bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies upon the copper fungicides. IX. Investigations with the exudate from fungus spores
Authors: Wain R. L. , Wilkinson E. H. 
Published: February 2008

Determinations have been made of the copper dissolved from pure copper compounds by water, by a standardized solution of the exudate ofNeurospora sitophilaspores, by standard solutions of malic and succinic acids and their sodium salts, and by glycine and mannitol.The results compared with the known fungicidal performances of the copper compounds show that the amounts of copper yielded to water and to the standardized spore extract or glycine solution provide an indication of fungicidal properties.Although soluble copper in excess of that dissolved by water can only appear from alkaline Bordeaux deposit by complex ion formation, results show that this is not necessarily the only means by which copper can dissolve from other copper compounds.In a chemical investigation of the exudate ofN. sitophilaspores, mannitol, succinate and fumarate have been isolated. None of these materials can dissolve an appreciable amount of copper from alkaline Bordeaux deposit. Malate, found by other workers to be a constituent of the exudate of N. sitophila spores cultured on potato dextrose agar, has not been detected in such a solution from spores grown on malt agar. The quantity of mannitol in spore exudate has been shown to depend on the nutrient medium on which the fungus is grown.
The influence of potato variety on the cyst of the potato‐root eelworm, Heterodera rostochiensis Wollenweber
Authors: Ellenby C. 
Published: February 2008

Experiments are described with eelworm cysts obtained from the roots of four potato varieties, Doon Star, Arran Banner, Redskin and Kerr's Pink. In a cyst‐type: excretion‐type hatching trial carried out in autumn, each group of cysts was stimulated by root excretions derived from the four types of plants. There were significant differences in the response to the root excretions from the different sources, and in the number of larvae emerging from the different cyst types, the number being highest for Arran Banner and practically nil for Doon Star cysts; but there was no correlation between cyst type and excretion type.In experiments the following spring with the same cysts, emergence was heavy for all cyst types; but it began considerably later for Doon Star than for the other cyst types. The lack of emergence from Doon Star cysts in the previous autumn was, therefore, not due to the death of the contents of these cysts.Fewer larvae emerged from Doon Star cysts than from either Arran Banner or Redskin (experiments with Kerr's Pink were discontinued). Doon Star cysts were smaller; however, comparing values for larval emergence and cyst volume for the different cyst types by the method of covariance, the larval emergence was found to be significantly lower for Doon Star cysts than for cysts of the other types, even after adjustment for cyst size.The number of eggs in each cyst was determined. Analysis by the method of covariance showed that, after adjustment for cyst size, there were significantly fewer eggs in Doon Star cysts than in cysts of the other types.A similar analysis was carried out of the relationship of larval emergence and egg number. The regression coefficients show that for each cyst type a constant proportion of eggs hatched; but the proportion is smaller in Doon Star cysts, for, after adjustment foreggnumber, the value for larval emergence is still significantly lower. Fewer larvae therefore emerged from Doon Star cysts partly because the cysts are smaller, partly because, for the same volume, they contain fewer eggs, and partly because a smaller proportion of these eggs hatched during the course of the experiments.The results are discussed in relation to a recent paper by Gemmell (1943). While the differences may be due to resistance on the part of the host plant, as claimed by this worker, there are other possibilities; it is considered that these should be investigated before the hypothesis of ‘resistance’ is accepted. In particular, it is suggested that the differences in cyst size and egg number may be due to differences in the seasonal behaviour of the different potato varieties; differences in the hatching response of the cysts may then be due to the fact that the eelworm cyst responds to root excretions as a unit and that egg concentration is a factor affecting the nature of the unit.
OBSERVATIONS ON THE PATHOGENICITY OF CALONECTRIA RIGIDIUSCULA (BERK. & BR.) SACC. ON THEOBROMA CACAO L
Authors: CROWDY S. H. 
Published: February 2008

Calonectria rigidiuscula has been found associated with an acute and a chronic form of dieback of cacao. It can also infect cankers caused primarily by Phytophthora palmivora, and the lesions following attack by the capsids Sahlbergella singidaris and Distantiella theobroma. The association with the capsid lesions is of great economic importance since it appears that capsids alone are capable of killing only green shoots, and that the severe damage caused to woody shoots follows C. rigidiuscula infection of the capsid lesions. Acute dieback occurs only in certain districts after exceptional drought and may be considered primarily the result of environmental conditions. The main importance of chronic dieback is that it prevents the recovery of cacao which has been seriously weakened from other causes. C. rigidiuscula infection retards the healing of P. palmivora cankers and also produces a lesion in the xylem tissue which may be extensive. C. rigidiuscula has been established in wounded cacao stems of all ages without difficulty. The spread of the fungus is slow, but is more rapid in the xylem than in the cortical tissues. Spread is greatest in the unlignified tissues.
WIREWORM POPULATIONS IN RELATION TO CROP PRODUCTION: II. POPULATION CHANGES IN GRASSLAND
Authors: ROSS D. M. , STAPLEY J. H. , COCKBILL G. F. 
Published: February 2008

Six grass fields were sampled once a fortnight from July 1943 to September 1944, and the wireworms in the samples counted by the washing and flotation method.The counts from twenty standard samples showed huge fluctuations which rendered them practically valueless as estimates of wireworm populations when treated singly. When treated as running means of four consecutive samplings, the counts showed certain seasonal trends, with minimum populations in July and August, rising populations throughout the autumn, maximum populations in the months from January to April and a sharp decline to the minimum populations again from April to July. On the average, the counts taken in winter were twice as high as those taken in the summer months.The fluctuation was evident in all size groups based on larval length but was most marked in the wireworms ‘under 4 mm.’, ‘4 mm.’ and ‘5 mm.’Samples taken to depths of 12 and 24 in. showed that on the average about 75 % of the wireworms were found in the 0–6 in. layer and about 90% in the 0–12 in. layer. These proportions varied considerably with the seasons.The seasonal changes in wireworm populations observed do not correspond with those expected from the life history of Agriotes spp. Possible explanations for this anomaly are discussed, but it cannot be attributed to any known technical or biological factor. Several possibilities remain to be explored.
THE EFFECT OF PLANT EXTRACTS ON THE GERMINATION OF THE CONIDIA OF VENTURIA INAEQUALIS
Authors: GILLIVER K. 
Published: February 2008

Of 1915 flowering plants 23 % gave extracts which completely inhibited the germination of the conidia of Venturia inaequalis under the experimental conditions used. The plants which gave active extracts are distributed throughout the Angiosperms, and there is no correlation with systematic position. The inhibitors were distributed generally in some plants and were localized in others, e.g. to the leaves.Some extracts appeared merely to inhibit the germination of the conidia while others killed them.Some inhibitors disappeared when the plants were dried, other dry material was still active when retested several months later. Hedera Helix contains an inhibitor which is active when the extract is diluted 128 times.
THE INFLUENCE OF LIGHT INTENSITY ON THE SUSCEPTIBILITY OF PLANTS TO CERTAIN VIRUSES
Authors: BAWDEN F. C. , ROBERTS F. M. 
Published: February 2008

Reducing the light intensity under which plants were grown in summer to one‐third increased their susceptibility to infection with tobacco necrosis, tomato bushy stunt, tobacco mosaic and tomato aucuba mosaic viruses. With the first two viruses shading increased the average number of local lesions per leaf by more than ten times and by more than five times with the second two.Reducing the light intensity increased the virus content of sap from leaves inoculated with Rothamsted tobacco necrosis virus by as much as twenty times. As it also reduced the total solid content of sap by about one‐half, purification was greatly facilitated; crystalline preparations of the virus were readily made from shaded plants but not from unshaded controls.Reducing the light intensity also increased the virus content of systemically infected leaves; the greatest effect was with tomato bushy stunt virus with which increases of up to ten times were obtained, but with tobacco mosaic and aucuba mosaic viruses there were also significant increases.The importance of controlled illumination in raising plants for virus work and the possible mechanisms responsible for the variations in susceptibility are discussed.
STUDIES ON THE RELATIONSHIPS BETWEEN EARTHWORMS AND SOIL FERTILITY: I. BIOLOGICAL STUDIES IN THE FIELD
Authors: EVANS A. C. , GUILD W. J. McL. 
Published: February 2008

Changes in the seasonal activity of several species of earthworms have been followed in a permanent pasture field for 18 months, 1945–6. The two soil conditions which chiefly determine activity are temperature and moisture. Other factors are the occurrence of an obligatory diapause in the two species Allolobophora nocturna and A. longa, and changes in population in A. chlorotica and Lumbricus terrestris.Soil temperature and soil moisture also determined the weight of soil thrown up in the form of wormcasts during autumn, winter and spring. It is suggested that only two species, A. nocturna and A. longa, are responsible for wormcasts and that the other four common species present play little or no part in this activity.At Rothamsted it was found that the previous agricultural history of the field is an important factor in determining the fauna. Old permanent pasture is characterized by a high percentage of A. nocturna and a rather lower percentage of A. caliginosa. Ploughing old permanent pasture and reseeding to grass after 1 or 2 years arable reduces the proportions of A. nocturna and A. caliginosa and increases that of Eisenia rosea. Arable fields have A. chlorotica as the dominant species and pasture fields 2–7 years grass after many years of arable fanning still show a high percentage of A. chlorotica and a low proportion of A. nocturna.A survey of the Carse of Stirling, Scotland, showed that soil type is also an important factor in determining the earthworm fauna. A. caliginosa was the dominant species on the three soil types studied, but the subdominant species varied. On clay soil, A. longa was subdominant; on loam, A. longa and L. rubellus; on sandy soil, A. longa, L. rubellus and A. chlorotica. The dominant species of pasture land at Rothamsted, A. nocturna, was not found at Stirling.
THE PRACTICAL CONTROL OF WIREWORM BY γ‐BENZENE HEXACHLORIDE (‘GAMMEXANE’): COMPARISONS WITH DICHLORODIPHENYLTRICHLORETHANE (D.D.T.)
Authors: JAMESON H. R. , THOMAS F. J. D. , WOODWARD R. C. 
Published: February 2008

Benzene hexachloride containing 13% of the insecticidally active gamma isomer known as ‘Gammexane’ has been used successfully in a considerable number of field trials in the control of wireworm. On heavily infested land the effective dosage rates associated with an appreciable reduction in wireworm population, and giving a marked improvement in plant establishment and substantial increases in yield, range between 1 and 6 lb./acre (2–12 oz./acre of Gammexane), on oats and wheat. The effective dosage rates vary and depend upon whether the insecticide is combine‐drilled, broadcast, or applied as a seed dressing.Although D.D.T. applied by similar methods was associated with similar reductions in wireworm population, the use of this insecticide resulted in smaller yield increases.
VIRUS DISEASES OF CACAO IN WEST AFRICA: I. CACAO VIRUSES 1A, 1B, 1C AND 1D
Authors: POSNETTE A. F. 
Published: February 2008

As an introduction to this series of papers, a brief history is given of swollen‐shoot disease of cacao in the Gold Coast, and the nomenclature for cacao viruses is discussed.The symptoms of four virus diseases of cacao are described in detail, together with experimental data under the headings: cross‐immunity reactions, latent period, seed transmission, staining reaction, heat inactivation and rate of spread.
VIRUS DISEASES OF CACAO IN WEST AFRICAL: II. CROSS‐IMMUNITY EXPERIMENTS WITH VIRUSES 1A, 1B AND 1C
Authors: CROWDY S. H. , POSNETTE A. F. 
Published: February 2008

Experiments on cross‐immunity reactions between three viruses attacking Theobroma cacao L. on the Gold Coast are described. A field trial involving 3 acres of graft‐inoculated trees revealed some degree of protection afforded by Theobroma virus 1B against infection with virus 1A. The protection appeared to be more effective against insect inoculation than against graft transmission, being only temporary in the latter. Virus 1C (probably unrelated but not to be called Theobroma virus 2 until more evidence is available) conferred no protection against virus 1A.The latent periods for these viruses were calculated from this experiment, which also provided data on their effects on yield. Virus 1A reduced yield by 50% in the first year after inoculation and killed the trees in the second. Virus 1B had no appreciable effect on yield; virus 1C reduced yield by 50 % in the third year after inoculation but there was no further decline in the fourth.The rates of spread of these viruses were compared and significant differences demonstrated.
THE DEVELOPMENT OF INTERNAL BOLL DISEASE OF COTTON IN RELATION TO TIME OF INFECTION
Authors: PEARSON E. O. 
Published: February 2008

Inoculations of Nematospora spp. into cotton bolls at successive weekly intervals from flowering to maturity show that the symptoms produced are closely dependent upon the stage of development reached by the boll when infected. Details are given of the nature and degree of the staining and of the effects upon weights of seed and lint finally produced. During the first 4 weeks of life bolls are in the stage of rapid growth and differentiation, and infection is followed by severe disorganization of all boll structures and complete commercial loss. Bolls infected later in life develop typical stained lint, but without general breakdown of other tissues, and the degree of staining diminishes steadily with the age when infected, until, towards maturity, little or no effect is produced.Subsidiary experiments show that inoculations of sterile water can cause death of the seed embryos, presumably by plasmolysis, in bolls up to 3 weeks of age. The effects upon the seed and consequently upon the lint following death of the embryo caused by such treatment are shown to be similar to those following feeding by uninfected insects of the genus Dysdercus, which are the normal vectors of internal boll disease.Staining of the lint by Nematospora is due to the post‐mortem discoloration of the protoplasm of the lint hair, and its extent consequently varies inversely with the degree of vacuolation, which increases with maturity. The mode of action of the fungus and the evidence suggesting that a toxin is involved are discussed.The bearing of the age‐damage relationship on the losses due to internal boll disease in African cotton‐growing countries is considered, and the advantages of promoting a steep flowering curve are emphasized.
The Relation Between the Size of Plant and the Spread of Systemic Diseases
Authors: van der Plank J. E. 
Published: February 2008

It is an implication of systemic infection by the aphis‐borne viruses that potato plants with large haulms should be specially vulnerable to infection, and this implication is supported by evidence in the field.Haulms are reduced in size by short days, low temperatures, under‐nutrition and varietal differences. Certain observations are adduced to show that these factors reduce vulnerability. It is suggested that the transference of the potato from the short days, infertile soils and primitive cultivation on the Andes to the long summer days and productive farming of Europe and North America enhanced its vulnerability to aphis‐borne virus diseases: the further effects of changes of temperature and manurial practices in the last century need elucidation.
The Effects of D.D.T. and of Benzene Hexachloride on Bees
Authors: Way M. J. , Synge A. D. 
Published: February 2008

Laboratory and field experiments were carried out during 1946 to determine the effects of D.D.T. and of benzene hexachloride (B.H.C.)* on honey‐bees and on several wild be species.Laboratory experiments show that B.H.C. is a powerful contact and stomach poison and results of field experiments with commercial preparations confirm its danger to the foraging bee population. A few minutes' contact with treated surfaces is sufficient to cause death and blossom may remain poisonous for at least 3 days after treatment.In the laboratory D.D.T. has a contact action at fairly high concentrations and as a stomach poison is rather more toxic than lead arsenate. In the field, commercial preparations on open blossom are apparently harmless to foraging bees.
The Toxic Action of Molybdenum in Relation to Soils and Crops
Authors: Brenchley Winifred E. 
Published: February 2008

The harmful effect of molybdenum on animals is well established, but there is comparatively little knowledge of the conditions in which molybdenum is poisonous to plants. Obvious differences in response to molybdenum poisoning in different soils have been previously noted, but no adequate explanation has been put forward.Tomatoes grown in ordinary loam showed little outward sign of poisoning with heavy doses of sodium molybdate, but some depression of crop occasionally occurred, especially when the dose was divided into early and late treatments. The response varied with season and variety. On certain light and fen soils the plants were killed at an early stage with the heavier dressing of molybdate, and seriously injured with the lighter dose, the leaves showing the golden colour characteristic of molybdenum poisoning in various plants.The reaction of different crops varied considerably in the same soil with similar treatments. On old cucumber soil tomatoes showed no sign of toxicity even with the heavy dressing, flax was progressively damaged with increasing doses, while Solanum nodiflorum was most seriously affected even with the lighter dressing of molybdate. It was impossible to predict the reaction between soil, poison and crop without actual experiment.The growth of flax was greatly impeded on a manganese‐deficient fen soil, and the molybdenum toxicity was masked in consequence. When the deficiency was corrected the poisonous effect of molybdenum on this soil was very marked, even with the lower dressing.The composting of loam with peat usually, but not invariably, resulted in a reduction of the toxicity of molybdenum. The different results obtained with several crops on a variety of soils still yield no definite clue to the factors which determine the relative toxicity of molybdenum to plant growth and such points as soil acidity, response to climatic conditions and nutritive deficiencies are among those which need further investigation.
Studies on the Relationship Between Earthworms and Soil Fertility
Authors: Guild By W. J. McL. 
Published: February 2008

Observations on earthworm populations in the Carse of Stirling indicate that there are definite differences according to soil type both in total population numbers and in the relative numbers of each species present. The light and medium loams appear to carry higher total populations than the heavier clay types or the more open gravelly sand or alluvial types. Within and between the respective soil‐type populations, species numbers are variable, but the actual numbers present on a soil type do not necessarily indicate the relative importance of each species. In all cases Allolobophora caliginosa is the dominant species, being more numerous on the light loam than elsewhere. A. longa is subdominant and forms a substantial percentage on the medium loam and clay. On the light loam A. longa is high in number, but forms a smaller percentage of the total population because of the abundance of A. caliginosa. A. longa is also of reduced importance on the open soils—gravelly sand and alluvium. This species does not differ very much from Lumbricus rubellus and L. terrestris, as a percentage of the population on these two later soils and the light loam. The percentages of these two species are similar within populations, though much lower on the clay than on the other soils, and the total Lumbricus population number is highest on the light loam and lowest on the clay. There is a fair similarity between the two populations on the two open‐textured soils, in both numbers and percentages.Areas of acid, natural pastures contain earthworm populations low in number and species variety. Some of the species typical of these areas are small active species, e.g. Dendrobaena rubida, D. octaedra and Bimastus eiseni, which are not found in well‐established field populations. When agricultural treatment improves an area the acid‐pasture species eventually decrease in relative number and importance as the species normally associated with good pasture land become established and build up their populations.
The Formation of Insecticidal Films on Building Materials
Authors: Hewlett P. S. 
Published: February 2008

The success of size and gelatin as pretreatments was not confined to films of pyrethrins in oil. Pretreatment of cement with 10 % w/v size and 5 % w/v gelatin greatly prolonged the toxic life of films formed by other insecticides in oil solution.The effects of adding different substances to size and gelatin solutions as pretreatments were investigated. 5 % w/v size or gelatin solutions containing suspended lime or distemper powder were, with the exception of gelatin containing distemper, less effective pretreatments than size or gelatin solutions alone. Magnesium silicofluoride, benzoic acid and salicylic acid, at concentrations up to 0.5 % w/v, appear suitable as preservatives for 5 % w/v gelatin. These three substances are, however, unsuitable for inclusion in size solutions, as they cause precipitates to form. Glycerin or turkey‐red oil at concentrations of 0.5 % v/v, appear suitable as plasticizers for inclusion in both 5 % w/v size and 5 % w/v gelatin solutions.