摘要:

Summary.The effect of carbon dioxide on tomato plants growing in a small greenhouse has been studied, the gas being produced by burning paraffin in a pressure burner.An increased yield of fruit of 23.9 per cent. for the first half of the season and 13.9 per cent. for the whole season was obtained.A significant increase in the growth‐rate of tomato seedlings was brought about by the treatment.The distribution of carbon dioxide in the glasshouse was investigated and the sources of loss of gas examined.The economic bearing of the results is briefly discusse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07703.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.1The loss of seed potatoes through blight (Phytophthora infestans) in Jersey may be subdivided into (a) loss in the field at digging time, and (b) loss in the seed boxes subsequent to harvesting.2It is shown that the loss in the field may be prevented in most seasons by regular and thorough spraying, whilst that in the boxes may be reduced by scorching or removing the diseased haulms before digging, or by immersing the tubers in a fungicide.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07704.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.1The occurrence of baeteriosis ofD. glomerata, with which is associated the non‐motile organismA. RathayiE. F. Smith, is recorded for Cambridgeshire definitely for the first time, but there seems little doubt that the disease has been present unrecognised for some time and is being constantly introduced on imported Danish seed.2The disease is similar to that originally observed near Vienna in 1897, but differs from the latest account from Germany where the damage caused was far more severe. The general symptoms were partial or complete destruction of the spikelets which were embedded in a bright yellow bacterial slime.3The associated organism was isolated and found to agree exactly in its cultural and growth characters with the descriptions of Rathay and Smith.4The naturally occurring bacterial slime proved pathogenic when inoculated into a healthy shoot ofDactylis, but no infection resulted when pure cultures on artificial media were use

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07705.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.A “yellow cucumber mosaic virus” is described, which appeared to develop spontaneously during experiments with ordinary cucumber mosaic on tobacco. This form is readily distinguishable from the ordinary cucumber mosaic virus by the conspicuous bright yellow mottling produced on tobacco and other hosts. In modes of transmission, properties and host range, the virus appears to be identical with ordinary cucumber mosaic virus, and is hence regarded as a strain variant of this form.A second virus is described on tobacco which appears to belong to the same general group, although showing differences of greater magnitude from the ordinary cucumber mosaic virus. This form is distinguished chiefly by the milder type of symptoms produced upon various common hosts, and by its somewhat lower thermal death‐point, tolerance to dilution and longevityin vitro.Additional evidence is thus offered of strain variation in the cucumber mosaic group, similar to that already recognised in certain other groups of plant vi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07706.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.Potato viruses obtained from nine foreign countries have been compared with typical American forms. The chief emphasis has been placed on the potato “mottle,”“ring‐spot,” and “veinbanding” viruses.The mottle and ring‐spot viruses were found in potatoes from all nine foreign countries, but only in about one‐half of the 75 varieties or lots tested. Hence these viruses appear to be less widespread in foreign than in standard American potato varieties. The veinbanding virus was found in potatoes from six of the nine foreign countries, and was often free from associated viruses.The remarkable constancy of the viruses secured from widely different sources, when compared under identical conditions, was outstanding. Some degree of variation was found in certain cases, as for example between the veinbanding virus and theYvirus from England, though these viruses are very similar in most respects.The possible relationships of certain other potato viruses are discussed, and a potato streak virus is briefly described.Incomplete or unsatisfactory descriptions and synonomy in nomenclature are believed to be largely responsible for the existing confusion in potato virus literature. These difficulties may largely be overcome by devoting more attention to the description of the v

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07707.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.Three cucumber mosaic diseases of this country and the causal viruses are described.The first disease, green‐mottle mosaic (cucumber virus3), and the second, yellow mosaic (cucumber virus4), are not transmissible to solanaceous plants.Cucumber virus3, on cucumber, causes a dark green mottle with blistering and distortion of the leaves, but the fruit is not usually marked; whilecucumber virus4 gives rise to a distinct type of leaf‐mottle, yellow to silver‐white in colour, and the fruit may be seriously marked. The third disease, yellow‐mottle mosaic (cucumber virus1), is characterised by a diffuse yellow mottle of cucumber leaves and fruit and is transmissible to solanaceous plants. Cucumber viruses 3 and 4 are described for the first time.Notes are given on fern leaf of tomato, insect vectors and control m

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07708.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.Experiments on the purification of the virus of yellow mosaic of tomato are described and discussed. Vinson and Petre's methods of purification of the virus from infectious juice and subsequent elution with phosphate solution were slightly modified in these experiments. It was found that there was no evidence that the virus could be recovered in a crystalline form and that viruliferous material always contained traces of organic nitrogen. This virus was found to be active over a wide range ofpH, viz. from 2.0 to 10.5. At the extremes of the scale, the excessive acidity or alkalinity was toxic to the inoculated leaves and adjustments had to be made before inoculation. Different protein precipitants were used in an attempt to free the virus from the proteins, and electrolytic methods were also tried. Proteolytic enzymes were employed on the purified virus juice but the results were rather unsatisfactory. Difficulty was experienced in ensuring that the effect of some reagents was on the virus and not on the tissues of the test plants.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07709.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.1The species of gall midges whose larvae live in the stems of willows have been briefly reviewed.2It is pointed out that, in the past, the so‐called “shot hole” midge damage on willow stems and branches has been frequently ascribed toR. saliciperdaDufour without considering either the insect itself or the species of willow.3This study has shown that several species of gall midges are responsible for this type of damage and that, so far as can be ascertained from an examination of cultivated species of willows, withS. fragilisin addition, each species of midge is restricted to one (in one case three) species of willow.4The adults, pupae and larvae ofR. saliciperdaDufour,R. triandraperdasp.n.,R. purpureaperdasp.n. andR. justinisp.n. have been described.5The bionomics of these species have been worked out. It has been found that, while all multiply by means of unisexual families, the first three species are single brooded but thatR. justinisp.n. has two broods a year.R. saliciperdaDufour lives onS. caerulea, S. fragilisandS. alba(Cecconi),R. triandraperdasp.n. will only attackS. triandra, whileR. purpureaperdasp.n. andR. justinisp.n. are restricted toS. purpurea.6The nature of the damage caused by the larvae of these midges has been described and control measures have been discussed. Tarring the stubs has been mentioned. It is suggested that cutting down the new growth in May, where practicable, would reduce the midge infestation. This latter treatment has the additional advantage of getting rid of initial caterpillar and frost damage which result in dead terminals and so produce side‐branching close to the stubs. Wild Crack willow (S. fragilis) should be destroyed as it can act as a reservoir forR. saliciperdaDufour.7Keys have been drawn up for the identification of the midges using host plants, larval, pupal and adult female characters.8The following parasites are recorded—Torymidae:Torymussp., nearauratusFonsc; Eurytomidae:Eurytoma aciculataRatz.,E. saliciperdae. Mayr.: Pteromalidae:Tridymus salicisNees; Eulophidae:Pleurotropis? caenusWalk.,Tetrastichus flavovariusNees,T. roesellaeDe Geer; Platygasteridae:Platygaster cecidomyiaeRatz.,P.sp. (?phili

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07710.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.1Contrasted differences in the intensity and nature of the infestation of aphides attacking the potato crop in certain districts in North Wales prompted a detailed study of the factors involved.2Migrating alatae are considerably more numerous in the Flintshire districts than in the south Caernarvon area. The mean monthly values for relative humidity are consistently and appreciably lower in the former district than in the latter.3Controlled laboratory experiments on the effect of variation in relative humidity upon the flight ofM. persicaeclearly demonstrate an inhibitive action of high humidities upon flight. The experiments were conducted at 0, 25, 50. 70, 85 and 100 per cent, relative humidities at the temperatures 55d̀ F., 70d̀ F., 80d̀ F. and 90°F.4The findings of the survey of aphis population at centres in North Wales during 1928–33 are discussed in the light of these re

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07711.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY

摘要:

Summary.Larvae ofCaliroaCosta andEndelomyiaAshmead are well known as slugworms and leaf skeletonisers of many cultivated trees and shrubs.C. limacinaRetz. oviposits on the under sides of leaves of plum, pear and cherry and the eggs hatch in 11–14 days. The larvae are covered with dark slime and feed on the upper surface of the leaves. The feeding stage lasts 18–21 days. The larvae moult and shed their coating of slime before entering the soil to make cocoons. The cocoons are composed mainly of soil particles, lightly cemented with saliva. In the north‐west of England some individuals emerge the same season and give rise to a second generation, and others continue in the cocoons until the following year. Reproduction is mainly dependent on parthenogenesis.C. annulipesKlug. oviposits on the upper surface of the leaves ofSalix, Grategus, Prunus, etc. The incubation period is 13–15 days. The larvae, unlike those ofC. limacina, are covered with transparent slime and feed on the under side of the leaves. The larval stage lasts 19–22 days and at maturity they lose their coating of slime and enter the soil to construct cocoons.C. annulipesis bivoltine in the north of England and the phenomenon of delayed development has not so far been observed.E. aethiopsFab. appears confined toRosasp. The flight period is May–June and the females oviposit in the edges of rose leaves, preferringRosa caninaandR. arvensis. The incubation period is 9–14 days and the larval feeding period 20–27 days. The larvae are yellowish; the thorax is enlarged but not as much as inCaliroasp., and the prothoracic glands and coating of slime are lacking. They feed on the under surfaces of the leaves and at maturity they moult and enter the soil to make cocoons.E. aethiopsis univoltine and hibernation takes place in the contracted prepupal condition in the cocoon.EndelomyiaAshm. can be separated fromCaliroaCosta on antennal characters and wing venation. A key for the identification of the five recorded British species ofCaliroaandEndelo

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1935.tb07712.x

出版商:Blackwell Publishing Ltd    

年代:1935

数据来源: WILEY