bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES ON APHIDES INFESTING THE POTATO CROP
Authors: DAVIES THE LATE W. MALDWYN , WHITEHEAD T. 
Published: February 2008

Summary

The investigations were planned to ascertain the extent of the migrations of Winged aphides, their ability to detect individual plants, the development of aphis population following colonization, and the extent to which Virus diseases may be transmitted to isolated plants by winged aphides.
Plants were isolated in root crops on seven farms and at varying distances from probable sources of virus infection. Four farms were located in districts where aphis population is usually high and viruses spread very rapidly; two in districts where both aphides and spread of viruses are minimal, whilst one farm could be regarded as intermediate in both respects.
Evidence is submitted to show that winged aphides have no difficulty in detecting and colonizing isolated plants. Their numbers were large at the four eastern centres and very small at the three western centres. In all cases the aphis population on isolated plants was less than that of the nearest general crop and suffered more from predators and parasites.
It is shown that isolated plants can be reached by migrants from a distance of at least a quarter of a mile, and probably much further. Additional evidence is given that these initial migrants introduce little virus infection to potato crops from extraneous sources. The importance, however, of the later movements of winged aphides, whether initial migrants or those subsequently produced on potatoes, in spreading Viruses from crop to crop, is emphasized.
The practical aspects of protecting potato stocks is discussed under conditions of (a) heavy infestation by winged aphides and proximity of partially diseased crops; (b) minimal winged aphis infeatation where numerous sources of virus infection occur in neighbouring crops; and (c) where both aphis infestation and sources of infection are minimal. It is considered that regulations for the improvement of health in seed‐potato stocks should take cognisance of these various possibilities.
THE VIABILITY OF WEED SEEDS AT VARIOUS STAGES OF MATURITY
Authors: GILL N. T. 
Published: February 2008

Summary

Certain plants within the family Compositae wher cut lown in the flowering condition produce viable seeds; others do not. The first group includes: Sonchus oleraceus, Senecio Jacobaea, S. vulgaris and Aster Tripolium, whilst the second group includes: Taraxcum vulgare, Hypochaeris radicata, Cirsium arvense and C. lanceolatum.
Certain species in other families produce viable seeds when cut down at various stages of maturation of the fruits following fertilization.
When the mature seeds exhibit a prolonged dormant period, the seeds harvested in an immature state exhibit a similar period of dormancy.
In Papaver dubium and Datura stramonium, the immature seed germinated more readily than the fully ripened seed, owing to the impermeability of the seed coat of the latter.
A combination of fluctuating temperature and illumination improved the germination of the two Rumex species when tested soon after harvesting, but had no effect on other species found difficult to germinate in an incubator at constant temperature. Three months after harvesting of the Rumex species the seeds germinated equally well in the incubator at constant temperature.
THE ECOLOGY OF THE LARGER FUNGI
Authors: WILKINS W. H. , HARLEY J. L. , KENT G. C. 
Published: February 2008

SummaryThe paper is the second of a series which is dealing with investigations into the ecology of the larger fungi.It represents a somewhat detailed examination of the fungus flora of a plateau beech wood in relation to (a) vegetation and (b) substrate.In the first case, distribution of fungi in the three subtypes—No field layer, Oxalis societies and Mercurialis societiesis recorded and discussed.The second section deals with distribution in relation to soil types, humus and leaf litter, with notes on hydrogen‐ion concentration.There is a brief discussion of results.
SOME SPECIES OF PYTHIUM PARASITIC ON WHEAT IN CANADA AND ENGLAND1
Authors: VANTERPOOL T. C. 
Published: February 2008

SummaryThe results of a comparative study of six species of Pythium pathogenic to wheat seedlings are presented. P. arrhenomnes, P. volutum, and P. tardicrescens n.sp., were found in both Canada and England; or, for P. graminicolum and P. torulosum [?] in England and not in Canada; and P. aristosporum. n.sp., only in Canada. The English forms were obtained from Bucks, Cambs, Kent, Herts, Berks, and Lincs, and the Canadian forms from Saskatchewan. The similarity of the English form considered as a geographic strain of P. torulosum with the form reported on wheat in Italy by Petri is pointed out. Attention is drawn to the wide geographic distribution of species of Pythium on graminaceous hosts. By the method of isolation used, it was relatively easy to obtain one or more of these fungi either from wheat seedlings grown in potted soil collected at random from virtually any field with cereals in the rotation, or from seedlings collected from the poorer looking parts of such fields. All of the parasitic species isolated belong to the group of the genus with lobulate sporangia. It is suggested that the many sphaerosporangial forms encountered may render the wheat seedlings more liable to attack by the pathogenic forms themselves. The use of fertilizers may prove beneficial.
FURTHER OBSERVATIONS OF THE INCIDENCE OF BLOTCHY RIPENING OF THE TOMATO
Authors: WHITE H. L. 
Published: February 2008

Summary

The annual fluctuation in percentage o‐f fruit affected with “blotchy ripening” on potassium‐deficient and nitrogendeficient plots at the Cheshunt Experimental Station is significantly negatively correlated with the mean daily number of hours of bright sunshine between 1 April and 31 August.
The weight of fruit of potassium‐deficient plants is raised and the percentage of blotchy fruit reduced, either by increase of potassium supply or by increase of light. This beneficial effect of increase of light on the crop of potassium‐deficient plants is of much greater magnitude than any corresponding effect on the crop of nitrogen‐deficient or completely manured plants.
The juice of the blotchy areas of potassium‐starved fruits has diminished capacity for starch hydrolysis.
Increasing severity of potassium starvation is associated with progressive increase in level of dry weight per unit area of the leaves.
The influence of potassium on the production of blotchy fruit is briefly discussed.
SHEEP BLOW‐FLY INVESTIGATIONS
Authors: HOBSON R. P. 
Published: February 2008

Summary

An investigation has been made of the effect of temperature upon the time required for the development of the ovaries in the sheep maggot fly.
It has been shown that two meat meals are essential for the development of mature eggs in the ovaries. This applies also to the further production of eggs after opposition.
Neither plant materials nor animal excreta can replace meat in the diet of the female fly if eggs are to develop in the ovaries.
Various products of putrehction stimulate gravid females to opposite, but these substances do not attract flies from a distance.
THE MANURIAL REQUIREMENTS OE PYRETHRUM (CHRYSANTHEMUM CINERARIAEFOLIUM TREV.)
Authors: MARTIN J. T. , MANN H. H. , TATTERSFIELD F. 
Published: February 2008

SummaryA small field experiment upon the manurial requirements of the insecticidal pyrethrum plant, grown upon sandy soil of low fertility, is described. Lime had the effect of producing slight, but not significant, increases each year in the yield of flowers and their content of the pyrethrins, and decreased the percentages of plant failures in the fourth and fifth years of the experiment. There was a significant depression in the yield of flowers in the year after the single application of double dressings of the manures, but no effect in later years. The yearly application of moderate dressings of manures gave significant increases in the yield of flowers in the second and fifth years, and significant increases in the pyrethrin I content of the flowers in the fourth and fifth years of the experiment.
STUDIES ON PUCCINIA ANOMALA ROST.
Authors: N‘OLIVBIRA BRANQUINHO 
Published: February 2008

Summary

Methods of establishing pure cultures of rusts are discussed and a new spore‐proof and insect‐proof cellophane cylinder is described.
Eighty‐two cultures, isolated from collections of P. anomala in Great Britain, Portugal and Spain, have been tested for the determination of physiologic races. The barleys used as differential hosts were those used by Hey and Mains and also Aegyptische 4‐zeilige Sommergerste. Eleven new physiologic races have been identified and are numbered 12–22. Race 12 was found to be widely distributed in Great Britain, Portugal and Spain, the other ten were localized. Races 13, 14, 15 and probably 18 were found in Britain, races 18, 19 and 20 in Portugal, and races 16, 17, 21 and 22 in Spain.
A mutant, differing in colour (orange and yellow) and in pathogenicity, is recorded for P. anomala. The mutant arose from an unstable culture of race 14 cultivated on Hordeum vulgare pallidum (Sudan), and is numbered physiologic race 23.
Segregation and hybridization of physiologic races occurred through the aecidial stage on Ornithogalum umbellatum L. The heterozygous condition of physiologic races 12, 13 and 23 was demonstrated. Self‐fertilized material from race 12 gave rise to the parent race, to races 16 (?) and 19 and to four new races described under the numbers 24, 25, 26 and 27. From self‐fertilized material of race 13, races 12(?), 13, 22 and 24 were isolated and also two new races numbered 28 and 29. From self‐fertilized material of race 23, races 12, 19, 20 and 22 were isolated. A reciprocal cross between physiologic races 13 and 23 was achieved; in one direction the progeny gave rise to a single physiologic race, which proved to be new and is numbered 30; in the other direction the two physiologic races 30 and 18 were produced. This result is discussed and is attributed to cytoplasmic inheritance.
Several biotypes of physiologic races 12 and 13 were found; they seem to establish a linkage between the two races.
A new selection of differential hosts for the differentiation of physiologic races of P. anomala on cultivated barleys is proposed. A “Numerical Table” of the thirty physiologic races and an “Analytical Key” for their determination are given.
The distribution of physiologic races of P. anomala on cultivated barleys in Great Britain, Portugal and Spain is discussed.
From field observations it is concluded that at Cambridge P. anomala may overwinter in its uredospore stage. Evidence is given that in Portugal the uredospores survive the summer in the mountains.
STUDIES ON APHIDES INFESTING THE POTATO CROP
Authors: DAVIES W. MALDWYN , Whitehead T. 
Published: February 2008

Summary

This communication is the substance of a report on a survey of the aphis population in certain districts of Scotland carried out from 24 July to 4 August 1936.
Forty‐three centres in eastern Scotland, from Midlothian in the south to Ross‐shire in the north, were examined by the standard method for determining the aphis “index” figure.
The varying figures obtained have been analysed with a view to establishing any relation there might be with (a) proximity to winter host plants, and (b) meteorological conditions such as temperature, humidity and wind velocity.
The results have been summarized in a discussion in which are indicated the special precautions necessary to ensure health in seed‐potato stocks.
THE ASSOCIATION OF APPLIED BIOLOGISTS AND THE ANNALS OF APPLIED BIOLOGY— A RETROSPECT (1904‐38)
Authors: BRIERLEY WILLIAM B. 
Published: February 2008

With the close of 1938 the Annals of Applied Biology completed its first 25 volumes, and the occasion appeared to be a suitable one on which to review progress in the Association and its journal.I am indebted to various senior Members who read this account in typescript and pave me the benefit of their greater knowledge and experience.
A STUDY OF CERTAIN SPECIES OF THE GENUS SCLEROTINIA
Authors: KEAY MARGARET A. 
Published: February 2008

SUMMARY

Investigations were carried out on Schrotinia serica, two strains of S. Sclerotiorum de Bary, five strains of S. Trifoliorum Eriks., two forms of S. minor Jagger, four isolations of a Sclerotinia from Vicia Faba considered to be a variety of Sclerotinia Trifoliorum, and a variant which arose from one of these isolations.
Their pathogenicity to several different plants was tested and the fungi were found to fall into three groups: (1) S. Sclerotiorum and S. minor, (2) S. Trifoliorum and its variety Fabae, and (3) S. serica.
A variant with light brown sclerotia which arose from S. Trifoliorum var. Fabae differed from the parent form in pathogenicity.
Ascospores of S. Sclerotiorum, S. minor and S. Trifoliorum did not infect healthy leaves.
The production of mycelium by sclerotia in the soil was not observed.
S. serica differed from the other fungi in that it produced numerous apothecial stipes and several apothecia in test‐tube cultures.
Exposing 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.
Sclerotia formed in cultures grown over a wide temperature range produced apothecia when subsequently buried in damp sand.
Single‐spore lines of S. serica, S. Sclerotiorum, S. minor and S. Trifoliorum produced apothecia.
Apothecial production took place over a wide temperature range.
Apothecia of one form of S. minor arising 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 of S. Sclerotiorum, S. minor, S. Trifoliorum and S. Trifoliorum var. Fabae.
Measurements are given of asci and ascospores.
The 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. serica spread more slowly than the other species. The variant of S. Trifoliorum var. Fabae had different temperature relations from the parent form.
A brief description is given of the cultural appearance of S. Sclerotiorum, S. Trifoliorum, S. minor, S. Trifoliorum var. Fabae and its variant.
The classification of the fungi is discussed.
A COMPARISON OF THE METABOLISM OF MOSAIC DISEASED POTATOES WITH THAT OF NORMAL POTATOES
Authors: COCKERHAM GEORGE 
Published: February 2008

SummaryThe effects of potato virus X upon the carbohydrate and total nitrogen contents of potato leaves have been followed over diurnal and seasonal periods in the varieties President and Arran Victory.The gross metabolism of carbohydrates has been found to be similar in both mosaic‐diseased and normal leaves.Three major trends of carbohydrate metabolism, each of which may be identified with a particular stage of leaf development, have been recognized and discussed.Slight modifications of the fundamental metabolism of diseased leaves have been found in a reduced photosynthetic activity, disturbed starch‐sugar relationships, and an impediment in translocation during the pre‐senescent stage. All these have been ascribed to secondary effects arising out of the pathological change brought about as a result of virus infection.Transient modifications in carbohydrate metabolism have been traced to prematurely retarded growth activities leading to a diminished demand for carbohydrate in support of growth in the diseased plants.A significantly greater content of nitrogen has been found in diseased leaves at all stages of growth, and it has been suggested that the pathological symptoms and prematurely retarded growth activities which give rise to disturbances in carbohydrate metabolism are direct manifestations of a disorganized nitrogen metabolism.
PHYTOPHTHORA ERYTHROSEPTICA PETHYBR. IN RELATION TO ITS ENVIRONMENT
Authors: CAIRNS H. , MUSKETT A. E. 
Published: February 2008

Summary

The present contribution, as part of a general study of pink rot of the potato, deals with Phytophthora erythroseptica Pethybr. in its relation to staling, light, acidity, moisture and temperature.
In natural media the fungus is not, or but very slightly, affected by its own staling products, but, in general, is intensely intolerant to the presence of other fungi and bacteria.
Ordinary daylight is not concerned in the growth or reproduction of the fungus.
Growth occurs over a wide pH range (3·2 to circa 9·0–10·0); sexual reproduction occurs over this range except towards the limits of acidity and alkalinity; asexual reproduction was not investigated experimentally. It is considered that modification of the soil reaction, within practical limits, does not offer a means for control of the disease.
The moisture factor controls directly the incidence of the disease in contaminated soil—with low moisture infection is inhibited; with normal moisture infection occurs via the dead or moribund stolon through the “heel” of the tuber; with high moisture the tuber is infected directly in the region of an “eye”. Sporangia are only formed under aquatic conditions and it is considered probable that “eye” infection is brought about through the agency of zoospores.
The temperature limits of growth are 0–32°C. with an optimum at 25°C. Oospore production occurs only between the optimum and minimum growth temperatures (0–25°C), being inhibited above the growth optimum. Asexual reproduction seems to be similarly related to temperature.
FACTORS AFFECTING THE RESISTANCE OF THE FLOUR BEETLE, TRIBOLIUM CONFUSUM DUV., TO HYDROGEN CYANIDE1
Authors: GOUGH H. C. 
Published: February 2008

Summary

Two types of apparatus for exposing insects to known concentrations of toxic gases, under controlled conditions, were constructed and are described.
The relative resistance of different stages of the flour beetle, Tribolium confusum Duv., to hydrogen cyanide was determined, the results being treated by Bliss's method. The order of resistance was pupa (most resistant), adult, larva, egg. The difference in resistance at different ages was found for the pupa, adult and egg. The application to all these results of Cotton's theory of the relation of rate of metabolism and susceptibility to fumigants is discussed. It is considered that this theory might hold for stages other than the egg.
A series of experiments was carried out to discover whether individual resistance to hydrogen cyanide was inherited. It was found that the offspring of resistant individuals were significantly more resistant than the offspring of susceptible individuals, and that this difference was maintained over several generations.
A considerable increase in resistance was found to occur if adult beetles were removed from their flour about an hour, instead of immediately, prior to their fumigation. The reason for this increase was not determined, but various suggestions to account for it are discussed.
It was noted that under certain conditions, adult beetles emitted a volatile substance which was self‐toxic, and also appeared to react with cyanide.
The dosage‐mortality curves for all the experiments are discussed and possible reasons for their apparent abnormality put forward.
The experiments here described, which must only be regarded as preliminary, emphasize
The complexity of the problems arising in the study of the resistance of living organisms to toxic substances.
The need for carrying out such experiments under as natural conditions as possible.
The importance of a careful analysis of factors which affect the resistance of the organism.
STUDIES UPON THE TIME OF FLOWERING OF PLANTS: ANATOMICAL, FLORISTIC AND PHENOLOGICAL ASPECTS OP THE PROBLEM
Authors: GRAINGER JOHN 
Published: February 2008

Summary

The growing points of more than 100 plant species of diverse habit have been examined between 1937 and 1939, in order to find the exact times of flower initiation.
Types of organization for flowering may be classified into (a) direct‐flowering plants, (b) indirect‐flowering plants, (c) cumulative‐flowering plants and (d) climax flowering plants. Initiation of the flower in (a), (b) and (c) may either begin (i) during the period of maximum vegetative growth or (ii) when vegetative growth is at a minimum. In the latter class, any direct cause of flowering operated entirely or largely by external influences, such as those affecting the vigour of photosynthesis, would appear to be eliminated.
Abnormal flowering of some indirect‐flowering plants during the autumn of 1938 suggests that their physiological rest periods were concluded at that time. Their normal extension of dormancy until the following spring is probably a direct effect of winter climate.
Plant habit, as annual, biennial, perennial, does not appear to affect the time of flowering, unless associated with a store of food, but not all plants with stored food flower early.
A series of correlation diagrams of the two variables, temperature and time of flowering, has been prepared from the Royal Meteorological Society's phenological data. These suggest that temperatures before the initiation of flower bud formation, in addition to those at other periods of floral development, may affect the time of flowering. Some species appear to be hastened by higher temperatures than normal at this period, e.g. ivy, and yet other kinds by temperatures lower than normal, e.g. coltsfoot.
Flower emergence in thirteen wild plants is hastened by a temperature higher than that of normal climate for a period just before the time of opening.
INTRANUCLEAR INCLUSIONS IN VIRUS INFECTED PLANTS
Authors: KASSANIS BASILIOS 
Published: February 2008

SummaryTwo kinds of intracellular inclusions in solanaceous plants infected with severe etch virus are described. One occurs in the cytoplasm and is similar to the X‐bodies found in many other plant virus diseases. The other occurs only in the nuclei. These intranuclear inclusions appear to be crystalline, have the form of thin rectangular plates, and resemble the inclusions described in the polyhedral disease of silkworms more than any other type of previously recognized virus‐inclusion.
THE MORPHOLOGY AND BIOLOGY OF THE BRAMBLE SHOOT‐WEBBER, NOTOCELIA UDDMANNIANA L. (TORTRICIDAE)
Authors: DICKER G. H. L. 
Published: February 2008

SummaryA detailed study of the morphology and biology of all stages in the life cycle of Notocelia uddmanniana L. has been made over a period of 2 1/2 years.This tortricid is a pest of loganberry in certain fruit‐growing areas.The widths of the head capsules in all larval instars have been measured and found to follow Dyar's Law.In the East Mailing district an ichneumonid, Omorgus mutabilis H.Gr., parasitizes 35–50 % of the larvae. A few specimens of an undescribed species of Apanteles have been bred from larvae, and also a tachinid fly, Nenwrilla notabilis Mg.Preliminary control measures have given poor results.