bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Genetic relationship between races of Pseudomonas syringae pv.pisi and cultivars of Pisum sativum
Authors: TAYLOR J. D. , BEVAN J. R. , CRUTE I. R. , READER S. L.
Published: April 2007

Isolates of Pseudomonas syringae pv. pisi from the UK and overseas were categorized into six races on the basis of their reactions to a range of differential pea (Pisum sativum) cultivars. Race 2 was predominant among the isolates examined and this probably reflects its relative international importance. A previously uncharacterized race (race 6) was virulent on all cultivars tested. Resistance to races 1‐5 was widespread in commercial cultivars and breeding lines with more than 75% showing resistance to one or more races. A preliminary study of the inheritance of resistance indicated that for races 1, 2 and 3, resistance was controlled by different dominant genes. The genetic basis for the relationship between races of P. syringae pv. pisi and pea cultivars was explained in terms of a gene‐for‐gene relationship involving five matching gene pairs. With further clarification of the genetics of resistance this host‐pathogen association will meet most of the requirements of a model system for the study of the genetic and molecular basis of pathogenicity and host specificity.
Vegetative compatibility of Fusarium oxysporum f.sp. dianthi from carnation in Israel
Authors: KATAN TALMA , KATAN J. , HADAR ESTHER
Published: April 2007

Auxotrophic mutants were used to determine vegetative relatedness among isolates of Fusarium oxysporum f.sp. dianthi (F.o.d.), the vascular wilt pathogen of carnation. At the first stage, different nitrate‐non‐utilizing (nit) mutants were produced from 11 isolates of F.o.d. collected in Israel. Complementation (heterokaryon) tests showed that all the isolates belonged to a single vegetative compatibility group (VCG), and two mutants were chosen as its testers. Additional isolates of Fusarium from carnation, collected during 1986‐88, were analysed for pathogenicity and vegetative compatibility with the testers. A total of 170 Fusarium isolates, obtained from 42 cultivars at 40 sites, were tested. All the nit mutants of all the 132 pathogenic isolates formed heterokaryons with the testers, indicating that they belonged to the same VCG. None of the 38 non‐pathogenic isolates was vegetatively compatible with the testers. The nit mutants retained pathogenicity to carnation. The F.o.d. testers were not compatible with testers of five other formae speciales of F. oxysporum. Thus, F.o.d. appears to constitute a distinct genetic population within the F. oxysporum complex.
Selection of a new set of homogeneously reacting bean (Phaseolus vulgaris) differentials to differentiate races of Colletotrichum lindemuthianum
Authors: DRIJFHOUT E. , DAVIS J. H. C.
Published: April 2007

Twenty‐two cultivars of Phaseolus vulgaris, mentioned in the literature as differential cultivars or sources of resistance, were screened with isolates representing 10 races of Colletotrichum lindemuthianum, to test their suitability as differentials. Single‐plant selections from eight cultivars were chosen, with genetic uniformity for resistance and with clear positive or negative reactions following inoculation with all 10 individual races. These differentials are proposed as a standard set for international use, to make the identification of C. lindemuthianum races internationally more comparable. The criteria for a set of differentials, and the influence of cultivar, fungus race and environment on the host‐pathogen reaction are discussed.
Fitting of simple models for field disease progress data for the take‐all fungus
Authors: BRASSETT P. R. , GILLIGAN C. A.
Published: April 2007

The properties of a number of non‐linear models are considered in relation to the description and interpretation of curves for disease progress of soil‐borne pathogens. The curves include the logistic function, with and without allowance for growth of the host population, as well as ‘custom‐built’ models with and without algebraic solution. The custom‐built models are used to separate the epidemic into primary and secondary infection and allowance is made for growth of the host population and for decay of initial inoculum. The models are compared with a simple polynomial model. All models are fitted to two disease progress curves derived from an extensive data set for infection and disease of winter wheat by the take‐all fungus, Gaeumannomyces graminis var. tritici. The results are discussed in relation to the role of primary and secondary infection, decay of inoculum and growth of the host population on epidemic development
Phytophthora citricola on rubber in Sri Lanka
Authors: LIYANAGE N. I. S.
Published: April 2007

Phytophthora citricola is reported for the first time on cultivated rubber.
Aetiology of stem canker diseases of pigeonpea in Fiji
Authors: DAVIS R. I. , OGLE H. , HAYWARD A. C. , MEEKIN J. S. , IRWIN J. A. G. , KUMAR J.
Published: April 2007

Xanthomonas campestris pv. cajani is reported for the first time from Fiji as the cause of potentially serious pustular stem lesions of pigeonpea. Cultivars and breeding lines differed in susceptibility. The cause of another stem canker disease, characterized by smooth lesions, remains undetermined.
Tyrophagus longior (Gervais) (Acarina; Acaridae) as a pest of ornamentals grown under protection
Authors: BUXTON J. H.
Published: April 2007

Two cases of severe damage by Tyrophagus longior to protected ornamentals were recorded in England in 1988. The symptoms, which included distortion and death of growing points and holing of young leaves, were seen on Verbena, Lavatera and Delphinium ajacis (larkspur). No organic matter such as straw or manure was associated with either infestation. A high‐volume spray of dichlorvos gave good control of the mite at one site.
Assessment of benomyl resistance and mating type in field isolates of Pyrenopeziza brassicae, cause of light leaf spot of brassicas
Authors: BALL ALISON M. , SIDDIQ ANJUM A. , GILTRAP N. J.
Published: April 2007

In 1987, 254 isolates of Pyrenopeziza brassicae from 27 winter oilseed rape crops in East Anglia were tested for their resistance to benomyl and for their mating type. All of the isolates were found to be susceptible to benomyl. Both the known mating types were represented amongst the isolates from 74% of the fields although in 33% of the fields 70% or more of the isolates were of one mating type. In two fields, only one mating type (MA T1‐l) was present. Some isolates were of neither of these mating types.
The effects of soil solarization on sclerotial populations of Sclerotinia sclerotiorum
Authors: PHILLIPS A. J. L.
Published: April 2007

Solarization reduced the populations of sclerotia of Sclerotinia sclerotiorum in soil and reduced the ability of the surviving sclerotia to form apothecia. The greatest reductions occurred in the top 5 cm layer of soil but significant effects were seen at 10 and 15 cm depths. These reductions were due mainly to microbial colonization and degradation of sclerotia weakened by the sublethal temperatures produced by solarization. A beneficial side‐effect was a significant reduction in the population of weeds in solarized plots.
The ubiquity of non‐specific eliciting activity in intercellular washing fluids from rust‐infected wheat leaves
Authors: SUTHERLAND M.W. , DEVERALL B. J.
Published: April 2007

Intercellular washing fluids (IWF) were harvested from a range of wheat cultivars infected with either the leaf rust fungus (Puccinia recondite f.sp. tritici) or the stem rust fungus (Puccinia graminis f.sp. tritici). These fluids were then tested for their ability to elicit symptoms of chlorosis and necrosis in 14 wheat cultivars. Eliciting activity was found in all samples tested, irrespective of both the host cultivar infected by the rust fungus and the genotype of the infecting pathogen isolate. Healthy test cultivars either responded to all IWF preparations or were responsive to none of them. Investigations into the nature of this non‐specific eliciting activity revealed that active molecules are periodate sensitive, negatively charged at neutral pH, and associated with a high molecular weight fraction.
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.
Sensitivity of cells and protoplasts of hop cultivars to cytotoxic components of culture filtrates of Verticillium albo‐atrum isolates from hop
Authors: CONNELL SARA A. , LEGG T. , HEALE J. B.
Published: April 2007

Leaf mesophyll protoplasts and cell suspension cultures obtained from resistant and susceptible cultivars of hop (Humulus lupulus) exhibited differential cell death responses when treated with sterile culture filtrates (CF) obtained from four isolates of Verticillium albo‐atrum showing a range of virulence towards hop. The extent of cytotoxicity was correlated with both the virulence of the isolates and the resistance of the cultivars. Cytotoxicity was attributed to a low‐molecular‐weight, heat‐labile, component of CF. Cell cultures from a susceptible and a resistant cultivar exhibited similar, growth‐related, patterns of sensitivity to CF. The extent of inhibition of callus growth caused by CF treatment was related to the level of the resistance of the cultivar.
Variation in sensitivity of Phytophthora infestans to fosetyl‐Al
Authors: BASHAN B. , LEVY Y. , COHEN Y.
Published: April 2007

Twenty‐three field isolates of Phytophthora infestans from North America, Europe and Israel were tested for sensitivity to fosetyl‐Al on rye‐seed‐agar medium and on leaf discs from 12 potato cultivars. Sensitivity varied greatly between fungal isolates; their sensitivity in vitro was not significantly correlated with sensitivity in vivo. In vivo, there was a significant effect of potato cultivars on sensitivity, which interacted with fungal isolates. The fungicidal effect of fosetyl‐Al was greater on older than on younger leaves, and greater with a 12‐h photoperiod than in continuous light. Sensitivity of isolates to fosetyl‐Al was significantly correlated with sensitivity to phosphorous acid (tested in vitro) but was not correlated with sensitivity to metalaxyl (tested in vitro and in vivo). The results explain some of the controversial reports on the efficacy of fosetyl‐Al in controlling potato late blight.
The reaction of two lettuce cultivars to mixed infection by beet western yellows virus, lettuce mosaic virus and cucumber mosaic virus
Authors: WALKEY D. G. A. , PAYNE C. J.
Published: April 2007

The interaction of beet western yellows virus (BWYV), lettuce mosaic virus (LMV) and cucumber mosaic virus (CMV) has been studied in lettuce cultivars Little Gem and Saladin. LMV infection alone or in combination with BWYV and or CMV caused the most severe symptoms and yield losses in both cultivars. BWYV caused more severe reactions in Little Gem than in Saladin; the reactions caused by CMV were mild in both cultivars. The interaction between BWYV and CMV infection resulted in a significantly greater yield loss in both cultivars than that caused by BWYV or CMV infection alone.
A serious disease of seedling rambutan caused by Pseudocercospora nephelii sp. nov.
Authors: PEREGRINE W. T. H. , AHMAD Hj. KASSIM BIN , ABAS AHMAD BIN Hj. , SUTTON B. C.
Published: April 2007

Pseudocercospora nephelii is described from necrotic lesions on leaves of Nephelium lappaceum seedlings in Brunei, sometimes causing complete defoliation and death. The pathogen also occurs in Sabah and Selangor in Malaysia. Recommendations for control include treatment with mancozeb or benomyl.
Damping‐off of sugar beet caused by Rhizoctonia cerealis
Authors: O'SULLIVAN E. , KAVANAGH J. A.
Published: April 2007

Rhizoctonia cerealis was isolated from diseased sugar beet seedlings collected from crops in Ireland. In pathogenicity tests, isolates of R. cerealis from beet seedlings, and from sharp eyespot lesions on wheat crops, caused severe damping‐off of sugar beet. Isolates from beet seedlings also caused symptoms of sharp eyespot on wheat.
Estimation of amounts of Phytophthora infestans mycelium in leaf tissue by enzyme‐linked immunosorbent assay
Authors: HARRISON J. G. , BARKER H. , LOWE R. , REES E. A.
Published: April 2007

A polyclonal antiserum, prepared in a rabbit immunized with a mycelium extract of Phytophthora infestans, reacted in an enzyme‐linked immunosorbent assay (ELISA) with mycelial extracts of two Phytophthora species but not with those of 10 other micro‐organisms found on potato. P. infestans mycelium in leaf tissue was readily detected by ELISA using either the plate‐trapped antigen or F(ab')2 antibody‐fragment techniques. The amount of mycelium in leaf extracts was estimated by comparing the values obtained in ELISA with those for known concentrations of P. infestans mycelium.
Pigment‐associated proteins of Xanthomonas campestris pv. juglandis
Authors: LAWANI L. O. , ARIRIATU L. E. , GOVEN A. J. , KESTER A. S.
Published: April 2007

Two pigment‐protein complexes extracted from the cell membrane of Xanthomonas campestris pv. juglandis with 2% Triton X‐100 were separated from other membrane proteins by electrophoresis on a 10%., non‐denaturing discontinuous polyacrylamide gel. One pigment‐protein complex band was distinct, while the other was diffuse. The apparent Mr of the protein from the distinct pigment‐protein band was 16400, while the protein in the diffuse band had an apparent Mr of about 45000. The protein in the distinct band consisted of 13 amino acids of which 10% were aromatic, 12% hydroxy, 16% basic, 16% acidic and 46% non‐polar. Polyclonal antibody, against the distinct protein, was used to assay for cross‐reactivity with cell wall and membrane proteins of 23 bacterial species by the Ouchterlony double‐diffusion assay. Seven of the bacteria, representing seven genera, cross‐reacted with the antibody, suggesting that a serologically‐related, pigment‐associated protein is commonly distributed among bacteria and which, unlike the pigment, may limit its use as a chemotaxonomic marker for Xanthomonas.
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.
Puccinia striiformis f.sp. tritici in Australasia: pathogenic changes during the first 10 years
Authors: WELLINGS C. R. , McINTOSH R. A.
Published: April 2007

Pathogenic attributes of the wheat stripe rust pathogen were monitored in annual surveys from the first recording of this disease in Australia in 1979. During the 10‐year period to 1988,15 different pathotypes were detected in Australia and New Zealand. The pathotypes included some of economic importance to commercial wheat cultivars and others with no obvious selective advantage to aid their survival. Single‐gene mutations were the most likely causes of variation. The implications of these results on pathogenicity surveys and breeding for resistance are discussed.
Virulence patterns in populations of Erysiphe graminis f.sp. hordei in Europe in 1986
Authors: LIMPERT E. , ANDRIVON D. , FISCHBECK G.
Published: April 2007

A total of 3166 single colony progeny of Erysiphe graminis f.sp. hordei, constituting random samples of the aerial inoculum from 68 regions of Western Europe, were analysed in the laboratory for virulence to barley resistance genes Mlra, Mlg, Mla6+Mlg. MILa, Mla7+Mlk, Mlall, Mla9, MlaI3 + MlRu3. Mlal, Mla3 and mlo. No isolate virulent to mlo was detected. Distinct regional patterns were observed for the frequencies of most of the other virulence genes. They stressed the role of selection exerted by the cultivars grown, as well as the effect of wind dissemination of mildew populations. These two phenomena are particularly well exemplified by the data on early stages in the evolution of the newly emerging Val3 virulence in Denmark. In contrast with the preceding evolution, there was a considerable decrease of the frequency of a broadly distributed virulence (Va6); the most probable reasons for this are outlined.
Genes for race‐specific resistance to yellow rust (Puccinia striiformis) in Indian wheat cultivars
Authors: SINGH H. , JOHNSON R. , SETH D.
Published: April 2007

Seedlings of Indian wheat cultivars (Kalyansona, Sonalika, WL711 and eight others released commercially) were tested with 13 British and four alien races of Puccinia striiformis. The data indicated the probable presence of the resistance gene Yr2 in the three cultivars named above and in six of the others. Reactions of the remaining two cultivars, PWB12 and WL2265, were consistent with the presence of the gene 177. The presence of Yr2 in Kalyansona, Sonalika and WL711 was supported by evidence from crosses between them and with Heines VII, which is known to carry Yr2. In crosses of Sonalika with a susceptible cultivar, Kharchia Local and also with WL711, tests of F1, F2 and F3 generations indicated that, in addition to Yr2, Sonalika possesses at least two other genes. Both these genes were difficult to detect but the F3 data supported the hypothesis that there is a single partially recessive gene giving resistance to alien race 6E16 and a different, possibly complementary, gene system effective against another alien race, 39E134. The presence of resistance in addition to Yr2 was also detected in WL711 and HD2329.
The incidence of Polymyxa betae and other fungal root parasites of sugar‐beet in Britain
Authors: PAYNE P. A. , ASHER M. J. C.
Published: April 2007

A 2‐year survey of soils from a total of 208 fields, using sugar‐beet seedlings as bait plants, showed Polymyxa betae to be ubiquitous in the sugar‐beet‐growing areas of Britain. It was detected in some soils which had not grown a host crop for up to 17 years. However, infection of roots was relatively infrequent in plant samples taken from 134 survey fields in early summer and the density of colonization always low. Three other non‐mycelial fungi, Olpidium brassicae, Lagena radicicola and Rhizophydium graminis were also common parasites of sugar‐beet roots detected in soil bioassays. Infection of plant samples by O. brassicae was particularly severe.
Control of damping‐off in cress and sugar‐beet by commercial seed‐coating with Pythium oligandrum
Authors: McQUILKEN M. P. , WHIPPS J. M. , COOKE R. C.
Published: April 2007

Seeds of cress and sugar‐beet were coated with oospores of Pythium oligandrum using commercial seed‐pelleting or film‐coating procedures. Following either procedure approximately 104 oospores were recovered from both seed types, achieving 75.94% of the targeted dose. Oospore germination (9.19%) was unaffected by the coating treatments. Both types of treatment reduced damping‐off of cress caused by P. ultimum in artificially infested sand and potting compost and by Rhizoctonia solani in artificially infested sand. In some cases, the level of control was equivalent to fungicide drenches. In general, pelleting of P. oligandrum on cress gave better control than film‐coating treatments. P. oligandrum also reduced damping‐off of sugar‐beet in soil naturally infested with Aphanomyces cochlioides and Pythium spp. Control was equivalent to that achieved with hymexazol fungicide seed‐coating treatments and was related to the inoculum potential of A. cochlioides in the soil; neither standard hymexazol coatings nor P. oligandrum treatments gave control at high inoculum potentials. P. oligandrum was not rhizosphere competent on cress or sugar‐beet.
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.
Population dynamics of dicarboximide‐resistant strains of Botrytis cinerea on grapevine in New Zealand
Authors: PAK H. A. , BEEVER R. E. , LARACY E. P.
Published: April 2007

Changes in the proportion of dicarboximide‐resistant strains of Botrytis cinerea were monitored in two vineyard trials conducted during the period from October 1985 to November 1987. Dicarboximide resistance frequency in samples taken prior to flowering from wood (dead cane‐ends, dead tendrils, old bunch remains) was high (66%) in the first trial, and low (12%) in the second trial. In treatments where resistance frequency was high on wood in spring, it decreased during the phase of disease establishment in new bunches irrespective of whether or not dicarboximide fungicides were applied. In the absence of dicarboximide applications, resistance frequency showed little change during the phase of disease development in bunches. The resistance frequency increased, however, if dicarboximide fungicides were applied, the extent of increase depending on the number and timing of applications and on disease severity at the time of application. Where resistance frequency was high on the wood at harvest, it decreased over the following winter but increased again in spring even though no dicarboximides had been applied. The best disease control in both trials was obtained with a programme in which dicarboximide fungicides were only applied during the period from veraison until harvest.
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.
Occurrence of cucumber mosaic virus in phlox in Israel
Authors: GERA A. , COHEN J.
Published: April 2007

A strain of cucumber mosaic virus (CMV) was isolated from phlox plants raised from imported cuttings and grown in plastic tunnels. The infection was acquired from local sources. Virus identification was based on electron microscopy, host range, aphid transmission, serology and physical properties.
The role of the abaxial leaf surface waxes of Lolium spp. in resistance to Erysiphe graminis
Authors: CARVER T. L. W. , THOMAS B. J. , INGERSON‐MORRIS S. M. , RODERICK H.W.
Published: April 2007

Field and glasshouse observations of Lolium spp. grasses indicated that the lower, abaxial, leaf surface was rarely infected by powdery mildew (Erysiphe graminis) even when the upper, adaxial, surface was densely colonized. Experiments showed that conidia of two strains of E. graminis, one from Lolium and one from Avena, germinated equally well on both surfaces of Lolium and Avena leaves, but that the subsequent growth and development of germlings was impaired on the lower surface of Lolium leaves, so that most formed only multiple short germ tubes or an abnormal long tube, and only c. 25% or fewer formed infection structures. This contributes to the apparent resistance of the lower Lolium leaf surface to powdery mildew and may help to explain why the disease is relatively unimportant in UK ryegrass crops, since infection structures develop at a high frequency on only 50% of the leaf area, i.e. the upper surface. Scanning electron microscopy showed that the epicuticular waxes on the lower Lolium leaf surface form amorphous sheets. This contrasts with the crystalline plate waxes seen on the upper surface of Lolium leaves and on both surfaces of oat leaves. However, when the lower Lolium leaf surface was washed with chloroform to remove epicuticular wax, normal germling and infection structure development was obtained on the wax‐free surface. This suggests that the sheet waxes prevent the pathogen gaining access to features of the cuticular membrane which trigger normal germling development.
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.
Pythium oligandmm associated with a cropping disorder of Agaricus bisporus
Authors: FLETCHER J. T. , SMEWIN BELINDA J. , O'BRIEN A.
Published: April 2007

Pythium oligandrum was consistently isolated from black patches of mushroom compost from two farms. When used in experiments it inhibited the growth of mycelium of Agaricus bisporus and this effect was enhanced in the presence of a compost supplement which contained high levels of nitrogen. The common name pythium‐black compost is proposed for the problem.
Incidence of soil‐borne plant pathogens isolated from barley and winter wheat, and other crops in the rotation, on Prince Edward Island
Authors: CELETTI M. J. , JOHNSTON H. W. , KIMPINSKI J. , PLATT H. W. , MARTIN R. A.
Published: April 2007

Barley and winter wheat were sampled over 3 years to characterize soil‐borne organisms involved with cereal crown and root disease complexes. Winter wheat crowns were infected more often by Fusarium avenaceum and F. sambucinum than barley crowns. Bipolaris sorokiniana and F. graminearum were more common in crown tissue of barley underseeded with clover than in winter wheat crowns. In roots, the incidence of F. avenaceum was highest in winter wheat. In soil, populations of Rhizoctonia solani and F. sambucinum were higher in winter wheat than barley underseeded with ryegrass. Stunt nematodes (Tylenchorhynchus spp.) were greatest in winter wheat and barley underseeded with ryegrass. The incidence of F. avenaceum in roots of winter wheat correlated positively with the severity of crown and root rot symptoms. The severity of barley crown and root rot correlated positively with the incidence of R. solani in crowns, F. avenaceum in crowns and roots, B. sorokiniana in roots, and numbers of stunt nematodes in the soil. The incidence of soil‐borne organisms was also recorded in annual ryegrass. soybean, potato, pea, and clover which were grown in rotation with barley and winter wheat. The incidence of R. solani and F. avenaceum was highest in clover crown tissue, and F. sambucinum was prevalent in soybean hypocotyls. Soil population levels of R. solani, F. avenaceum, and stunt nematodes were greatest in ryegrass and pea soil just prior to ploughing down or harvesting these crops, respectively.
Biological control of peach twig blight (Monilinia laxa) with Penicillium frequentans
Authors: DE CAL A. , M.‐SAGASTA E. , MELGAREJO P.
Published: April 2007

In 1986 and 1988 various preparations of spores and or mycelium of the antagonist Penicillium frequentans, alone or in alternation with captan were applied to field‐grown peach trees inoculated with Monilinia laxa, the cause of twig blight. Some preparations of P. frequentans containing nutrients gave significant reductions in severity of disease (from 38 to 80%) over control, comparable to that given by captan. Combinations of P. frequentans and captan gave a level of control similar to or less than that given by the antagonist or chemical alone. Populations ofP. frequentans on shoots were monitored after application in 1986. When applied with nutrients, levels of P. frequentans on shoots remained higher than when the fungus was applied in the absence of nutrients. In a glasshouse experiment the effect of P. frequentans treatments on twig blight was influenced by the type and amount of M. laxa inoculum applied.
Storage rot of swede caused by Phytophthora sp.
Authors: GEESON J. D. , BROWNE K. M. , McKEOWN B.
Published: April 2007

During long‐term storage trials of swedes (Brassica napus) carried out during five seasons between 1982 and 1987, storage rots caused by a Phytophthora sp. were observed, the first report of the disease in the UK.
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.
Interference of nutrients with fungicide activity against Septoria nodorum on wheat leaves
Authors: DIK A. J. , FOKKEMA N. J. , VAN PELT J. A.
Published: April 2007

The effect of nutrients on reduction of the germination and mycelial growth of Septoria nodorum by the fungicides propiconazole, fenpropimorph and prochloraz, and on the reduction of S.nodorum infection by prochloraz, was tested on wheat plants in a controlled environment. The nutrients tested were aphid honeydew, sucrose, a mixture of amino acids and combinations of sucrose with yeast extract and amino acids, all in different concentrations. All nutrients could stimulate S. nodorum infection in combination with the tested prochloraz concentrations (4.5–45 mg a.i./1), but amino acids did not significantly stimulate infection in the fungicide‐free treatments. The stimulating effect of the nutrients was generally stronger with higher nutrient/fungicide ratios. Aphid honeydew had more effect than its main components sucrose and amino acids separately. Antagonism between nutrients and prochloraz was determined with the Colby method and from dose‐response curves by comparing ED50 S and drawing antagonism isoboles. Aphid honeydew, sucrose and amino acids caused an up to 10‐fold increase of the ED50 and can be considered antagonistic to prochloraz.
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.
Glasshouse trials of Coniothyrium minitans and Trichoderma species for the biological control of Sclerotinia sclerotiorum in celery and lettuce
Authors: BUDGE S. P. , WHIPPS J. M.
Published: April 2007

Coniothyrium minitans, Trichoderma harzianum (HH3) and Trichoderma sp. (B1) were tested for ability to control disease caused by Sclerotinia sclerotiorum in a sequence of a celery crop and two lettuce crops in the glasshouse. In control plots, over 80% of celery and 90 and 60% of lettuce in first and second crops, respectively, were infected at harvest. Only the C. minitaris treatment in the first lettuce crop decreased disease and increased marketable yield. Nevertheless, C. minitans reduced the number of sclerotia recovered at harvest in the celery and first lettuce crops and decreased sclerotial survival over the autumn fallow periods following the celery and second lettuce crop. C. minitans survived in soil for over 1 year and spread to infect sclerotia in virtually all other plots. C. minitans infected sclerotia at all times of the year but sclerotia still failed to degrade during the summer months when the soil was dry. The Trichoderma species tested had no effect on disease and almost no effect on the survival of the sclerotia. even though they could be recovered from soil for the duration of the experiments.
Aspects of biology and control of a stem rot of cucumber caused by Penicillium oxalicum
Authors: O'NEILL T.M. , BAGABE M. , ANN DM.
Published: April 2007

In 1989 penicillium stem rot affected 12 crops of protected cucumbers in the Lea Valley, Essex and one on the Isle of Wight; all of the affected crops were growing on rockwool slabs. Generally the disease incidence was low, but in one crop the majority of plants were affected and over 50% died. The causal fungus, identified as Penicillium oxalicum, occurred on stubs left after fruit picking and leaf and side‐shoot trimming, and developed to cause stem softening and withering. Blue‐green sporulation of penicillium on the main stem was usually surrounded by a ring of brown tissue. P. oxalicum failed to infect undamaged fruit, but was an aggressive pathogen of damaged fruit, with rot progressing more rapidly at 20 C and above than at 15 C. Inoculation of damaged cotyledon leaves induced lesions on a range of cultivars, with Cilla and Elka more resistant than others. Young plants of cv. Corona grown at 22‐25 C and 90% r.h. and inoculated with mycelial plugs on the stems at fresh leaf scars developed stem lesions with Canadian isolates but not with UK isolates; in the former case wilting and collapse of the plant sometimes followed. No lesions developed following inoculation on plants grown at 70‐80% r.h. P. oxalicum was consistently recovered from within the stem of most plants at the leaf axils two leaves above and two leaves below the inoculation site. Growth on potato dextrose agar of isolates of P. oxalicum from cucumber occurred more rapidly at 20 C than at 15 C. Spore germination of most isolates on agar occurred more rapidly at 20 or 25 C than at either 15 or 30 C. Isolates of P. oxalicum grew on agar amended with benomyl at 2 and 20 μg/ml but showed no growth on agar amended with iprodione at the same rates. In a crop with a high incidence of the disease, sprays of iprodione and imazalil appeared to reduce the rate of disease spread; sprays of benomyl and vinclozolin were less effective. Iprodione and vinclozolin were the most effective of five fungicides applied as paints to stem lesions to limit their development.
Occurrence of barley yellow dwarf virus in pastures of western France
Authors: HENRY M. , DEDRYVER C. A.
Published: April 2007

As pasture grasses are preponderant in the agriculture of western France, their role as reservoirs of barley yellow dwarf virus (BYDV) and its aphid vectors has been studied from 1984 to 1986. Aphids were observed on most crops of five pasture grass species (brome grass, cocksfoot, tall fescue, Italian and perennial ryegrass) but in very low numbers. Rhopalosiphum padi was the most numerous species. The incidence of BYDV was high, with levels of infection ranging from 6 to 80% depending on the species of pasture grasses. Fescue pastures were highly infected with BYDV, whereas the virus was not detected in cocksfoot pastures. PAV‐, RPV‐, MAV‐like isolates of BYDV were detected in pasture grasses, but RPV‐ and MAV‐like isolates were only detected from ryegrass and brome grass, respectively. The role of these grasses as source of viruliferous aphids infecting cereals is discussed.
Lithium chloride and cucumber powdery mildew infection
Authors: ABOOD J. K. , LÖSEL D. M. , AYRES P. G.
Published: April 2007

Lithium chloride solutions (1 mM), supplied to cucumber plants via the root system, conferred protection against powdery mildew infection of the leaves by Sphaerotheca fuliginea. The development of infection structures was significantly inhibited by this treatment. Effective concentrations of the lithium salt increased the growth of shoots but resulted in some reduction of root growth, The incorporation of lithium by different parts of plants was assessed during a 20‐day treatment period, The possible mode of action of lithium on this host‐pathogen system is discussed.
Characteristics and pathogenicity of isolates of Rhizoctonia spp. associated with damping‐off of sugar beet
Authors: O'SULLIVAN E. , KAVANAGH J. A.
Published: April 2007

Rhizoctonia solani and R. cerealis were isolated from diseased sugar‐beet seedlings in Ireland. Isolates of R. solani were assigned to anastomosis groups AG‐2, AG‐4, AG‐5 and an unidentified group that did not anastomose with recognized tester isolates. Cultures of AG‐2 were similar to those of AG‐5 on oatmeal agar (OA) and potato‐dextrose‐marmite agar (PDMA). Cultures of AG‐4, the unidentified group and R. cerealis were morphologically distinct from one another, AG‐2 and AG‐5. The optimum temperature for growth of AG‐2 was 225 C, with optimum growth of AG‐4, AG‐5 and the unidentified group at 275‐C. R. cerealis grew slower than all groups of R. solani, with optimum growth at 225°C. Hyphae of R. cerealis were significantly narrower than those of the groups of R. solani studied. In glasshouse pathogenicity tests, some AG‐2 and all AG‐4, AG‐5 and isolates from the unidentified group caused damping‐off of beet seedlings. In controlled environments of 10‐25°C, an AG‐2 isolate was the most aggressive at 10 C whilst AG‐4, AG‐5 and the unidentified group caused most disease at or above 15°C. R. cerealis was also pathogenic to beet seedlings, causing damping‐off at 10 and 15 C.
Bacterial soft rot of Agaricus bitorquis
Authors: LINCOLN S. P , FERMOR T. R. , STEAD D. E. , SELLWOOD J. E.
Published: April 2007

A new pathovar of Pseudomonas gladioli, pv. agaricicola is described to accommodate a bacterium pathogenic to Agaricus bitorquis. The bacterium causes a rapid soft rot of cultivated mushrooms at temperatures above 25 C. The pathotype culture has been deposited at the National Collection of Plant Pathogenic Bacteria, Harpenden, UK and designated NCPPB 3580.
Alternaria brown spot on Minneola tangelos in Israel
Authors: SOLEL Z.
Published: April 2007

Brown spots were observed on the rind of fruit and foliage of Minneola tangelo (Citrus reticulata C. paradisi) for the first time in Israel. The causal organism was isolated in culture and identified as Alternaria alternata, citrus pathotype. Typical disease symptoms were produced on inoculated leaves and fruit.
Discovery of Didymella fabae sp. nov., the teleomorph of Ascochyta fabae, on faba bean straw
Authors: JELLIS G. J. , PUNITHALINGAM E.
Published: April 2007

The teleomorph of Ascochyta fabae has been recorded for the first time on overwintering bean straw of Viciafaba in Cambridge. Single ascospores gave rise to typical cultures of A. fabae, the conidia of which infected faba bean plants to give ascochyta blight. Comparison with similar fungi described from Vicia spp. indicated that this is an undescribed species. The name Didymella fabae Jellis & Punith. is introduced for this teleomorph and its significance in the epidemiology of the disease is discussed.