bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors affecting development of Septoria tritici in winter wheat and its effect on yield
Authors: THOMAS M. R. , COOK R. J. , KING J. E 
Published: April 2007

Severe infection with Septoria tritici occurred in four of five experiments designed to create a series of different disease epidemics. These experiments successfully identified periods suitable for infection. They also indicated the effect of sprays, timed before and after these periods, on disease development and yield.Analysis of disease progress and weather records suggested that critical conditions for initial development of S. tritici occurred during early May at four sites. Heavy rain giving at least 10 mm on 1 day or a total of 10 mm or more on 2 or 3 successive days occurred at all four sites prior to the appearance of symptoms on a particular leaf layer, though less heavy rain may suffice to splash inoculum onto upper leaves in shorter, immature canopies where stem elongation is incomplete. At the fifth site, infection occurred later in May and disease failed to develop to a significant degree. At all sites, the length of the incubation period on any of the top three leaves was found to be between 396 and 496 degree days.Control of winter epidemics of S. tritici had little effect on yield, whereas spray sequences commencing later than growth stage (GS) 31 but immediately prior to the critical periods provided the best disease control and yield benefit. Regression models incorporating, as independent variables, area under the S. tritici disease progress curve for any of the top three leaves from their emergence (GS 32‐37) satisfactorily explained yield loss at the four sites where disease was severe. Consideration of leaf 2 or leaf 3 alone accounted for more than 82% of the variance at each site and a yield loss from infection of leaf 2 related to thermal time is suggested as 0.00265% per C per day from the appearance of symptoms.
Antifungal activity, acid and sugar content in the wood apple (Limonia acidissima) and their relation to fungal development
Authors: ADIKARAM N. K. B , ABHAYAWARDHANE YAMUNA , GUNATILAKA A. A. LESLIE , BANDARA B. M. RATNAYAKE , WIJERATNE E. M. KITHSIRI 
Published: April 2007

Unripe wood apple fruit is generally free from visible fungal growth before and at harvest but a succession of fungi appears on the fruit shell, and sometimes in the pulp, during ripening. A TLC‐Cladosporium bioassay of the chloroform extract taken from unripe fruit shell demonstrated three inhibition areas. Similar extracts from stem‐bark and root‐bark produced these three, and one additional, inhibition areas. The four compounds responsible for inhibition were identified as psoralene, xanthotoxin, 2,6‐dimethoxybenzoquinone and osthenol.Concentrations of the three antifungal compounds on unripe fruit shell increased during the first 4 days after harvest and then declined. They remained much below those required to inhibit the development of three fungi on TLC plates. Titratable acidity of the unripe fruit pulp was high but decreased by about 50% during ripening. Levels of reducing sugars were very low in the unripe fruit pulp but increased by about five times during ripening. Levels also increased in the fruit shell and its washings. The possible role of these factors in restricting fungal growth in unripe fruits is discussed.
Molecular variation in populations of Erysiphe graminis on barley, oats and rye
Authors: O'DELL M. , WOLFE M. S. , FLAVELL R. B. , SIMPSON C. G. , SUMMERS R. W. 
Published: April 2007

DNA isolated from the formae speciales of Erysiphe graminis that grow on barley, wheat, rye and oats was studied using restriction endonucleases and DNA/DNA hybridization procedures. DNA fragments were purified by molecular cloning and a few containing repeated sequences were used to demonstrate the many variations in restriction fragments both within and between the fourformae speciales. In an analysis of six single‐colony isolates of the barley mildew pathogen collected from different UK sites in different years, more than a quarter of the fragments scored varied among isolates. One isolate, with an uncommon pathogenicity character, differed from the remainder in the distribution of DNA bands. Isolates of rye mildew were also distinct from one another but isolates of oat mildew from a population of similar size appeared to belong to a single clone.It is concluded that the chromosomes of E. graminis contain many families of dispersed repeated sequences and that there may be extensive polymorphism for restriction endonuclease cleavage sites associated with these repeats. Such unselected polymorphisms could be useful in helping to understand and discriminate among the factors affecting population structure in the pathogen as it responds to different agricultural practices.
Factors affecting the efficacy of post‐harvest fungicide applications for the control of blue mould (Penicillium expansum) in stored apples
Authors: PENROSE L. J. , KOFFMANN W. , RIDINGS H. I. 
Published: April 2007

The effects of apple fruit maturity, temperature of fruit or dip solution, period of time in fungicidal dip, storage conditions, and spore inoculum concentration, on the efficacy of fungicides for control of blue mould (Penicillium expansum) were examined in various experiments.Iprodione and imazalil were only effective when inoculum concentration was low, whilst prochloraz was highly effective in controlling rot on fruit inoculated with 3 × 106 spores/ml. There was no consistent effect of dip temperature or fruit maturity on the efficacy of the fungicides. Iprodione was more effective on warm fruit (19°C) than cold fruit (6°C) whilst the reverse was true of imazalil. Extended periods of immersion in the fungicides slightly reduced the incidence of rotting but not to any useful degree.The incidence of rotting in fruit treated with prochloraz and etaconazole was less in fruit stored under controlled‐atmosphere cold storage conditions than in fruit stored in air cold‐storage. Both fungicides were also effective for short‐term storage at 20 C in air. Captan, benomyl, captan plus benomyl or vinclozolin were either ineffective or of poor efficacy under all storage conditions.
Studies on resistance to beet western yellows virus in lettuce (Lactuca sativa) and the occurrence of field sources of the virus
Authors: WALKEY D. G. A. , PINK D. A. C. 
Published: April 2007

An effective method based on glasshouse and field procedures was developed for screening commercial cultivars and other lettuce types for resistance to beet western yellows virus (BWYV). Field experiments in 1985, 1986 and 1987 showed that lettuce cultivars varied in their reaction to BWYV, but no high levels of resistance were identified in the main commercial types. Crisp types generally showed milder symptoms than butterhead or cos types, but individual butterhead cultivars were identified with resistance equal to the best crisp types. The highest levels of resistance were identified in Batavian type cultivars and extreme resistance or possible immunity was found in Lactuca perennis and L. muralis. BWYV caused yield reductions in some cultivars as high as 63% and reduced maturation by up to 38%, in others. There was no correlation between chlorotic leaf symptom severity and yield reduction.BWYV was isolated from a range of weed and non‐lettuce host species growing near affected lettuce crops. Isolates of BWYV obtained from infected lettuce and brassicas appeared to be similar. They infected sugar beet with difficulty but caused no symptoms, and could only be detected by ELISA serology.
Sources, survival and transmission of Cladosporium allii and C. allii‐cepae, leaf blotch pathogens of leek and onion
Authors: JORDAN MARY M. , MAUDE R. B. , BURCHILL R. T. 
Published: April 2007

Neither Cladosporium allii nor C. allii‐cepae was detected in seed samples of 46 commercial cultivars of leek and nine of onion.In glasshouse tests where flower inflorescences of onions and leeks were dusted with conidia of C. alliicepae and C. allii, respectively, few onion seeds and no leek seeds became contaminated. In field crops of leeks some spathes and inflorescences became diseased and gave 0 002%C. allii contaminated seeds. No infected onion seeds were obtained from naturally‐infected plants in the field.Conidia of both fungi survived for less than 6 weeks in sterile and non‐sterile soil (during which time the temperature varied from ‐8 to +11 C); pseudothecial bodies survived longer.Both pathogens survived for 3 months in debris of onion or leek on the surface of soil in pots under similar conditions. In debris buried at a depth of 7 cm in sterile or unsterile soil they survived for 2 months. Although C. allii survived only 1 month in debris on the soil surfaces following a leek crop, conidia of the fungus were trapped from the air above the area for at least 6 months and healthy leeks transplanted into this area developed the disease. No leaf blotch developed in leeks grown on land which had not previously borne that crop.
Distinguishing pathovars of Pseudomonas syringae on peas: nutritional, pathogenicity and serological tests
Authors: MAZAREI MITRA , KERR A. 
Published: April 2007

Of the published methods to distinguish Pseudomonas syringae pv. syringae and Pseudomonas syringae pv. pisi, inoculation of susceptible cultivars was the most reliable. Results were confirmed by inoculation of lemon fruit.A much more rapid and convenient serological method was developed to distinguish the two pathovars. Antisera against glutaraldehyde‐fixed cells had a high level of specificity in Ouchterlony gel double‐diffusion tests and, after cross‐absorption with heterologous antigens, in indirect ELISA. Antiserum to P. syringae pv. pisi has considerable potential to detect pea seed infected with this pathogen.
Biological control of fire blight of hawthorn (Crataegus monogyna) with Erwinia herbicola under protected conditions
Authors: WILSON M. , EPTON H. A. S. , SIGEE D. C. 
Published: April 2007

Isolates of Erwinia herbicola, obtained from flowers and leaves of hawthorn (Crataegus monogyna), were screened as potential control agents of fire blight disease (caused by Erwinia amylovora) using an immature pear fruit assay. Selected isolates were subsequently tested for disease control by infection of hawthorn blossom in the laboratory, and by shoot infection of hawthorn plants grown under controlled (glasshouse) and fluctuating (polythene tunnel) environmental conditions.Although the immature pear fruit assay provided a general screen for the selection of antagonists for the control of both blossom and shoot blight, it had two major limitations when quantitatively applied. Firstly there were inconsistencies in the relative effects of different isolates on the pear‐slice surface, with some isolates being more suppressive than the standard antagonist Eh252 in the first screening and less in the second. Secondly the assay was not able to predict accurately the level of control in the intact plant‐as no correlation occurred between the level of control in the pear fruit assay and the percentage control of either blossom blight or shoot blight.Two isolates of E. herbicola, WL9 and WL40, reduced both blossom‐ and shoot‐blight. WL9 provided over 80% control of blossom blight, equivalent to that provided by chemical agents, and also gave total control of shoot blight when applied at a WL9: pathogen ratio of 10:1.
Normal germling development by Erysiphe graminis on cereal leaves freed of epicuticular wax
Authors: CARVER T. L. W. , THOMAS B. J. 
Published: April 2007

Experiments were conducted to test the hypothesis that recognition of the physical structure of epicuticular leaf waxes by Erysiphe graminis may be important to the development of normal germlings and the formation of functional appressoria. Comparisons of germination rates and characteristics of germling development by E. graminis f.sp. avenae, and in one experiment by f.sp. hordei, were made between intact cereal leaves and leaves from which the epicuticular waxes had been stripped away.Overall, fungal development was very similar on intact and wax‐free leaves: although germination rates were slightly, but significantly, lower, and lengths of appressorial germ tubes slightly greater, on stripped than intact leaves, a very similar proportion of germlings formed apparently normal appressoria in both cases. This was true for f.sp. avenae on first‐ and fifth‐formed leaves of susceptible and adult plant resistant oats, and on barley and wheat first leaves, and for f.sp. hordei on first leaves of barley, oat and wheat. The appressoria formed on stripped leaves not only appeared normal, but also formed haustoria with at least the same frequency as on intact leaves; in several experiments, a higher proportion formed haustoria in stripped than intact leaves. Wax removal did not affect the adult plant resistance of oat cv. Maldwyn, which limits haustorium formation by appressoria, indicating that epicuticular wax was not involved in this resistance. It is concluded that the physical structure of epicuticular wax is not involved in the recognition processes leading to normal germling development.
The distribution of barley yellow mosaic virus (BaYMV) and barley mild mosaic virus (BaMMV) in UK winter barley samples, 1987‐1990
Authors: ADAMS M. J. 
Published: April 2007

Improved diagnosis of barley yellow mosaic (BaYMV) and barley mild mosaic (BaMMV) viruses was obtained by adjusting the buffers used in immunospecific electron microscopy (ISEM) to ensure a pH ≥ 7‐0 and in ELISA by replacing ovalbumin with 10 g/l full cream milk powder.Over 70% of samples of winter barley with symptoms of mosaic received from different sites in the UK during 1987‐90 had BaYMV and 37% had BaMMV, with 11% containing both viruses. BaMMV was much more common on malting cultivars than on those grown for feed and this resulted in an easterly bias to the geographical distribution of the virus. Both viruses were, however, widely distributed in areas where winter barley is grown intensively. A small number of BaYMV records were from cultivars previously regarded as resistant and these are probably a distinct strain of the virus.
Forecasting the national incidence of sugar‐beet powdery mildew from weather data in Britain
Authors: ASHER M. J. C. , WILLIAMS G. E. 
Published: April 2007

In a national survey of the incidence of powdery mildew (Erysiphe betae) in sugar beet in Britain, between 1980 and 1989, in which between 335 and 717 fields were inspected at the end of August each year, the average crop area infected ranged from 2% in 1986 to 68% in 1989. The effect of various climatic factors that might be expected to influence powdery mildew development over this period was examined, using meteorological records from Broom's Barn Experimental Station, Using simple linear regression analyses, a significant association was found between disease incidence and both air temperature and rainfall incidence in the period April‐August, However, air temperature and frost incidence in some winter months were also closely associated with the incidence of powdery mildew in the following crop.Combinations of these variables were examined in stepwise multiple‐regression analyses, The model of best fit, incorporating winter frost incidence with summer temperature and rainfall incidence, accounted for 95% of the variation. Model validation procedures demonstrated the superiority of this model over those involving single variables. Nevertheless, for forecasting purposes, the best correlation was found between the crop area infected at the end of August each year and the number of days with a ground frost in the preceding February and March. This single climatic variable accounted for 82% of the variation and its potential use to forecast powdery mildew incidence in the national sugar‐beet crop is discussed.
The assessment of infectious disease for brown rust (Puccinia hordei) of barley
Authors: BERESFORD R. M. , ROYLE D. J. 
Published: April 2007

The measurement of infectious disease (sporulating area), as opposed to the more conventional visually estimated total disease (sporulating area and chlorosis), was investigated for brown rust on spring barley. Visual estimates by four assessors of percentage leaf area occupied by uredinia overestimated the actual percentages by, on average, 8.7 times. It was concluded that better estimates of infectious disease came from uredinium densities (uredinium counts and measurements of leaf area).The progress of uredinium density in crops was exponential up to the time when leaves senesced at the end of their development. Three‐parameter exponential functions were fitted to epidemics on 26 different leaf layers in five crops grown in three years. It is suggested that the lack of sigmoid progress curves, as would be found with conventional total disease assessments, occurred because chlorosis was excluded from the assessment. Chlorosis, which can affect a large proportion of leaf area, has an upper limit which gives rise to the asymptotic form of conventional disease progress curves. Uredinium densities had skewed distributions and the variances were correlated with the mean values. These characteristics were rectified most effectively by cube‐root transformation. An incidence‐severity relationship between the percentage of diseased leaves in a sample and the mean cube‐root transformed uredinium density was linear up to incidences of about 83%.
Evaluation of physiological and serological profiles of Pseudomonas syringae pv. pisi for pea blight identification
Authors: GRONDEAU C. , SAUNIER M. , POUTIER F. , SAMSON R. 
Published: April 2007

Phenotypic variability of the pea blight bacterium, Pseudomonas syringae pv. pisi, was studied on a large collection of strains isolated in France, as well as those obtained from foreign collections. Some other pseudomonads encountered on peas, particularly P.s. pv. syringae, were included in the study to evaluate differential tests for identification purposes. All the isolates that induced watersoaking on the pea cultivar Kelvedon Wonder after inoculation were considered to be P.s. pv. pisi. The other pseudomonads gave either no reaction or a hypersensitive reaction. When they corresponded to P. syringae according to the LOPAT test, they were referred to as P.s. pv. syringae. P.s. pv. pisi did not show a single uniform phenotype. The variation of the different tests was estimated (fluorescence+ 93%; esculin‐86%; dl‐lactate‐85%; homoserine + 75%; INA + 97%). Three O‐sero‐groups contained P.s. pv. pisi strains: APT‐PIS (88.5%), HEL2 (11.4%) and RIB (0.1%). When the main criteria were combined, eight profiles were encountered within P.s. pv. pisi. This diversity was not linked to race structure or geographical origin of the strains. Profile PI was the most frequent (72.8%), and it was specific to the pathovar pisi. The strains belonging to the other profiles could be confused with some P.s. pv. syringae strains because of the serological heterogeneity of that pathovar. For instance, the pv. pisi strains belonging to profiles P2 and P4 resembled some of the P.s. pv. syringae found on peas and required pathogenicity tests on pea for their identification. The confusing pea isolates represented 12.8% of the total 4740 strains studied.
Comparative pathogenicity of Pythium species associated with poor seedling establishment of rice in Southern Australia
Authors: COTHER E. J. , GILBERT R. L. 
Published: April 2007

Isolates of Pythium attributable to thirteen named species and to species group F (sensu van der Plaats‐Niterink) were isolated from roots of field‐grown rice seedlings showing poor root development and lack of vigour. P. arrhenomanes and group F were the most commonly isolated species. The roots of 15‐week‐old rice plants yielded only P. flevoense, P. vanterpoolii, P. rostratum and Pythium group G of which the latter two were not obtained from seedling roots.In pot tests with representative Pythium isolates, P. arrhenomanes was most pathogenic to rice seedlings, causing pre‐ and post‐emergence death and average reductions in shoot and root growth in surviving seedlings of 48 and 70%, respectively. P. irregulare killed seedlings before but not after emergence, whilst the response of rice seedlings to P. myriotylum apparently depended on the length and timing of a cold shock treatment. P. pyrilobum did not reduce seedling number or shoot growth but reduced root growth. P. vanterpoolii and group F were not pathogenic in the tests. P. coloratum, P. echinulatum, P. flevoense, P. oedochilum, P. oligandrum, P. periilum, P. pyrilobum and P. rostratum were isolated infrequently and had no adverse effects on seedlings in pathogenicity tests, although P. myriotylum, P. oligandrum, and P. periilum were associated with significant increases in shoot growth. P. tracheiphilum was isolated from one site but its pathogenicity was not tested.This is the first record of P. coloratum, P. echinulatum, P. flevoense, P. irregulare, P. oedochilum, P. oligandrum, P. periilum, P. pyrilobum and P. tracheiphilum from rice roots.
Examination of the relationships between vegetative compatibility groups and races in Fusarium oxysporum f.sp. dianthi
Authors: ALOI C. , BAAYEN R. P. 
Published: April 2007

The feasibility of identifying races of Fusarium oxysporum f.sp. dianthi by tests for vegetative compatibility type was investigated. Nitrate non‐utilizing nitl and NitM mutants were generated from 51 isolates of F. oxysporum f.sp. dianthi, 18 isolates of f. oxysporum from Dianthus spp. not belonging to f.sp. dianthi and, for comparison, 11 isolates of F. proliferatum from Dianthus spp. Vegetative compatibility groups (VCGs) among the isolates were identified by pairing all nitl with all NitM mutants.Vegetative compatibility was found between isolates of F. oxysporum f.sp. dianthi races 1 and 8 (VCG 0022), races 2, 5 and 6 (VCG 0021) and race 4 (VCG 0020), and wilt‐causing isolates previously classified as F. redolens from D. caryophyllus (VCG 0023) and D. barbatus (VCG 0024), Three self‐compatible wilt‐causing isolates were vegetatively incompatible with all other isolates (VCGs 0025,0026 and 0027), Two VCGs were found among isolates of F. oxysporum from D. caryophyllus not belonging to f.sp. dianthi; six non‐pathogenic isolates were self‐compatible but vegetatively incompatible with all other isolates. The foot‐rot‐associated isolates of F. proliferatum from D. caryophyllus constituted a separate VCG.Virulence analyses revealed at least four new races among VCGs 0023 to 0027, New Isolates could be categorized as races as a result of VCG analysis and VCG classification correctly indicated that the race identities previously ascribed to two old isolates had been incorrect. Vegetative compatibility tests offer the prospect for rapid identification of races, although inoculation tests continue to be necessary to differentiate races that belong to a single VCG.
Host specialization of Verticillium dahliae, with emphasis on isolates from cocoa (Theobroma cacao)
Authors: RESENDE M. L. V. , FLOOD J. , COOPER R. M. 
Published: April 2007

Isolates of Verticillium dahliae from cocoa (four Brazilian and one Ugandan) were screened against cocoa, aubergine, tomato, cotton, and pepper. Isolates originating from hosts other than cocoa were also inoculated. In general, all inoculated crops were systemically invaded by isolates from cocoa. Isolates from each host tended to be more aggressive on their original host. All isolates from cocoa were pathogenic to cocoa, but exhibited various degrees of aggressiveness to other crops. They induced severe symptoms on aubergine, but few symptoms on tomato, although colonization occurred up to the stem apex in both cases. Likewise, symptomless invasion of pepper was found with some Brazilian isolates. The Ugandan isolate was significantly more aggressive on cotton and pepper than the Brazilian isolates.A Brazilian isolate from cocoa from the State of Bahia was also used to inoculate 12 common weed species from the same geographical area. Four species showed wilt symptoms, while V. dahliae was readily recovered from the stems of a further four species. The role of alternative hosts on disease spread in cocoa growing areas is discussed.