摘要:

AbstractThe elicitation of pathogenesis on potato tuber slices by 6 strains ofErwinia carotovorassp.atrosepticawas investigated by neutral red vital staining and has been compared with bacterial growth rate, penetration ability, enzyme production and enzyme spectrum. The induction of enzyme synthesis (particularly, of the extracellular polygalacturonase) elicites the rot attack on tuber tissue and this requires a sufficient bacterial density.Due to wound healing, the inductors of enzyme production are removed, and after 48 h enzymes do not attack tuber tissue any more. Therefore, growth rate and penetration ability (to get the necessary bacterial density and inductor substances) may limit virulence. A similar influence of enzyme production and enzyme spectrum of the strains on the virulence was not detected.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00633.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractFusarium oxysporum, F. moniliformeandF. semitectumisolated fromBrassica campestrisvar.dichotomaseeds were grown on autoclaved seeds and after several weeks of incubation the oil was analysed. All the threeFusariumspecies reduced oil content and altered its colour. The infested oil emitted mouldy odour and the refractive index increased. The free fatty acid content increased progressively. The saponification value increased but the iodine value decreased.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00634.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractEighty‐three isolates of the rice blast fungus(Pyricularia oryzae)were tested with respect to genetic diversity and the possibility of race differentiation by electrophoresis. The fungus was genetically very heterogeneous. The isolates were differentiated into 6 races by pathogenicity on race differential varieties. There was little correlation between pathogenicity and zymogram types of one particular enzyme such as esterase, phosphatase or catalase. The isolates were divided into 14 groups by the combination of the zymogram types of the three enzymes. The isolates in the same group showed similar pathogenicity. A new method is proposed which differentiates the blast fungus races by the combination of zymogram type of enzymes. The details, are discusse

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00635.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractTime course absorption and desorption of metalaxyl by seeds of pearl millet was analysed by following chemical kinetics equations. Uptake of metalaxyl through roots, leaves and seed, its translocation and distribution in different plant parts and persistence following seed application were studied in pearl millet using14C‐metalaxyl. Both uptake and efflux of metalaxyl by pearl millet seeds were complex and compartmentalized. Distribution inside the seed was not uniform. A major part of applied fungicide remained within the treated plant part, particularly after seed and foliar applications. Metalaxyl was ambimobile inside the plant and was found to get accumulated at apex and margins of leaf blade. No metalaxyl could be detected in grains, harvested from plants grown from metalaxyl treated seed

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00636.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe accumulation of pisatin was induced non‐specifically by elicitors prepared from the high molecular weight fraction (molecular weight: more than 10,000 daltons) of the spore germination fluid of three species ofMycosphaerella‐plant pathogens in pea leaves with epidermis removed, regardless of the pathogenicity of the fungi to pea. Before the elicitation of pisatin synthesis, local resistance to infection byMycosphaerella pinodeswas induced by elicitors again non‐specifically inpea leaves in which wax had been removed from the leaf surface. The substance responsible for local resistance could be extracted with ethylacetate from the elicitor‐containing drop diffusate which was placed on pea leaves. The substance prevented the penetration ofM. pinodesthrough heat‐killed pea epidermis, but did not affect spore germination. The suppressor prepared from the low molecular weight fraction (molecular weight: less than 10,000 daltons) of the spore germination fluid ofM.pinodescounteracted the ability of elicitors to induce both phases of resistance m

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00637.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe anatomy of five‐week old roots of rape (Brassica napusL.) infected byPlasmodiophora brassicaeWor. was studied and compared with corresponding non‐infected roots using light microscopy and scanning electron microscopy techniques. The club‐root gall was characterized by atypically initiated vascular strands separated by large, proliferating parenchymatic cells originating from secondary tissues and infected by the parasite. Similarities in the anatomy of the club‐root gall and storage roots ofBrassicaare discussed together with aspcets of the pathogen control of the host

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00638.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractOn screening the leaf extracts of some higher plants for their volatile antifungal activity against the test organismAspergillus flavus, the extract ofOcimum adscendensexhibited the strongest fungitoxicity. The leaves showed maximum, fungitoxicity as compared with other plant parts. The volatile fungitoxic fraction obtained as an essential oil was standardized by various physico‐chemical properties. The oil showed its fungicidal nature and broad range of activity at its minimum inhibitory concentration. The oil was thermostable and the toxicity remained unchanged even on autoclaving and on storage for up to 360 days. Moreover, the oil proved more active than some prevalent synthetic fungicides and exhibited no phytotoxic effect onVigna radiat

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00639.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractDuring a four year study it was shown that the mean lesion area (M.L.A.) developed on leaflets of different potato cultivars by isolates ofP. infestansafter artificial inoculation varied periodically during the year.Disease symptoms observed changed from pinpoint necroses to regular sporulating lesions depending on the season and the cultivar.Analysis of variance revealed that differences in lesion size between experiments performed in different seasons were significant. The largest M.L.A. was found in late spring or in autumn but autumnal increase of M.L.A. was usually significantly lower than that in spring.Periodicity of M.L.A. was accompanied by a similar phenomenon in sporulation density ofP. infestansisolates culturedin vitro.However, the peaks of sporulation, in comparison with peaks of M.L.A. appeared in different seasons. The highest disease level coincided with a decline in sporulation density ofP. infestansculturedin vitroand the decrease of M.L.A. corresponded with an increase in sporulation density per cm2of medium.Variation in M.L.A. found in this study seemed not to be related to variability in plant reaction. In this connection a hypothesis has been proposed that the changes of M.L.A. were due to variation in pathogenicity of the fungus.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00640.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractSix fungicides were used either alone or in binary combination to controlFusarium solanif. sp.phaseoli.Of the three methods of application used, seed treatments and soil drenches were the best, although phytotoxicity was evident in some instances. Application as a seed soak for 1 h proved to be the worst method with most treatments showing signs of phytotoxicity.The results are discussed with reference to the use of fungicide mixtures to control foot rot of beans.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00641.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractAn enzyme‐linked antigen distribution assay (Makleret al.1981) was used to detect and to visualize the location of the lentil strain of pea seed‐borne mosaic virus, a non‐persistently transmitted potyvirus, on dissected vector st

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00642.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY