摘要:

AbstractAlterations in the total and individual lipids in healthy andRhizoctonia solaniinfected groundnut hypocotyl tissues were determined. Infection resulted in an increase in the total as well as individual lipid components at various stages of disease development.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01031.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractRaces 6, 7 and 10 ofXanthomonas campestrispv.malvacearum(Smith) Dye, the causal organism of bacterial blight of cotton, were identified among twelve isolates of the pathogen from the three cotton growing zones of Nigeria. Races 7 and 10 were, however, predominant. The races were distinguished by inoculation of eight cotton lines known to differentiate through possession of different resistance genes. Further work is necessary, on a much greater number of isolates, to determine therange and distribution of different virulence types in Nigeria.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01032.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe relationship between inoculum density and mortality or infection was studied for various pepper varieties (Capsicum annuumL.) inoculated with zoospores of twoP. capsiciisolates. The inoculum concentrations required for 50% mortality (LD 50) varied greatly between pepper varieties andP. capsiciisolates: with one isolate, LD 50 was 40 zoospores/ml for a susceptible variety and reached 4,380 to 97,300 zoospores/ml for resistant varieties. For another isolate, LD 50 for the, same varieties ranged from 26 to 800 zoospores/ml. Comparisons between LD 50 and inoculum doses required for 50 % Infection (ID 50) also revealed differences between varieties but not between isolates. After multiple infection correction, regression slopes of infections/inoculum concentration were low for resistant varieties (0.28 to 0.50) but higher for susceptible varieties (0.72 to 0.94), indicating strong competition between spores for infection of resistant plants, but not for infection of susceptible plants. This analysis provided many criteria which can be used to differentiate susceptible from resistant varieties and to evaluate with precision the resistance level of the different resistance genitors used in our breeding program.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01033.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractResistance was induced in barley by virulent and avirulentErysiphe graminisf. sp.hordeiand byE. graminisf. sp.tritici.The diameters of fluorescent haloes and papillae at the site of the primary germ tube of the inducers were larger until 12 hours after inoculation withEg. f. sp.triticithan in the corresponding periods after inoculation withE.g. f. sp.hordei.Fluorescence at the site of appressorial lobes of the inducers developed, gradually from 10 and 12 hours after inoculation withE.g. f. sp.hordeiandE.g. f. sp.tritici, respectively. Penetration success of single infection units of the challenger was reduced in cells with inducer fluorescence, suggesting that resistance is principally localized to cells previously attacked by the inducer. But penetration success was independent of the average distance to the ten nearest inducer fluorescences, and penetration failures did also occur in cells without inducer fluorescence, suggesting that the induced resistance to some extent is translocated to other epidermal cells. The average diameter of the fluorescent papillae at the site of unsuccessful challenger infection units increased as a result of induced resistance.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01034.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe rabi maize, that is being popularised in the eastern parts of the country may suffer from charcoal rot disease [Rhizoctonia bataticolaTaub. Butl. (Macrophomina phaseolina(Tassi) Goid.)] if the pathogen gets timely entry into the host, as has been revealed in the present study.In vitrostudies show that the spread of the pathogen within the maize stalk is influenced by high temperature, the optimum being 38°C. The role of RH on the incidence of this disease was, however, not well defined. These observations hold true as well for the data recorded in the field

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01035.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractColletotrichum gloeosporioidesandPestalotia psidiiwere found to be the dominant pathogens causing leaf spots and fruit diseases of guava. Effects of two fungicides in rainy (wet) and four fungicides in the winter (dry and cool) seasons separately, in concentrations of 500, 1500 and 3000 mg a.i. I−1(ppm) have been investigated on the pathogens and on composite phylloplane fungi. Benomyl was found most effective against the population of pathogens and checked disease development. However, it was effective only at the schedule of three successive foliar applications. The application of captan did not checkP. psidiias effectively as benomyl but it had a marked adverse effect on many of the phylloplane fungi. A signif, icant decrease in the number of fungal species colonizing mancozeb and dichlone‐treated leaves was observed. Lesion measurement and spore germination tests against both pathogens following chemical treatmentsin vivoandin vitrorespectively have also been m

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01036.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPathogenicity tests with 103 isolates ofFusarium oxysporumfrom crucifers worldwide were conducted using a standard set of six differential crucifer cultivars. Based on their reaction to the standard differentials, all isolates could be grouped into the five major pathotypes in the threeformae speciales, f. sp.conglutinans.f. sp.raphaniand f. sp.matthioli.When two additional crucifers,Brassica nigraandB. campestriswere added to the differe, ntial set, and the reactions of the host differentials were analyzed, an increased range of virulence profiles was observed, implying the existence of more virulence factors in theF. oxysporumpopulation. An isolate from the U.S.S.R., was identified with virulence capable of overcoming dominant monogenic “type A” resistance inBrassica oleraceasuggestive of a potentially new location for this pathot

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01037.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractRhabdovirus particles were detected in greenhouse‐grownGynura aurantiacaplants during a study of citrus diseases, and some of their biological and physicochemical properties were determined. The gynura plants displayed vein clearing of young leaves as the earliest symptom and later on, an anomalous growth of some leaves. This syndrome could be easily transmitted by graft, dodder and, with more difficulty, by sap inoculation. Electron microscopy showed bacilliform virions of about 260 × 70nm, in perinuclear spaces. Purified rhabdovirus particles inoculated to healthy plants were infectious, showing that this virus was the causal agent of the gynura syndrome. An estimate of the buoyant density in sucrose of the virus gave a value of 1.17g/,cm3. Analysis of virion proteins by SDS‐PAGE revealed four major bands of relative molecular mass 81.5, 56.6, 31.6 and 24.6 x 103, suggesting that these corresponds to the G, N, M1 and M2 proteins respectively, of the subgroup B of plant rhabdoviruses. From these data we conclude that the rhabdovirus here described should be placed in the potato yellow dwarf virus subgroup of plant rhabdoviruses. The fact that aCitruscould be the original source of the virus is discu

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01038.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe results show great seasonal variation in number and composition of the fungi isolated from the upper soil layer, especially owing to an increased isolation of primary saprophytic fungi during the late growing season. Before fungicide treatment no statistically significant difference was measured between the number of isolated fungi from the examined soils. During the treatment period significantly fewer fungi were isolated from plots treated with ‘captafol’ or ‘propiconazol’ than from the untreated plots. The differences between untreated and treated plots were not statistically significant 30 days after the last treatment. The ecotoxicological effect on the total isolated fungal flora thus seems negligible. However the fungi responded differen, tly to treatment with ‘captafol’ and ‘propiconazol’. None of the fungi were significantly affected for more than a month when treated with ‘propiconazol’. The number of primary saprophytic fungi (Cladosporiumspp.,Alternariaspp.,Epicoccum purpurascens, andStemphyliumsp.) and Sphaeropsidales, however, was significantly reduced for more than a month when trea

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01039.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPhytophthora drechslerif. sp.cajani(Palet al.) Kannaiyanet al.causes stem and leaf blight in pigeon pea (Cajanus cajan[L.] Millsp.) in India. The asexual phase occurs in artificial culture as well as on the host tissue. Sparse oospore formation has been observed in old cultures. A technique has been evolved in which abundant mature oospores are formed on the leaflets of pigeon pea and also on glass slides using zoospores and mycelial discs on the former butonly mycelial discs on the glass slides. The largest number of oospores was formed after incubation for 36 h at 25°C

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01040.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY