ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03775.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYBioassay techniques were used to compare the toxicities of formulations of pyrethrum containing different amounts of surface‐active agents (mainly non‐ionic condensates of ethylene oxide) and synergists (Bucarpolate, piperonyl butoxide, S 421 and Sulfoxide). Phytophagous species of Arthropoda used in the tests were:Acyrtho‐siphon pisumHarris (Aphididae);Phaedon cochleariaeF. (Chrysomelidae);Pieris brassicaeL. (Pieridae); andTetranychus telariusL. (Acarina, Tetranychidae).The insects were dosed by spray tower, and the mite by dipping infested leaves. The LC50pyrethrins with unsynergized formulations were: aphid (adult), 150 p.p.m.; beetle (adult), 50,910 p.p.m.; caterpillar (third instar), 325 p.p.m.; mite (adult) 1168 p.p.m. Formulations whose wetting powers were increased by adding surface‐active agents were more toxic to the aphid and caterpillar (LC50of 20 and 50 p.p.m., respectively). Addition of piperonyl butoxide or Sulfoxide to formulations, at up to 8 times the concentration of pyrethrins, increased their potencies for the aphid, beetle and mite by factors of 7–10 times, but were ineffective with the caterpillar. Bucarpolate and S 421 were poor synergists.A detailed study was made, usingAcyrthosiphon pisum, of the synergizing effect of surface‐active agents on formulations of pyrethrum. Hypotheses for their modes of action suggest that toxicity is influenced by the fineness of dispersion of pyrethrum emulsions, and by the improved coverage and penetration of spray on insects, which results from increased wetting power.The results of bioassay studies are interpreted to indicate that a formulation of pyrethrum synergized with both surface‐active agent and piperonyl butoxide would be a very effective aphicide, with some ovicidal and larvicidal properties, when applied to infested plants as a high

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03776.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYThree kinds of damp sacks, taking 10 min. to pass through a drying plant, the heating panels of which averaged approximately 200°C., were heated to temperatures ranging from 46 to 95°C. and remained above 60°C. for not more than 5·5 min. All insects (Oryxaephilus surinamensis) attached to the sacks were killed. Seeds ofAvena fatuaandA. ludovicianawere more heat‐resistant than insects. Even when similar dry sacks withAvenuseeds attached were passed through the drier at its slowest rate (18 min.) with the heaters set as hot as possible without damaging the sacks, not more than 40% of the seeds were killed, although temperatures reached 81–135°C., and 105°C. was maintained or exceeded for 4–7°5 min. on the sides and faces

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03777.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYExperiments have been made with rainbow trout in solutions of ammonium chloride and zinc sulphate to examine the empirical rule that a mixture of two poisons,PandQ, should be at the threshold concentration for acute toxicity whenPS/PT + QS/QT= I, where the suffixSstands for the concentration in solution andTfor the threshold concentration of a poison when tested by itself. The most detailed experiment, with a hard dilution water in which the dissolved‐oxygen concentration was at the air‐saturation value, gave results within 4% of those expected from the hypothesis. Agreement was not so close in a soft dilution water, nor in a hard dilution water containing a reduced concentration of dissolved oxygen, but in these two cases the threshold concentrations for the mixtures were within 26 and 17% of the expected value of unity. In every case the rule under examination provided a better description of the data than models based on the hypothesis of independent joint act

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03778.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYThe isolation from plant tissues of cuticular waxes uncontaminated by cellular extractives is described. Surface waxes are removed by washing leaves and fruits with chloroform at room temperature; other solvents give lower yields of waxes, apparently because of selective solvent action.A method is described for the quantitative fractionation of apple fruit and leaf waxes, and the levels and distribution of the wax components in the fruit and leaf cuticles are reported. Ursolic acid predominates in the apple fruitlet wax; esters and ursolic acid are the chief components of the wax of apple fruits in store. Ursolic acid also occurs in apple leaf wax; paraffins and esters are important constituents of blackcurrant and rose leaf waxes. The esters of apple, blackcurrant and rose leaf waxes contain long‐chain fatty and hydroxy‐fatty acids of the kind known to occur in apple fruit wax esters.Recent literature on plant waxes is revie

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03779.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYWork is described on the isolation of wax‐free cuticular membranes by enzymic and chemical treatment, and on the products of hydrolysis of the membranes. Fatty acids in the approximate range C12to C12are associated with hydroxylated fatty acids in the apple cutin complex. Methods for the determination of cutin in cuticular membranes are discusse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03780.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYKinetin supplied to the lower surfaces of petunia leaf strips reduced the number and size of local lesions following mechanical inoculation of the upper surfaces with tomato spotted‐wilt virus' (TSWV). Glucose increased lesion production, but glucose with kinetin reduced it. Kinetin mixed with infective sap did not affect lesion production.Lesions were increased with increasing water content of leaf strip and the regression equation for the relationship is given. Treatment with kinetin after inoculation reduced lesion production over a wide range of water contents, but was most effective at high values.Kinetin inhibited virus multiplication in excised tomato leaflets only when supplied at the site of infection and caused some necrosis of veins and midribs. Treated leaflets took up more water than controls and uptake continued for 4 days.Water uptake by kinetin‐treated petunia leaf strips was less than by controls but continued for 6 days with only slight discoloration of the veins.It is suggested that the inhibitory effect of kinetin may be associated with a capacity to cause increased activity of ribonuclease in the tiss

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03781.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYIn 1959 and 1961, when the willow‐carrot aphid,Cavariella aegopodiae, infested carrots at Rothamsted and Woburn early and severely, crops were infected with motley dwarf virus in late May or early June and yielded about 6 tons of roots per acre. In 1962, when invasion was late and sparse, the crops remained almost uninfected and yielded 24–25 tons/acre. In 1960, when aphids invaded early but multiplied slowly, about 85% of carrots on unsprayed plots became infected in July and August, and the yield was 9.2 tons/acre. Spraying three times with Metasystox starting at an early stage of growth affected yield little in 1961, or in 1962, but increased yield by about 3 tonslacre in 1960.Field‐plots experimentally infected in 1962 by aphids fed on infected plants in the glasshouse, lost II tons/acre from infection in early June, 8 tons/acre from infection in late June and 6 tons/acre from infection in July. Plots cultured with virus‐free aphids in early June yielded as much as control plots. Experimental infection did not affect yield in 1959 and 1961, when the crop became naturally infected before treatment.The yields in different years were linearly related to the log. mean weekly numbers ofC. aegopodiaecaught on sticky traps near the sites, and the regression accounted for much of the variance in yield. The residuals of the log. mean weekly trap‐counts were negatively related to residual weekly rainfall in inches; I in. of rain above average approximately halved the increase in aphids. This may explain the failure of early invading aphids to become numerous at Woburn in 1960, when an inch of rain fell in three consecutive weeks in June.Treating seed or seedlings with systemic insecticide did not prevent young plants from becoming infected when infective aphids were cultured on them 10–14 days after treatment.Aphids taken from willow in the spring did not transmit motley dwarf to healthy carrots, but did so after they had fed on infected carrots. Aphids from wild umbellifers often transmitted motley dwarf to heal

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03782.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYLettuce mosaic virus (LMV) was partially purified from homogenates of infected lettuce leaves in 0·5 M sodium borate buffer (pH 7·5) containing 0·1% thioglycollic acid. The filtered homogenate was clarified by adding butanol and the virus was concentrated and partially purified by differential centrifugation. Such preparations were infective at dilution up to 10‐3. Comparable preparations made in potassium phosphate buffer were not infective.Electron‐micrographs showed the virus preparations to contain long, flexuoiis particles with a mean length of 746 and width of 13 mμ. Antisera made by injecting such preparations intravenously into rabbits precipitated specifically with the preparations and with extracts from infected

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03783.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

SUMMARYCarnation mottle virus (CarMV) was present in every plant tested of over forty‐four varieties from commercial carnation stocks. Inhibitors of infection in carnation sap prevent transmission to many species, but not toChenopodium amaranticolor, which proved the best indicator and assay host. CarMV infected thirty‐three of 113 plant species inoculated, but onlyDianthusspp. are likely to be affected in practice. Healthy carnations were infected when handled after diseased ones. CarMV was not transmitted byMyzus persicae, through carnation seed, or through dodder (Cuscuta campestris).The type strain occurred in all ‘Sim’ carnations tested; another strain, designated ‘PSR’, occurred in vars. Pink Shibiuya and Orchid Beauty. The two strains were distinguished by the symptoms caused inChenopodium amaranticolorand other plants. The type strain protected against the PSR strain inAtriplex hortensis.An ‘attenuated’ form of the virus, which multiplied much more slowly than the typical form, withstood adverse conditions better.Although the virus concentration decreased in the terminal 1–2 mm. of the carnation shoot apex, CarMV was always detected in the meristem dome. Nevertheless, some virus‐free clones were obtained by aseptic culture of excised tips. CarMV was not eliminated by growing plants at 38°C., although its concentration in the apical tissues was diminished.Sap was infective after dilution to I/200,000, heating (10 min.) to 85°C. (but not 90°C.), storage for up to 81 days at 18°C., or over 3 years at o°C. Purified and concentrated preparations of CarMV were readily obtained from carnation by several methods: they contained ‘spherical’ particles about 28 mμ diameter, were antigenic, and produced a specific light‐scattering virus zone in density‐gradient centrifugation. The S20,wat infinite dilution was 122.Although CarMV shares manyin vitroproperties with eleven other viruses having similar particle shape, it is not serologically related to any of them and differs in other respects.Control of the virus depends on the production and distribution

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1964.tb03784.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY