bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Physiological Aspects of Bacterial Wilt of Forage Grasses Caused by Xanthomonas campestris pv. graminis
Authors: Leyns F. , Cleene M. De , Bogaert G. Van , Van de Vijver L. , Ley J. De 
Published: May 2008

AbstractThe effect of host‐plant age, environmental humidity and temperature on the development of the wilting disease of Lolium perenne L., caused by Xanthomonas campestris pv. graminis, was examined. Very young plants were more resistant than older ones. Dry and warm conditions favoured the development and expression of the disease symptoms. Losses in yield were observed under several environmental conditions.
The Expression of Partial Resistance of Wheat to Puccinia recondita
Authors: Poyntz B. , Hyde P. M. 
Published: May 2008

AbstractA range of winter wheat cultivars, which appeared to show no race‐specific resistance to Puccinia recondita f. sp. tritici, was studied at seedling and adult growth stages to determine the components of partial resistance which might contribute to slow‐rusting in the field. Under controlled environmental conditions, adult plants of cvs Atou, Bouquet, Cappelle‐Desprez and Maris Freeman produced less uredospores per unit area than the control cv. Armada, and uredosori were smaller on these cultivars. Fewer uredosori erupted on cv. Cappelle‐Desprez than on the control, and both cv. Bouquet and cv. Cappelle‐Desprez showed longer latent periods than other cultivars. Cultivar Holdfast had a shorter latent period, with larger and more numerous uredosori than even the highly susceptible cv. Armada. Cultivar Waggoner displayed a similar response to infection to that of the control. The components of partial resistance detected in adult plants were not displayed by seedling leaves.
Nutritional Requirement for Production of Antifungal Substance by Enterobacter aerogenes and Bacillus subtilis Antagonists of Phytophthora cactorum1
Authors: Gupta V. K. , Utkhede R. S. 
Published: May 2008

AbstractAnker's medium with glucose and Thornton's medium were most suitable for growing Enterobacter aerogenes and Bacillus subtilis respectively, antagonists of P. cactorum, the causal agent of apple crown rot. Calcium nitrate was thebest source of nitrogen for growing cultures of E. aerogenes and B. subtilis. E. aerogenes produced the maximum amount of antifungal substance at 200 and 400 mg/l of nitrogen in the medium. Phosphate supplied either in the potassium or calcium form did not change the growth of either antagonist. An addition of 200 mg/l of N and 400 mg/l of P significantly enhanced the production of antifungal substance by E. aerogenes on Anker's medium with glucose. Thornton's medium supplemented with 200 mg/l of N and 100 mg/l of P produced the maximum amount of antifungal substance from B. subtilis. Generally, soil extracts without enrichment did not support the growth of either antagonist; E. aerogenes required at least 400 mg/lof, both N and P while B. subtilis required 200 mg/l of N and 800 mg/l of P for the maximum production of antifungal substance. When ammonium phosphate was added to soil extracts, only a small amount of antifungal substance was produced by E. aerogenes and none by B. subtilis. These results indicate that E. aerogenes and B. subtilis need N and P fertilization of the sterilized soil for the maximum production of the antifungal substance that inhibits the growth of P. cactorum.
Temperature‐Light Intensity Effect on the Antagonism of Species of Cladosporium to Melampsora larici‐populina on Cultivars of Populus X euramericana (Dode) Guinier
Authors: Sharma I. K. , Heather W. A. 
Published: May 2008

AbstractThe antagonistic and colonistic effect of post‐inoculation temperature and light intensity was investigated in a factorial experiment involving four Cladosporium spp., three poplar cultivars, two levels of temperature and light intensity, anda race of Melampsora larici‐populina. The species of Cladosporium were more antagonistic to uredinial production on the inoculated leaf discs of the cultivars when these were incubated in high temperature – high light intensity than in any other regime. Whilst colonisation of the uredinia was usually minimal in discs incubated on the high temperature – high light intensity regime, the condition of incubation favouring maximum colonisation varied with the cultivar and the species of Cladosporium employed. All the major factors and most of their two‐, three‐ and four‐way interactions were significant determinants of variation in both antagonism to uredinial production and in colonisation of the uredinia produced. The validity ofextrapolation from such experiments to the field environment is discussed.
The Influence of the Concomitant Microflora on Establishment and Dieback of Decay Fungi in Standing Timber
Authors: Gramss G. 
Published: May 2008

AbstractThe microbiological aspects that designate development of decay in standing timber were assessed by determining the resistance to succession as well as the competitive saprophytic ability (kratovirulence, KV) of 40 species of wood destroying basidiomycetous fungi (WBF), proved to be members of 7 ecological categories. The categories (i) to (iv) comprise predominantly pathogenic WBF (pathogens) with high pathovirulence (PV) and correspondingly low KV properties that are dominant in the decay of standing timber. The categories (v) to (vii) include saprophytic WBF (saprophytes) with occasional or no PV and increasingly dominant KV properties which are native to slash and plant residues. On sterilely overgrown blocks of fertilized wood meal which had been exposed to airborne contaminants, most pathogens displayed the same degree of resistance to the insinuation of successive microbes as did the saprophytes. In the inoculation attempts of randomly contaminated wood meal, however, the low‐kratovirulence, pathogens were unable to repress the multitude of the antagonistic resident microorganisms in order to establish themselves in this substrate. In contrast, most high‐kratovirulence saprophytes reduced the number of, or completely eliminated, these antagonistic resident microorganisms in wood meal to create the preconditions for colonizing this substrate themselves for up to 1,200 days. In application of these results to the conditions in standing timber it is concluded that the wounded living tree involuntarily promotes the entry of a pathogenic WBF by keeping its natural antagonists down. The once established WBF can then protect its vegetative thallus itself from being overgrown by successive microbes.
Purification and Identification of a South African Isolate of Watermelon Mosaic Virus – Morocco
Authors: van der Meer Francine W. , Garnett Helen M. 
Published: May 2008

AbstractCucurbit crops in South Africa are seriously affected by a flexuous rod‐shaped virus 706 to 770 nm long which causes the plant to be stunted, the leaves to display symptoms of chlorotic mosaic, dark green blisters and malformation, and fruit to be malformed. The virus was purified from infected Cucurbita pepo by extraction in 0.5 M borate buffer, pH 8, containing ethylenediaminotetra‐acetic acid and mercapto‐ethanol, clarification with chloroform, addition of Triton X‐100, sedimentation by ultracentrifugation for which a sucrose cushion was used and centrifugation in 10 to 40 % sucrose gradients. The virus was mechanically transmitted to a limited host range with Chenopodium album, C. amaranticolor, C. quinoa and Gomphrena globosa being the only hosts infected outside the Cucurbitaceae. Luffa cylindrica, Cucumis metuliferus, Coccinia sessilifolia and Citrullus ecirrhosus all members of the Cucurbitaceae, were not infected by the virus. The virus was non‐persistently transmitted by Myzus persicae, produced pinwheel and bundle inclusions in the plant cell cytoplasm and has a single coat protein with a molecular weight of 36,000 daltons and a degraded lighter component of 26,000 daltons. Serological comparisons with antiserum to watermelon mosaic virus 2, Papaya ringspot virus strain W and watermelon mosaic virus Morocco (WMV‐Mor.) identified the virus as an isolate of WMV‐Mor. It was found that WMV‐Mor. is the dominant virus in all the main cucurbit producing areas of South Africa which were surveyed.
Analysis of Resistance to Eyespot in Wheat Using Small Seed‐Samples
Authors: Heun M. , Mielke H. , Martin Regina 
Published: May 2008

AbstractSix different inoculation methods have been tested to determine Pseudocercosporella herpo‐trichoides resistance of wheat using small seed‐samples. The observed differentiation among hosts corresponds to that known from the literature:‘Diplomat’ and ‘Caribo’ are susceptible whereas ‘VPM1’, ‘Rendezvous’ and ‘Roazon’ carry resistance transferred from Aegilops ventricosa. The modified method of Frauenstein and Roskothen (1979) seems to be most efficient: it is timesaving, easy to use and only small seed‐samples are necessary. Such resistance testing can be used in early generations of breeding programmes.
An Attempt to Predict Response of Sunflowers to Races of Plasmopara halstedii Using Cultured Sunflower Cells
Authors: Gray A. Bruce , Sackston W. E. 
Published: May 2008

AbstractCultured sunflower cells reacted alike to inoculation in compatible and incompatible combinations with three races of Plasmopara halstedii, cause of downy mildew. Infection structures formed on the surfaces of cells derived from both resistant and susceptible sunflowers, but no intracellular fungal structures or other signs of penetration were evident in either case. There was no indication of a hypersensitive reaction (rapid death) in cells within 20 h of inoculation in incompatible combinations. The reaction of cells in culture was not like that of intact plants in either compatible or incompatible combinations.
The Effect of Temperature on Symptom Expression and Colonization in Resistant and Susceptible Carnation Cultivars Infected with Fusarium oxysporum f. sp. dianthi
Authors: Harling R. , Taylor G. S. , Matthews P. , Arthur A. E. 
Published: May 2008

AbstractSix commercial carnation cultivars were inoculated with Fusarium oxysporum f. sp. dianthi race 2, and grown under three different temperature regimes. Colonization by the pathogen and development of wilt symptoms were assessed at intervals up to 40 days. No symptoms and very little colonization were seen in any of the cultivars at 14–15°C. At a temperature of 22°C, the cultivars were clearly differentiated into three groups: those with resistance, partial resistance or susceptibility to the pathogen depending on the severity of symptoms and the extent of fungal colonization. Symptom severity was associated with the extent of colonization. This differentiation was not seen at 26°C, when all cultivars except the most resistant, cv.‘Carrier 929′, rapidly became diseased and died by 23 days after inoculation. ‘Carrier 929’ also showed some wilt symptoms at this temperature and was colonized throughout the height of the stem after 40 days. The pathogen caused disease at 26°C by a combination of vascular wilting and stem base and root rotting.Fungal colonization was assayed at 22°C by the dilution plate/homogenization method and by estimation of fungal chitin in a highly resistant (‘Carrier 929′) and in a highly susceptible (‘Red Baron’) cultivar. Both methods of assay gave similar results. In ‘Red Baron’, colonization increased slowly up to 20 days after inoculation then progressed rapidly, closely following the development of severe wilt symptoms. In ‘Carrier 929’, colonization remained very low. The low level of fungal biomass in ‘Carrier 929’ compared with ‘Red Baron’ indicated that the former cultivar showed true resistance as opposed to tolerance to the disease.
Reduction of Take‐all Inoculum by Rotation with Lupins, Oats or Field Peas
Authors: Cotterill P. J. , Sivasithamparam K. 
Published: May 2008

AbstractThe feasibility of use of lupins, oats and field peas as alternative rotation crops to reduce inoculum of the take‐all fungus (Gaeumannomyces graminis var. tritici) (under Western Australian field conditions) and disease in following wheat was investigated with a one year field trial, the soil from which was used in two succeeding pot experiments. The possible mechanisms of reduction of inoculum and disease by these crops were examined testing the soil for pathogen and disease suppression. Rotation with lupins or oats for two seasons reduced (P <0.05) inoculum of the take‐all fungus and lupins, oats or field peas reduced (P <0.05) disease in following wheat. Lupins alone reduced inoculum and disease, (P <0.1) after one season. No apparent suppression of the pathogen in the absence of host plants was recorded after one season of rotation, but after two seasons, lupins, oats or field peas all suppressed (P <0.02) growth of the pathogen within soil. However only field pea soil suppressed take‐all in comparison with the wheat control.Although after two seasons all rotation crops were effective in reducing inoculum and disease the mechanisms of reduction appear to differ between the rotation crops used in this study.
Resident Populations of Pseudomonas syringae pv. syringae on Leaves, Blossoms, and Fruits of Apple and Pear Trees1
Authors: Mansvelt E. Lucienne , Hattingh M. J. 
Published: May 2008

AbstractPopulations of pathogenic Pseudomonas syringae pv. syringae were monitored on apparently healthy leaves, blossoms, and fruit from two apple orchards with known histories of blister bark and a pear orchard with a known history of blossom blast. Populations on blossoms and fruits were higher on pears than on apples. Yellow‐pigmented, non‐pathogenic bacteria might have suppressed or masked the presence of P. syringae pv. syringae on apple trees. Populations of P. syringae pv. syringae on apple and pear leaves fluctuated sharply but higher levels generally occurred during the 1984/85 growing season than during the drier 1983/84 season. This investigation indicates that the resident phase of P. syringae pv. syringae is probably a major source of inoculum for apple blister bark and pear blossom blast in South Africa.
Effect of Moisture and Temperature on the Survival of Sclerotia of Sclerotium rolfsii in Soil
Authors: Maiti Satyabrata , Sen Chitreshwar 
Published: May 2008

AbstractThe sclerotia of Sclerotium rolfsii Sacc. survived in natural soil for 225 days under controlled moisture at 50% water holding capacity (WHC) after which there was a progressive reduction in the population of viable sclerotia. At 390 days only 48% were recovered. Sclerotia survived well at moisture contents upto 75% WHC but at 100% the population declined rapidly and none were recovered after 60 days. The contents of the sclerotia were found to lyse without germination leaving hollow rinds. Such lysis was found to be favoured between 25 and 40°C. At and below 20°C no such lysis was recovered and more than 80% sclerotia were recovered even after 60 days.
Morphologie und Physiologie von Rebblättern mit lokalen Aufwölbungen
Authors: Blanke Michael 
Published: May 2008

Abstract Anatomy and photosynthesis of grapevine leaf affected by protuberant growth Grapevine cultivated under controlled environmental conditions developed leaves affected by abaxial protuberant growth in form of raised patches in the intercostal region which were examined by SEM and porometry. Cross‐sections of freeze‐fractured raised patches without prior fixation showed an increase in the number of mesophyll cells responsible for the emergence, without superficial epidermal cracks, necrosis or deformed stomata. Leaves with wide spread symptoms appeared more shiny and curled and, showed a larger reduction in photosynthesis, by up to 76 %, than in transpiration, by up to 20 %, relative to unaffected leaves. It is concluded that this reduction in photosynthesis may be caused by increased mesophyll resistance to CO2 andless light transmission. The protuberant growth was not correlated with ambient CO2 concentrations ranging from 340–700 μl CO2 l−1.
Characterization of Pseudomonas fuscovaginae and Differentiation from Other Fluorescent Pseudomonads Occurring on Rice in Burundi
Authors: Duveiller E. , Miyajima K. , Snacken F. , Autrique A. , Maraite H. 
Published: May 2008

AbstractIn various pathogenicity, serological, physiological and biochemical tests, performed in Belgium and Japan, the Pseudomonas fuscovaginae strains associated above 1,350 m elevation in Burundi with sheath brown rot of rice, rusty seed and black, stripes on seedlings, were found to be similar to reference strains of this pathogen from Japan. The same bacteria was detected on rice seeds imported from Asia to Burundi. Beside the serological characteristics, P. fuscovaginae can be differentiated from other oxidase and arginine dihydrolase positive non‐pathogenic fluorescent pseudomonads, also isolated from lesions on rice seedlings, by the simultaneous occurrence of no production of 2‐ketogluconate, acid production from trehalose, but not from inositol. Occasionally, other symptoms inducing, oxidase positive, fluorescent pseudomonads, different from any described species, were isolated from rice seedlings and sheath rot in Burundi.
Serological Studies on Mung Bean Yellow Mosaic Virus
Authors: Ikegami Masato , Shimizu Shin‐ichi 
Published: May 2008

AbstractParticles of mung bean yellow mosaic virus (MYMV) were purified by a method that yields up to 3 mg per kg of systemically infected Phaseolus vulgaris“Top Crop” and used to prepare antiserum. MYMV antiserum prepared gave a single precipitin line and had a titre of 1/512 with homologous virus in gel double‐diffusion tests. MYMV was shown to be serologically related to other whitefly‐transmitted viruses, bean golden mosaic virus, tobacco leaf curl virus and cassava latent virus.
Effects of Fusarium graminearum Metabolites on Wheat Tissue in Relation to Fusarium Head Blight Resistance
Authors: Wang Y. Z. , Miller J. D. 
Published: May 2008

AbstractFusarium head blight (FHB) of wheat is caused by Fusarium graminearum which produces many secondary metabolites including the trichothecene mycotoxins deoxynivalenol (vomitoxin) and 3‐acetyldeoxynivalenol. Coleoptile tissue segements from 14 spring wheat cultivars were exposed to the F. graminearum metabolites deoxynivalenol, 3‐acetyldeoxynivalenol, butenolide (all known mycotoxins), sambucinol, culmorin and dihydroxycalonectrin in a bioassay. The tissue of most cultivars was inhibited, at a concentration of 10−6M by the trichothecenes tested and up to 10−3M for the other compounds. Deoxynivalenol and 3‐acetyldeoxynivalenol, which affect protein synthesis at the ribosome, are therefore potent phytotoxins in addition to being mycotoxins. The resistance or susceptibility of each cultivar to FHB was established in a field experiment. A comparison of the two sets of data indicated that resistant cultivars could tolerate much higher concentrations of the metabolites tested than susceptible cultivars. Some resistant material can tolerate 10 to 1000 times the concentration of the trichothecenes, compared with susceptible cultivars, with no effect on growth. The data suggest that it may be possible to screen germplasm rapidly for FHB resistance in vitro and a new type of resistance in wheat to this disease is proposed based on the apparent insensitivity to trichothecenes by resistant cultivars, additional to the three types of resistance described in the literature.
Methode zum Nachweis der Dauersporen des Kohlhernieerregers Plasmodiophora brassicae in gärtnerischen Kultursubstraten
Authors: Botz Thomas , Mattusch Peter , Hilgenberg Willy 
Published: May 2008

Abstract Method for the demonstration of resting spores of the clubroot causing fungus Plasmodiophora brassicae in horticulture soil samples The investigation based on the biochemical determination of the polymer chitin for a specific demonstration of the clubroot causing fungus Plasmodiophora brassicae. For separation of resting spores from soil material a special apparatus has been constructed which allows the continuous isolation and concentration of this fungal developmental stage.The specificity of the test is improved by a differential density gradient centrifugation. N‐acetyl glucosamine as the measurable reaction product was formed by chitinase. Only two days are necessary for the whole test procedure. Its sensitivity is 2.5 × 107 resting spores/litre soil material. The method allows a first screening of soil samples and increases the efficiency of common biological tests.
Necrotrophic Mycoparasitism of Chalara elegans (Thielaviopsis basicola) by a Sterile Basidiomycete
Authors: Baard S. W. 
Published: May 2008

AbstractInteractions between Chalara elegans and a sterile hyaline basidiomycete (SHB) were studied by light, scanning and transmission electron microscopy. Young colonies of C. elegans were quickly overgrown by the mycoparasite, with lysis of, hyphae and conidia. Direct penetration of host hyphae and conidia was observed, but simple coiling around these also occurred. Chlamydospore development was inhibited, but 12.5% of mature chlamydospores were able to survive attack for 120 days. Chlamydospore germination was apparently stimulated by the SHB, whereupon lysis followed. Evidence of invasion of intact chlamydospores is also presented.
Evaluation of Rate‐Limiting Resistance to Blast Disease in Rice Cultivars Using Sub‐Lethal Concentrations of a Systemic Fungicide
Authors: Brodny Uzi , Zapata J. Castano , Nelson R. R. 
Published: May 2008

AbstractSix rice cultivars were shown to have measurable levels of rate‐limiting resistance (RLR) to blast disease in the seedling stage in the greenhouse, as compared to a susceptible cultivar. The criteria for RLR were: a consistent ability to reduce receptivity, sporulation capacity and an extension of the latent period. Another method for a quantitative evaluation of the RLR to blast disease was developed. This procedure used sub‐lethal concentrations of the systemic fungicide Tricyclazole. It was found, that a certain threshhold (225–525 μg a.i./ml) of fungicide concentration could be used to determine different levels of RLR and that the minimum concentration of the fungicide needed for complete inhibition of the disease in a given cultivar is related to the level of its RLR.
Changes in Chemical Constituents of Tobacco Leaves Infected with Corynespora cassiicola and Colletotrichum nicotianae
Authors: Oke O. A. 
Published: May 2008

AbstractChanges in nicotine alkaloids, total sugars, reducing sugars, nitrogen and phenol contents were determined in young and matured leaves of healthy and infected leaves of tobacco (cv. Spheight). These constituents accumulated as the healthy leaves aged. In infected leaves, all constituents investigated decreased except nitrogen which increased. Possible effects of the changes in chemical constituents on the quality of tobacco leaves are discussed.
Influence of Mycorrhizal Tobacco Roots, Incorporated Into the Soil, on the Development of Thielaviopsis basicola
Authors: Tosi L. , Giovannetti M. , Zazzerini A. , Torre G. della 
Published: May 2008

AbstractThe interaction between the soil‐borne pathogen Thielaviopsis basicola and mycorrhizal roots infected by Glomus microcarpum has been studied during 4 months. A significant reduction in the number of propagules was observed in soils treated with mycorrhizal roots and an inhibition of T. basicola growth by a substance produced by mycorrhizal roots is suggested.