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Mycosphaerella papuana sp.nov., from Papua New Guinea, is proposed as the teleomorph of Cercospora dioscoreae-pyrifoliae.

Ascus development in the teleomorph of Phoma arachidicola was examined using light and electron microscopy. Ascus initials developed from pseudoparenchymatous elements in the pseudothecium and ascospores were delimited by a double-layered membrane produced independently of the plasmalemma. Ascospores were hyaline and became dark after discharge. No pseudoparaphyses were observed but threadlike strands, apparently remnants of the pseudoparenchymatous centrum compressed by developing asci, were interspersed among the asci. On the basis of these findings, the teleomorph of P. arachidicola cannot be accommodated in Didymella, Didymosphaeria or Mycosphaerella .

The development of the teleomorph of Cladosporium allii-cepae on sterile overwintered leek tissue is reported. Single ascospore isolates grown on malt extract agar produced the anamorph and these were pathogenic on Allium cepa . There was variation in the growth rate on malt extract agar of colonies derived from single ascospores from the same ascus. The name Mycosphaerella allii-cepae sp.nov. is introduced for the teleomorph of C. allii-cepae .

The correct binomial for the chrysanthemum ray blight pathogen is Didymella ligulicola (Baker, Dimock & Davis) von Arx. Taxonomic, nomenclatural and plant pathological evidence for rejection of Didymella chrysanthemi (Tassi) Garibaldi & Gullino, based on Sphaerella chrysanthemi Tassi, is presented and this fungus is shown to be a species of Mycosphaerella. No evidence could be found of the presence of the ray blight pathogen in Italy before 1960.

Invertase, cellulase and pectinolytic enzymes were detected in conidial matrix of Colletotrichum gloeosporioides . That of Mycosphaerella pinodes contained invertase but showed only low cellulolytic and pectinolytic activity. In both plant pathogens invertase activity declined as matrix aged. These findings are discussed in relation to the possible role of matrix during infection.

On the basis of microscopical examination of the type collections of Paracercospora fijiensis (anamorph of Mycosphaerella fijiensis ) and P. fijiensis var. difformis (anamorph of M. fijiensis var. difformis ) these names are considered to be synonymous.

Mycosphaerella pongamiae , based on Stigmatea pongamiae , is described and illustrated as the teleomorph of Asperisporium pongamiae . The genetic connexion between the teleomorph and the anamorph has not been established in culture but is undoubtedly suggested by close association and connexion to each other by common mycelia.

Two distinct types of leaf spot on juvenile leaves of Eucalyptus globulus were found to be caused by two species of Mycosphaerella. M. cryptica caused a small circular spot while M. nubilosa caused a larger, spreading lesion. M. parva Park & Keane was only found on older lesions caused by M. nubilosa, and appears to be saprophytic. M. cryptica was also shown to be the cause of large, blighting lesions on mature foliage of a wide range of species from both major subgenera of Eucalyptus. Observations on symptom development, sporulation, pathogenicity and leaf penetration for M. cryptica and M. nubilosa are presented. Preliminary results of field studies are also given.

Inoculations of eucalypt seedlings with Mycosphaerella nubilosa and M. cryptica were carried out to determine infection requirements. M. nubilosa could only infect susceptible leaves when spores were applied to the abaxial surface. M. cryptica was able to infect leaves from either surface. Young expanding leaves were most readily infected, and leaves became more resistant with age. M. nubilosa was able to infect slightly older expanded leaves, but the incubation period was much longer. Optimal infection by both fungi occurred with 5–7 d leaf wetness at 15–20 °C. Spores of M. nubilosa and M. cryptica survived with little loss in infectivity for up to 7 and 4 d respectively following deposition on the leaf surface.

Mycosphaerella henningsii nom.nov. (syn. M. manihotis Ghesquire & Henrard) is redescribed and illustrated as the teleomorph of Cercosporidtum henningsii. Mycosphaerella manihotis Ghesquiere & Henrard (1924) is correlated with Cercosporidium henningsii (Allescher) Deighton. Unfortunately it is necessary to provide a new name for this teleomorph because it is a later homonym of Mycosphaerella manihotis H. Sydow & P. Sydow (1901). The name Mycosphaerella henningsii nom.nov. is therefore proposed for this species. It is redescribed and illustrated with its anamorph, and compared with M. manihotis for which no anamorph is known. Although the genetic connexion between the teleomorph and the anamorph has yet to be established in culture, it is undoubtedly suggested by connexion to each other by a common stroma and mycelia and by the development of ascostroma in a stroma bearing conidiophores and conidia.

The production of ascospores of Mycosphaerella nubilosa and M. cryptica was monitored at two field sites at monthly intervals. Ascocarp initiation and early development occurred throughout the year. Ascospore production was greatest from summer to mid autumn; lower temperatures then appeared to limit ascospore production from late autumn to early spring. Adequate leaf wetness is also necessary for ascocarp development and spore production. Under laboratory conditions, ascospores of both fungi matured at 15 °C with 12 h but not 1 h leaf wetness daily. Ascocarps of M. nubilosa continued to discharge spores for up to 17 months in the field, while ascocarps of M. cryptica remained active for at least 8 months. Ascospore production by M. parva was often recorded on older lesions caused by M. nubilosa or M. cryptica supporting the hypothesis that this species is saprobic.

The influence of conidial matrix on germinability was studied using Leptosphaeria maculans, Mycosphaerella pinodes and Septoria apiicola . In all species an increase in spore density resulted in decreased germinability, this decrease being greater in the presence of conidial matrix. Matrix-free (washed) spores subjected to freezing and ultraviolet radiation, or incubated at constant or fluctuating r.h. showed reduced germinability when compared with unwashed spores receiving similar treatments. In L. maculans and M. pinodes restoration of matrix to matrix-free spores before exposure to laboratory temperature and r.h. increased subsequent germinability to levels significantly above those for matrix-free spores similarly exposed. The possible eco-physiological roles of matrix are discussed in the light of these results.

Botryosphaeria foliicola sp. nov. and Rosenscheldiella intermedia sp. nov. are described and illustrated from India. Heptameria obesa is reported for the first time from India and is also the first record of the genus from India. Dothidella welwitschii , described from Southern Africa, is transferred to Mycosphaerella as M. welwitschii (A. L. Smith) Sivan. comb.nov.

Teleomorph connexions of Mycosphaerella sesami sp. nov. with Cercospora sesami , and M. sesamicola sp. nov. with Cercoseptoria sesami are reported. Species of Cercospora and allied genera causing disease of Sesamum crops are described and a key provided.

Three species of Mycosphaerella were found to be associated with two distinct types of lesion on juvenile leaves of Eucalyptus globulus. M. cryptica caused smaller circular lesions, but on mature leaves of many other eucalypt species it caused large blighting lesions. M. nubilosa has been found only on large, blighting lesions on juvenile leaves of E. globulus and three other species in the eucalypt subgenus Symphyomyrtus. A saprophytic species, which is described here as Mycosphaerella parva sp.nov., was commonly found on lesions in association with M. nubilosa.

The morphology of M. fijiensis and the pattern of sympton development in Western Samoa was similar to that found elsewhere. Rain, as little as 0.25 mm, was more important than dew in releasing ascospores of M. fijiensis from leaf tissue. In the laboratory ascospore release started within 10–15 min of wetting leaves and most spores were discharged within 3 h. When leaves were wetted on successive days more spores were released but the effect on total spore production was not determined. The midrib spotting infection pattern appeared to be caused by ascospore infections and could be simulated under defined conditions by weedkiller sprays. The tip spotting pattern found on most leaves in Samoan banana plantations indicated that ascospores were the major source of inoculum. Percentage germination, germ-tube growth, number of germ tubes and location of germ tubes on both ascospores and conidia were significantly affected by temperature, type of substrate and moisture.

Ascochyta pisi (Lib.), Mycosphaerella pinodes (Berk. & Blox.) Vestergr., Phoma medicaginis var. pinodella (L. K. Jones) Boerema, which cause leafand pod spot, and foot rots of pea grow on filter paper as a sole carbon source in pure culture. Different isolates of the same pathogen utilized cellulose at different rates and decomposition was affected by the amount of nitrogen in the culture. These results have relevance to studies of the saprophytic survival of these organisms.

Three previously described species of Mycosphaerella are discussed in relation to their original descriptions and type specimens. M. eucalypti does not appear to be a species of Mycosphaerella . However M. heimii is a distinct species but no Latin diagnosis was provided by the original author and the type specimen could not be located. M. molleriana is also distinct but it has not yet been collected from eucalypts in Australia. Three new species are described from diseased eucalypt leaves collected in southern Australia: M. delegatensis sp.nov., M. swartii sp.nov., and M. walkeri sp.nov. M. swartii and M. walkeri have identical teleomorphs, but distinct anamorphs, Hendersonia eucalyptorum and H. fraseri respectively, and have different host ranges.

The effects of two fungicides on phylloplane mycoflora and on the Mycosphaerella leaf-spots of groundnut have been investigated. No qualitative differences were found in the phylloplane mycoflora of two cultivars PG1 and M13. The location of leaves on the plants was found to exert significant qualitative and quantitative effects on the phylloplane mycoflora. Benlate sprays greatly increased the phylloplane mycoflora in comparison with control whereas Dithane M45 sprays reduced the mycoflora population. The possibility of resistance induced by the non-pathogenic mycoflora against leaf-spot pathogens is discussed.

The asexual sporulation pattern of Mycosphaerella ligulicola Baker, Dimock & Davis was followed on agar culture. At 23°C pycnidial initials were laid down only in mycelium which was 10–30 h old. Spore production commenced in mycelium which was 18 h old and continued for at least 20 days. Where septate spores were produced, evidence suggested that septa were formed after abstriction of the spores from the sporogenous cells of the pycnidium. On agar medium and host leaf disks the spore number per unit area of culture increased with increase in temperature but spore size and the proportion of septate spores decreased. The increase in spore number was due primarily to a higher productivity per pycnidium. Total volume of the spore mass remained virtually unchanged over a wide temperature range. Within limits determined by temperature, illumination caused a reduction in spore size which was associated with a reduction in total volume of the spore mass.

Spore traps were set up in Hawaii and Fiji in 1969 and 1970 in plots of bananas severely affected by black leaf streak disease (Mycosphaerella fijiensis). Ascospores of M. fijiensis were trapped on almost every day of sampling at both sites. During dry weather ascospore concentration increased during the night, became maximal near 06.00 h, and decreased to a low level during the day. On rainy days peak concentrations were recorded shortly after rain started. Seasonal increases in daily mean concentrations of ascospores were associated with increased rainfall and r.h. There was no evidence that ascospore production or release was reduced at temperatures between 10 and 15°C.

The number of pycnidia and spores formed by Mycosphaerella ligulicola Baker, Dimock & Davis per unit area of culture was influenced by the type of medium and the nutrient level, whereas the number of spores produced per pycnidium was less affected. Spores were smaller on media of low nutrient status and there were large differences in total spore volume per pycnidium. Large, diffuse pycnidia lacking defined ostioles and invested with vegetative hyphae were formed on medium with excess of the carbon source (or low nitrogen). The continuous provision of nutrients extended the period during which pycnidia were produced, increased the total number of pycnidia and spores, and caused changes in hyphal morphology. Removal of spores from cultures by washing did not influence the sporulation pattern.

Pseudothecial development is initiated by the growth of a weft of hyphae in the cortex of the host receptacle. This weft enlarges to form a solid plectenchyma-tous stroma in which (1)3–5(7) ascogonia arise. Evidence available indicates that spermatization of the ascogonia occurs by means of filiform spermatia produced in flask-shaped spermogonia which also develop in the host receptacle simultaneously with the pseudothecial stromata, from similar hyphal wefts. Further development leads to the production of bitunicate asci which discharge their ascospores forcibly in water and in air. No paraphyses or pseudo-par aphyses occur. Pseudothecial development of Mycosphaerella ascophylli Cotton differs little from that of known terrestrial species of Mycosphaerella. Infection of the host appears to occur by egg-borne ascospores and egg-borne hyphae. A comparison of M. ascophylli and M. pelvetiae Sutherland indicates that these species do not differ sufficiently to be regarded as distinct.

The growth, development and life history of Venturia rumicis on its Rumex host and in culture are described. The fungus is homothallic, producing its perfect state on the living host and in culture ; no asexual reproductive state has been found. Centrum development in Pleospora herbarum (Pers.) Rabenh.., V. inaequalis (Cke) Wint., V. pinna Aderh. and Mycosphaerella maculiformis (Pers.) Rabenh. is described and compared with that in V. rumicis. It is of the Dothidea-type in M. maculiformis, but of a Pleospora-type in the other four. The classification of the ascostromatic Ascomycetes is considered, and in the light of this the taxonomie position of V. rumicis is discussed, with the conclusion that the correct name is V. rumicis (Desm.) Wint.

Summary 1. Nine fungi causing blight or foot-rot diseases of pea, gram, lentil and vetch (Vicia sativa) have been studied. 2. The symptoms of disease and nature of injury caused, as observed on naturally or artificially infected plants, have been described. 3. A comparative study of the various fungi has been made as regards the following: (i) Morphology on the natural host and on various artificial culture media. (ii) Response to environmental conditions, such as nature of medium, acidity of medium and temperature. (iii) Manner of spore germination under a variety of conditions. 4 Inoculation experiments by three different methods under glasshouse and field conditions have been carried out. The main results were: (i) Each fungus with the exception of Mycosphaerella pinodes and Ascochyta pinodella is specialised largely to its own host plant. (ii) Mycosphaerella pinodes and Ascochyta pinodella are the only ones which cause severe foot-rot. 5 A discussion of the experimental results in relation to the taxonomy of these forms is given, and the following conclusions are reached: (i) The fungus causing blight of peas in India is typical Ascochyta Pisi Lib. (ii) The fungi isolated from lentil in India and from wild Vicia sativa in England are varieties of Ascochyta Pisi Lib. (iii) The fungus causing blight of gram in India is identical with Phyllosticta Rabiei (Pass.) Trotter. Reasons are given in support of the transference of this species to Ascochyta as Ascochyta Rabiei (Pass.) Labrousse. (iv) Ascochyta pinodella Jones and Ascochyta pinodes Jones (perfect stage = Mycosphaerella pinodes (Berk. & Blox.) Stone) are confirmed as good species and distinct from Ascochyta Pisi Lib. and Ascochyta Rabiei (Pass.) Labrousse. The two former are characteristically associated with the foot-rot phase of the disease and are both rather unspecialised in their parasitism. (v) A fungus isolated from peas in India, in association with Ascochyta Pisi Lib., is considered to be a weakly parasitic race of Ascochyta pinodella Jones.

Mycosphaerella osborniae sp.nov., Paradidymella holci sp.nov. and Pezicula dennisii sp.nov. are described as new. Guignardia istriaca Bubak, Mycosphaerella euphorbiae Niessl ex Schrot., Nectria flammea (Tul.) Dingley (as Fusarium coccophilum (Desm.) Wollenw. & Reink.) and Pezizella parasitica Velen, are reported from the British Isles for the first time. A fungus tentatively referred to Buellia (Karschia) stygia (Berk. & Curt.) E. Mull, is discussed and the new combination B. bloxamii (Berk. & Phillips) comb.nov. made. Information on an unnamed Calonectria species on fallen Ilex leaves and an unnamed Pseudohelotium species on Pteridium is also presented.

Surveys of bananas in the Hawaiian Islands failed to reveal typical symptoms of Sigatoka disease and its causal fungus Mycosphaerella musicola Leach. However, a similar form of leaf-spot disease is widespread and sometimes very severe. Evidence is presented showing that this disease is the same as ‘black leaf streak’, first recorded in 1963 in Fiji, caused by M. fijiensis (unpublished). Symptoms of black leaf streak in Hawaii are described, and the first detailed account of the conidial ( Cercospora ) state of M. fijiensis is given. The conidial state of M. fijiensis is contrasted with that of M. musicola , and with other Cercospora species recorded on bananas. Preliminary observations on spermo-gonia, perithecia, and ascospores of M. fijiensis are noted. Possibilities concerning the origin of black leaf streak disease in the Pacific region are discussed.

In vitro tests with air-dried agar cultures and greenhouse tests in sand and soil revealed that the maximum longevity of sclerotia of Colletotrichum coccodes was generally at least 2.5 times that of sclerotia of Mycosphaerella ligulicola . After 83 weeks' burial in natural soil, which had been subjected to the normal greenhouse watering routine, 53 % of the sclerotia of C. coccodes sampled were viable, whereas all sclerotia of M. ligulicola sampledafter 30 weeks' burial were dead. Of twenty-eight sclerotia of C. coccodes retrieved from soil after 84 weeks, three infected tomato test plants, but sclerotia of M. ligulicola lost the ability to infect chrysanthemum cuttings after only 8 weeks in compost. The numbers of conidia of both fungi declined rapidly after a few days' burial in natural soil and none survived for 3 weeks. The sclerotia of C. coccodes and M. ligulicola are considered to have ‘strand’ and ‘loose’ types of formation respectively. For sclerotia in general, there is no evidence that morphological complexity is indicative of persistence value in soil. The results are related to what was previously known about the life-histories of both pathogens under greenhouse conditions.

Lists of all marine and terrestrial fungi described from mangrove plants are compiled and relations between these fungi and mangrove forest plants ( Avicennia, Hibiscus, Pluchea, Rhizophora ) are described. Marine ascomycetes, basidiomycetes and deuteromycetes occur on submerged parts of roots (proproots, pneumatophores), stems and branches. Six of thirty-one species appear to be host specific. Most frequent marine species are Lulworthia sp., Metasphaeria australiensis and ‘ Phoma ’ sp. The majority of the forty-four terrestrial fungi described from mangrove trees are parasites on living leaves. High contents of tannin do not protect mangrove plants from decomposition by marine fungi and wood boring animals (shipworms and isopods). Submerged bark and wood of mangroves are deteriorated by higher marine fungi. Wood destruction is of the ‘soft rot’ type. Fewer kinds of fungi occur on bark than on wood; Mycosphaerella pneumatophorae (in Avicennia ) and Keissleriella blepharospora (in Rhizophora ) are exclusively corticolous. Some fungi develop within calcareous layers of shipworm tubes in mangrove roots or branches. Rhizophora forms adventitious roots above injured and fungus-infested root tips. There is a zonation of fungi and other organisms along vertical roots, stems, or branches of mangrove trees. Submerged parts are inhabited by marine fungi, algae, balanids, worms, shipworms, and gribbles. Several species of fungi are usually found together on the submerged part of one root, but no distinct pattern of vertical distribution among the species is evident. Growth of marine and terrestrial fungi overlaps at the high tide line. Organisms above the water include ascomycetes, deuteromycetes, basidiomycetes, and lichens. Horizontal distribution of fungi in a Hawaiian mangrove swamp along a transect from salt to fresh water is described. Marine fungi are absent in the freshwater part. Thus, host specific K. blepharospora occurs only on Rhizophora plants in salt water. Dispersal and geographical distribution of mangrove fungi are discussed. Knowledge of occurrence of marine fungi in the eastern mangrove is almost absent. Some fungi, chiefly host specific ones, have a limited distribution, while omnivorous species are found in mangroves throughout the tropics and sub-tropics. Most mangrove fungi are warm water species.