摘要:

SUMMARY.1Attempts to accelerate the germination of cocksfoot seeds by treating them with solutions of several chemical compounds have been unsuccessful.2A pronounced acceleration of germination can be produced by soaking the seeds in water and drying for an indefinite period before sowing.3No evidence has been obtained that with any condition of the soil is such treatment undesirable.The author wishes to thank Professor R. G. Stapledon, to whom he is indebted for criticism and at whose suggestion the work was begun.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07435.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.Gibberella Saubinetii(Mont.) Sacc. occurred in its perfect stage under field conditions on wheat ears in 1932. The meteorological conditions are compared with those of a season when perithecia were not developed outdoors.Single ascospore growths in culture are normally of the Fusarium type, with a characteristic modification on salts‐glycerine agar. The ascigerous type of growth may arise from ascospores developed under abnormal condition

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07436.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.1. A survey of the occurrence and importance of pink rot of the potato is given. The disease is widespread in Britain, but is only occasionally of serious economic importance.2. The nature of pink rot is explained and it is shown how the disease may be caused by more than one pathogenic fungus.Phytophthora erythrosepticaPethybr. is the normal pathogene, but two other species ofPhytophthorahave been recorded as causing the disease in the field, viz.P. drechsleriTucker in the U.S.A. andP. megaspermaDrechsler in Northern Ireland.3. The disease may be systemic in the potato plant, causing “misses” and “pink rot wilt” in the crop; normally, however, it is of importance only as a disease of the tuber.4. Under conditions of high humidity and poor aeration the disease may cause heavy loss in an affected crop during storage.5. Under normal conditions in the field the tuber becomes infectedviathe mother stolon; if conditions in the field or store are sufficiently moist, however, the tuber becomes infected directly, generally through the “eyes.”6. Varietal susceptibility of the potato has been considered on the three bases: (a) artificial infection of the tuber withP. erythroseptica, (b) natural infection of the tuber when stored in contaminated soil, (c) susceptibility in the field when planted in contaminated soil. Altogether fifty‐one varieties (including nine mentioned as susceptible by Pethybridge and which were not tested) have been considered, all of which proved to be more or less suceptible. No variety was found to be particularly resistant.7. Large numbers of oospores are produced byP. erythrosepticain the haulms and stolons and also to some extent in the roots of the dead potato plant. These oospores become disseminated and greatly increase the prevalence of the fungus in the soil.8. It has been shown that, in the absence of the host plant, the fungus may persist indefinitely in the soil. This persistence is apparently principally due to the resting spores, but the fact that the fungus may exist to some extent as a saprophyte in the soil cannot be ruled out.9. The disease may be satisfactorily controlled in practice by paying attention to the general principles of crop hygiene. Satisfactory crops can be grown in contaminated soil, provided that strongly sprouted tubers are planted and that soil drainage is sufficiently good to prevent the land from becoming unduly wet in times of heavy rainfall. Early harvesting of the crop tends to secure a minimum percentage of affected tubers at the time of digging. Prevention of the spread of the disease during storage may be obtained by ensuring dry and well aerated conditions in the store.The writers wish to express their very sincere thanks to Mr A. Murray, Culnafay, Toomebridge, County Antrim, who has given every facility for the carrying out of field experiments on his farm, and to the Potato Inspectors in Northern Ireland who assisted in recording occurrences o

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07437.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.Experiments on the incidence and spread of the angular leaf‐spot disease of cotton, carried out at two centres in Uganda, are described.Treatment of the seed by sterilisation with sulphuric acid and mercuric chloride resulted in a reduction in the amount of the disease throughout the season.Treatment of the seed with a bactericidal dust had a significant effect on total germination, the plots sown with this seed having a greater number of plants at the end of the season, independently of those killed by the disease.Primary infection was almost entirely limited to plots sown with seed inoculated with the organism.Spread of the disease occurred in a direction down the slope of the ground and along the lines of surface wash.The implications of the experiment are discussed and proposals made for modifications in techniqu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07438.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.Virus diseases of tomato of the mosaic, “stripe,” streak type as occurring in glasshouses in the British Isles have been examined.Ordinary or mild mosaic (tomato mosaic) has been identified with true tobacco mosaic and found not to be implicated in most of the “stripe” disease.The symptom picture generally known as “stripe” may be due to several causes, and in this paper the diseases have been distinguished as follows:stripewhen attributed toBacillus lathyri, glasshouse streakwhen caused by a single virus (the most frequently occurring form), andstreakwhen due to a mixed virus infection (typically tomato mosaic and potato mosaic).Descriptions are given of tomato mosaic, glasshouse streak, and streak, and they are compared with each other and with spotted wilt.The author wishes to express his best thanks to Dr W. F. Bewley for helpful criticism and advice.The work has been carried out with the aid of a grant from the Empire Mark

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07439.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.Observations on the biology ofHoplocampa flavaL. are given.Reasons are given for stating that all records of plum sawfly damage in England referred toH. fulvicornisshould be referred toH. flavaL.Observations are given showing the variation in intensity of attack during 1925–32.Control experiments with the object of killing the larvae were promising in 1929, but yielded no control in 1932.The authors are indebted to Dr H. W. Miles and Mr H. Kingston, who were associated with us in the above observations in 1926, and to Messrs M. H. Ivatt and G. H. Cannon, on whose plantations the observations were mad

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07440.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.An account has been given of the life history and habits of the mothCacoecia crataegana, in the Wisbech area, where it attacks fruit trees.The egg and egg‐laying habits have been described and the external anatomy and biology of the larva and pupa have been studied.The measurement of the larval head capsule in relation to Dyar's hypothesis has been discussed.The effect on the egg and on the larva of routine control measures has been observed.The parasitism of the moth has been studied. One Dipterous, and five Hymenopterous parasites have been bred out, and the biology of one of these, the egg parasiteTrichogramma evanescensWestw., has been studied in detail.The writers wish to acknowledge their indebtedness to Mr P. R. Petherbridge, under whose supervision the work has been carried out, and to Dr A. D. Imms and Mr J. C. F. Fryer for criticism of the manuscript. They also wish to thank members of the staff of the British Museum of Natural History, for identification of the moth and its parasites, and for supplying references to the literature, and to Mr M. H. Hey, of the Mineralogical Department, for the analysis of the egg‐masses. Thanks are also due to Messrs J. Lefevre, E. G. Davison, and G. E. Munday, for reporting, the presence of egg‐masses at the various centres, and to the growers in whose orchards the observations were

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07441.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.The paper deals with observations made on the desert locust in East Africa in 1928–9. Two broods were observed to develop between May, 1928 and April, 1929. Females slightly outnumbered the males in a number of random collections of adults. A list of plants eaten or avoided by the adults is given including species from 62 natural orders, of which 18 are represented by both edible and inedible species. Notes on the food plants of the hoppers are also included. Hoppers of the IVth and Vth stages were observed to have a maximum speed of about1/4mile per hour.The chief natural enemies seen wereStomatorrhyna lunata, a Dipterous parasite of the egg, andSphex aegyptiacum, a predator on the adult locusts. The latter had developed a migratory habit and followed its host.No regular relation between direction of flight and direction of wind was observed.Trekking activity in swarms of hoppers of the IVth and Vth stages was most noticeable when the air temperature was above 15° C.Feeding was most general when the air temperature was above 10° C, and in the swarms observed, which were probably short of food, took place at almost any hour of the day.Continual observation of one band of hoppers throughout a whole day showed that the direction of movement was by no means constant. In fact two complete circles were made in the course of the day.Adult locusts were found to orientate head towards the sun when the black‐bulb temperature was 130° F. or above.Adult locusts were found to be insensitive to sounds such as the banging of tin cans (often used for scaring purposes) or the firing of a gun, but were much frightened by the noise of a file drawn down the edge of a saw.Railway trains were got through swarms of egg‐laying adults on the ground by having several boys running in front of the train at short intervals. This procedure frightened the locusts off the line and was much more successful than any system of brushes in front of the wheels.A few small‐scale experiments with poisoned bran showed no difference in effectiveness between sodium arsenate and sodium fluosilicate.A few individuals from a swarm of just hatched hoppers were kept in isolation until the last larval stage, but did not assume the pale colouring of the solitary phase.Dissections of adult females showed that the ovaries remained small (about 11 mm. long) as long as the locusts remained purple‐bro

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07442.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

SUMMARY.1. A brief resume is given of the information available concerning Dipterous cambium miners (Agromyzidae).2. The morphology of the egg, larva, pupa and adult ofDizygomyza barnesisp.n. Hendel is described.3. The bionomics of this fly receive detailed attention. There is only one brood a year and the larvae mine in the cambium of different species ofSalix.Pupation takes place in the soil. WhileS. viminalisis attacked most commonly,S. triandra, S. purpurea, S. viminalis×purpureaandS. triandra×viminalisoccasionally suffer. In addition the larvae can live onS. caerulea.The damage caused by the larvae is considerable. The Braconids,Symphia ringensHalid. andS. hiansNees, are recorded as primary parasites.4. Two gall midges are described, the larvae of one living as inquilines in the burrows of theDizygomyzalarvae. The bionomics of this species are describe

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07443.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

Book reviewed in this article:Cacao.By Dr C. J. J. VAN HALL. 2nd edition.Chromosomes and Plant‐breeding.By C. D. DARLINGTON.Recent Advances in Agricultural Plant Breeding.By H. HUNTER and H. MARTIN LEAKE, with, a Foreword by Sir ROWLAND H. BIFFEN.Recent Advances in Botany.By E. C. BARTON‐WRIGHT.Atlas der Krankheiten der landmrtschaftlichen Kulturpflanzen.Mit aus‐fuhrlichen Textheften.The Farm and the Nation.By Sir JOHN RUSSELL.The Medicinal and Poisonous Plants of Southern Africa.By J. M. WATT and M. G. BREYER‐BR

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1933.tb07444.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY