bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES ON A CANKER DISEASE OF CYPRESSES IN EAST AFRICA, CAUSED BY MONOCHAETIA UNICORNIS (COOKE & ELLIS) SACC
Authors: JONES D. RUDD 
Published: February 2008

Strains A and B of Monochaetia unicornis produced cankers following inoculation into Cupressus arizonica, C. benthami, C. lusitanica, C. macrocarpa, C. sempervirens, C. torulosa, Cupressocyparis leylandii, Chamaecyparis lawsoniana, Juniperus procera and Thuja orientalis. Strain D was parasitic only on Juniperus procera. Monochaetta unicornis grew well on agar media prepared from bark and sapwood extracts of Cupressus species and Juniperus procera but only slowly on Podocarpus gracilior bark agar.Test trees of five species of Cupressus, grown commercially in East Africa, were alternated with artificially inoculated trees of C. macrocarpa in field plots. The subsequent development of natural infections in trees of the test species confirmed field observations that C. macrocarpa was the most susceptible.Plots (each of 340 trees) of the five species were inoculated with mycelium. In 4 months, the most extensive cankers had developed in C. benthami, and this species also had the largest number of active cankers and the most rapid height growth. When examined again 4 months later, C. macrocarpa had the most extensive cankers and 60% of them were still active as compared with 20% in C. lusitanica and 6% in C. benthami. Delayed inoculation following wounding confirmed these results and in the dry season the number of successful infections was always highest in C. macrocarpa.Periderm was formed in the bark and sapwood of the Cupressus species in response to wounding, the process being slower in C. macrocarpa and C. torulosa than in other species. Secondary growth was most rapid in C. macrocarpa. It is suggested that rapid height growth coupled with rapid secondary growth in this host favour the growth of the pathogen rather than the host reaction, and C. macrocarpa is consequently very susceptible. During the rains the fungus develops as rapidly in species having a slower secondary growth rate but in the ensuing dry season such infections dry out and the cankers are occluded.
EFFECT OF CERTAIN CHLORONITROBENZENES ON GERMINATION, GROWTH AND SPORULATION OF SOME FUNGI
Authors: REAVILL MARY J. 
Published: February 2008

When grown in an atmosphere saturated with tetrachloronitrobenzene (TCNB) vapour, Botrytis cinerea showed retarded germination and colony growth and its sporulation was completely suppressed. Retardation of growth was greater on dilute or acidified media and at lower temperatures.Similar effects were shown by Bhizoctonia solani, Phytophthora parasitica, Mucor hiemalis and Trichoderma viride but none of these was as sensitive as Botrytis cinerea, especially as regards linear growth. Of two strains of Fusarium caeruleum, one was much more sensitive than the other, both in linear growth and sporulation. Pythium deBaryanum was unaffected in its growth rate.TCNB, as a growth repressant, is fungistatic without being fungicidal.With fungi which are sensitive, tetrachloronitrobenzene was more effective than the penta‐derivative, except for Trichoderma viride where the converse applied.
THE FUNGICIDAL CONTROL OF LETTUCE DOWNY MILDEW, CAUSED BY BREMIA LACTUCAE
Authors: POWLESLAND RUTH , BROWN W. 
Published: February 2008

Protection experiments carried out in the greenhouse showed that preparations of thiram, zineb, ferbam and ziram were superior to cuprous oxide and copper oxy‐chloride preparations, in controlling downy mildew of lettuce and in lack of phytotoxic effect.Tests made in winter on lettuce seedlings grown in Dutch lights, showed that Bremia lactucae attack reduced the stand of seedlings, diminished their size and weight, and, when the crop was planted out into the open ground, reduced survival in the field and slightly delayed the date of reaching maturity. The best overall results in protecting foliage against downy mildew were given by thiram and zineb preparations.
THE ABSORPTION, TRANSLOCATION AND BREAKDOWN OF SCHRADAN APPLIED TO LEAVES, USING 32P‐LABELLED MATERIAL
Authors: BENNETT S. H. , THOMAS W. D. E. 
Published: February 2008

When 32P‐labelled schradan was sprayed on the leaves of apple stocks and seedlings, broad and runner beans, Coleus and chrysanthemums, some was absorbed, some evaporated and the rest remained for a considerable time on the leaf surface as a residue removable by aqueous leaching. Absorbed material is defined as that present on or in the plant and not removable by aqueous leaching at the time of harvest.Evaporation losses even from glass slides were lower than theoretical expectation, from leaves they were much less.It is possible that some breakdown of the schradan occurs within the cuticular layer. Comparisons of the absorption rates of upper and lower surfaces of leaves support the theory that absorption proceeds through the cuticle in preference to vapour phase entry through the stomata.Temperature and illumination have important effects on absorption.Young leaves have been shown to be generally more absorptive than the older leaves. Comparisons have also been made of the absorption by different species. Such data must be accepted with caution as, although physical conditions were the same for all the species within an experiment, the physiological stage of development of the different plant species will not be strictly comparable.
EXPERIMENTS ON BLACK LEG DISEASE OF SUGAR‐BEET SEEDLINGS
Authors: GATES L. F. , HULL R. 
Published: February 2008

Phoma betae was usually the predominant pathogen attacking sugar‐beet seedlings in the field in eastern England, but Pythium spp. sometimes predominated when the seedlings were very young. Fusarium spp. were associated with acid soil conditions. Rhizoctonia solani only occasionally caused severe losses.Black leg, caused chiefly by Phoma betae, was most prevalent at low soil temperatures when, in stands from untreated seed, up to 45 % of the seedlings were attacked. Disease decreased by 0·8 to 2·4 diseased seedlings per 100 in stands from untreated seed per 1° F. rise in soil temperature. Seed treated with Panogen,* thiram and ethyl mercury phosphate regularly gave better stands in small‐scale trials than seed treated with Ceresan or Agrosan. In large‐scale experiments average increase in seedling emergence following treatment with Panogen, thiram and Agrosan varied in different years between + 6·4 and + 19·2 %. Average response to BHC soil dressing was + 4·2 and + 8·6 %. Response to seed dressings increased as the time taken for emergence increased and as percentage emergence decreased; when emergence was 50 % of the possible, dressing gave on average 20 % more seedlings. Response to dressing increased as soil became more acid or alkaline than the optimum for beet, and was lower on heavy soils and on soils dressed with farmyard manure.Maximum emergence varied from year to year between 2100 and 2700 seedlings per oz. seed; minimum between 690 and 1050. Emergence of both treated and untreated seed varied greatly and was related to time taken for emergence, suggesting that effects of soil moisture, temperature or texture are important. Emergence WM not correlated with pH, but when the pH was below 6·5 or above 8·7 it was not more than 75 % of that at pH 7·0–7·4. In 2 out of 3 years emergence was increased by 32 and 84 seedlings/oz. seed by each extra cwt. per acre of inorganic fertilizer (N, P, K). Seed rate, cultural operations and drill type had no consistent effect.A 1 % increase in seedling stand increased the final plant population on average by 0·2%.
TOXIC EFFECTS OF HEAVY METALS ON CROP PLANTS GROWN IN SOIL CULTURE
Authors: FORSTERM W. A. 
Published: February 2008

A number of pot experiments were made on various crops, to study the effects on the chemical composition of the plants of treating the soil with cobalt, copper or nickel sulphates, or with the cupric or ferric salts of ethylenediamine‐tetraacetic acid (EDTA).The tops of copper sulphate‐treated plants usually contained higher concentrations of copper, manganese, calcium and magnesium and lower concentrations of potassium and phosphorus, than those of control plants.The most marked effect of cobalt on oat was to increase the concentration of Ca+Mg in the tops; nickel had a profound effect on the composition of barley tops.Total iron concentration was reduced in oat by cobalt and copper, and in barley by copper and nickel application. Symptoms of iron deficiency appeared only in the oat plants, their incidence being correlated with the reduction in iron concentration in the tops.The ferric salt of EDTA tended to reduce the incidence of iron deficiency symptoms produced in oat by copper sulphate, but also gave rise to distinct toxic effects. Plants given the cupric salt of EDTA contained unusually large amounts of iron.
THE APPLIED BIOLOGIST, THE CHILD, AND SOCIETY
Authors: KRAMER L.M.J. 
Published: February 2008

Consideration of the characteristics of past and current applied biology reveals its fundamentally ecological nature, and also indicates the potent influence of the applied biologist upon society. It is urged that in order to impress influence upon pupils biological education should be based mainly upon field studies, rather than upon predominantly evolutionary, morphological and physiological studies. The nature of past and existing school biology strongly reinforces the abovel conclusion.The results of attempts to find and evaluate evidence of the social influences of past and present biological education are presented, both in relation to the whole population, as well as to particular aspects, like food poisoning, the press, and the education of Civil Servants and Members of Parliment.The potentialities of a Sixth Form biology resting chiefly upon field study are discussed not only as a means of developing an outlook valuable to‐day, but also of treating suitably the pre‐university education of future applied biologists.
THE SEASONAL RESPONSE OF THE POTATO‐ROOT EELWORM HETERODERA ROSTOCHIENSIS WOLLEN‐WEBER: EMERGENCE OF LARVAE THROUGHOUT THE YEAR FROM CYSTS EXPOSED TO DIFFERENT TEMPERATURE CYCLES
Authors: ELLENBY C. 
Published: February 2008

Air dried cysts collected in 1945 were maintained under five different conditions. One lot was maintained at room temperature, and other lots at 23h° C. and at about 5° C; of the remaining two lots, one spent 6 months of each year at 23° C. and 6 months at 5° C, while the other was subjected to the opposite treatment. Hatching trials were carried out at 1‐ or 2‐month intervals, beginning about a year after the establishment of the regime, and were continued until 1949. Throughout, cysts were stimulated with solutions of the same sample of concentrated hatching solid.Larval emergence was high throughout in cysts from all treatments. Although there was considerable variation in larval emergence there is no evidence of any dormancy period. Significant differences in the level of emergence from cysts on the different treatments are demonstrated, the cysts stored at room temperature showing the highest levels of larval emergence. It is also shown that there are significant differences in the responses in the different hatching trials; however, there is no suggestion that these are of a seasonal nature.Other experiments suggest that many of the eggs in apparently mature cysts do not reach maturity for some months.
PARTICLE SIZE OF INSECTICIDAL SUSPENSIONS AND THEIR CONTACT TOXICITY: V. EFFECT OF PHYSICAL PROPERTIES ON TOXICITY OF COMPOUNDS IN THE DDT GROUP
Authors: McINTOSH A. H. 
Published: February 2008

With each of nine DDT analogues, two types of simple aqueous suspension were made, one containing crystals of uniform size, and the other containing colloidal particles. The toxicities of each pair of suspensions were compared by a dipping method on adult Oryzaephilus surinamensis L., kept at n° C. for 24 hr. after treatment. The colloid was always as toxic as the crystals, or more toxic. This difference in toxicity varied from one analogue to another. It was related to the physical properties of the analogue in the following way.Dipping applies poison to the insects; the amounts retained could usually be found by extraction and microanalysis. Retention of poison from colloidal suspension was about the same for each analogue; but crystals were retained either more or less efficiently than colloid, depending on their size and shape. Poorest retention was found with plate‐like crystals of about 25μ.The true ratio of toxicities for each analogue (colloid : crystals) was found by correcting the observed ratio for differences in retention; but even then there were still big differences amongst the ratios given by the different analogues.The true ratio was taken as a measure of the difference in speed of action between the two forms of poison. If the compound could kill O. surinamensis by fumigant action alone, the true ratio was very small. Otherwise, it seemed to depend on two physical properties related to the process of solution of poison in the wax of the insect cuticle. They were both measured in in vitro tests. The film made by evaporating a drop of colloidal suspension on glass is at first globular, but it may sooner or later crystallize. The film made by evaporating a drop of a suspension of crystals can be dissolved in olive oil. If the film of crystals brought about saturation of olive oil slowly and if, in addition, the deposit from colloid crystallized slowly, the true ratio was large. Unless the analogue had both of these properties, the true ratio was small. If the analogue had one or other of the properties, the true ratio could be increased either by increasing the crystal size or by decreasing the rate of crystallization.Physical properties of this sort may often affect the results of tests of insecticides, and should be taken into account when the toxicities of different compounds are compared.There seems to be no relation between lipoid‐solubility and toxicity of compounds in the DDT group. Rate of solution is probably more important.
THE SYSTEMIC PROPERTIES OF DIETHYL‐S‐z‐ (ETHYLTHIOETHYL) PHOSPHOROTHIOLATE (DEMETON‐S) WITH REFERENCE TO THE CONTAMINATION OF NECTAR
Authors: Thomas W. D. E. , JONES G. D. GLYNNE 
Published: February 2008

The fate of diethyl 5‐2‐(ethylthioethyl) phosphorothiolate (demeton‐S) in white mustard (Brassica alba), borage (Borago officinalis) and field beans (Viciafaba) has been followed over several weeks using the radioactive tracer technique. Radio‐assay of nectar samples from flowers which opened a few days after spraying showed that no unchanged demeton‐S, but that small amounts of degradation products were present. The highest value for total radioactivity found in the nectar corresponded to 2–7 p.p.m. expressed as demeton‐S.Radioassay of treated leaves and new growth after spraying confirmed that demeton‐S is rapidly con, erted in the plant into two primary degradation products extractable by chloroform. Further breakdotvn is more rapid in new growth and appreciable quantities of the two primary products believed to be biologically active are retained by the treated leaves.
THE INFLUENCE OF DISSOLVED‐OXYGEN CONCENTRATION ON THE TOXICITY OF UN‐IONIZED AMMONIA TO RAINBOW TROUT (SALMO GAIRDNERII RICHARDSON)
Authors: DOWNING KATHLEEN M. , MERKENS J. C. 
Published: February 2008

Periods of survival of rainbow trout in concentrations of un‐ionized ammonia in the range 0.86‐1.96 parts per million of nitrogen increased as the concentration of dissolved oxygen was raised from 1–5 to 8‐5 p.p.m.At each concentration of dissolved oxygen the period of survival decreased as the concentration of un‐ionized ammonia increased from 0.86 to 1.96 p.p.m.The effect of oxygen in increasing survival time was greater in the lower concentrations of un‐ionized ammonia.
THE EFFECT OF COMMERCIAL TRAPPING ON RABBIT POPULATIONS
Authors: PHILLIPS WINIFRED M. 
Published: February 2008

The effect of commercial trapping on two rabbit populations in West Wales, was investigated during 1946 to 1949. On two farms rabbits were caught alive in snares, marked and released just before trapping; the total number of rabbits marked, divided by the fraction of marked rabbits recovered in the trapped sample gave an estimate of the population before trapping started. Trapping usually removed 30–40 % of the rabbits present, a proportion compatible with a careful cropping of the population. At one farm, studied for 3 years, the population increased steadily.Breeding was intense from January to June inclusive, and from weight and age distributions it was apparent that in 1948 and 1949 considerable breeding also occurred in autumn. The sex ratio varied around a mean of about 50%.Data are given on movements, obtained from recapture records of zog marked animals. They suggest that rabbits probably forage over an area of not more than 150 yards in diameter. The records from recaptured marked animals indicate that the mean expectation of life is about 6 months.
EFFECTS OF NUTRITION AND LIGHT INTENSITY ON SYMPTOMS OF LEAF‐ROLL VIRUS INFECTION IN THE POTATO PLANT*
Authors: WILSON J. H. 
Published: February 2008

Increased nitrogen supply to potato plants infected with leaf‐roll virus greatly reduced the intensity of leaf symptoms, and caused a smaller and less consistent reduction in phloem necrosis. Application of phosphatic fertilizer initially reduced leaf symptoms, but later increased them; it increased phloem necrosis at all stages of growth. Potash slightly intensified leaf symptoms, but not phloem necrosis. Shading, which approximately halved the light intensity, reduced leaf symptoms but had no effect on phloem necrosis.The masking of leaf symptoms by nitrogen, and by phosphorus in the early stages of growth, was closely correlated with increases in relative leaf growth rate produced by these nutrients.Leaf rolling and phloem necrosis are considered to be independent symptoms not causally related, because they were differentially affected by nutrient supply and shading, and each could occur without the other.
THE PRODUCTION OF ANTIBIOTICS IN SOIL: II. PRODUCTION OF GRISEOFULVIN BY PENICILLIUM NIGRICANS
Authors: WRIGHT JOYCE M. 
Published: February 2008

A study has been made of the conditions affecting production of griseofulvin by Penicilliiim nigricans in two types of soil, an acid, sandy podsol from Wareham Heath and a garden soil. The characteristic morphogenetic response of many fungi to low concentrations of griseofulvin was made the basis of a highly specific bioassay.The essential prerequisites for production of griseofulvin in either soil were sterilization and enrichment with organic matter; no griseofulvin could be detected in autoclaved soil which had not been supplemented or in normal soil even when organically enriched. Garden soil was a better medium for growth of P. nigricans and production of griseofulvin than Wareham soil although this soil could be improved in this respect by liming.The yield of griseofulvin was decreased in soil re‐infected by other soil organisms, particularly by some which were known to produce antifungal antibiotics, e.g. Penicilliunr expansum, P. frequentons and two strains of Trichoderma viride. The antagonism shown to Penicilliunz nigricuns was not entirely a matter of antibiotic activity, as some fungi believed not to produce antifungal substances had an antagonistic effect. These were mostly fungi with a characteristically rapid growth rate, e.g. Mucor rarnmannianus and one strain of Trichoderma riride. In some cases Penicillium nigricans was itself antagonistic to other fungi irrespective of their ability to produce antibiotics or of their fast‐growing habit.The results were compared with those obtained from a previous study of the soil conditions affecting the production of gliotoxin by Trichoderma viride. A higher level of nutrient was required for the production of griseofulvin, and the effect of antagonism by other soil micro‐organisms was more important than in the production of gliotoxin by T. viride in the soil.
TRANSMISSION OF GROUNDNUT ROSETTE VIRUS
Authors: STOREY H. H. , RYLAND A. K. 
Published: February 2008

The rosette virus was transmitted to groundnut plants, if previously etiolated, bymechanical inoculation of juice with ‘Celite’ addition; but only a small proportion of the inoculations succeeded.Aphis craccivora (Koch), the known vector, transmitted the virus by feeding on germinating groundnut seeds; and from this fact we developed an experimental technique that is convenient and flexible.Different races of this species appeared to vary in inherent efficiency in transmission, and one failed ever to transmit. Within races that could transmit, all larval forms and alate and apterous adults might transmit; but alatae were sometimes significantly more efficient than apterae, and at other times the converse held. A field experiment showed that wingless forms, moving over the soil surface, might play a predominant part in secondary spread around a rosetted plant.Comparative tests with groups of I, 2, 3 and 4 infective aphids supported the hypothesis that infections by this vector are individual and independent.Single aphids, tested for 24 hr. on 10 successive days without access to an outside source of virus, might infect on any day up to the tenth. Similar results were obtained in a succession of I hr. tests on a single day. In the infected seed the virus rapidly became available to feeding aphids; previously non‐infective aphids acquired the virus by feeding on a seed during the third day from the first exposure of this seed to infective aphids.
THE RELATIONSHIP BETWEEN NICKEL‐TOXICITY SYMPTOMS AND THE ABSORPTION OF IRON AND NICKEL
Authors: CROOKE W. M. , KNIGHT A. H. 
Published: February 2008

During a 70‐day experimental period from germination to maturity, the iron content of oat plants that showed symptoms of nickel toxicity changed little, but the nickel content increased rapidly for about 30 days and then decreased slowly. Necrosis varied little with time, while chlorosis increased in severity for 40 days, then decreased until unfolding young leaves were no longer chlorotic. This change in chlorotic symptoms was correlated with the nickel‐iron ratio in the plant.Autoradiographs of leaves from plants supplied with radioactive iron showed that necrotic areas in the leaf matched areas in the autoradiograph having a very low content. Chlorotic areas were found to correspond with areas whose iron content was lower than that of healthy tissue. More iron was found in the veins than in the interveinal tissue, and its distribution was the same whether supplied as ferric citrate or in a chelated form.The concentration of iron in mature leaves from oat plants growing in a nickel toxic soil was lowest in the necrotic areas of the leaf, suggesting a migration of nutrients out of this dying tissue.
FURTHER ASPECTS OF THE RELATIONSHIP BETWEEN NICKEL TOXICITY AND IRON SUPPLY
Authors: CROOKE W. M. 
Published: February 2008

Absorption of nickel by oat plants increased with increasing pH for a fixed iron supply. Nickel uptake and toxicity symptoms (necrosis and chlorosis) were both reduced when the concentration of iron in the nutrient solution was high. Nickel‐iron ratio in the nutrient solution. For solutions with the same nickel‐iron ratio, toxicity symptoms increased with increase in the absolute amount of nickel. There was a linear relationship between the degree of necrotic symptoms and the nickel‐iron ratio in the plant.Nickel consistently reduced the iron content of roots and tops. In the absence of nickel, the iron content of the roots but not of the tops, increased with iron supply. In nickel‐toxic plants, the magnesium, calcium and phosphorus contents of the tops and the potassium, calcium and phosphorus contents of the roots were higher than in healthy plants, but the potassium content of the tops and the magnesium content of the roots were lower.Similar results were found with tomato.