Search on : Taxa descriptions

 


   
Literature:
 
Remarks (public):For a complete description including images see www.cababstractsplus.org/dfb 
Remarks (internal):A largely saprophytic fungus reported mainly from decaying plant material in tropical and temperate climates. It has been recorded as a primary pathogen of rice and sorghum in West Africa (35, 165; 37, 351) causing necrosis of the leaf blade and glumes. Earlier reports suggest that this disease also occurs in Nyasaland (Malawi) on rice (32, 669) and recently it has been recorded on rice in India (53, 944). It is also responsible for facial eczema of sheep, a disease that occurs in New Zealand and Australia (Atherton et al., 1974). The condition has been known for about 70 yr in New Zealand where its occurrence is limited to well defined regions. Severity of incidence of facial eczema varies from year to year. It occurs in late summer and autumn. At these times severe outbreaks are related to periods of rain and warm weather which favour colonisation of pasture debris by P. chartarum with subsequent sporulation. Mycotoxins (sporidesmins) in the spores affect the liver and phylloerythrin (a breakdown product of chlorophyll) accumulates in the blood. As a result, non-pigmented parts of the skin become photo-sensitive and develop eczema. Control methods based on this hypothesis have had moderate success by (a) withdrawing sheep from pasture when weather forecasts and spore trapping show rises in spore populations of P. chartarum to be likely, (b) selective chemical control of the fungus by spraying pastures with thiabendazole, (c) the partial protection achieved by feeding sheep on a high protein diet. Optimum growth in culture occurs at c. 24°C with little variation over a pH range of 5,5-8,6; growth declines on media more acidic than this. A wide range of carbon and nitrogen sources can be utilised. Total spore production in culture is much the same between 20°C and 28°C (Brook, 1963; Ross, 1960a). It has been suggested that as P. chartarum grows saprophytically on grass residues, crown rust control by use of fungicides, or reducing the period of closed pastures, may indirectly contribute to control of facial eczema by reducing the substrates on which the fungus may sporulate (45, 3358).  
Description type:Non-original description 
Description:Pithomyces chartarum (Berk. & M.A. Curtis) M.B. Ellis, Mycological Paper 76: 13, 1960.
Sporidesmium chartarum Berk. & M.A. Curtis, 1874.
Piricauda chartarum (Berk. & M.A. Curtis) R.T. Moore, 1959.
Sporidesmium echinulatum Speg., 1879.
Scheleobrachea echinulata (Speg.) S. Hughes, 1958.
Sporidesmium bakeri Syd., 1914.
Mycelium superficial, branched, anastomosing, septate, smooth or verruculose, subhyaline to pale olive. Colonies black,separate, later becoming confluent, up to 0,5 mm diam. Conidiophores micronematous, mononematous, branched andanastomosing, pale olive, smooth or verruculose, 2,5-10 x 2-3,5 µm. Conidiogenous cells monoblastic or polyblastic, integrated, intercalary or terminal, indeterminate, with 1-2 loci of similar width in the conidiogenous cells. Conidia muriform, medium to dark brown, echinulate to verruculose, 3 (-4)-euseptate, slightly constricted at the septa, with one or both median cells divided by longitudinal septa, thick-walled, broadly ellipsoid, apex obtuse, base truncate and characteristically with part of the conidiogenous cell remaining attached as a small pedicel, 18-29 x 10-17 µm.
Hosts: Isolated from a very wide range of plant material, also from air, soil, hay, sawn timber and ceiling plaster.
Disease: Facial eczema of sheep, glume blotch of rice and sorghum.
Geographical distribution: Europe (UK, Italy); Africa (Ghana, Guinea, Kenya, Malawi, Mauritius, Nigeria,
Rhodesia, South Africa, Sierra Leone, Sudan, Tanzania, Togo, Zambia); Asia (Brunei, Burma, Hong Kong, India, Japan, Malaysia (W., Sabah), Nepal, Philippines, Sri Lanka); Australasia (Australia, New Zealand, New Guinea, Fiji, Tonga, British Solomon Islands); North America (USA, Canada); Central America (Cuba, Honduras, Jamaica, Panama, Trinidad, Windward Isles); South America (Argentina, Bolivia, Brazil, Guyana).
Physiologic specialization: None reported.
Transmission: By air-borne spores.
Literature: Atherton et al., in Mycotoxins, ed. Purchase, Elsevier, 1974; Brook, New Zealand Journal of Agricultural Research 6: 147-228, 1963; Ross, New Zaland Journal of Science 3: 15-25, 1960; Ross, New Zealand Journal of Science 3: 441-452, 1960.

 
Taxon name: