their leaves. These begin as a yellow area on the upper surface which soon turns brown and brittle. Leaves affected in this way usually drop off. The leading shoot and terminal bud may also die. The down, which develops on the lower surface of infected leaves, is pale to medium brown depending on age and weather conditions. GEOGRAPHICAL DISTRIBUTION: Europe (Britain, France). TRANSMISSION: Not known.

Pseudoperonospora cubensis. [Descriptions of Fungi and Bacteria].

1975 ◽  
Author(s):  
J. Palti
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Lower Surface ◽  
Pseudoperonospora Cubensis ◽  
Bright Yellow ◽  
Arid Conditions ◽  
Winter Crops ◽  
Cultivated Species ◽  
China And Japan ◽  
Semi Arid

Abstract A description is provided for Pseudoperonospora cubensis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Chiefly of cultivated species of Cucumis (cucumber, melon), Cucurbita (squash, marrow, pumpkin) and Citrullus (watermelon). Less frequent on approximately 40 wild and cultivated species of 18 other genera (e.g. Benincasa, Lagenaria, Luffa, Momordica, Trichosanthes). DISEASE: Causes downy mildew of Cucurbitaceae. Infection normally confined to bright yellow spots on upper surface of leaves, with light spots covered by greyish-black down on their lower surface, spots become necrotic and turn brown from their centre outwards. On cucumbers the spots are angular, clearly limited by leaf veins, but on melons and most other hosts vein delimination is not so clear. Cotyledons sometimes affected, but very young true leaves are not. Strongest development on leaves 5-15 days after their formation. Affected leaves dry up, do not shed. Flower parts are rarely affected and fruit and seeds never affected. GEOGRAPHICAL DISTRIBUTION: Widely distributed especially on cucumbers and melons in warm and humid zones (CMI Map 285. ed. 3. 1969). TRANSMISSION: All year round transmission in warm and humid climates from older to younger crops, under semi-arid conditions from irrigated summer crops to winter crops grown under cover and then to spring crops. Summer invasions from countries wilh mild winters to those with cooler winters is likely. Overwintering by oospores held to be possible in China and Japan.

Peronospora dianthicola. [Descriptions of Fungi and Bacteria].

1983 ◽  
Author(s):  
S. M. Francis
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Disease Transmission ◽  
Dianthus Caryophyllus ◽  
Weather Conditions ◽  
Axillary Buds ◽  
Pseudoperonospora Humuli ◽  
Resistant Varieties ◽  
Weed Hosts ◽  
Pale Green

Abstract A description is provided for Peronospora dianthicola. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOST: Dianthus caryophyllus. DISEASE: Downy mildew of carnation. Early symptoms are seen on the leaves which have pale green to yellowish transverse bands and may bend at these lesions. Infected plants are stunted and become withered. Infection of the growing point may result in the development of axillary buds giving the plants a bushy appearance. Barthelet describes the shoots which can develop in some resistant varieties as resembling the basal spikes of Pseudoperonospora humuli on hops, i.e., shoots with smaller leaves, thickened stem and shortened internodes. GEOGRAPHICAL DISTRIBUTION: Europe (Britain*, Denmark, France, Greece, Turkey); N. America (California, USA); S. America (Colombia). *no herbarium material, but recorded by F.A. Mason, The Naturalist no. 848: 270, 1927; on leaves of carnation under glass, Duncombe Park, Helmsley, Yorks. (Sept. 1920). TRANSMISSION: Oospores, which are formed abundantly in the tissues of diseased plants, are thought to be important in disease transmission. A small amount of infection is often seen on the plants in the autumn and these foci can allow the pathogen to overwinter until more favourable weather conditions permit the spread of the disease the following spring. Possible weed hosts for the pathogen such as Cerastium and Stellaria, growing in the vicinity, were examined and found to be infected with a different species of Peronospora belonging to the P. alsinearum group (33, 230).

Peronospora antirrhini. [Descriptions of Fungi and Bacteria].

1981 ◽  
Author(s):  
S. M. Francis
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Seed Transmission ◽  
Lower Surface ◽  
Flowering Plants ◽  
Antirrhinum Majus ◽  
High Humidity ◽  
Secondary Infections ◽  
Leaf Surfaces ◽  
Definite Proof

Abstract A description is provided for Peronospora antirrhini. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Antirrhinum majus, A. nuttallianum, Misopates orontium. DISEASE: Downy mildew of antirrhinum. This is mainly a disease of seedlings and young plants. The infection is systemic and affected plants appear stunted and pale yellowish-green. The leaves are curled inwards and droop down. Conidiophores develop on the lower surface forming a fine white to purple down. In heavy infections the down is found on both leaf surfaces and also on the stems. The growing point may be killed and then plants often break from the base and produce several new shoots. Conidia can cause secondary infections on the leaves of older plants especially in conditions of high humidity. These appear as pale yellowish spots. GEOGRAPHICAL DISTRIBUTION: Worldwide, see CMI Map No. 222 ed. 2, 1971. TRANSMISSION: Seed transmission by oospores was tentatively suggested by Yarwood (1947). Moore & Moore (1952) refer to circumstantial evidence but say there is no definite proof. Peronospora antirrhini is not recorded as a seed pathogen by Richardson (1979) but Neergaard (1977) points out that for seed-borne infection of a downy mildew to be effective all that is needed is a mere trace of the fungus on the seed. As Yarwood (1947) indicates, terminal infections of flowering plants could easily contaminate seed.

Peronospora cytisi. [Descriptions of Fungi and Bacteria].

1983 ◽  
Author(s):  
S. M. Francis
Keyword(s):  
Downy Mildew ◽  
Geographical Distribution ◽  
Rapid Development ◽  
Severe Infection ◽  
Weather Conditions ◽  
Botanic Garden ◽  
Pale Yellow ◽  
Source Of Infection ◽  
Potential Source

Abstract A description is provided for Peronospora cytisi. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Laburnum alpinum, L. anagyroides; Robinia pseudacacia (fide Lindtner, 1957, but not confirmed by cross inoculation). DISEASE: Downy mildew of laburnum. The disease is most severe on young seedlings about 6-8 inches high. Symptoms are first seen on the upper surface of the leaves as pale yellow spots, these areas rapidly become brown, dead and brittle. The down, which is greyish brown, develops in a dense felt on the undersurface of these spots. The infected leaves may become completely withered and drop off and the seedlings then soon die. Infection of older plants has been reported by Magnus (1892) who described a single shrub (no indication of size given) with many leaves fallen and the remainder with numerous spots. Berlese (1903) records that in older plants the parasite develops especially in the upper leaves but the plants are not killed. The following year they can look perfectly healthy unless attacked again by the disease. GEOGRAPHICAL DISTRIBUTION: Europe (Britain, Denmark, France, Germany, Poland, Spain, Sweden (fide Gaumann (1923) but no specimen seen by Gustavsson (1959)), Yugoslavia. TRANSMISSION: No reports. Contaminated seed was not thought to be the source of the attack reported by Kirchner (1892) on seedlings raised from seed from the local botanic garden where the disease was not present nor did it subsequently appear. Oospores form in considerable numbers in the withered leaves and must form a potential source of infection on fallen debris in the soil. However the sporadic outbreaks of the disease suggests that the fungus may perhaps exist on other hosts such as Robinia pseudacacia or be present in small and undetected quantities on older laburnum plants in most seasons and only cause severe infection, and thus attract attention, when weather conditions favour its rapid development.

Peronospora destructor. [Descriptions of Fungi and Bacteria].

1975 ◽  
Author(s):  
K. G. Mukerji
Keyword(s):  
South Africa ◽  
New Zealand ◽  
East Asia ◽  
Downy Mildew ◽  
Geographical Distribution ◽  
Wild Species ◽  
Peronospora Destructor ◽  
North East

Abstract A description is provided for Peronospora destructor. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Affects species of Allium; common on A. cepa, rarer on A. ascalonicum, A. fistulosum, A. porrum, A. sativum, A. schoenoprasum, and a few wild species. DISEASE: Downy mildew (mildiou, falscher Mehitau) of onion. GEOGRAPHICAL DISTRIBUTION: On onion in all parts of Europe and America; north, east and south Africa, west, south and east Asia, Australia, New Zealand; and Tasmania. On other Allium crops in a few countries in Europe and on other continents (CMI Map 76. ed. 3, 1969).

Melampsora medusae. [Descriptions of Fungi and Bacteria].

1975 ◽  
Author(s):  
J. Walker
Keyword(s):  
New Zealand ◽  
Geographical Distribution ◽  
Northern Hemisphere ◽  
Populus Deltoides ◽  
Leaf Damage ◽  
Main Method ◽  
Melampsora Medusae ◽  
Nursery Stock ◽  
Eastern Australia ◽  
Incremental Growth

Abstract A description is provided for Melampsora medusae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Pycnia and aecia on Coniferae, especially Larix and Pseudotsuga, less commonly on Pinus and other genera (Ziller, 1965). Uredinia and telia on species of Populus, especially Populus deltoides, and its varieties and hybrids P. balsamifera, P. nigra var. italica and others. Its exact host range on species of Populus is not known due to confusion with other species of Melampsora and to uncertainty in the reported identity of some species of Populus and clones (Walker, Hartigan & Bertus, 1974). DISEASE: Leaf rust of poplars, causing severe leaf damage and early defoliation on susceptible species and clones. Continued defoliation of successive flushes of growth predisposes trees to winter injury and dieback (Peace, 1962) and can cause death of trees, especially nursery stock and trees 1-2 yr old (25, 204; 47, 241; Walker Haitigan & Bertus, 1974). Reduction in incremental growth of timber occurs with susceptible varieties. Some damage can occur to the conifer hosts. It is often severe on Pseudotsuga menziesii (45, 459; 47, 126) and in nurseries Pinus spp. and Larix spp. can be heavily attacked (Ziller, 1965). GEOGRAPHICAL DISTRIBUTION: North America (Canada, USA), Asia (Japan); Australasia and Oceania (Australia, New Zealand); Europe (France, Spain). Reports of Melampsora spp. on poplars (including P. deltoides and P. canadensis) from South America (Argentina, 21, 173), Uruguay (Lindquist & de Rosengurtt, 1967) may refer in part to M. medusae. TRANSMISSION: By air-borne urediniospores, often over long distances (suspected from eastern Australia to New Zealand). Urediniospores survive the winter in milder climates on semi-evergreen lines and on green sucker growth of deciduous trees. This is probably the main method of overwintering in the Southern Hemisphere and in warmer parts of the Northern Hemisphere. The possibility of bud carryover as occurs with M. epitea on Salix in Iceland (Jorstad, 1951) and the Canadian Arctic (Savile, 1972) should be investigated. Telia survive the winter and basidiospores formed in spring infect susceptible conifers in parts of the Northern Hemisphere (Ziller, 1965) but no conifer infection has so far been found in Australia.

Septoria antirrhini. [Descriptions of Fungi and Bacteria].

2004 ◽  
Author(s):  
T. V. Andrianova
Keyword(s):  
South Africa ◽  
Czech Republic ◽  
New Zealand ◽  
Great Britain ◽  
South America ◽  
Geographical Distribution ◽  
Infected Plant ◽  
Weather Conditions ◽  
Plant Debris ◽  
Wet Weather

Abstract A description is provided for Septoria antirrhini. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Leaf spot, leaf drying, defoliation. HOSTS: Antirrhinum antirrhiniflorum, A. majus, A. siculum (Scrophulariaceae). GEOGRAPHICAL DISTRIBUTION: AFRICA: South Africa. NORTH AMERICA: Canada, USA. SOUTH AMERICA: Chile, Colombia. ASIA: Armenia, Azerbaijan, China, Iran, Israel. AUSTRALASIA: Australia, New Zealand. EUROPE: Bulgaria, Czech Republic, Estonia, France, Germany, Great Britain, Hungary, Ireland, Italy, Netherlands, Portugal, Romania, Ukraine, former Yugoslavia. TRANSMISSION: Not reported, but almost certainly by airborne, splash-dispersed conidia from infected plant debris and seed stocks. The disease is significantly more severe under wet weather conditions (SINADSKIY et al., 1985).

Scirrhia pini. [Descriptions of Fungi and Bacteria].

1973 ◽  
Author(s):  
E. Punithalingam
Keyword(s):  
New Zealand ◽  
Geographical Distribution ◽  
Pseudotsuga Menziesii ◽  
Forest Floor ◽  
Republic Of Georgia ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Nursery Stock ◽  
Airborne Conidia ◽  
Infected Material

Abstract A description is provided for Scirrhia pini[Mycosphaerella pini]. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On pines including Pinus radiata and its hybrids, P. halepensis, P. canariensis, P. carbaea, P. ponderosa, P. nigra and others, Pseudotsuga menziesii (46, 2860), Larix decidua (49, 273). DISEASE: Dothistroma blight; red band. GEOGRAPHICAL DISTRIBUTION: North America (Canada, USA including Alaska), South America (Argentina, Brazil, Chile, Uruguay), Australasia and Oceania (New Zealand), Asia (Brunei, India, Japan), Africa (Ethiopia, Kenya, Malawi, Rhodesia, Swaziland, Tanzania, Uganda), Europe (Austria, France, Rumania, UK, USSR (Republic of Georgia), Yugoslavia) (CMI Map 419, ed. 2, 1970; record in CMI Herbarium). TRANSMISSION: By airborne conidia released and dispersed by a splash take-off mechanism for short distances. Long distance dispersal may be by transport of infected material, such as nursery stock and, under special conditions, clouds may carry sporal inoculum (43, 2100). Survival time of inoculum in the form of cast, infected foliage on the forest floor is limited to 2-6 months under moist conditions (50, 2003).

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.

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