Showing papers in "Transactions of The British Mycological Society in 1968"
TL;DR: The occurrence of Endogone spores was studied in some 250 samples of Australian and New Zealand soils, and in some Rothamsted field soils; seven of the nine spore types formed vesicular-arbuscular mycorrhiza with inoculated host plants.
Abstract: The occurrence of Endogone spores was studied in some 250 samples of Australian and New Zealand soils, and in some Rothamsted field soils. The main diagnostic features of nine Endogone spore types are described, with notes on some of their developmental stages. Seven of the nine spore types formed vesicular-arbuscular mycorrhiza with inoculated host plants.
144 citations
TL;DR: In a Rothamsted field soil that had received different manurial treatments (no manure, dung and mineral fertilizer) for over 100 years, spore populations differed greatly.
Abstract: Some 250 Australian and New Zealand soil samples were examined. Endogone spores were usually more numerous and diverse in cultivated soils than under natural vegetation. It is suggested that the spores develop particularly under conditions of intermittent root growth. In a Rothamsted field soil that had received different manurial treatments (no manure, dung and mineral fertilizer) for over 100 years, spore populations differed greatly. The reliability of the sampling method is discussed.
103 citations
77 citations
TL;DR: A comparative physiological study of pyrophilous discomycetes has been carried out in relation to changes in the physico-chemical and biological properties of soil after burning.
Abstract: A comparative physiological study of a number of pyrophilous discomycetes has been carried out in relation to changes in the physico-chemical and biological properties of soil after burning. Comparison of the effect of heat on spore germination showed that short exposures to temperatures of 50 °C stimulated germination. There was no significant difference between the temperature and moisture requirements for growth and sporulation of these fungi and other soil fungi. Experiments showed that ascospores and conidia of pyrophilous discomycetes germinated over a wide range of pH. Vegetative growth and sporulation also took place over a wide pH range. Evidence was obtained that these fungi tended to be basiphilic in contrast with other soil fungi which tended to be acidophilic. Possible methods of survival in the soil are discussed.
66 citations
TL;DR: The kinds of imperfect state known in the Xylariaceae are discussed and those of several British species are described and it is suggested that they be used as an additional source of taxonomie information for the classification of the corresponding perfect states.
Abstract: The kinds of imperfect state known in the Xylariaceae are discussed and those of several British species are described. It is suggested that they be used as an additional source of taxonomie information for the classification of the corresponding perfect states.
61 citations
TL;DR: The incidence of mycorrhizal associations in fifty-one tree species indigenous to the Lowland Rain Forest of Nigeria and in fifteen exotic tree species was investigated, and all theexotic tree species and forty four of the indigenous species were found to have endotrophic mycorRHZal associations, and three indigenous species had ectotrophic associations.
Abstract: The incidence of mycorrhizal associations in fifty-one tree species indigenous to the Lowland Rain Forest ( Keay, 1959 ) of Nigeria and in fifteen exotic tree species was investigated. All theexotic tree species and forty four of the indigenous species were found to have endotrophic mycorrhizal associations, and three indigenous species had ectotrophic associations. The significance of this is discussed. The types of association and their occurrence are described. The amount of external mycelium on the root was positively correlated with the incidence of the internal associate but neither was correlated with the presence or absence of root hairs and both were negatively correlated with rootlet depth in the soil.
57 citations
TL;DR: The snow mould Fusarium was not recovered from the soil, which agrees with the fact that F. nivale does not normally form chlamydospores, whereas ‘Culmorum’ produces them abundantly and therefore is ideally soil-borne.
Abstract: Soil samples were collected from plots on Broadbalk, Hoosfield and Barnfield and from Broadbalk Wilderness, and their Fusarium content was estimated by plating on the Nash medium, selective for Fusarium . At the same time isolations of Fusarium were made from diseased wheat and barley plants where present in the plots. Of the Fusarium pathogens recovered, F. roseum f. cerealis ‘Culmorum’ was found in high populations, i.e. 2000–3000 or more propagules per g of soil in Broadbalk continuously sown to wheat, and the same fungus was recovered from brown lesions on culms of wheat growing in these plots. The most ‘Culmorum’ occurred where complete fertilization, including much nitrogen, had been applied, and fewest where fertilizer had not been used. On Barnfield, where only broad-leaved crops have been grown for more than 100 years, and in Broadbalk Wilderness, ‘Culmorum’ was very rare. Although F. nivale and its perithecial state, Calonectria nivalis , were commonly isolated from fusarium-infected wheat and barley plants at Rothamsted in addition to F. roseum ‘Culmorum’, the snow mould Fusarium was not recovered from the soil. This agrees with the fact that F. nivale does not normally form chlamydospores, whereas ‘Culmorum’ produces them abundantly and therefore is ideally soil-borne.
51 citations
TL;DR: Decomposition of naturally occurring and artificially buried chitin in a pine forest soil was brought about by fungi, bacteria and actinomycetes, whilst in the alkaline horizon Mortierella alpina, Paecilomyces carneus, Gliomastix murorum and to some extent Verticills sp.
Abstract: Decomposition of naturally occurring and artificially buried chitin in a pine forest soil was brought about by fungi, bacteria and actinomycetes. In the acid horizons, Verticillium sp. I, Mortierella marburgensis and Trichoderma viride were the most important chitin decomposers, whilst in the alkaline horizon Mortierella alpina, Paecilomyces carneus, Gliomastix murorum and to some extent Verticillium sp. I predominated. Bacteria and actinomycetes, mainly species of Pseudomonas, Bacillus and Streptomyces , were found in all horizons, but predominated only during the early stages of breakdown in the alkaline horizon. Some chitin decomposers were restricted to chitin and were not found on other soil particles, e.g. Verticillium sp. I and Calcarisporium arbuscula . The survival of these and other forms is discussed in relation to the occurrence of chitin in the soil and the ability of organisms to utilize chitin breakdown products.
47 citations
TL;DR: It is tentatively suggested that the high temperatures prevailing in tropical and semi-tropical soils may limit initiation and growth of A. mellea rhizomorphs.
Abstract: The growth rate of Armillaria mellea mycelium in malt agar ranged from o·ii mm/day at 5 and 32 ° C to 0·75 mm/day at 25 ° , which was the optimum. Rhizomorphs of one isolate grew 9·8 mm/day in malt agar at 25 ° , again the optimum, and 6·8 mm/day at 30 ° . By contrast the optimum for rhizomorphs growing from woody inocula through tubes of soil was about 22 ° , and no growth occurred at 30 ° . Rhizomorphs were not initiated from woody inocula at temperatures above 25 ° . The growth rates of mycelial sheets along lengths of woody stem were similar to those of rhizomorphs in malt agar. Comparisons are made with some rates of spread occurring naturally. It is tentatively suggested that the high temperatures prevailing in tropical and semi-tropical soils may limit initiation and growth of A. mellea rhizomorphs.
42 citations
TL;DR: It is suggested that the failure of Trichoderma in fumigated soils to control R. solani and A. mellea was due to the fact that the dominant populations of TrICHoderma must have been made up largely by strains of the fungus that were not effective antagonists against the two pathogens.
Abstract: A study was made of the extent to which Trichoderma recolonized fumigated soils with a view to biological control of root disease fungi. Treatment of Kettering soil with allyl alcohol, chloropicrin, dichloropropene—dichloropro-pane mixture (D-D), methyl bromide, sorbic acid or acetylenedicarboxylic acid promoted the development of dominant populations of Trichoderma reaching about 100% of the recolonizing fungus flora as assessed by the dilution plate method. Trichoderma was the dominant fungal recolonizer of both acid and alkaline soils treated with allyl alcohol. Analyses of Trichoderma isolates showed that several species-groups of Trichoderma, namely, T. hamatum, T. harzianum, T. koningii and T. viride, were included within these dominant populations of Trichoderma in the fumigated soils. T. harzianum was, however, the predominant species-group except in limed Kettering soil where it was replaced by T. hamatum. There was no difference in the general spectrum of Trichoderma species groups between naturally acid and alkaline soils treated with allyl alcohol. Fumigated soils containing dominant populations of Trichoderma were tested for their effect on the growth of two root disease fungi, Rhizoctonia solani and Armillaria mellea, which are known to be susceptible to antagonism by Trichoderma. No inhibitory effect was observed; in fact, both pathogens grew better in the fumigated soils than in untreated soil. Cultural studies of the interaction between R. solani and A. mellea, respectively, and Trichoderma species-groups from fumigated soils showed that not all the species-groups of Trichoderma nor even all isolates of any one species-group were antagonistic to the two pathogens. It is suggested that the failure of Trichoderma in fumigated soils to control R. solani and A. mellea was due to the fact that the dominant populations of Trichoderma must have been made up largely by strains of the fungus that were not effective antagonists against the two pathogens.
39 citations
TL;DR: It is confirmed that high temperatures and low soil moistures are very favourable for death of wheat and barley seedlings caused by Fusarium culmorum and F. avenaceum, and spore load may act as a substitute for unfavourable conditions such as lower temperatures.
Abstract: It is confirmed that high temperatures and low soil moistures are very favourable for death of wheat and barley seedlings caused by Fusarium culmorum , and tend to favour the incidence of disease caused by F. avenaceum . The importance of the interaction of environmental factors in determining the incidence of severe attacks of the diseases caused by these two parasites is emphasized. The level of seed inoculum present is of particular importance since little disease occurs under any set of environmental conditions until the spore load reaches a certain minimum value which is higher for F. avenaceum than for F. culmorum . High levels of inoculum of F. culmorum permit the occurrence of severe attacks on seedlings under a wider range of conditions than when the spore loads are lower. In this connexion spore load may act as a substitute for unfavourable conditions such as lower temperatures. Soil reaction and depth of sowing do not influence the incidence of disease caused by Fusarium spp. to the same extent as soil moisture, temperature or seed spore load. F. avenaceum is regarded as being a much weaker parasite than F. culmorum .
TL;DR: The ultrastructure of sporangia of Phytophthora infestons (Mont.) de Bary has been studied using young sporangi before and during indirect germination as well as old sporangias incapable of germinating indirectly.
Abstract: The ultrastructure of sporangia of Phytophthora infestons (Mont.) de Bary has been studied using young sporangia before and during indirect germination as well as old sporangia incapable of germinating indirectly. The sporangial wall is single-layered, having an apical pore blocked by a papilla into which the sporangial wall is inserted. The papilla is laminated and on the basis of enzyme studies it is suggested that it is composed of protein and pectin compounds. The sporangial cytoplasm contains structures such as have been recorded for other fungi. Storage vesicles and vesicles containing flagella are included, the latter being present before the induction of indirect germination. When indirect germination of sporangia is induced by chilling, the sporangial wall remains unaltered, but a new granular and vesicular layer appears between the papilla and the plasma membrane. It is suggested that this layer contains enzymes which degrade the papilla before zoospores are discharged. Degradation of the papilla is preceded by a rapid cleavage process, the lines of cleavage being composed of membranes and small vesicles. Old sporangia which are unable to germinate indirectly possess organelles similar to those of young sporangia. With ageing, a large vacuole appears and in some old sporangia a dense, non-vesiculated region occurs around the vacuole. Mitochondria may accumulate near the boundary between vesiculated and non-vesiculated regions. Ageing is also associated with an increase in osmo-philic particles. Flagella were never observed in old sporangia.
TL;DR: Germination of spores of several species of fungi is shown to be delayed by each of these two factors, glucose concentration and pH, which influence the magnitude of sporostasis in cultures, and in solutions of the two types of sporOSTatic factors.
Abstract: Sporostatic factors of two types—volatile substances and a non-volatile vacuola-tion factor—are produced in cultures of a wide range of fungi. Germination of spores of several species of fungi is shown to be delayed by each of these two factors. In static liquid culture both types of factor are thought to contribute to the sporostasis observed when spores are added to the culture. Glucose concentration and pH influence the magnitude of sporostasis in cultures, and in solutions of the two types of sporostatic factors.
TL;DR: The mechanism of cuticular penetration by the germ-tubes of uredospores of two rusts is described and compared with the normal mechanism of penetration through stomata.
Abstract: The mechanism of cuticular penetration by the germ-tubes of uredospores of two rusts is described and compared with the normal mechanism of penetration through stomata. In Puccinia psidii an appressorium forms at the tip of a short germ-tube and from it an infection peg penetrates between epidermal cells to establish an intercellular mycelium with haustoria in the host leaf. In Ravenelia humphreyana appressoria are frequently produced sessile to the uredospore and an infection peg penetrates directly into an epidermal cell of the leaf and enlarges as a vesicular haustorium; adjacent cells become similarly infected without the establishment of an intercellular mycelium. These mechanisms of penetration are discussed in relation to the behaviour of the germ-tube and the process of appressorium formation.
TL;DR: The production of alkaloids by certain strains of Claviceps purpurea (Fr.) Tul has been correlated with the morphological form of constituent hyphae, both in surface and submerged culture and in the sclerotia produced on host plants.
Abstract: The production of alkaloids by certain strains of Claviceps purpurea (Fr.) Tul. has been correlated with the morphological form of constituent hyphae, both in surface and submerged culture and in the sclerotia produced on host plants.
TL;DR: Sclerotia of C. purpurea from a number of grass species from differing habitats required several weeks incubation at 0–10 °C to activate germination and the significance of this in the life cycle of the pathogen is discussed.
Abstract: Sclerotia of C. purpurea from a number of grass species from differing habitats required several weeks incubation at 0–10 °C to activate germination. Within this range the higher the chiuing temperature the longer was the period required at that temperature to activate maximum germination. After chilling, germination took place most freely at 10–25° but final percentage and rate of germination were reduced at temperatures above 25°. Optimum temperatures for germination were below those optimal for mycelial extension and the significance of this in the life cycle of the pathogen is discussed. Sclerotia stored wet or dry at 15–30° showed a gradual loss of response to germination-inducing cold periods. However a high proportion of ergots stored at 15° were capable of germination even 12 months after they had been formed.
TL;DR: It is suggested that attempts to establish nematode-trapping fungi in agricultural soils for the purposes of biological control of eelworm pests are unlikely to meet with success.
Abstract: Fifteen species of nematode-trapping fungi have been studied with respect to sensitivity to soil mycostasis. A wide range of unfavourable responses to mycostasis has been demonstrated and it is suggested that attempts to establish these fungi in agricultural soils for the purposes of biological control of eelworm pests are unlikely to meet with success.
TL;DR: It was found empirically that the percentage yield loss was equal to 3 times the square-root of the yellow rust assessment at the 10.5.3 growth stage, and suggested that greater yield losses result when ear infection as well as foliar infection occurs.
Abstract: Yellow rust caused similar yield losses (8–20%), in susceptible spring and winter wheat varieties. It was found empirically that the percentage yield loss was equal to 3 times the square-root of the yellow rust assessment at the 10.5.3 growth stage. The maximum yield loss occurring when the foliage is fully infected is 30%. It is suggested that greater yield losses result when ear infection as well as foliar infection occurs. Appreciable amounts of yellow rust occurred in 7 years between 1956 and 1966. The trial sites at which varieties were most frequently and most severely infected were those in the southern, central and eastern areas of the country. The relative absence of yellow rust from commercial crops, during that period, is attributed to the extensive cultivation of resistant spring and winter varieties.
TL;DR: A common root rot of conifers in Rhodesia is attributed to Armillaria mellea (Vahl ex Fr.) Kummer, but the familiar rhizomorphs typical of this pathogen in Europe are, however, rarely produced under field conditions.
Abstract: A common root rot of conifers in Rhodesia is attributed to Armillaria mellea (Vahl ex Fr.) Kummer. The familiar rhizomorphs typical of this pathogen in Europe are, however, rarely produced under field conditions. Spread of the fungus is thus apparently dependent on the presence of host roots. Rhizomorphs are produced by the fungus in agar culture and in autoclaved forest soils. Their growth in such soils can be inhibited by the addition of sterile water extracts of untreated soil. The absence of rhizomorphs in diseased areas is attributed to the influence of a water soluble inhibitor present in the soil.
TL;DR: The role of carotenoid and of dark pigments is discussed in relation to the ecological advantages which may be derived from the possession of such pigments.
Abstract: Fungi were isolated from aerial stems and leaves, from those which had been buried by drifting sand, and from roots. Altemaria tenuis and other dark, pigmented fungi were more common on the aerial parts than elsewhere. Cephalosporium spp. and Fusarium spp. were frequently isolated from all parts of the plant and were the main components of the mycoflora on the roots. The distribution of these fungi on the propagules, seedlings, mature and decaying plants is considered. The role of carotenoid and of dark pigments is discussed in relation to the ecological advantages which may be derived from the possession of such pigments.
TL;DR: The competitive abilities of some pyrophilous discomycetes have been investigated and it is found that if burnt soil is colonized some of them grow more rapidly than many other soil fungi.
Abstract: The competitive abilities of some pyrophilous discomycetes have been investigated. Some of the fungi studied appeared unable to colonize non-sterile soil. If, however, burnt soil is colonized some of them grow more rapidly than many other soil fungi. The fruiting and growth of Pyronema domesticum was inhibited by the presence of Trichoderma and Penicillium spp. Pyronema was able to fruit in the presence of a bacterial population isolated from burnt soil.
TL;DR: Some asci with an abnormal number of ascospores may have arisen by the inclusion of varying numbers and types of nuclei at their initiation, and there must be mutation to the ‘small spore’ type during the course of development from a large spore, and also preferential selection of unlike nuclei in the initiation of the dicaryophase.
Abstract: An isolate, provisionally identified as Podospora arizonensis (Griff.) Cain, differs from the type in having asci with four large black and four small, hyaline spores. The small spores do not germinate, but the large spores, after a dormant period, show a low percentage of germination and form a mycelium which produces perithecia with asci containing dimorphic spores. There are numerous hyphal fusions, but no microconidia. The perithecium develops from an ascogonial coil and shows the typical Diaporthe -type of development. Asci arise from the binucleate, penultimate cell of a crozier, but the two nuclei do not fuse; instead they submit to two mitoses to give the eight haploid ascospores. The fungus is therefore apomictic. The haploid chromosome number is two. The four large, black and four small, hyaline spores show all seventy of the possible spore arrangements in the ascus. Since more than 98% of the asci produce four large, black and four small, hyaline spores it is suggested that the two nuclei which initiate the ascus are normally of different genotype. Some asci with an abnormal number of ascospores may have arisen by the inclusion of varying numbers and types of nuclei at their initiation. If this hypothesis is correct, there must be mutation to the ‘small spore’ type during the course of development from a large spore, and also preferential selection of unlike nuclei in the initiation of the dicaryophase.
TL;DR: It is concluded that success of any species in colonization of staled nutrient agar is determined both by its tolerance to fungistatic growth products and by its population level in the soil inoculum.
Abstract: The species spectrum of fungi colonizing plates of nutrient agar from soil inocula changed progressively with the degree of staling caused by earlier established fungal colonies. At the highest degree of staling, colonies were produced only by Trichoderma viride and three species of Penicillium . Tolerance of fourteen species of soil fungi to fungistatic growth products was independently assessed through the growth made by each species on a series of culture filtrates. It is concluded that success of any species in colonization of staled nutrient agar is determined both by its tolerance to fungistatic growth products and by its population level in the soil inoculum.
TL;DR: Samples of Scottish and Ulster seed oats were examined for the effectiveness of treatment with an organo-mercurial fungicide in controlling Pyrenophora avenae Ito & Kuribay, the cause of leaf spot, and there were indications that micro-organisms antagonistic to P. avenae might have an inhibitory effect on the pathogen both in non-treated and mercury-treated seed.
Abstract: Samples of Scottish and Ulster seed oats were examined for the effectiveness of treatment with an organo-mercurial fungicide in controlling Pyrenophora avenae Ito & Kuribay, the cause of leaf spot Seedling infection was initiated by mycelium on the caryopsis which was little affected by fungicide treatment Superficial mycelium on the lemma and palea was of minor importance and was more readily eradicated Several samples from both regions did not respond to fungicide treatment, and in one sample disease incidence was increased This was attributed to the presence of mercury-tolerant strains of the fungus There were indications that micro-organisms antagonistic to P avenae might have an inhibitory effect on the pathogen both in non-treated and mercury-treated seed
TL;DR: In this article, the authors compared media for the isolation of chitinoclastic micro-organisms from soil and found that media containing chitins as a sole carbon and nitrogen source were as good as others tested.
Abstract: Media for the isolation of chitinoclastic micro-organisms from soil have been compared. Agar media containing chitin as a sole carbon and nitrogen source were as good as others tested. The chitin in the media was prepared by ball milling shrimp chitin for 48 h at 2 ° C. Addition of antibiotics to the media made them selective for different groups of micro-organisms.
TL;DR: An account is given of some types of spore found in the foam of streams and rivers in Britain and a species of Dendrospora showing a close approach to the genus Triscelophorus is described.
Abstract: An account is given of some types of spore found in the foam of streams and rivers in Britain. The presence of spores of both Culicidospora aquatica R. H. Petersen and C. gravida R. H. Petersen is reported. Spores of a species of Dendrospora showing a close approach to the genus Triscelophorus are described. Spores of Tricladium eccentricum R. H. Petersen are illustrated from Wales, a new British record. Tetraradiate cells, believed to be shelled rhizopods and not fungal spores, are figured.
TL;DR: In the field, wheat plants of the varieties Viking and Jufy I developing from seeds soaked for 3 h in water were less susceptible to both the seedling and foot rot stages of the disease than those from unsoaked seeds.
Abstract: The incidence of pre-emergence death of wheat seedlings due to Fusarium cuimorum (W. G. Sm.) Sacc. is higher in dry as compared with wet soils because of longer time elapsing between sowing and emergence of seedlings above the soil. Soaking Viking wheat seeds for 3 h in water prior to inoculation with F. cuimorum or sowing in inoculated soil increased seedling vigour, so that seedlings escaped infection leading to pre-emergence death, and the severity of disease was reduced. Pre-emergence death was reduced by soaking seeds for 1–12 h as compared with seeds soaked for shorter or longer periods or unsoaked seeds. Disease incidence was influenced by the temperature of the water in which seeds were soaked. After soaking seeds in various concentrations of gibberellic acid the resulting seedlings emerged through the soil more rapidly than those from seeds soaked in water but a combination of factors caused more disease to develop in the former. In the field, wheat plants of the varieties Viking and Jufy I developing from seeds soaked for 3 h in water were less susceptible to both the seedling and foot rot stages of the disease than those from unsoaked seeds. Plants developing from inoculated seeds produced fewer tillers and the ears emerged 10–14 days earlier than in plants from uninoculated seeds. Soaking seeds for 3 h before inoculation increased the seed yield of the resulting plants.