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Remarks (public):For a complete description including images see www.cababstractsplus.org/dfb 
Remarks (internal):Major distinctions from S. laxa (CMI Descript. 619) are entire colony margins, conidium colour, and long conidium germ tubes; from S. fructicola (CMI Descript. 616) generally less abundant conidia, stromata and spermatia in culture; slightly larger conidia and hyphal diameter; colour. See Byrde & Willetts (1977). The pathogen is here described under a name by which plant pathologists have known it for many years, but Dennis (1978) and Dumont & Korf (1971) have accepted the genus Monilinia and adoption of the Monilinia combinations is recommended by Byrde & Willetts (1977). Apothecia are recorded less frequently than those of S. fructicola. It is not known whether the spermatia are functional. There is an extensive literature, summarised by Wormald (1954) and Byrde & Willetts (1977). The pathogen is active at moderate temperatures and high humidities (55, 1468; 53, 2433); disease is rare in arid climates (42, 451). Light, particularly in the blue region, stimulates growth and sporulation (50, 1095); IAA has a similar effect on sporulation and can replace light (46, 884). Growth occurs over pH range 2 3-10, optimum for mycelial growth about 4,2, for sporulation 7,3 (54, 324; 52, 3552). Fructose and starch are good C sources, sucrose is hydrolysed, mannitol, sorbitol, dulcitolanduronic acids are utilised (54, 324; 55, 1648, 1657; 57, 3293, 3294). Amongst nitrogen sources asparagine, ammonium sulphate and various amino acids are satisfactory (54, 324; 51, 4680). Pyridoxin and ascorbic acid stimulate growth, thiamine, pyridoxin, riboflavin and nicotinamide spore germination (56, 4853; 48, 2798). Cell wall degrading enzymes have been studied intensively (54, 48; 53, 4311; 48, 1513, 2155; 47, 3149; 44, 3403, 2725); their production is correlated with virulence and has taxonomic significance (55, 1344; 57, 2431) and some have been partially purified (54, 49; 49, 946). Although probably no apple variety is entirely resistant (43, 1974) studies on resistance in this host continue (44, 1149; 48, 1817; 55, 1338; 56, 1651) and there are indications of resistance in plum (41, 721). Orchard hygiene, fertilizers, pruning, avoidance of mechanical injury, adjustment of transport conditions and gamma irradiation give some control (47, 1615; 46, 2474; 43, 2320; 56, 3098; 51, 2676; 48, 3552). There is continuing interest in chemical control measures (46, 2474; 47, 1615; 48, 1839, 2466; 51, 4176; 53, 612, 3096), particularly in view of the development of benomyl tolerance (52, 2313; 54, 2592, 1581; 55, 2305; 57, 4030) and the fungus is a popular test organism in fungicide trials (42, 522; 43, 676; 51, 58; 53, 366). It is sensitive to antibiotics, produced by microorganisms including Cochliobolus and Trichoderma (54, 1134, 1121; 42, 443; 56, 2403; 43, 2509; 41, 280, 396; 55, 315), to oils from aromatic plants and to furcocoumarins from Heracleum (57, 4309; 45, 3049b). It is antagonistic to Alternaria brassicicola and produces antifungal phenolic acids (45, 3372; 46, 3494). Other studies include conidium ontogeny (48, 1559), sclerotium ontogeny and structure (48, 842, 3566), intrabyphal hyphae (48, 724), Iysis of hyphal walls (56, 2868), cell wall composition (52, 994), nuclear condition (50, 739), heterokaryosis (51, 4714), polysaccharide production (57, 966), host penetration and behaviour as a wound pathogen (46, 2279; 49, 937; 57, 1299; 56, 3098), starch and sucrose contents and ethylene production in infected fruits (57, 1606; 52, 2323, 4135; 55, 1344) and induction of a phytoalexin-like reaction on wheat against Puccinia recondita (54, 3832).
 
Description type:Non-original description 
Description:Sclerotinia fructigena Aderh. & Ruhl., Arbeiten aus der Biologischen Abteilung fur Land- u. Forstwirtschaft Berlin 4: 432, 1905.
Monilinia fructigena (Aderh. & Ruhl.) Honey, American Journal of Botany 23: 105, 1936.
Conidial state: Monilia fructigena Pers.
Colonies on PDA initially colourless, margins of colony even; aerial mycelium at first sparse, later developing concentric zones of dense mycelium and light buff sporogenous tissue, the zonation intensified by diurnal illumination; small discoid sclerotia or irregular stromatal flakes or crusts sometimes develop on agar surface or within the medium, but in many isolates only darkening of the mycelium with age occurs. Primary Hyphae at advancing edge of colony thin-walled, frequently over 300 µm long, 7-11 µm wide, with one or more branches initiated before the first septum, contents dense, granular; cells behind tip about 40-90 µm long. Secondary and subsequent branch Hyphae are often much narrower than primary hyphae. In lactophenol mounts some shrinkage of cell contents occurs and the septal pore may show clearly, particularly in cotton blue stain. Sclerotial initials are small strands or tufts of hyphae formed by branching and anastomosis; mature sclerotia show a clearly differentiated closely interwoven rind 3-4 cells thick, the cell walls thickened and strongly pigmented, and a medulla of intertwined fairly infrequently branched hyphae with granular contents, ranging from approximately the diameter of the primary hyphae to about 2 µm; the inter hyphal spaces contain gelatinous material; stromatal crusts are similar but have a rind on exposed surfaces only. Conidia (macroconidia) blastic, formed in chains with the youngest spore at the distal end, or occasionally arthric, ellipsoid, ovoid or limoniform often with truncate ends, thin-walled, hyaline (buff-coloured in mass) 12-34 x 6-15 µm (average about 21 x 13 µm); in tap water (18 h at 25°C) conidia form a single long unbranched germ tube. Phialidic spermatial state (microconidial) is usually present. On the host, conidial sporodochia (about 1-1,5 mm wide) occur on all infected organs; discrete sclerotia are not usually formed, but infected fruits develop dry substratal stromata ('mummies') in which a stromatic layer replaces most of the pericarp.
Hosts: On almond, apple, apricot, cherry, fig, loquat, medlar, nectarine, peach, pear, persimmon, plum, quince, grapevine, Amelanchier canadensis, barberry, blackberry, cherry laurel, Cornus mas, Corylus, Cotoneaster, Crataegus oxyacantha, C. subvillosa, Fragaria, Prunus divaricata, P. spinosa, Pyrus purpureum, P. sieboldii, Sorbus aucuparia, S. dacica, Vaccinium.
Disease: Brown fruit rot particularly of apple, pear, plum, cherry, peach, nectarine, apricot, quince; black apples; less frequently, twig blight and canker.
Geographical distribution: Widespread in Europe and Asia, also present in Egypt, Morocco, Brazil, Chile and Uruguay. CMI Map 22, ed. 4, 1976.
Physiologic specialization: None reported, although distinct morphotypes exist (53, 4500, 2433) and isolates are generally most pathogenic on their respective hosts (50, 769).
Transmission: Mummified fruits overwinter either on trees or on the ground beneath and at the start of the growing season give rise to sporodochia and, infrequently, apothecia. In addition conidia form on other infected tissues such as cankers and blighted twigs. Spores are disseminated by air currents and water splash. There is limited spread by mycelial growth (43, 2320; 44, 1139; 56, 281).
Literature: Byrde & Willetts, The brown rot fungi of fruit, their biology and control, 171 pp., 1977; Wormald, Technical Bulletin of the Ministry of Agriculture, Fisheries and Food, London No. 3, 113 pp., 1954; Whetzel, Mycologia 37: 648-714, 1945; Dennis, British Ascomycetes, 585 pp., 1978; Dumont & Korf, Mycologia 63: 157- 168, 1971.

 
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