bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of calcium cyanamide on the reaction of swede cultivars to populations of Plasmodiophora brassicae
Authors: WILLIAMSON CYNTHIA J. , DYCE PATRICIA E. 
Published: April 2007

The effect of using calcium cyanamide to control clubroot in four swede cultivars was examined in a field trial and two pot trials. Three populations of Plasmodiophora brassicae were used which differed in pathogenicity. The four swede cultivars showed a similar ranking for disease severity with all three pathogen populations; in intermediate environments which were neither very conducive nor unfavourable to disease development, resistance was expressed differentially.Increasing the concentration of calcium cyanamide increased the yield of uninoculated plants, probably due to a response to nitrogen, but at the highest concentration (2.55 g/kg soil), yields were reduced due to phytotoxicity. In inoculated plants, disease severity was progressively reduced with increasing concentrations of calcium cyanamide. A higher inoculum density was required to initiate disease symptom development in the more resistant cultivars. Similarly, higher concentrations of inoculum were required to cause disease when increasing concentrations of calcium cyanamide were used. The effect of the chemical appeared to be to reduce the inoculum density. These data could be interpreted in terms of a disease threshold effect related to the number of viable pathogen propagules required to cause disease on particular host genotypes. The ways in which the breakdown products of calcium cyanamide may interact with host and pathogen are discussed in relation to disease development.
Cross‐reactivity of antiserum raised against Phytophthora fragariae with other Phytophthora species and its evaluation as a genus‐detecting antiserum
Authors: MOHAN S. B. 
Published: April 2007

Antiserum (anti‐PfM) raised against mycelial suspensions of Phytophthora fragariae isolates reacted strongly with antigens from several Phytophthora species. Some cross‐reactions with antigens from Pythium species were decreased by fractionating on an affinity column of Sepharose 4B bound to extracts of Fragaria vesca roots infected with P. fragariae. The affinity‐purified anti‐PfM retained its high cross‐reactivity with the various Phytophthora species tested. It also detected infection of raspberry and strawberry roots by some Phytophthora species. This antiserum could, therefore, prove useful as a broad‐spectrum Phytophthora‐detecting antiserum.Anti‐PfM could not be made specific for P. fragariae because it was raised against components shown to be antigenically similar in all Phytophthora species tested. However, immunoblotting with the affinity‐purified anti‐PfM produced distinct patterns for P. fragariae, P. erythroseptica and P. cactorum: three serotypes were identified for the latter species. This antiserum might therefore prove useful in classifying Phytophthora species.
Factors affecting the production of apothecia and longevity of sclerotia of Sclerotinia sclerotiorum
Authors: MITCHELL SUSAN J. , WHEELER B. E. J. 
Published: April 2007

Sclerotia of Sclerotinia sclerotiorum produced naturally on winter oilseed rape and by an isolate from this host on sterile wheat grain were placed in two different soil types in pots, either on the soil surface or 1. 2, 3, 4 or 6 cm deep. Nitrogen (as TN 34, Thames Nitrogen Co.) was applied to one set of pots in autumn 1982 and spring 1983. Production of apothecia was recorded in this set in 1983 only. In pots without added N apothecia were counted in 1983 and 1984 and sclerotia were recovered from these pots at the end of the experiment.Overall, production of apothecia was not affected by soil type. More apothecia formed from cultured sclerotia and they appeared earlier than from natural sclerotia. More apothecia were produced from sclerotia placed at 0–2 cm than from those buried deeper. Fewer apothecia were produced in pots with added N and their production was delayed. Fewer sclerotia were recovered from the upper layers of soil with a higher clay content, and when sclerotia were obtained from oilseed rape rather than from cultures.
Biology and control of Polystigma ochraceum, the cause of almond red leaf blotch
Authors: BANIHASHEMI Z. 
Published: April 2007

Polystigma ochraceum is a major leaf pathogen of almond in Fars Province of Iran. Over a 4‐year study period it was found that ascospore discharge began at flowering and continued for 4–5 weeks. The maximum discharge occurred at petal fall. The incubation period was estimated to be 4–5 weeks under experimental conditions. Although the mature ascospores could produce short germ tubes in distilled water or water agar, the fungus could not be cultured or grown on conventional media from either ascospores, pycnidiospores or stromatic tissues under laboratory conditions.Of several systemic and non‐systemic fungicides evaluated under field conditions, triforine at 100–400 μ/ml was most effective. Other fungicides which significantly reduced leaf infection were, in order of efficacy, copper oxychloride (2000 μg/ml), copper hydroxide (2000 mUg/ml), Bordeaux mixture (10 000 μg/ ml) and mancozeb (2000 μg/ml). Carbendazim and thiophanate methyl (500 μg/ml) increased the level of infection. One application of the fungicide at petal fall and then two at 14‐day intervals were found to be effective in reducing the disease.
Biological and integrated control of Fusarium basal rot of Narcissus using Minimedusa polyspora and other micro‐organisms
Authors: BEALE R. E. , PITT D. 
Published: April 2007

In laboratory experiments several soil‐ and bulb‐borne micro‐organisms exhibited antagonism towards Fusarium oxysporum f.sp. narcissi. One‐third of these micro‐organisms were also found to be tolerant to thiabendazole, a fungicide commonly used for the control of this pathogen. Micro‐organisms showing high levels of in vitro antagonism and/or tolerance to thiabendazole were screened in pots of natural soil artificially infested with the pathogen. Six of the micro‐organisms were found significantly to suppress basal rot development when used as pre‐planting bulb treatments. Minimedusa polyspora and a Streptomyces species were most effective, giving disease levels 55.72% and 56.88% lower than the control.In a 1‐year field trial pre‐planting bulb treatments with M polyspora, a Streptomyces species and an isolate of Trichoderma viride significantly suppressed reductions in flower numbers, reductions in bulb yield, and percentage infection. The integration of T. viride with thiabendazole gave bulb yields significantly greater than either T. viride or thiabendazole alone whilst the integration of M. polyspora and thiabendazole resulted in significantly greater flower numbers and significantly fewer bulb infections than either treatment alone.
Occurrence of Polyscytalum pustulans, Phoma foveata and Fusarium solani var. coemleum in field soils in Scotland
Authors: CARNEGIE S. F. , CAMERON A. M. 
Published: April 2007

The effectiveness of various methods for detecting three fungal potato pathogens was compared with artificially infested soil, naturally infested tuber‐borne soil and field soil. In the spring of 1985 and 1986 field soils from 30 farms in north‐east Scotland were sampled just before planting a seed potato crop and 6 months after harvesting such a crop. The minimum statutory gap between crops is 5 years. Polyscytalum pustulans was recovered from 32 out of 60 field soil samples taken 6 months after harvest while from fields sampled in the spring before a potato crop was planted the fungus was isolated from 10 out of 30 soils in 1985 and five out of 30 in 1986. Phoma foveata was isolated from only one out of 60 pre‐planting soil samples but Fusarium solani var. coeruleum was recovered from eight of these soils.Microplant bait plants were grown over 3 years at an experimental farm near Edinburgh in various fields at different intervals after a previous potato crop. Contamination by P. pustulans was not related to interval after potatoes between 1 ‐ 7 years. No contamination was recorded in fields where potatoes had not been grown for more than 30 years.
Serological detection and identification of bacteria from plants by the conjugated Staphylococcus aureus slide agglutination test
Authors: LYONS N. F. , TAYLOR J. D. 
Published: April 2007

A rapid slide agglutination test using polyclonal antisera conjugated to protein A‐rich whole‐cell Staphylococcus aureus was developed for the detection and identification of bacteria from plants. The specificity and sensitivity of the technique was evaluated in 18 antibody/antigen combinations, representing six bacterial genera (Erwinia, Lactobacillus, Pseudomonas, Rhizobium, Rhodococcus and Xanthomonas). For two pathovars of Pseudomonassyringae the specificity of the technique was increased by the use of antisera prepared to somatic extracts.The advantages of the Staphylococcus aureus agglutination technique include speed, simplicity and the ability to identify organisms directly from infected plant tissues. It was applied to the detection of Pseudomonas syringae pv. phaseolicola and pv. pisi in lesions on bean and pea, respectively, to P. gladioli pv. alliicola and Lactobacillus sp. from rotted onion bulbs and specific strains of Rhizobium phaseoli in bean root nodules.
Analysis of disease‐progress curves for take‐all in consecutive crops of winter wheat
Authors: WERKER A. R. , GILLIGAN C. A. , HORNBY D 
Published: April 2007

Disease‐progress curves of take‐all, caused by Gaeumannomyces graminis var. tritici, were analysed for consecutive crops of winter wheat. Comparisons were made over 9 years amongst a sequence of consecutive wheats and first and second successive wheats grown after non‐susceptible break crops (spring beans). The principal objectives were to identify differences in the shapes of the disease‐progress curves that could be attributed to the rotational treatments. Shapes of disease‐progress curves were summarized by average rate of disease increase and components for curvature together with the mean amount of disease. Analyses were done for curves based upon percentages of diseased plants and of diseased roots.Mean levels of disease in second and continuous wheats rose from the start of the experiment (1979) to reach a maximum in the middle years (1982‐84) and thereafter declined. This pattern was absent in first wheats in which disease progress within years was rectilinear and comparatively slow. In second and continuous wheats, years of high disease were characterized by more marked curvature than years of low disease. For proportions of diseased plants, the rate of disease increase in second and continuous wheats slowed as the season progressed. Differences in shapes of disease‐progress curves for second and continuous wheats were apparent when proportions of diseased roots rather than plants were considered. The average linear rate of increase in the proportion of diseased roots in continuous wheats was intermediate in magnitude between those of first and second wheats. Epidemics in second wheats were initially slow and accelerated as the season progressed, whilst in continuous wheats, an early faster rate of increase in disease subsequently slowed. Some epidemiological consequences of these effects are discussed in relation to the phenomenon of take‐all decline, which is associated with the suppression of the disease in cereal monoculture. The effects of cropping history on the relative importance of infections arising from soil‐borne inoculum and infections arising from the spread of disease from neighbouring infected roots are inferred and epidemiological hypotheses for take‐all decline are advanced. Methods involving the use of weighted linear functions were used to overcome statistical problems of repeated observations within plots as well as variable sampling frequencies and intervals within and amongst years These methods, which have general applicability for epidemiological work, are described.
The relationship between antifungal diene levels and fungal inhibition during quiescent infection of unripe avocado fruits by Colletotrichum gloeosporioides
Authors: PRUSKY D. , PLUMBLEY R. A. , KOBILER I. 
Published: April 2007

Quantitative changes in the antifungal compound, 1‐acetoxy‐2‐hydroxy‐4‐oxo‐heneicosa‐12.15‐diene, in freshly harvested avocado fruits during the initial stages of fungal development were investigated to determine the possible involvement of the compound in quiescent infections of Colletotrichum gloeosporioides. The concentration of the antifungal compound in the peel decreased to subfungitoxic concentrations 16 h after harvest. Fifty‐six hours later the antifungal diene had increased to c. 3800 μg/g fresh weight. At this stage, germinated appressoria had penetrated the cuticle to the epidermal cells but no fungal development was observed until 7 days later when the concentration of the diene had decreased to 100‐110μg/g fresh weight. Following a dip treatment at 55°C for 5 or 10 min, the antifungal diene concentration decreased as in the controls, but it remained at subfungitoxic concentrations for a longer period enabling fungal development and early symptom expression.The concentration of the diene in the flesh of freshly harvested fruit decreased to 120 μg/g fresh weight 24 h after harvest. Inoculation of peeled fruits with spores of C. gloeosporioides showed germination without appressoria formation and symptom expression occurred 24‐48 h later. Symptom expression was delayed if fruits were inoculated after coating the flesh with epicuticular wax extracts or if the flesh was inoculated 3 days after harvest when the antifungal diene had regained a fungitoxic concentration. Disease symptoms were expressed in soft fruits containing subfungitoxic concentrations of the diene.We conclude that the diene in unripe avocado fruits inhibits fungal development of germinated appressoria or conidia. The quiescent structure of C. gloeosporioides in unripe avocado fruit is a subcuticular hypha.
Infection of sugar beet by Polymyxa betae in relation to soil temperature
Authors: BLUNT S. J. , ASHER M. J. C. , GILLIGAN C. A. 
Published: April 2007

The effects of soil temperature on infection of sugar‐beet roots by the soil‐borne fungus Polymyxa betae were investigated in controlled environments. Pre‐germinated seeds were sown in pots of naturally infested soil and seedlings sampled at frequent intervals over a period of several weeks. Within the range 10‐30°C, the optimum soil temperature for infection was c. 25°C; the time between sowing and the first detectable infection was shortest and the subsequent rate of infection most rapid at this temperature. No infection was observed over 80 days at 10°C.Both root and shoot dry weight were reduced on plants growing in infested soil at 15, 20 and 25 C compared with those growing in uninfested soil. In general, root growth was more severely affected than shoot growth and the effects were most pronounced at 20°C. These results were confirmed in a subsequent experiment in which P. betae‐infected root material was used as the inoculum. In addition to its role as the vector of beet necrotic yellow vein virus (the cause of Rhizomania disease), the significance of P. betae as a plant pathogen in its own right is discussed.
The role of soil, seed‐potato tuber and haulm in the transmission of Phoma foveata from infected seed to daughter tubers
Authors: CARNEGIE S. F. , CAMERON A. M. 
Published: April 2007

Infestation of ridge soil by Phoma foveata was examined over 4 years by collecting soil samples at various distances from seed tubers which were either naturally infected or inoculated with a distinctive strain. Samples were taken on four occasions during each growing season. Infestation was greatest immediately around the tuber and was largely confined to a distance of 15 cm until haulm destruction, after which P. foveata was detected more widely in the soil.The effects of various seed‐tuber and haulm treatments on the incidence of daughter‐tuber contamination by P. foveata were assessed over 5 years. Removing the infected seed tuber at emergence significantly (P < 0.05) reduced the contamination at haulm destruction of daughter tubers harvested by hand in only 1 out of 4years. In all years, tuber contamination was much less(P < 0.05) when stems were pulled and removed than when they were desiccated by applying diquat dibromide. The incidence of tuber contamination did not increase between haulm destruction and harvest when stems were pulled and removed. In another experiment, tuber contamination increased linearly with the delay in pulling haulms after applying diquat dibromide. Cutting and removal of stems tended to reduce gangrene contamination, relative to the desiccation of stems by applying diquat dibromide, in all years where the seed tuber had been removed, but in only 2 out of 5 years where the tuber was present.
Biological diversity of citrus tristeza virus (CTV) isolates in Spain
Authors: BALLESTER‐OLMOS J. F. , PINA J. A. , CARBONELL E. A. , MORENO P. , DE MENDOZA A. HERMOSO , CAMBRA M. , NAVARRO L. 
Published: April 2007

A survey of citrus tristeza virus (CTV) isolates was carried out in most citrus‐growing areas in Spain. Twenty‐two isolates were selected by geographical origin, cultivar of source tree, and symptoms observed on the host or in preliminary tests, and were biologically characterized.A wide range of variation in transmissibility by aphids and symptom intensity on nine different indicator species or scion‐rootstock combinations was observed among CTV isolates. Mexican lime. Citrus macrophylla, and to a lesser extent citron were the most useful hosts for characterizing these isolates, and leaf symptoms and stem pitting were the most discriminating traits. Positive correlation was observed between symptoms induced on Mexican lime and C. macrophylla, but not between the symptoms induced on these indicators under greenhouse conditions and the homologous symptoms on plants grown in the screenhouse. Some of the traits studied enabled us to establish relatively well‐defined groups of isolates, but in most cases a continuous range of variation was obtained and no clear group could be defined.
Take‐all in autumn‐sown wheat, barley, triticale and rye grown with high and low inputs
Authors: GUTTERIDGE R. J. , HORNBY D. , HOLLINS T. W. , PREW R. D. 
Published: April 2007

Winter cultivars of wheat, barley, triticale and rye were grown under two contrasting husbandry systems (low and high inputs) at two locations (Woburn and Rothamsted) known to be infested with the take‐all fungus. The sandy loam at Woburn is less fertile than the silty clay loam at Rothamsted. Root infection in these crops was assessed in spring and summer.Rye was least infected by the take‐all fungus, wheat the most infected and barley and triticale had intermediate levels of infection. Barley yields were less affected by take‐all than those of wheat or triticale, because barley was at a later growth stage by the time severe infection occurred. Yields of wheat and barley responded most to the high‐input husbandry on the less fertile soil at Woburn. On the basis of quantity of grain, triticale would appear to be a good substitute for wheat on the less fertile soil when inputs are low, but not where they are high. At Rothamsted, yields of wheat and triticale were similar in both input systems. There was no strong support, at either site, for the contention that triticale could be a useful substitute for barley where low or high inputs are used. A total of 177 isolates of Gaeumannomyces graminis var. tritici (the causal fungus of take‐all) were obtained from infected roots in these experiments and tested for their pathogenicity on wheat and rye seedlings. These tests revealed a range of pathotypes with varying pathogenicities to wheat and rye, but pathogenicities were not correlated with the host plant from which the fungi were isolated.
An ultrastructural study of tomato roots inoculated with pathogenic and non‐pathogenic necrotrophic fungi and a saprophytic fungus
Authors: BESWETHERICK J. T. , BISHOP C. D. 
Published: April 2007

Tomato cultivar Moneymaker was independently inoculated with Alternaria alternata, Cunninghamella elegans, Fusarium culmorum, F. oxysporum f.sp. lycopersici, F. oxysporum f.sp. pisi and Stromatinia gladioli and analysed ultrastructurally. The extent and amount of superficial fungal growth on tomato roots was similar but C. elegans, a saprophyte, was exceptional in that hyphae were not closely appressed to plant surfaces and did not adhere to plant cell walls.In general, the type of plant responses to fungal colonization and infection were similar in all of the interactions studied, with the exception of C. elegans which did not infect tomato root tissue. The failure to penetrate tomato roots by C. elegans may have been associated with the lack of hyphal adhesion to plant cell walls. Migration of cytoplasm and wall apposition/penetration papilla formation were regularly observed in tomato root tissue beneath appressed hyphae and at sites of fungal infection. Specific cellular reactions in the exodermis, namely the formation of wall ‘inclusions’ and appearance of ‘sensitive’ cells, indicated that exodermal cells were particularly responsive to fungal challenge. Fusarium oxysporum f.sp. lycopersici, a pathogen of tomato, invaded tomato root tissue more extensively than the other fungi inoculated onto tomato roots. Infection of tomato by the other fungi studied was variable, and the extent and success of fungal invasion was tentatively associated with their necrotrophic capability and typical host range.
Disease assessment of pea lines with resistance to foot rot pathogens: protocols for in vitro selection
Authors: GRETENKORT M. A. , HELSPER J. P. F. G. 
Published: April 2007

Cultural conditions were optimized so that disease reactions of plantlets and callus tissue from partially resistant and susceptible genotypes of Pisum sativum could be differentiated when inoculated with Fusarium solani f.sp. pisi. Disease was assessed using both semi‐quantitative (disease score/fungal diameter) and quantitative methods (ergosterol assay).After optimization of inoculum concentration and incubation period it was possible to differentiate the disease reactions of plantlets using disease scores and amount of ergosterol in the tissues.Incubation period, temperature and the auxin added to the media were important in allowing differentiation of callus tissue cultures. These differences were visible by measurement of the diameter of fungal growth on the callus and the amount of ergosterol in the tissues, but not with disease scores.The plantlet test was also applicable to the other foot rot pathogens Phoma medicaginis var. pinodella and Aphanomyces euteiches, allowing differentiation of the disease reactions of a partially resistant and susceptible genotype using disease scores. The ergosterol assay could be used to quantify infection caused by P. medicaginis var. pinodella, but this sterol was not detectable in mycelium of A. euteiches. In this fungus the presence of cholesterol was detected, which may be used to quantify infection.