bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE PHYTOTOXIC EFFECTS OF D.D.T., B.H.C., PARATHION AND TOXAPHENE ON TOBACCO
Authors: ASHBY D. G. 
Published: February 2008

No phytotoxic effect was seen following a pre‐sowing spray of tobacco seed‐beds with 27 lb./acre technical D.D.T. or after an application of the same material at 75.6 lb./acre to 3‐week‐old tobacco seedlings.A pre‐sowing application of parathion (diethyl paranitrophenyl thiophosphate) (2 % dust) at 1–8 lb. parathion per acre had no harmful effect. Used on 3‐week‐old tobacco seedlings at the excessive rate of 22.7 lb./acre it caused serious stunting and many deaths.Toxaphene (chlorinated camphene: empirical formula C10H10Cl8), applied as a 25 % wettable powder in a pre‐sowing spray at 6‐4 lb. toxaphene per acre, did not injure tobacco seedlings.No residual phytotoxic effects appeared in beds re‐sown 4 months after being treated with parathion or toxaphene at the pre‐sowing doses given above.Benzene hexachloride, applied before sowing at doses above 1.6 lb. technical B.H.C. per acre, suppressed root development in newly germinated tobacco seedlings. B.H.C. dusts used on n‐day‐old seedlings at 2–25 lb. technical B.H.C. per acre caused temporary distortion and stunting. Up to 11 lb./acre these symptoms were transitory: at 37.5 lb./acre many plants were killed and the remainder severely stunted. Resistance to these phytotoxic effects increased with age of plant, but 3‐week‐old tobacco seedlings showed considerable mortality after the application of 75.6 lb./acre of technical B.H.C.Beds re‐sown 4 months after the application of 6‐4 and 12.8 lb. respectively of technical B.H.C. per acre showed no phytotoxic effect, but, as tobacco seed is sown on the soil surface, the effect of the B.H.C. may have been merely masked, and it is not safe to assume that there was no residual effect. The actual persistence of B.H.C. in the soil was not determined.The possible mechanism of action of the B.H.C. effect is discussed.
ROGUING POTATO CROPS FOR VIRUS DISEASES
Authors: BROADBENT L. , GREGORY P. H. , TINSLEY T. W. 
Published: February 2008

Removing virus‐infected plants from plots of Majestic potatoes at Rothamsted on 2 July 1947 did not reduce the spread of leaf roll but reduced rugose mosaic (potato virus Y) to about one‐fifth of that in plots rogued on 21 July or left unrogued. Roguing Arran Pilot potatoes on 16 June or 2 July reduced leaf roll to five‐sixths of that in unrogued plots; roguing on 16 June reduced rugose mosaic to about half that in plots rogued on 2 July, and about a quarter of that in unrogued plots. Lifting Arran Pilot potatoes in mid‐August reduced virus diseases to about two‐thirds.Roguing flattened the gradient (decrease in percentage plants diseased with increasing distance from the source of infection) with rugose mosaic, but had little effect with leaf roll. Evidently any plants prevented by roguing from contracting virus Y were near the initially infected plants.In 1948, Majestic and King Edward potatoes at three places were rogued during 22–24 June and tubers were dug during 28–30 July and again at the end of the season. Leaf roll spread more in Majestic than in King Edward, and rugose mosaic spread more in King Edward. Roguing reduced the spread of both by about one‐fifth at Rothamsted, but had no effect at Sutton Bonington. At Bretton, in the Derbyshire hills, roguing had no effect on leaf roll, but prevented the spread of rugose mosaic.The small benefit occasionally achieved by roguing in the ware‐growing districts of England does not make the practice economically worth while.
THE COMPETITION BETWEEN BARLEY AND CERTAIN WEEDS UNDER CONTROLLED CONDITIONS
Authors: MANN HAROLD H. , BARNES T. W. 
Published: February 2008

Chickweed (Stellaria media) is one of the commonest annual weeds on almost all soils, and forms 20–30 % of the weed herbage on the lower greensand soils of Woburn, Beds. It occurs in all crops in this area except on very acid soils.When barley and chickweed are planted together, with abundance of water and nutrients for both, it is found that increasing the density of planting of the barley reduces the loss due to chickweed competition, but even with very close‐planted barley, the loss caused by the weed amounts to nearly two‐thirds of the total fresh weight and to four‐fifths of the grain yields. This is much greater than with the two annual weeds previously studied (spurrey and mayweed). In a sparse crop of barley, increase in chickweed growth may reduce the barley to less than 10 % of its growth without the weed, while the chickweed itself is relatively little affected by the presence of the barley.There is no evidence of any specific effect of the roots of the one plant on the other; they intertwine without any sign of attraction or repulsion between them.Comparisons are made with other annual weeds previously studied, and it is suggested that the method adopted furnishes a means of assessing the relative effectiveness of these weeds in competing with barley.
THE CONTROL OF DISEASES OF LETTUCE BY THE USE OF ANTAGONISTIC ORGANISMS I. THE CONTROL OF BOTRYTIS CINEREA PERS.
Authors: WOOD R. K. S. 
Published: February 2008

The antagonism of a number of bacteria, actinomycetes and fungi to Botrytis cinerea in pure culture on lettuce extract agar has been investigated. A considerable number were antagonistic at 25° C., a few showed antagonism at 15° C. and a limited number grew and were active at 5° C.Certain of these organisms were able to control rot of detached lettuce leaves when inoculated before or simultaneously with B. cinerea. The latter is unable to penetrate areas of dead tissue colonized by selected antagonists.Control of rot was also obtained when leaves of growing plants were similarly inoculated.Substantial control of disease occurred when young potted plants in frames were sprayed with suspensions of selected antagonists in 1.0 % glucose solution.The practicability of this method of control is discussed.
THE CONTROL OF DISEASES OF LETTUCE BY THE USE OF ANTAGONISTIC ORGANISMS II. THE CONTROL OF RHIZOCTONIA SOLANI KUHN.
Authors: WOOD R. K. S. 
Published: February 2008

The antagonism of a number of bacteria, actinomycetes and fungi in pure culture on soil extract agar has been investigated. A considerable number of each of the three groups were highly antagonistic at 25° C., fewer were active at 15° C. and only a very limited number were effective at 5° C.In greenhouse experiments damping‐off of lettuce seedlings was substantially controlled by selected antagonists in sterile sand, soil or in sand/soil mixtures. Under similar conditions in unsterile soil, forms highly antagonistic in pure culture were generally ineffective in controlling disease. In one experiment control of disease in natural soil was obtained by the use of soil amendments, the effect being enhanced by the inoculation of one of these amendments with suspensions of antagonists.Attempts to control disease in the field by the use of soil amendments are described. In one year a substantial increase in the stand of healthy seedlings was obtained with certain treatments.
STUDIES ON SYSTEMIC FUNGICIDES. I. FUNGICIDAL PROPERTIES OF THE ARYLOXYALKYLCARBOXYLIC ACIDS
Authors: CROWDY S. H. , WAIN R. L. 
Published: February 2008

A method is described for assessing the systemic activity of compounds in checking the infection of broad bean (Vicia faba) by the fungi Botrytis cinerea or B. fabae. Treatment consisted in allowing the roots of young seedlings to stand in a solution containing 10 p.p.m. of the chemical for 2–3 weeks. The plants, together with controls, were then inoculated and when symptoms had had time to develop, the degree of chocolate spot infection was assessed. Several methods of disease assessment were examined and are critically discussed.Certain phenoxyalkylcarboxylic acids tested by this method consistently gave a reduction in the mean size of fungus lesions on the bean leaves, clearly indicating systemic fungicidal action. The most promising substances were 2:4:6‐trichlorophenoxyacetic, pentachlorophenoxyacetic and pentachlorophenoxyisobutyric acids. Further experiments with these compounds involving soil treatment, stem injection and spray application are described, and in most cases systemic fungicidal activity was clearly demonstrated. Certain compounds caused visible damage to the plants or resulted in a reduction in growth.The results presented indicate that phenoxy acids can be fairly readily translocated in bean plants and that they tend to accumulate in actively growing tissues. It is considered unlikely, however, that they persist for long periods in plant tissue.In the soil, the compounds appeared to remain effective for a considerable time, particularly the less soluble pentachloro acids, suggesting that soil application might provide a safe and useful method of treatment.
THE SUBEPIDERMAL FUNGI OF CEREAL GRAINS II. THE NATURE, IDENTITY AND ORIGIN OF THE MYCELIUM IN WHEAT
Authors: HYDE M. B. , GALLEYMORE H. B. 
Published: February 2008

An internal fungal mycelium between the epidermis and cross‐layer cells in normal wheat grains is shown to consist of extracellular septate hyphae forming a network on the inner surface of the epidermis, whose cells are occasionally penetrated. The mycelium, which is first observed at a comparatively late stage of maturation of the grain, usually remains as a loose network, although sclerotia and plate‐like structures suggestive of drought forms are occasionally present. These appearances support the view, derived from comparison of the drying rates of grain under various climatic conditions, that the spread of the subepidermal mycelium is finally restricted by desiccation beneath the epidermis during the drying out of the ripening grain.Cultures from surface‐sterilized grains of Bersée wheat have shown that the most common subepidermal fungus is Alternaria tenuis (in 64.4% of the grains). Bacteria (28.8%), Mycogone sp. (?) (7.7%), Cladosporium herbarum (5.8%), Pullularia pullulans (4.8%), Fusarium sp. (1.9%), Botrytis cinerea (1.9%) and Stemphylium botryosum (0.9%) were also isolated.The subepidermal mycelium apparently arises either from systemic infection of the wheat plant or from fungal spores and hyphae present on the outside of the developing grains and among the dead floral parts.
SOME PROPERTIES OF FOUR STRAINS OF CUCUMBER MOSAIC VIRUS
Authors: BHARGAVA K. S. 
Published: February 2008

Different strains of cucumber mosaic virus differ in their host range, symptoms caused, virulence towards different plants, transmissibility by aphids, dilution end‐point and thermal inactivation point.There are seasonal variations in the susceptibility of some host species; French bean is apparently immune during the summer but during the winter produces countable local lesions suitable for quantitative assays.Different host species differ in the ease with which cucumber mosaic virus is transmitted to and from them; systemic infection in beet rarely occurs unless the virus is introduced into young tissues. Inhibitors of infectivity in sap of sugar beet and Phytolacca sp. make mechanical transmission from these to other hosts difficult; the inhibitors interfere less with the infection of hosts in which they occur than with the infection of tobacco.Cucumber mosaic virus has a low temperature coefficient of thermal inactivation and much infectivity is destroyed by heating at temperatures below the thermal inactivation point. Myzus persicae (Sulz.) is a more efficient vector than M. ornatus Laing which is more efficient than Macrosiphum euphorbiae (Thomas); although individual aphids can cause more than one infection, most cease to be infective in feeding periods of from one to five minutes.
EXPERIMENTS ON THE COLONIZATION OF POTATO PLANTS BY APTEROUS AND BY ALATE APHIDS IN RELATION TO THE SPREAD OF VIRUS DISEASES
Authors: BROADBENT L. , TINSLEY T. W. 
Published: February 2008

Batches of potato plants in pots were placed in the field for limited periods among plants infected with potato virus Y and leaf roll virus. Some of the potted plants were surrounded by sticky boards which prevented apterous aphids from reaching them. Almost as many plants within the boards as without became infected, indicating that most of the spread of virus was by winged aphids.Apterae were probably responsible for spreading the viruses throughout a hill after one or more stems were infected. They may carry infection to neighbouring plants, but most of these will have been infected already by alatae.The number of plants contracting infection was unaffected by watering.
THE EFFECT OF MANURES ON THE BOLTING OF THE BEET PLANT
Authors: MANN HAROLD H. 
Published: February 2008

In sugar beet, the effect on bolting of additions of potash manures, of superphosphate, and of the mixture of these was not significant, whether applied at the time of sowing or previously. Dung applied in the previous autumn slightly increased the number of plants which went to seed, and when applied just before sowing it had a more marked effect. An amount of sulphate of ammonia which would have approximately the same stimulating effect as the dung gave a slightly larger amount of bolting.On red beetroot, it was possible to compare larger and smaller dressings of various coarse organic manures, and of each of these with and without dressings of sulphate of ammonia. In all cases the sulphate of ammonia and each of the organic manures largely increased the amount of bolting, and a doubling of the organic manure dressing or the addition of sulphate of ammonia to it caused a further increase. Sewage sludge gave an abnormally large amount of bolting, but it is doubtful whether this was due to the larger amount of organic matter and nitrogen applied in this manure. In general, any manurial addition causing more vigorous growth leads to an increase in bolting. There is a very large variation in the amount of running to seed in the crop of red beetroot from different parts of the same field, but the effect of the manures on the proportion which bolted was not widely different.The general question as to the reason why beet plants should bolt more in one season than in another is discussed, and it is suggested that a check to the plants in an early stage, whether caused by dryness or waterlogging, or by low temperature, followed by a vigorous growing period may have something to do with the matter. This would agree with the experiences recorded in the present paper.
RAT POPULATIONS AND CONTROL IN TWO ENGLISH VILLAGES
Authors: BARNETT S. A. , BATHARD A. H. , SPENCER MARY M. 
Published: February 2008

Rat (Rattus norvegicus Berkenhout) populations have been studied in two villages in Devonshire. One village had a human population of 266, the other, of 364. The main activity in each village is mixed farming, with poultry and pig keeping on a small scale.From spring 1947 to spring 1950 visits were made to both villages at six‐monthly intervals. At each visit a relative census of the rat populations was taken. This was done either by test baiting, which records only the visits by rats to bait points; or by census baiting, in which a surplus of wheat is laid each day until the amount taken levels off. The level so reached is a measure of the rat population. Test baiting was found to be less reliable, as an index of changes in the rat populations, than census baiting. In some instances treatments, consisting of one, two or three strikes, i.e. poisonings after prebaiting, were carried out after the census.Complete clearance of a whole village was not achieved on any occasion. Lasting reductions of the rat populations were achieved only by comprehensive double or triple strikes. After such treatments the rat populations took more than a year to recover; probably the recovery to the maximum rat population would often have taken 2 years or more had it been allowed to take place.In each village the rats were distributed in discrete colonies, most of them in farms or chicken runs. Poor hygiene and dilapidation of buildings were important factors in promoting rat infestation. When a new source of food became available near an existing infestation, e.g. as a result of the setting up of a new chicken run, rats soon appeared.Apart from rats five species of small mammals visited the bait points: Mus musculus, Apodemus sylvaticus, Microtus agrestis, Clethrionomys glareolus and Sorex araneus. Their presence was detected by their droppings, by characteristic nibbling of the grain, and by trapping. Allowance was made for their presence in recording the results of census baiting.Mouse activity at the bait points was greatest when the rat population was low, but there is no certain evidence that mouse numbers greatly increased when the rats were reduced.It is suggested that, for effective control and the economical use of manpower, treatments in rural areas should always consist of at least two strikes. It may be expected that such treatments, if carried out with a high degree of thoroughness and efficiency, need normally be carried out only once a year; and it might often be possible to leave an area for 18 months or 2 years.
CONTROL OF THE EUROPEAN RABBIT (ORYCTOLAGUS C. CUNICULUS L.) AN EXPERIMENT TO COMPARE THE EFFICIENCY OF GIN TRAPPING, FERRETING AND CYANIDE GASSING
Authors: THOMPSON HARRY V. , ARMOUR C. J. 
Published: February 2008

Two similar adjacent areas of grass‐heath were enclosed by rabbit‐proof netting and the bulk of the rabbits on one area removed by gin trapping (in the holes) and on the other by ferreting. Trapping was followed by pump gassing and ferreting in its turn by spoon gassing, with a cyanogenetic powder.Gin trapping yielded a higher return of rabbits per man hour (1.5) than ferreting (1.0), particularly during the initial stages of clearance. Ferreting gave a steady return.Pump gassing of burrows, when surface‐living rabbits were present, proved ineffective, owing to re‐opening of holes from the outside.Spoon gassing of burrows, integrated with the removal of surface‐living rabbits by ‘dog and gun’, was successful but expensive in time (0.5 rabbits per man hour), compared with gin trapping and ferreting.The valuable place of ‘dog and gun’ in planned rabbit clearance was clearly demonstrated.Trapping yielded equal numbers of bucks and does. Ferreting yielded a higher proportion of does. Spoon gassing (after ferreting) yielded more bucks than does when the holes were dug out. Surface‐living rabbits were predominantly bucks.
THE CONTROL OF BLOWFLIES INFESTING SLAUGHTER‐HOUSES I. FIELD OBSERVATIONS OF THE HABITS OF BLOWFLIES
Authors: GREEN A. A. 
Published: February 2008

The habits of blowflies infesting slaughter‐houses have been studied to determine the conditions under which control measures are most likely to be effective. Flies found in such numbers as to be considered pests of economic importance were: Calliphora erythrocephala (Meig.) and C. vomitoria (L.); Lucilia caesar (L.), L. illustris (Meig.) and L. sericata (Meig.); and Phormia terrae‐novae (R.‐D.). All were found breeding profusely on slaughter‐house refuse.The reactions of adult blowflies to weather and the working conditions at the slaughter‐house are recorded; the three genera react in differing degrees to relatively minor changes in weather conditions, and redistribution of populations caused by these changes is so rapid as to make difficult the accurate assessment of degree of infestation. It was found that blowflies normally do not settle on the internal fabric of slaughter‐house buildings but tend rather to congregate on nearby vegetation. The preferences were studied of adult flies for certain types of meat, for particular parts of carcasses, and for meat exposed to sunlight.Conditions favouring rapid development of larvae were determined and the rates of breeding recorded for the three genera when in natural competition and when breeding independently. The larvae of P. terrae‐novae were found to be predacious on other species and each other. Lucilia sericata was found to oviposit and breed successfully in vegetable matter.Blowflies overwinter as fully grown larvae which pupate only a short while before emerging in the spring.Various methods are discussed whereby the findings of this investigation into the life history and habits of blowflies can be utilized in the control of these pests.
INSECTICIDAL‐ACTION STUDIES WITH BISDIMETHYLAMINOPHOSPHONOUS ANHYDRIDE CONTAINING 32PHOSPHORUS
Authors: DAVID W. A. L. 
Published: February 2008

Bisdimethylaminophosphonous anhydride containing 32P has been used to study the absorption of this systemic insecticide into plants and its action on aphids.The radio‐anhydride is absorbed by the roots of broad beans placed in culture solutions containing it. The level of radio‐activity in the plant increases as the solution is absorbed and is higher in the washed roots than in the rest of the plant. The activity of the remaining culture solution increases as more is absorbed showing that the roots selectively reject the radio‐anhydride. The material is absorbed more slowly from soil than from sand. In both cases the concentration per gram of tissue is highest in the leaves on the middle part of the stem.By introducing the insecticide by the cut tap‐root technique it can be shown that about 50% of the radio‐anhydride is decomposed within the plant in 8 days. The concentration of undecomposed anhydride in the plant necessary to give a complete kill of Aphis fabae Scop. is about 50 mg./kg. of beans. Dead aphids were found to contain about 15–20 mg./kg. of radioactive material calculated on the assumption that it was undecomposed anhydride. The honey‐dew of aphids feeding on treated plants is also radioactive.Absorption and translocation of radioactive material occurs following the application of the radio‐anhydride to the leaves of the broad bean, cabbage, hop, pea and strawberry. In the broad bean radioactive material can be detected within the leaf a few hours after it has been applied to the surface. In all plants there is evidence that radioactive material is translocated to untreated parts. Much more is translocated to leaves younger than those treated than to leaves older than those treated. In favourable cases, where a large number of leaves on the plant are treated, where the plant holds a large quantity of the anhydride applied or where a heavy dose is given, either by repeated treatments or the use of high concentrations, it is found that insecticidal quantities of what is presumed to be the anhydride are translocated to untreated young growing parts of the plants.No measurable quantity of radioactive material is transpired by plants taking up the radio‐anhydride by the roots.