bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECTS OF STREPTOMYCIN AND TERRAMYCIN, SINGLY AND IN COMBINATION, ON THE LEAF BLIGHT DISEASE OF MAIZE CAUSED BY BACTERIUM CAROTOVORUUM F. ZEAE SABET
Authors: SABET K. A. 
Published: February 2008

The growth in vitro of Bacterium carotovorum f. zeae Sabet, the cause of the root and stalk rot and leaf blight disease of maize, was inhibited by dihydrostreptiomycin sulphate and by Terramycin (oxytetracycline). Joint applications showed a synergistic action, and the bacterium was most susceptible to a 1:1 mixture of the two antibiotics. This mixture is effective in checking the development of resistant strains which develop rapidly after treatment with streptomycin alone.Roots of maize seedlings in water cultures, and leaves of older plants readily absorb both antibiotics. High water content of soil favoured absorption; sunlight had no effect. Absorption from leaf applications first increased with higher concentration and frequency of spraying, but after eight daily applications of streptomycin toxic symptoms appeared and there was evidence that the antibiotic was inactivated.Antibiotic treatment of maize leaves shortly before inoculation with B. carotovorum f. zeae reduced the incidence and severity of leaf blight. The therapeutic effect extends at first both downward and upward but later only upward. Treatment of the leaves did not induce resistance to infection in the stems and roots.
GROWTH AND NUTRITION OF TIMOTHY (PHLEUM PRATENSE)
Authors: LANGER R. H. M. 
Published: February 2008

Individual tillers of timothy (Phleum pratense) growing from seed in pots were labelled and their life history studied over a period of two years.The leaf axil position of the first‐produced tiller depended on its time of origin. A minimum of five leaves on the parent axis was necessary before its appearance, and no tiller emerged from the axil of any of the three terminal leaves of a shoot.Ear‐bearing capacity was high in early‐formed tillers, but decreased progressively with later dates of origin despite favourable day length; all tillers arising after the end of July failed to produce inflorescences. A greater proportion of tillers on the main stem formed ears than secondary tillers of the same age. Time of ear emergence varied only within a few days for all tillers arising before the end of April. The number of leaves formed up to ear emergence varied linearly with date of origin and tiller position, the lowest recorded number being six.Dry weight and length of inflorescence as well as seed yield per tiller varied linearly with the date of origin of tillers. Primary tillers generally had longer and heavier inflorescences and produced more seed per stem than secondary tillers of the same age.Tillers arising at all times were found to have a limited span of life, not normally exceeding just over a year. The mean age of ear‐bearing tillers varied linearly with their date of origin. Death‐rates of all tillers generally increased with their age. Relative death‐rates of fertile and vegetative tillers rose rapidly in the autumn but decreased during winter and early spring. Vegetative tillers which elongated in the year of formation survived for a shorter time than equivalent tillers in which stem elongation was delayed until the following year.The perennial habit of grasses is discussed in relation to tiller survival. Successive new formation and death of tillers keep the plant in a condition of continuous dynamic change.
THE EFFECT OF DATE OF PLANTING AND OF HARVESTING POTATOES ON VIRUS INFECTION AND ON YIELD
Authors: BROADBENT L. , HEATHCOTE G. D. , McDERMOTT N. , TAYLOR C. E. 
Published: February 2008

Experiments during 1953–6 tested the effects of early and late planting of King Edward potatoes on the incidence of virus diseases in the tubers and the suitability of the tubers for use as seed. Plantings were made each month from April to August and tubers were lifted after 12 weeks' growth or after the haulms had died.Aphids began to colonize the early‐planted plots about mid‐June each year, but their multiplication and flying were influenced by weather and varied greatly from year to year. The May‐planted plots usually carried the most aphids. Winged aphids visited the July and August plantings, but few bred extensively though the plants were young and green. The incidence of virus diseases in the tubers was not related to the maximum aphid populations on the plants. Most of the plants that became infected became so by aphids flying from diseased potato plants in the same field, and the late‐planted plots did not escape. Crops planted in mid‐April and harvested in early July produced the fewest virus‐infected tubers.Planting in April and lifting at the end of the season produced most ware‐sized tubers. In plots lifted after 12 weeks, May or June planting produced more ware than April planting. Few or no ware‐sized tubers were produced from July or August planting, and yields of seed‐sized tubers also were poor. Most seed‐sized tubers were produced by the late‐lifted May or June plantings. The date of lifting had little effect on the total number of tubers, but the date of planting affected it greatly. Most tubers were usually set by the May plantings and the number decreased with successive plantings.Early‐lifted immature tubers were easily damaged and were difficult to store. Blighted tubers occurred only in the July or August plantings, which also suffered most from slug and cutworm damage.Infection with leaf‐roll virus reduced yield by about three‐quarters, whether the seed had been lifted early or late the previous year. Healthy or virus‐infected mature seed produced a bigger crop the next year than immature seed obtained by early lifting or late planting.Late‐planted tubers produced more main stems than those planted at the normal time, but growth of axillary shoots was reduced and total leaf area remained small, even when the plants were not attacked by blight.
FACTORS AFFECTING THE PATHOGENICITY OF BACTERIA TO POTATO TUBERS. II
Authors: MURANT A. F. , WOOD R. K. S. 
Published: February 2008

Potato tubers in the laboratory were rotted by an isolate of Erwinia aroideae, but isolates of Pseudomonas sp. (probably P. marginalis), Flavobacterium sp., and Pseudomonas syringae were only weakly pathogenic. Differences in the amount of rotting of tubers of different varieties were not related to differences in the rates of browning of outer cells, of suberin development or of phellogen formation.Growth‐regulating substances which affected the rate at which healing occurred at the wound surface did not affect rotting when they were added to inocula of Erwinia aroideae or Pseudomonas sp.Increasing the water content of tuber tissue by soaking had little effect on the rotting caused by Erwinia aroideae, but greatly increased rotting by the other organisms. The rotting by each of the four organisms was increased further when the tissue was injected with water. Cell‐free filtrates from cultures of each of the four bacteria rotted soaked and injected tissue in much the same way as did the bacteria, but in normal tissue filtrates from cultures of the non‐pathogenic bacteria caused more rotting than did E. aroideae preparations, although in maceration tests with disks cut from potato tubers they had about the same activity.The non‐pathogenic bacteria caused active rots when the outer surfaces of tubers were sealed with Vaseline; this treatment also increased rotting by E. aroideae. Only E. aroideae grew to any extent anaerobically in liquid culture. E. aroideae and Pseudomonas sp. rotted Vaseline‐sealed tubers more than unsealed tubers kept in a desiccator over alkaline pyrogallol.Rotting of tubers by Erwinia aroideae, but not by Pseudomonas sp., was increased when the tubers were kept in a moisture‐saturated atmosphere.The two species of Pseudomonas, but not the other two bacteria, caused appreciable rotting at 5°C.Allowing surfaces of inoculation cavities to heal for 1–4 days before inoculation reduced the number and size of active rots caused by Erwinia aroideae, but did not prevent attack. Delaying inoculation for 1 day did not affect rotting by cell‐free filtrates from cultures of this organism and of Pseudomonas sp.The surface layers of tubers, peeled and exposed to the air for 2 days, did not contain readily extractable materials toxic to Erwinia aroideae or Pseudomonas sp. Pseudomonas sp. could be made to attack the healed surface of sealed tubers, by keeping the surface moist for twelve hours after inoculation.The significance of these results is discussed.
AN ANALYSIS OF THE GROWTH RESPONSE OF YOUNG TOMATO PLANTS TO INFECTION BY VERTICILLIUM ALBO‐ATRUM
Authors: SELMAN I. W. , PEGG G. F. 
Published: February 2008

Infection of seedling tomatoes with Verticillium albo‐atrum checked growth but did not result immediately in leaf yellowing. Localized wilting occurred in some plants 2 weeks after the check to growth was evident. 8 weeks after inoculation, dry weights of leaf, stem and root were decreased by 72, 70, and 65% respectively.Of the growth attributes studied, leaf area was most reduced by infection and this was due to a failure of the leaves to expand rather than to a fall in the rate of leaf production. Neither water nor nitrogen appeared to be limiting factors in this respect. The water content of infected leaves was not reduced until 6 weeks after inoculation, when leaf yellowing and necrosis had also appeared. The percentage N contents of stem, root and leaf of infected plants exceeded those of the healthy controls 24 days after inoculation. N uptake was not seriously impaired until 21 days later.The photosynthetic efficiency of the green leaves of infected plants was reduced. The mean values for net assimilation rates were: Healthy 0.47 and infected 0.39 g./dm.2/week.Plants, in which two‐thirds of the root system had been killed by crushing, were placed in contact with mycelium in soil. This initial root injury did not significantly affect the growth of infected plants.The data accord with a toxin theory of damage to infected plants, but the slow development of chlorosis and wilting symptoms in the young plants suggested a greater tolerance to the toxin than is found in older plants.
THE ANALYSIS AND RECONSTRUCTION OF DIURNAL FLIGHT CURVES IN ALIENICOLAE OF APHIS FABAE SCOP.
Authors: JOHNSON C. G. , TAYLOR L. R. , HAINE E. 
Published: February 2008

Experiments, in which alate aphids were marked immediately after eclosion from the last nymphal instar and observed until they took flight, gave information which, together with the measured rate of moulting and a continuous record of temperature, has been used to construct theoretical daily curves for numbers flying from a bean crop. These curves have been matched against the observed curves for the same days.The differences between curves so constructed for a period of 17 days and the observed curves for the same period are of the same order and kind as the differences between two measured curves in different sites at the same time.The different types of daily flight curve can thus be accounted for in terms of the rate of production of alatae by moulting, the effect of temperature on the teneral (‘drying out’) period and the effect of low light intensity and temperature on take‐off behaviour.
INVESTIGATIONS ON RESISTANCE OF OATS TO STEM EELWORM, DITYLENCHUS DIPSACI KÜHN
Authors: GRIFFITHS D. J. , HOLDEN J. H. W. , JONES J. M. 
Published: February 2008

A procedure adopted for testing many varieties of oats and segregating progenies for reaction to attack by stem eelworm (Ditylenchus dipsaci Kühn) is described, and its merits and limitations discussed in relation to the breeding of resistant varieties.A study of some 250 forms of oats revealed new sources of resistance in cultivated and wild species. New sources of resistance in the cultivated species Avena sativa were found only in winter types, and in the other hexaploid species in forms belonging to A. byzantina (C) Koch, and the winter wild oat A. ludoviciana Dur.Segregate progenies in advanced generations could be selected in the field by their reaction in a single drill in the first year followed by a head‐row progeny test in the next season. Reaction was sufficiently well defined to identify the truebreeding resistant and susceptible lines.The inheritance of reaction to stem eelworm in crosses involving Grey Winter and susceptible types depended on a single factor pair with resistance dominant.
BACTERIAL CANKER OF STONE‐FRUITS III. INOCULUM CONCENTRATION AND TIME OF INOCULATION IN RELATION TO LEAF‐SCAR INFECTION OF CHERRY
Authors: CROSSE J. E. 
Published: February 2008

Leaf scars on the fruiting spurs of the cherry varieties Roundel (high resistance) and Napoleon (low resistance) were inoculated with Pseudomonas mors‐prunorum on four separate occasions in the autumn, using, on each occasion, the same range of five different inoculum concentrations. The results, recorded the following year, showed that the percentage diseased spurs (disease incidence) and the severity of the disease symptoms (disease severity) both increased with inoculum concentration.The median threshold concentration of inoculum (T. C. 50), defined as the concentration necessary to give 50% diseased spurs, varied with time of inoculation, but on all occasions was considerably higher for Roundel than for Napoleon.In another experiment the leaf scars at the nodes of the current year's growth, inoculated at weekly intervals throughout the autumn, were found to be susceptible from the beginning of September to the latter part of October. During this period disease incidence varied considerably with time of inoculation. There was evidence that this variation was related to two factors which influenced the numbers of bacteria penetrating into leaf scars, namely, (1) the rate of evaporation of the infection drop, and (2) the rate of suction of inoculum into the vessels of the leaf traces.The experiments provided evidence of a long infection period beginning early in the autumn. It is suggested, therefore, that the timing of bactericidal sprays in the autumn be advanced and that the present concept of ‘protective’ sprays in disease control be replaced by one based on the eradication of external sources of inoculum.
THE TOXICITY OF DDT IN ABRASIVE AND NON‐ABRASIVE DUSTS TO THE RICE WEEVIL, CALANDRA ORYZAE L. (COLEOPT., CURCULIONIDAE)*
Authors: HARLOW P. ANNE 
Published: February 2008

The toxicity of DDT in different dust carriers to the rice weevil, Calandra oryzae, was determined under standardized conditions, using deposits large enough to ensure that the insects accumulated an excess of dust.Some evidence was obtained that DDT is transported to the cuticle as a vapour.At high humidity, the toxicity of DDT was not markedly affected by any carrier except charcoal which reduced the toxicity, probably by absorption of DDT vapour. Small differences in toxicity of DDT caused by other carriers could not be accounted for by differences in their average particle size, bulk density, amount adhering to insect, surface area, abrasiveness to insects or effect on behaviour of the insect.At low humidity, abrasive dusts killed the insects by desiccation, thus adding to the toxic effect of DDT. Abrasion of the insect's cuticle did not affect the apparent rate of penetration of DDT at 50% R. H. or at 95% R. H.Starved insects were more susceptible to DDT poisoning, and in some experiments abrasive carriers increased the toxicity of DDT by preventing the insects from feeding.
THE CUMULATIVE TOXICITY OF γ‐BHC AND DIAZINON APPLIED IN SMALL DOSES TO LOCUSTS
Authors: MACCUAIG R. D. 
Published: February 2008

The toxicity of γ‐BHC and Diazinon when applied over a period of time to adults of the desert locust, Schistocerca gregaria (Forsk.), has been determined. The insecticides were applied in oil solutions, by means of the micro‐drop syringe, to the ventral surface of the abdomen.When doses were applied in two equal portions with a 72 hr. interval, or in four equal portions at 24 hr. intervals, no significant decrease in toxicity, in comparison with a single dose, could be detected with either insecticide. It is concluded, therefore, that if similar effects occur when locusts are sprayed with these insecticides in the field, successive spraying will be fully cumulative over a period of 72 hr. Previous work using DNC has shown that doses applied over 4 days were only half as effective as equivalent single doses and that continued dosing after 4 days brought about very little increase in kill.The sexes were similar in resistance to γ‐BHC when the doses were measured in μg./g., but females were considerably more resistant to Diazinon than males.
THE COMPARISON OF YELLOW CYLINDRICAL, FLAT AND WATER TRAPS, AND OF JOHNSON SUCTION TRAPS, FOR SAMPLING APHIDS
Authors: HEATHCOTE G. D. 
Published: February 2008

Different traps were compared to find the type most suitable for studying aphid vectors of plant viruses quantitatively.A Moericke water trap caught more aphids than a flat sticky trap of equal area. A flat sticky trap (930 sq. cm.) caught half as many aphids as a cylindrical trap (945 sq. cm.), which caught about one‐third as many as a water trap (1200 sq. cm.) or a Johnson suction trap (9 in. fan) when operated at between 2 and 3 ft. over bare soil.Yellow traps caught proportionally more Tuberculoides annulatus, and in summer more Capitophorus species than a suction trap, but significantly fewer Anoecia corni, Sitobium spp. and Pemphigus bursarius. Traps with a level surface caught proportionally more Brevicoryne brassicae, Aphis fabae and Myzus persicae, but fewer Anoecia corni and Drepanosiphum plantanoides than vertical cylindical traps. Attraction by colour influences the catch on horizontal traps more than on cylindrical traps because there is less impaction by the wind.Only suction traps indicate the number of aphids per unit volume of air and are non‐selective, but they are expensive and require an electric power supply. Water traps effectively catch those aphids that are attracted to yellow, but they require frequent attention. Sticky traps catch fewer aphids than either suction or water traps, but they can be left unattended for about 2 weeks. Flat sticky traps catch aphids likely to land on a crop, and cylindrical traps show when aphids are in the air, but not if those aphids are able or wanting to land. For routine work cylindrical sticky traps have other advantages; they are cheap and do not require skilled handling, and their catches of alate Myzus persicae have been correlated with the spread of some plant viruses.
REVIEWS
Authors: CRAGG J. B. 
Published: February 2008

Book reviewed in this article: The Rabbit. By HARRY V. THOMPSON and ALASTAIR N. WORDEN. The Distribution and Abundance of Animals. By H. F. ANDREWARTHA and L. C. BIRCH. Biology of the Laboratory Mouse. Edited by GEORGE D. SNELL. Features of Evolution in the Flowering Plants. By RONALD GOOD. Tobacco Diseases with Special Reference to Africa. By J. C. F. HOPKINS. Bibliographie der Pflanzenschutz‐Literatur 1950. Edited by J. BÄRNER. Principles of Fungicidal Action. By JAMES G. HORSFALL. Progress in Nuclear Energy. Series VI. Biological Sciences. Vol. 1. Edited by J. C. BUGHER, J. COURSAGET and J. F. LOUTIT. Bacterial Diseases of Plants. By C. STAPP. The Biology of the Heteroptera. By N. C. E. MILLER. Man's Role in Changing the Face of the Earth. Edited by W. L. THOMAS.
FIELD EXPERIMENTS ON POTATO SKIN‐SPOT DISEASE CAUSED BY OOSPORA PUSTULANS OWEN & WAKEF
Authors: BOYD A. E. W. 
Published: February 2008

In experiments on skin‐spot disease of potatoes, caused by Oospora pustulans Owen & Wakef., Kerr's Pink proved the most susceptible of twenty‐four commercial varieties; Arran Banner, Majestic and King Edward were highly susceptible; Home Guard and Golden Wonder were highly resistant.Thymol and tetrachlornitrobenzene, applied as dusts to pits of potatoes at lifting, did not give satisfactory control of the disease. The efficacy of an organo‐mercury dip treatment at lifting time was confirmed.The incidence of the disease was considerably decreased by storing tubers in boxes instead of in pits, by digging the crop about a month before normal harvest, or by cutting the haulms at this time and digging at the normal time.Ware tubers showed a significantly higher infection than seed tubers of the same crop, indicating that susceptibility of tubers increases towards maturity.The difference in eye infection between varieties may not be related to that of general superficial infection. It is suggested that, in future, the assessment of varietal susceptibility should be based upon the degree of eye infection, which is in practice the measure of the economic importance of the disease. Tubers having pustules at or near all the eyes gave markedly reduced sprout emergence and plant stand.
VIRUSES CAUSING ROSETTE AND OTHER DISEASES IN GROUNDNUTS
Authors: STOREY H. H. , RYLAND AUDRIE K. 
Published: February 2008

From plants with a form of groundnut rosette disease, characterized by discrete areas of green and chlorotic tissue on the leaflets and here designated ‘mosaic rosette’, a virus was separated that produced only a mild mottle or sometimes a mottle with rare chlorotic flecks. It was separated by leaf grafts, by mechanical inoculation and by Aphis craccivora.Plants inoculated simultaneously with the mottle virus and normal rosette virus usually developed the mosaic‐rosette symptoms. When the mottle virus was introduced 14–35 days before the rosette virus, the plants failed to develop the severe chlorosis of rosette; the mottle virus thus protected the plant from rosette, and this was true whether the rosette virus was inoculated by aphids or by grafting.Plants showing two other forms of mild mottle were collected in the field; viruses from them were readily transmitted by grafting or by mechanical inoculation, but not by A. craccivara. In plant‐protection tests with one of these, it failed to protect plants from developing chlorotic symptoms when later inoculated with the rosette virus, although a form of interaction was evident and the doubly‐infected plant was less severely chlorotic and less stunted than one infected with the rosette virus alone.
A TECHNIQUE FOR THE BIOLOGICAL EVALUATION OF INSECTICIDAL AEROSOLS
Authors: GOODWIN‐BAILEY K. F. , HOLBORN J. M. , DAVIES M. 
Published: February 2008

The development of a technique for testing insecticidal aerosols produced from pressure dispensers is described. The method of rearing the test insect, Musca domestica L., is given in detail.Both free‐flying and caged flies were exposed in a room of 1194 cu. ft. Six insecticidal solutions were selected for test.The biological efficiency of each aerosol was judged on the time required to paralyse 50% of the test insects (KD 500) and on the percentage kill obtained in 24 hr. Statistical analysis of some of the estimated figures for KD 500 showed a standard error of 4–5% of the mean.The effects of temperature, of distribution and of dosage of the aerosol on the results were investigated.Free‐flying flies were preferred, mainly because of better replication of results.The technique adopted is described as a specification and suggestions are made for its practical application.