摘要:

Address of thePresident of theAssociation ofAppliedBiologistsDelivered to theAnnualGeneralMeeting onFriday, 5 April1963

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03701.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYA diffusion method for measuring the antifouling effectiveness of chemicals is described. The chemicals under test are allowed to diffuse through a porous container which is suspended in the sea under natural fouling conditions. These tests showed both tri‐n‐butyltin oxide and atrazine to have considerable antifouling activity. The test method is discussed in relation to conventional laboratory tests against single organi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03702.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYA survey of the guineacorn (Sorghum vulgare) crop in Northern Nigeria in 1957 and 1958 indicated that, in both years, about 1% of all guineacorn spikelets were infected by covered smut (Sphacelotheca sorghi). This level of infection represents the annual loss of about £500,000 worth of grain or the unrewarded cultivation of at least 70,000 acres. There is evidence that the levels of infection are highest in those areas where temperatures at sowing time are relatively low

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03703.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYA dense spotting of leaves of young Lacatan banana plants is reported; the diameter of individual lesions rarely exceeds 2 mm. The disease is common near grassland or sugar‐cane but rare in grass‐free areas removed from sugar‐cane. Although widespread throughout Jamaica, it appears to be of negligible economic importance. Direct microscopic examination of lesions, spore‐trapping, isolation work and pathogenicity tests show thatCochliobolussp. (?C.heterostrophus), Curvularia lunataandC. geniculata, and several species ofHelminthosporiumare associated with the disease and that spores of these fungi are regular components of the air‐spora in the vicinity of spotted banana leaves. The evidence suggests that grasses and sugar‐cane are major sources of inoculum. Other spots are caused byDetghtoniella torulosawhich sporulates abundantly on decaying ba

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03704.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYThe number of conidia ofGloeosporium albumreleased from infections on the wood of Cox's Orange Pippin apple trees has been measured over a period of 21 months. The application of phenyl mercuric chloride at 0·10 and 0·05% in March 1960 reduced the amount of inoculum dispersed in the period May‐July and there was less rotting of the fruit in store. A similar reduction in sporulation occurred following the application of sprays in autumn 1960 and spring 1961, but spore production was enhanced when the effect of the sprays had disappeared. After an initial application of dichlorophen (5,5‐dichloro‐2,2‐dihydroxy‐diphenyl‐methane) at 0·25% in June 1961, two subsequent sprays were applied, when the records of spores trapped indicated that the previous spray was no longer effective. This treatment also reduced losses from ro

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03705.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYTwo isolates ofRhizoctonia solaniwhich differed in their pathogenicity toward lettuce and cauliflower seedlings were obtained. Each was highly pathogenic toward one host and almost non‐pathogenic to the other. Mineral nutrition of the host, illumination and temperature had little effect on pathogenicity, although very different types of plants were produced. A resistance that developed rapidly with age depended on adequate nutrition and active growth of the seedlings. The nutrition of the fungus, its vigour, and the quantity of inoculum were important in establishing infection, but did not affect the pathogenicity to resistant hosts. High relative humidity reduced the resistance of cauliflower seedlings to the lettuce isolate and also increased the pathogenicity of the lettuce isolate to this host.Pathogenicity depended mainly on intrinsic properties of the host and isolate, and environmental factors were rarely of more than secondary importance in determining whether or not an isolate would attack a particular host plan

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03706.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYMature leaves from trees of lime (Citrus aurantifolia) given one small‐volume application of phenylmercuric nitrate showed a deposit of 0·68 p.p.m. mercury compared with 3·99 p.p.m. on similar leaves which were completely wetted. Repeated applications of the fungicide resulted in a build‐up of mercury on both mature and young leaves. Small amounts of mercury were found in new shoots which developed after spraying. Assessments of small‐volume spray deposits using Saturn Yellow as a fluorescent tracer showed good correlation with the analytical values.Lime fruits produced during an intensive spraying programme using small‐volume applications of phenylmercuric nitrate, and harvested 3 months after the last application, showed a mercury content of 0·04 p.p.m., distributed between the peel (65%) and pith (35%). Juices prepared in the laboratory from these fruits and those extracted commercially from fruits similarly sprayed were substantially free from mercury. Fruits picked immediately after one full‐coverage application of phenylmercuric nitrate or acetate showed mercury contents of 0·10‐0·18 p.p.m. The implications of these resul

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03707.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYLime leaves (Citrus aurantifolia) of different ages were examined chemically to ascertain the relationship between cuticle development and susceptibility to withertip disease. Marked differences were found in the contents of waxes and cutin between the young susceptible and the older resistant leaves. The rapid rate of deposition of cutin, and the exceptionally high level of deposition attained, indicated that cuticle development was an important factor in the resistance of the older leaves to infection.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03708.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYAmendment of soil with roots of certain leguminous crops, molasses and oil cakes markedly increased the antibiotic production byBacillus subtilis.A soil amendment consisting of a combination of groundnut cake and molasses was about five times more effective than a dextrose amendment in increasing the production of bulbiformin and also favoured its persistence in the soil. The antibiotic was found to act systemically and to be non‐phytotoxic when taken up by the roots of pigeon pea (Cajunus cajan).In a pot experiment, inoculation ofB. subtilisinto autoclaved soil amended with molasses, sweet clover roots and groundnut cake brought about a reduction of 88% in the incidence of pigeon pea wilt caused byFusarium udu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03709.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYUsing64Cu a quantitative study has been made of the factors influencing the uptake of copper, from buffered solutions of pH 5·6, by conidia ofNeurospora crassa.The initial uptake is probably an ion‐exchange reaction which is followed by permeation throughout the cell; there was no evidence of an adsorption process. Copper is considered to be accumulated passively by the spores by unspecific reaction with cell constituents; the process is complicated by the high uptake of dead cells which results in a variable response by the spore population. The apparent activation energy of the initial exchange has been calculated and the competitive effect of other metal ions shown. A small proportion of the copper uptake was inhibited by respiratory poisons whilst increased copper uptake was observed under anaerobic conditions.The distribution of accumulated copper in disrupted conidia ofAlternaria tenuis, N. crassa, andPenicillium italicumhas been found to vary with fungal species. Cell walls, particularly ofA. tenuisandP. italicum, had a much greater avidity for copper than has been previously supposed. The copper‐binding sites onA. tenuiswere more accessible to acid washing, chelation by EDTA, and to radioactive exchange than those onN. crassa.High levels of copper uptake are required for fungicidal action against both these species of fungi and it is suggested that there are different sites of action for the fungistatic and fungicidal proce

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1963.tb03710.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY