bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on Aphides Infesting the Potato Crop: Ii. Aphis Survey: Its Bearing Upon the Selection of Districts for Seed Potato Production
Authors: DAVIES W. MALDWYN 
Published: February 2008

Summary.1. A comparative study has been made during 1928–1933 of the aphis infestation at successful seed potato producing centres, where there has been no increase in virus infection among the stocks, and also at unsuccessful centres, where the increase in virus infection has been large and rapid.2. The technique developed for this study—one which is applicable for an aphis survey of prospective seed potato producing areas—is given. Identification, in the field, of the different species of aphides infesting potato is desirable in such a survey, and descriptions, with photographs, are presented.3. Ecological notes on the development of the aphis infestation show that M. persicae—the species that is generally responsible for the spread of virus diseases among potatoes—hibernates as apterae in considerable quantity on winter Brassicae, particularly savoys. These plants constitute the main source of alate spring migrants in most rural districts. The main migration of alatae takes place, normally, in early June, and, in North Wales, is largely from the east. Alatae are not common during July and August and do not increase until the late September migration from potatoes.4. The index figure of infestation at centres in which there was a rapid increase in virus diseases among the potato stocks always exceeded 100 M. persicae per 100 leaves, and attained such numbers as 1000 individuals per 100 leaves. At centres where there has been no increase in virus infection, the index figure of infestation has not exceeded 20 M. persicae per 100 leaves. The period at which this index figure should be obtained is important, and, with certain exceptions, mid‐July proved to be the most satisfactory. It is essential that the figure should be an index of the intensity of the initial infestation of alatae from outside Bources and their subsequent spread, and should not be simply an index of the rate of reproduction of aphides within the field.
A COMPARISON OF ENGLISH AND CANADIAN TOMATO VIRUS DISEASES
Authors: AIXSWORTH G. C. , BERKELEY G. H. , CADWELL J. 
Published: February 2008

Summary.It has been found from a comparative study of English and Canadian tomato virus diseases that the commoner viruses which affect the tomato occur in both countries.Tomato streak caused by the same single virus occurs in both countries, but streak due to a mixed‐virus infection appears to be more frequent in Canada than in England.The following diseases with their causal viruses are described in this paper. Tomato mosaic (tobacco virus No. l), yellow mosaic of tomato (tobacco virus No. 6), single‐virus streak (tomato streak virus No. l), mixed‐virus streak (a tobacco virus + a potato virus) and spotted wilt (spotted wilt virus). The presence of the last‐named disease in Canada was not established. Ring mosaic virus and tobacco virus No. 9, which have not been recorded in England, are also described.
A COMPARISON OF CERTAIN ENGLISH AND CANADIAN POTATO VIRUSES FOUND INFECTING TOMATOES
Authors: AINSWORTH G. C. 
Published: February 2008

Summary.Potato viruses isolated from Canadian tomato material have been compared with standard English material.The different viruses, which corresponded to the mild and virulent forms of the “latent” or “healthy potato” virus, were all considered to be strains of potato virus X which differed primarily in virulence.It was found that immunity against a virulent strain of the virus was conferred on tomato plants by inoculation with a mild strain.In conclusion I wish to thank Dr G. H. Berkeley to whom I am indebted for all the Canadian material.
THE LIFE HISTORY AND CULTURAL CHARACTERISTICS OF TYPHULA GYRANS (BATSCH) FRIES
Authors: MACDONALD J. A. 
Published: February 2008

Summary.A description is given of the life history and cultural characteristics of Typhula gyrans (Batsch) Fries.The parasitism of the fungus was investigated. Infection experiments yielded entirely negative results.The fungus forms resting sclerotia. The mycelium is either pure white and rapidly growing or, under adverse conditions, dark brown and slow‐growing. The sporophore consists typically of a stalk and club‐shaped head. The hymenium is borne all over the surface of the head. The sporophore usually arises from a sclerotium.The mycelium contains numerous clamp connections. Their function is doubtful.The development of the sclerotium is traced with special reference to the limiting layer.The sequence of nuclear changes in the basidium is suggested.Various abnormal forms, intermediate in construction between sclerotium and sporophore, are described. It is suggested that a consideration of these, together with the resemblance in structure between normal sporophore and normal sclerotium, proves these latter to be fundamentally the same. The proportion of each formed at any time is governed by external conditions.The fungus is heterothallic. Monospore strains fail to produce clamp connections, sclerotia, or sporophores. When monospore cultures are grown in pairs, in some cases mixing and fusion of the hyphae take place, with subsequent production of clamps, sclerotia, and sporophores; in others no fusions take place.
PRODUCTION OF AN ARTIFICIAL EPIDEMIC OF WHEAT STEM RUST IN KENYA COLONY
Authors: THOROLD C. A. 
Published: February 2008

Summary.Four physiologic forms of wheat‐stem rust are known to occur in Kenya Colony. Only one or two of these forms may occur in any one year, and the work of selecting wheat varieties resistant to several forms is hampered on that account.A method is described whereby an artificial rust epidemic has been produced. The hybrid wheats have thereby been subjected to infection by the four physiologic forms.Certain susceptible varieties were planted as “surround rows” amongst the hybrids, and utilised for inoculations.The inoculum consisted of uredospores, taken from inoculated plants grown in muslin cages, and was applied to leaves of plants in the surround rows. Afterwards these plants were covered for about 50–60 hours with bell‐jars or with large “cloches” described as “V” glasses.Suggestions are made as to modifications in the methods of procedure which might be adopted in the production of future artificial field infections in Kenya Colony.
ON THE BIOLOGY OF ARAECERUS FASCICULATUS DE GEER (COL., ANTHRIBIDAE), WITH SPECIAL REFFERENCE TO THE EFFECTS OF VARIATIONS IN THE NATURE AND WATER CONTENT OF THE FOOD
Authors: SAYED M. TAHER EL. 
Published: February 2008

Summary.

The time necessary for maize and cacao (the two important foods of Araecerus fasciculatus) to come in equilibrium with atmospheric humidities between 50 and 100 per cent. r.h. have been determined. The same determination has been made more roughly for nutmeg.
Under ideal conditions (maize at high, humidities) the sex ratio of A. fasciculatus is about 1:1. On nutmeg (which appears to be a less suitable food) more females than males are produced.
At 27d̀ C., the male is mature 3 days and the female 6 days, after emergence.
Fertilisation takes place at 6 days after emergence, and lasts 6.5–8 min., at 27d̀ C. Females are normally fertilised more than once, but once is enough to render all the eggs fertile.
Females in which fertilisation is delayed lay more rapidly when once they are fertilised. The effect gradually increases for delays of 1, 2 and 3 weeks and after that ceases.
Oviposition in maize is described. It takes on the average 8 min. (at 18d̀ C.) whether in light or darkness. Unfertilised eggs are laid loose and are not inserted into the food.
The incubation period is 5–8 days at 27d̀ C. at all humidities between 50 and 100 per cent. r.h.
The maximum number of eggs was laid by groups of 25 females on maize (at 27d̀ C.) at r.h. 90 and 100 per cent. At lower humidities the number laid was less and the viability smaller. 60 per cent. r.h. is about the limit at which the life cycle can be carried on with maize and nutmeg, 80 per cent. r.h. for cacao.
For maize and nutmeg, the minimum length of the total life cycle varies inversely with the relative humidity of the atmosphere, the period always being about 10 days less on the former. For cacao there is a similar relation, but the curve is not parallel to those for maize and nutmeg. On maize the minimum life cycle at 27d̀ C. varies from 57 days at 60 per cent. r.h. to 29 days at 100 per cent, r.h., the variation occurring only in the period spent as a larva.
The pupa is the only stage which can survive humidities lower than 60 per cent. r.h.
On maize, the adults live 27–28 days at 50 per cent. r.h. and 86–134 days at 90 per cent. r.h. (at 100 per cent, the food becomes mouldy). On cacao, few live more than 20 days at humidities less than 80 per cent. r.h. The reduction in length of life is principally due to failure to feed at lower humidities, for when starved, the beetles live about the same time at all humidities.
A VIRUS DISEASE OF PRIMULA OBCONICA AND RELATED PLANTS
Authors: SMITH KENNETH M. 
Published: February 2008

Summary.A virus disease of Primula obconica is described. The virus is shown to be transmissible to various Solanaceous plants on which it produces symptoms closely resembling those caused by cucumber virus I on the same host plants. Comparison of the virus from the Primula with a strain of cucumber virus I suggests that the two are very similar if not identical.
A VIRUS DISEASE OF CULTIVATED CRUCIFERS
Authors: SMITH KENNETH M. 
Published: February 2008

Summary.An account is given of an apparently undescribed virus disease affecting cultivated crucifers and other plants. The virus is sap‐transmissible and has been so transmitted to young cabbages and also to various members of the Solanaceae. On Nicotiana glutinosa it produces a disease which is usually fatal.Preliminary tests with the virus differentiate it from the viruses of tomato spotted wilt and cabbage mosaic.
FURTHER SEROLOGICAL STUDIES OF PLANT VIRUSES
Authors: BIRKELAND JORGEN M. 
Published: February 2008

Summary.Precipitin reactions with several plant viruses propagated in serologically unrelated hosts offer additional evidence that the virus is, in itself, antigenic.Reciprocal precipitin tests show that the viruses of cucumber mosaic, tobacco ringspot, and tobacco mosaic are serologically distinct; whereas tobacco mosaic virus, aucuba mosaic virus (green and yellow strains), and probably tomato streak virus remain serologically indistinguishable.No soluble specific substance was isolated from the juice of virus diseased plants or of healthy tomato by the methods employed.
THE EFFECT ON THE TOMATO PLANT OF CARBON DIOXIDE PRODUCED BY COMBUSTION
Authors: BOLAS B. D. , MELVILLE R. 
Published: February 2008

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 discussed.
MOSAIC DISEASES OF THE CUCUMBER*
Authors: AINSWORTH G. C. 
Published: February 2008

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 measures.
STUDIES ON APHIDES INFESTLNG THE POTATO CROP
Authors: DAVIES W. MALDWYN 
Published: February 2008

Summary.

Contrasted 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.
Migrating 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.
Controlled laboratory experiments on the effect of variation in relative humidity upon the flight of M. persicae clearly 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.
The findings of the survey of aphis population at centres in North Wales during 1928–33 are discussed in the light of these results.
BIOLOGICAL STUDIES OF CERTAIN SPECIES OF CALIROA COSTA AND ENDELOMYIA ASHMEAD (HYMENOPTERA SYMPHYTA)
Authors: MILES HERBERT W. 
Published: February 2008

Summary.Larvae of Caliroa Costa and Endelomyia Ashmead are well known as slugworms and leaf skeletonisers of many cultivated trees and shrubs. C. limacina Retz. 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. annulipes Klug. oviposits on the upper surface of the leaves of Salix, Grategus, Prunus, etc. The incubation period is 13–15 days. The larvae, unlike those of C. 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. annulipes is bivoltine in the north of England and the phenomenon of delayed development has not so far been observed. E. aethiops Fab. appears confined to Rosa sp. The flight period is May–June and the females oviposit in the edges of rose leaves, preferring Rosa canina and R. 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 in Caliroa sp., 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. aethiops is univoltine and hibernation takes place in the contracted prepupal condition in the cocoon. Endelomyia Ashm. can be separated from Caliroa Costa on antennal characters and wing venation. A key for the identification of the five recorded British species of Caliroa and Endelomyia is included.
SOME EFFECTS OF TOBACCO MOSAIC VIRUS ON THE GROWTH OF SEEDLING TOMATO PLANTS
Authors: AINSWORTH G. C. , SELMAN I. W. 
Published: February 2008

SUMMARYA negative correlation has been shown to exist between the growth rate of seedling tomato plants and the length of the incubation period.Evidence has been presented, which suggests that the relative effects of tobacco virus 1 on the growth rate of the plant subsequent to the appearance of symptoms is the same in both summer and winter.The percentage water content of all parts of infected plants was found to be lower than that of the controls, during the early stages of the disease. Later the water content tended to rise above that of healthy plants.In conclusion we wish to express our thanks to Mr B. D. Bolas for his interest and valuable advice.
STUDIES IN BACTEMOSIS. XXII
Authors: LACEY MARGARET S. 
Published: February 2008

SUMMARY

An organism has been isolated from fasciated sweet peas and found to reproduce the disease on inoculation into young seedlings.
Bacterial strains culturally similar to the sweet‐pea organism have been isolated from “leafy galls” on chrysanthemums, carnations and Schizanthus, and from “cauliflower” of strawberry. On inoculation all these strains produced marked fasciation in sweet‐pea seedlings, and also produced fasciation of sweet‐pea seedlings growing in inoculated sand cultures.
A preliminary description of the organism has been given.

REFERENCES
THE INSECTICTDAL PROPERTIES OF SOME EAST AFRICAN PLANTS
Authors: WORSLEY R. R. LE G. 
Published: February 2008

SUMMARY Mundulecc bark from Moa district is as toxic to insects as Ammi Derris root containing 6.4 per cent. rotenone. That obtained from two other dietricts is only about half as toxic. The former tree may be a variety of the ordinary M. suberosa.The powder dusted on cockroaches and flies, although having a much smaller initial effect than pyrethrum and not producing any rapid knock‐down, yet causes death in about half the time; Derris has the same action. The same remarks apply to paraffin extracts of these substances. Mudulea seeds are about three‐quarters as toxic as the bark, but are unlikely to be of any commercial value on account of their scarcity. Experiments are in progress in the cultivation of M. suberosa from Moa seed, and it is hoped that the bark will h d a commercial outlet.
THE BIOLOGY OF LEPTOBYRSA RHODODENDRI HORVATH (HEMIPTERA, TINGITIDAE), THE RHODODENDRON LACEBUG
Authors: JOHNSON C. G. 
Published: February 2008

SUMMARY

A brief review of the literature dealing with the history of Lepto‐byrsa rhododendri Horvath as a pest is given. The original home and subsequent dispersal are discussed.
The distribution of the insect in Great Britain, as known to the author, is given.
The bionomics of the insect are dealt with.
Detailed descriptions of the structure of the egg and its position in the leaf tissue are made, together with a short description of the egg gall and an account of the hatching process.
The external appearance of each of the four instars is described in detail. Comments upon the descriptions of the immature stages of previous workers are given.
The list of references contains all the more important papers which deal with the insect mainly from general economic and bionomic aspects.
SOME NOTES ON THE BIOLOGY AND ECONOMICS OF SOME BRITISH CHAFERS
Authors: FIDLER J. HAVELOCK 
Published: February 2008

SUMMARY

Adult chafer beetles do not usually occur in very extensive swarms in the British Isles, and their general importance lies in the characters of the larvae which are notable for their voracity and large size. Another factor of importance is the tendency towards concentration, large numbers of beetles often ovipositing in one field while neighbouring crops remain free.
There are few crops which the larvae do not attack, but the damage done by the adult beetles in this country is not important.
The distribution, which is local, is shown to be controlled by the sparseness of suitable habitats and by the prevailing conditions of temperature and humidity.
The factors which control the varying lengths of the life cycle are also considered to be mainly temperature and humidity. Thus, although Serica always takes 2 years to develop, Amphimattus solstitialis may take either 2 or 3 and M. melolontha 3 or 4 years, according to the conditions controlled by these two factors.
Regular flight‐years are usual on the Continent, but are much less definite in the British Isles, and the numbers of beetles appearing are relatively small. It is suggested that the reason for this is the differences in climatic conditions, particularly in spring.
A STUDY OF FOMES FRAXINEUS AND ITS EFFECTS ON ASHWOOD
Authors: MONTGOMERY H. B. S. 
Published: February 2008

SUMMARY

An account is given of the occurrence and distribution of Fomes fraxineus.
The appearance of the fungus in culture and details of the hyphae are described.
Fruit bodies, in the form of pore surfaces bearing basidiospores on typical basidia, were obtained. Monosporous cultures derived from these spores were found to be heterothallic, sex appearing to be determined by two factors.
The formation of fructifications is favoured by certain media but does not seem to be influenced by light, temperature or moisture.
The optimum temperature for growth is 26o C, and the optimum hydrogen‐ion concentration is pH. 6.
The fungus was found to be moderately resistant to zinc chloride, sodium fluoride and coal‐tar creosote.
A list of enzymes found to be present is given and some preliminary experiments on the effect of nitrogen on the activity of diastase and oxidase produced by the fungus are outlined.
The growth of the fungus on ashwood and some other woods was investigated. The fungus grows well on ash, beech and elm and is able to attack oak, Scot's pine, Sitka spruce and Robinia pseudacacia. Ann Biol xxIII 32A description of the hyphae in the cells of the wood and their effect upon the walls is given.