摘要:

Summary1The growth curves obtained by plotting successive fresh as well as dry weights are of the usual sigmoid type. The percentage of dry matter is the highest in young fruits and thereafter declines and remains fairly constant during maturity and ripening of fruits. The respiration curve during the growth of the fruits shows two high values separated in time: one is initial and represents a high rate of respiration in young fruits, while the other occurs at the onset of senescence.2Irrespective of the stage of ripening at picking, winter‐grown tomatoes show the usual “climacteric” rise during the colour change from orange to red. In certain tomatoes there was no evidence of the occurrence of the climacteric, though the sequence of colour change from green through yellow and orange to red was of the usual type.3The storage life of the fruits is longest at 5·7 followed by 9·8 and 14·7°C. At a given temperature the storage life is longest in fruits picked green as compared to those picked in the yellow and orange stages.4The respiration curves obtained in fruits after transference from low to high temperatures are divisible into two parts: (i) high R.Q. associated with a rapidly falling respiration intensity, and (ii) a value of R.Q. approximating to unity accompanying either a falling or a steady respira

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06966.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

Summary1A canker and die‐back of roses caused byGriphosphaeria corticola(Fckl.) v. Höhnel is described.2Conidial fructifications, which may be acervuli or ill‐defined pycnidia. precede the formation of perithecia. Conidial isolations are of slightly differing types as regards size and shape of spores, cultural behaviour and relative pathogenicity, but at present they are all referred provisionally toCoryneum microstictumB.&Br. Some of the conidial isolations have given rise to perithecia, but others have not.3Successful inoculations both with conidia and ascospores are described.4In Nature, infection by this parasite may occur through pruning wounds, dead buds, leaf scars, wounds made by thorns, and rust lesions.5The following varieties of roses appear to be particularly susceptible to the disease: Duchess of Atholl, Lady Inchiquin and Golden Emblem.6The pathological anatomy of the disease is described. Infection may occur at all times of the year except summer, when the rapid formation of “gum barriers” by the host tissues checks invasion.7The disease is not likely to become widespread unless neglected. Diseased shoots should be cut out; with some varieties normal pruning operations should sufficiently control the

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06967.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

SUMMARY1Investigations were carried out onSchrotinia serica, two strains ofS. Sclerotiorumde Bary, five strains ofS. TrifoliorumEriks., two forms ofS. minorJagger, four isolations of aSclerotiniafromVicia Fabaconsidered to be a variety ofSclerotinia Trifoliorum, and a variant which arose from one of these isolations.2Their pathogenicity to several different plants was tested and the fungi were found to fall into three groups: (1)S. SclerotiorumandS. minor, (2)S. Trifoliorumand its varietyFabae, and (3)S. serica.3A variant with light brown sclerotia which arose fromS. Trifoliorumvar.Fabaediffered from the parent form in pathogenicity.4Ascospores ofS. Sclerotiorum, S. minorandS. Trifoliorumdid not infect healthy leaves.5The production of mycelium by sclerotia in the soil was not observed.6S. sericadiffered from the other fungi in that it produced numerous apothecial stipes and several apothecia in test‐tube cultures.7Exposing sclerotia to different conditions of temperature and moisture after their removal from culture and before their burial in damp sand did not hasten apothecial production.8Sclerotia formed in cultures grown over a wide temperature range produced apothecia when subsequently buried in damp sand.9Single‐spore lines ofS. serica, S. Sclerotiorum, S. minorandS. Trifoliorumproduced apothecia.10Apothecial production took place over a wide temperature range.11Apothecia of one form ofS. minorarising from sclerotia formed on sterilized vegetables were larger than those from sclerotia formed on malt‐extract. The dimensions of the apothecia are given and a description of the apothecia ofS. Sclerotiorum, S. minor, S. TrifoliorumandS. Trifoliorumvar.Fabae.12Measurements are given of asci and ascospores.13The minimum, maximum and optimum temperatures fpr linear spread of mycelium are given: also the time taken by cultures to reach a diameter of 6 cm. at 207deg;C. The view is expressed that such data should not be used for differentiating species.S. sericaspread more slowly than the other species. The variant ofS. Trifoliorumvar.Fabaehad different temperature relations from the parent form.14A brief description is given of the cultural appearance ofS. Sclerotiorum, S. Trifoliorum, S. minor, S. Trifoliorumvar.Fabaeand its variant.15The classification of the fungi is disc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06968.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

Summary1Isolations ofOphiobolusfrom infected wheat roots gave the maximum percentage of recovery 2–4 weeks after inoculation. Later the percentage of recovery declined. Disappearance ofOphiobolusmycelium was most rapid in acid soils, and slower in sand and in alkaline soil. In soils of more normal type an intermediate behaviour was shown.2From such infected roots a large number of soil fungi and bacteria were isolated and, in part, identified. It is suggested that disappearance ofOphiobolusmycelium from invaded roots is conditioned by the activity of these contaminants, and more particularly of such species asTrichoderma lignorum.Long persistence of the parasitic mycelium in roots growing in sand suggests that this is a poor medium for the growth of micro‐organisms.3A systematic study in plate cultures of the interaction betweenOphiobolusand the various soil contaminants isolated showed various degrees of interference with the growth of the former. These effects are described and tabulated. Similar interference effects were seen whenOphioboluswas grown in sterilized soil which had been inoculated with each of the contaminants.4These effects of the living contaminants can, to some extent, be reproduced by their metabolic products, viz. by filtered cultural solutions in which these organisms have grown. The inhibiting or retarding effects so produced are not due to the abstraction of food substances but to the presence of deleterious metabolites. In certain cases it was shown thatOphiobolusmycelium when exposed to such metabolic products was killed. This result was established both by cultural and pathogenic tests.5Tests with wheat seedlings planted overOphiobolusmycelium, with or without the simultaneous presence of the various contaminating organisms, showed that the antibiotic effect varied from no appreciable effect to complete inhibition of attack. The various organisms are divided into three groups on this ba

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06969.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

Summary1Bact. fascians(Tilford), the causal agent of fasciation of sweet peas, leafy galls, etc., has been isolated from abnormal growths on plants of twenty‐five different genera belonging to sixteen families, including both Monocotyledons and Dicotyledons.2All these strains ofBact. fascianswere inoculated on to sweet pea seedlings which, in the majority of cases, became severely fasciated.3Characteristic galls have been produced on chrysanthemums, carnations,Schizanthussp.,Nicotianasp.,Heuchera sanguinea, petunia,Asparagus sprengeri, Pisum sativum, Phaseolus vulgarisandVicia Fababy inoculation with various strains ofBact. fascians.No distinct biological variations among the strains could be detected.4Inoculation of gladiolus, tomato and potato gave negative results.5The galls are invariably produced in the region of bud tissue. In young growths the bacteria are mainly confined to the exterior of the galls.6The organism may be carried on the seeds ofSchizanthus.7A study of the physiological reactions of forty strains ofBact. fascianshas failed to disclose any means by which virulent and a virulent strains can be distinguished in cultur

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06970.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

SummaryPrevious records of lettuce mosaic are cited. The symptoms of the disease on lettuce are described, and the variation in the reaction of different varieties of cabbage lettuce indicated. The host range is extended to certain composite weeds (including groundsel,Senecio vulgaris) and to members of the family Leguminosae(Pisum sativum. Laihyrus odoratus).Experiments in which the virus was seed transmitted through lettuce to the extent of about 6 % are described, and the results of experiments with aphis vectors reported. An account of field observations on the influence of the weather on the disease is given. Certain properties of the virus are described and the status of the virus is discussed. Control measures are suggested.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06971.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

SummaryA disease of winter spinach common in the Thames Valley has been shown to be of a virus nature. It is characterized by a mottling and malformation of the leaves, stunting of growth and death of the plants. The causal agent has been shown to be identical with cucumber mosaic I of Ainsworth.The disease is most prevalent in the earlier sown crops, and this appears to be correlated with their liability to be infested with aphides. Field observations on a number of farms indicated a correlation between intensity of aphis infestation and intensity of disease.Seed‐borne infection, though possible, has not been proved.Under field conditions in the Thames Valley it is suggested that a main source of contamination of winter spinach is the outdoor vegetable marrow crop.Postponement of date of sowing until the latter half of September is suggested as a method of reducing the amount of diseas

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06972.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

Summary1Typhlodromus thripsin.sp., of which a description is given, is a predacious mite feeding onThrips tabaciLind. It appears to be one of the few natural enemies of this insect.2There are five stages in the life cycle of the mite; these are: egg, larva, protonymph, deutonymph and adult.3The mites first appear in June and are found on the plants until December, by which time the thrips have disappeared for the season.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06973.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06974.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

Summary1An apparatus and method for testing the effect of atomized sprays on flies and mosquitoes are described. The apparatus consists of a revolving wire gauze cage placed in a thermostatically controlled chamber, the whole of which may be easily cleaned and freed from toxic residues. The insecticide is sprayed into the chamber by means of an Aerograph MP gun and distributed by means of a slow‐moving fan. When the insecticide has been injected and an interval allowed for the initial rapid fall of concentration, the movement of the cage is stopped and the insects are introduced into it by means of a special tube and plunger. The time required for paralysis to take place is recorded. After a given interval the insects are removed from the gauze cage and kept to ascertain the mortality.2A technique for sampling the concentration of insecticide in the air space is described. The insecticide carrier is coloured with a dye, Sudan III for petroleum oil bases and methylene blue for water bases. The percentage of atomized material remaining in the atmosphere at any given time is determined by aspirating a known quantity of the atmosphere of the chamber through a sintered glass filter. The dye is retained in the filter, it is washed out with a measured quantity of liquid and compared with known standards. Reasons are given for the assumption that the dye molecules will behave in the same way as the insecticide molecules.This sampling method has been used to study the behaviour of a light oil, a heavy white oil and water at different degrees of atomization. Tables and graphs are given which show that, except with a fine atomization where most of the insecticide remains suspended for a considerable time, there is an initial rapid fall, which varies in amount with the degree of atomization. This initial fall is followed by a much more gradual decrease of concentration. The experiments show clearly that oil bases of different physical properties cannot be compared adequately unless a sampling method is used to ascertain the quantities of material remaining suspended. Where water bases are used it is shown that the time concentration curve varies not only with the degree of atomization, but also with the degree of saturation of the atmosphere before spraying. The concentration remains higher in an unsaturated atmosphere than in a saturated on

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1939.tb06975.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY