bluuebunny/crossref_metadata_2025 huggingface dataset:
OBSERVATIONS ON THE BEET EELWORM AND OTHER CYST‐FORMING SPECIES OF HETERODERA
Authors: JONES F. G. W.
Published: February 2008

An account is given of observations made between 1944 and 1948 on beet eelworm and related species of Heterodera. The host ranges of beet‐, potato‐, pea‐, carrot‐ and Galeopsis‐root eelworms were studied in the field, on sites where previous information had been obtained of the species of Heterodera present. The beet eelworm attacked plants in the Polygonaceae, Chenopodiaceae, Amarantaceae, Aizoaceae, Caryo‐phyllaceae, Cruciferae, Onagraceae and Labiatae. Considerable differences were observed in the intensity of attack upon different hosts. The Cruciferae contains many efficient hosts and is the most important host family in the British flora. The Galeopsis eelworm, like the beet eelworm, attacked plants in several families, including the Chenopodiaceae, Caryophyllaceae and Labiatae, which also contain hosts of the beet eelworm. The other root eelworms were more specific, the carrot eelworm attacked only cultivated and wild carrots (Daucus carota L.), the potato eelworm attacked only plants in the genera Solanum and Ly copersicum (potato, Solatium dulcamara L. and tomato), while the pea eelworm attacked only peas (Pisutn), beans and tares (Vicia). The potato eelworm did not attack Solanum nigrum L. or S. sarrachoides Sendt. and there was no evidence that potato eelworm is capable of attacking weeds in natural orders other than the Solanaceae. In pot‐tests, the hop eelworm attacked only hops and nettles and the cabbage eelworm only plants in the family Cruciferae. The rates of development of cysts of the beet, potato, pea and carrot eelworms were studied in the field. In all four species, the rate of development was similar and varied with the soil temperature, being slow in spring, more rapid in summer, falling off during the autumn and becoming negligible during the winter. In the pea eelworm, drought caused delay in the invasion of rootlets by eelworm larvae and reduced the intensity of attack. Assuming adequate moisture, the maximum number of generations for all four species is between two and three per year. In practice, the number of generations is also governed by the vegetative period of the host crop. During the host‐range trials and observations on rates of development, fresh cysts were examined in large numbers. Some differences in shape were observed between the larger cysts of the various species. There were also differences in colour and in the number of eggs extruded into the gelatinous egg sac. Analysis of length and breadth measurements suggested that size ranges and regression coefficients are somewhat more valuable than average lengths and breadths, and length‐breadth ratios, which are usually given. The carrot‐root eelworm (Heterodera carotae Jones) is described, and the status of the Galeopsis‐root eelworm is discussed. The latter is distinct from beet eelworm and appears to be identical with a form found by Goffart in 1936, for which the name Heterodera galeopsidis is proposed. The observations here recorded do not support the theory of adaptability of root eelworms to new hosts.
METHODS FOR MASS REARING AND INVESTIGATING THE HOST RELATIONS OF APHIS FABAE SCOP.
Authors: KENNEDY J. S. , BOOTH C. O.
Published: February 2008

A method is described for producing some hundreds of apterous and thousands of alate virginoparous Aphis fabae every day continuously throughout the year. Broad beans are used as the host plants, in a ‘production‐line’ arrangement of eleven ventilated breeding cages, with additional cages for starting subcultures and rearing alatae, all contained in a portion of a small greenhouse with supplementary lighting in winter. When running smoothly, the culture requires about half an hour's work by one man per day.

An ‘aphid gun’, being a modified type of aspirator catcher, is described, with which large numbers of aphids could be handled and counted rapidly without damaging them.

Amodified technique for host‐transference experiments is described, which permits individual leaves to be compared one with another as host‐units for the aphids. Two types of small metal cages are used, both easily attached to leaves in their natural positions on growing plants. One type confines the aphids to a part of a single leaf and is used mainly for determining relative reproduction rates on different leaves. The other type encloses equal areas of two different leaves between which the aphids can move freely, and is used for determining their behavioural preferences. The principles underlying the use of such cages, the experimental procedures and the interpretation of the results obtained are discussed.
THE TOXICITY OF CERTAIN SYNTHETIC ORGANIC COMPOUNDS TO THE FRUIT‐TREE RED‐SPIDER MITE
Authors: EATON J. K. , DAVIES R. G.
Published: February 2008

The acaricidal activity of ninety synthetic organic compounds has been investigated in the laboratory. Considerable differences were found between the winter eggs, the summer eggs and the adult female stages of the fruit‐tree red‐spider mite (Meta‐tetranychus ulmi (Koch)) in their susceptibility to many of the compounds but two substances, namely azoxybenzene and n‐dodecyl thiocyanate, were appreciably toxic to all three stages. Of the compounds showing promise against summer eggs and mites, bis‐(p‐chlorophenyl) methyl carbinol and 4‐chloroazobenzene were the best, being highly toxic to both summer stages. Of the remainder, diphenylsulphone, 4‐chlorodiphenylsulphone, azobenzene and hydrazobenzene were highly ovicidal, while C12‐C13 alkyl thiocyanates and sec.‐dodecyl thiocyanate gave high kills of the adult female mite.

Relationships between molecular structure and acaricidal activity have been sought. In a series of compounds characterized by the presence of two benzene nuclei connected by certain bridging groups, it has been found that activity to the summer stages of the mite can be influenced by alterations to the bridging group and by substitution in the benzene nuclei. Maximum activity appears to be associated with chlorine substitution in the para position in one nucleus and also with compounds of this type having unsubstituted nuclei.
WHEAT POWDERY MILDEW INVESTIGATIONS
Authors: SMITH H. C. , BLAIR I. D.
Published: February 2008

The development of Erysiphe graminis f. tritici Em. Marchal, from spore germination to spore formation, occupied 6 days and ascospore discharge in the field covered a period of i month. On immune hosts development of the fungus generally ceased at the point of invasion of cell cytoplasm. The features of host plant resistance have been discussed.

Lithium chloride soil applications were made as o‐8% solution in glasshouse seedling plant experiments and at 56 lb./acre rate in a factorial field trial. In the former, mildew was reduced from 11% leaf area infected to 1 %, but under field conditions only from 1–29 to 1–04% over two sampling periods. The limiting effects of lithium on mildew began to decline 18 weeks after soil treatment.

Race 4 of E. graminis f. tritici (Canadian typing) was present in all, and Race 3 in about half the New Zealand wheat localities during 1948‐9. The infection types of Races 3 and 4 on 180 wheat varieties and breeding selections have been recorded, and the basis for a mildew resistance plant‐breeding programme is discussed, including consideration of adult plant resistance.
OBSERVATIONS ON NARCISSUS LEAF SCORCH IN SOUTH‐WEST ENGLAND
Authors: BEAUMONT A.
Published: February 2008

Narcissus leaf scorch caused by Stagonospora Curtisii (Berk.) Sacc. is very common in south‐west England, where it causes economic damage arising from flower spot and leaf decay. Information is given as to the varying susceptibility of many different varieties, a comparative measure of which is obtained by counting the primary infections.

No certain control measures can be recommended, but results of experiments on bulb disinfection and on spraying are given.
THE EFFECT OF VARIATIONS IN CALCIUM SUPPLY, PH VALUE AND NITROGEN CONTENT OF NUTRIENT SOLUTIONS ON THE RESPONSE OF LETTUCE AND RED CLOVER TO MOLYBDENUM
Authors: WARINGTON KATHERINE
Published: February 2008

Lettuce and red clover were grown in nutrient solutions with varied calcium supply, pH value, and nitrogen content, and the response to molybdenum compared under each set of conditions.

The calcium requirement was greater in solutions at pH 4‐4 than at 6‐3, but the quantity of calcium supplied did not affect the response of the plant to molybdenum. Growth was best in the more acid of a range of solutions from pH 4‐2 to 8‐2 in spite of a rapid levelling up to a pH between 6 and 7, but with the possible exception of the solution at pH 8‐3, the need for molybdenum was unaffected by the reaction of the medium. When the calcium supply and/or the initial pH value of the solution was varied, the effect of molybdenum was most pronounced in the largest plants.

When the nitrogen supply was deficient, lettuce showed a slower response to molybdenum than when it was plentiful. With both inoculated or uninoculated clover the reverse was true. This difference in behaviour is explained on the assumption that lettuce has a smaller requirement for molybdenum than clover.

In both lettuce and clover the percentage nitrate‐nitrogen in the dry matter of the shoot was higher when molybdenum was not supplied, but the total nitrogen content was increased in the case of lettuce only. At any level of nitrogen supplied, 5 or 10 p.p.m. molybdenum was of no more benefit than o‐i p.p.m. though the liability to damage from toxicity was possibly greater when nitrogen was plentiful.
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.
MICROBIOLOGICAL CONTROL OF BOTRYTIS CINEREA PERS. I. THE ROLE OF pH CHANGES AND BACTERIAL ANTAGONISM
Authors: NEWHOOK F. J.
Published: February 2008

Strains of Bacillus, Pseudomonas and Chromobacterium isolated from dead leaves of lettuce seedlings overwintering in the open have been proved to be antagonistic in various degrees to Botrytis cinerea on nutrient agar, on wounded detached lettuce leaves and on wounded leaves of lettuce seedlings at temperatures ranging from 4 to 25° C. under conditions of high moisture and humidity. A strain of Micrococcus was completely non‐inhibitive. Antagonism by the strains of Bacillus and by Bacterium coli was evident only at temperatures above 15–20° C. while the other strains were effective also at temperatures as low as 4° C. Bacterial growth on agar and on dead lettuce tissue usually raised the pH from 6.1 to 7.8–8.4 at which level growth of Botrytis cinerea is almost negligible and the activity of any pectinase it produces is very much reduced. The antagonism of the bacteria investigated, however, was largely due to antibiotic substances quite independently of the effect of the high pH. Some bacteria which did not give rise to wide inhibition zones were nevertheless strongly antagonistic in the immediate neighbourhood of the colony. B. cinerea on nutrient agar and on lettuce leaves produced a strongly acid reaction. This was capable of neutralizing the alkaline reaction due to most bacterial activity only if the latter was not already well established. The mixed bacterial flora of all dead lettuce leaves tested was potentially inhibitory to B. cinerea to a level as high as or higher than that shown by the majority of the test strains in pure culture. Many strains of bacteria cause lysis of young active Botrytis mycelium and germ tubes. In association with many bacteria, B. cinerea has exhibited features such as stimulation or depression of sporulation, continuation of aerial growth with inhibition of lateral spread of mycelium, vesicular distortion of hyphae and germination of spores while still attached to the conidiophores. Some spores of the test strain of B. cinerea used gave rise to new strains more resistant to antagonism than the original.
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.
THE INFLUENCE OF HEAT ON SOME APHIDS
Authors: BROADBENT L. , HOLLINGS M.
Published: February 2008

The thermal death‐points of five species of aphids removed from their host plants lay between 38 and 41°C., when tested for 1 hr. at 60%r.h. Many aphids alive after 1 hr. at high temperatures died within the next day; no Myzus persicae recovered and reproduced after 1 hr. above 37.5°C. Third and fourth instars and adult apterae withstood heat better than first and second instars and alatae. More aphids died at 90%r.h. than at 60%r.h, and more at 60% than at 30%r.h. Aphids kept at 15%r.h. for 4 hr. before being heated showed a higher mortality than those kept at 95%r.h. Aphids on plants withstood temperatures higher than their thermal death‐point off the plant. Presumably aphids can continue to cool themselves by evaporation while feeding; also lower temperatures on the surface of transpiring plant tissues will aid survival.
POPULATION STUDIES ON HYLOBIUS ABIETIS (L.) (COLEOPTERA, CURCULIONIDAE
Authors: SWAINE G.
Published: February 2008

Populations of third‐stage larvae, pupae and adults of Hylobius abietis in the stumps of pine trees, Pinus sylvestris L., have been assessed. On a felled area the relative numbers of adults have been obtained by trapping; the most reliable estimate of absolute numbers was obtained from the stump sampling data.
OBSERVATIONS ON THE ATTACK BY THE STEM EELWORM, DITYLENCHUS DIPSACI, ON STRAWBERRY
Authors: GOODEY J. B.
Published: February 2008

Four biologic races of Ditylenchus dipsaci can cause stem eelworm disease on twelve varieties of strawberry, all but one cultivated in Great Britain. The course of attack on strawberry, host reaction and the ways in which the disease originates and is disseminated are described.
EFFECTS OF CULTURAL TREATMENTS ON WHEAT AND ON THE INCIDENCE OF EYESPOT, LODGING, TAKE‐ALL AND WEEDS. Field Experiments 1945–8
Authors: GLYNNE MARY D.
Published: February 2008

An experiment was made on the fourth, fifth and sixth successive crops of winter wheat to determine the effects of various treatments on the troubles which result from close cereal cropping. Eyespot and lodging were prevalent in the first year (1946); weeds in the second; eyespot, lodging, take‐all and weeds in the third.

Spraying with H2SO4 reduced the incidence of eyespot, lodging and weeds, and increased yield of grain on plots which received sulphate of ammonia (by 2.7, 2.2 and 10.0 cwt./acre in successive years).

Sulphate of ammonia increased the incidence at harvest of eyespot and lodging, reduced take‐all and consistently increased yield of straw. Eyespot and lodging reduced the effect of the fertilizer on yield of grain, take‐all increased it.

Increase in seed rate increased the incidence of severe eyespot and of take‐all; it increased lodging except when plants were dwarfed by take‐all.

Weight of straw and percentage straws with severe eyespot lesions independently affected lodging, together accounting for 51% of the variance in percentage area lodged at harvest and 64 % of that lodged 33 days earlier.

Mean yields of grain on untreated plots sown with 3.3 1/2 bushels seed/acre fell from 26.0 to 22.5 to 11.7 cwt./acre in successive years, whereas yields of 28.4, 29.9 and 29.1 cwt./acre were obtained on sprayed plots sown with 1 1/2.2 bushels seed/acre which received 4 cwt./acre sulphate of ammonia, showing that high yields were maintained when eyespot, lodging, take‐all and weeds were controlled.

By 1948 yields of grain on unsprayed plots had fallen to the level of those on similarly manured plots on the continuous wheat experiment on Broadbalk field. Spraying increased grain by amounts similar to those resulting from one year's fallow on Broadbalk; but fallow had its greatest effects on plots with low nitrogen, spraying on those with high nitrogen.
A VIRUS DISEASE OF RED CURRANT (RIBES RUBRUM L.)
Authors: KLESSER P. J.
Published: February 2008

A virus causing ringspot patterns and vein clearing of red currant leaves is reported. It is inactivated at 66–68°C., tolerates a dilution of 1:2000 but not 1:5000, loses infectivity after 7–9 days in vitro and has been transmitted only by sap inoculation.

The virus infects plants in a wide range of families, resulting in chlorotic and necrotic symptoms. On Nicotiana tabacum it causes local and systemic symptoms of the ringspot type. Its host range and physical properties differ from other viruses causing ringspot symptoms, and the name red currant ringspot virus is therefore suggested.
SOME PROPERTIES OF BROAD‐BEAN MOTTLE VIRUS
Authors: BAWDEN F. C. , CHAUDHURI R. P. , KASSANIS B.
Published: February 2008

A severe disease affecting many plants in a crop of broad beans was found to be caused by a previously undescribed virus, provisionally named broad‐bean mottle virus. The distribution of diseased plants suggested spread by a vector, but none of the six insects tested transmitted it. The virus was transmitted to several species of leguminous plants by mechanical inoculation of sap; infectivity for some hosts seemed to be increased by propagation in these hosts.

The virus has an unusual combination of properties. Its thermal inactivation point is about 95°C., whereas sap becomes non‐infective within 3 weeks at room temperature. The infection end‐point of broad‐bean sap is 1/1000, only a little higher than the precipitation titre with specific antiserum. Precipitation with antiserum occurs over a smaller range of antigen/antibody ratios than with other viruses previously studied, possibly because of its greater solubility; it is not precipitated with (NH4)2SO4 until the salt concentration exceeds 75% saturation.

A specific nucleoprotein, containing nucleic acid of the ribose type, can be isolated from infective broad‐bean sap in yields up to 2 g./l. Purified preparations, made by salt precipitation and ultracentrifugation, contain uniform spherical particles approximately 17 mμ in diameter. It is suggested that much of this nucleoprotein is non‐infective, but may otherwise resemble infective particles.
INSECTICIDAL‐ACTION STUDIES WITH BISDIMETHYL‐AMINO FLUOROPHOSPHINE OXIDE CONTAINING 32PHOSPHORUS
Authors: DAVID W. A. L.
Published: February 2008

The absorption of the systemic insecticide bisdimethylamino fluorophosphine oxide containing 32P by plants has been studied, and where possible comparisons have been made with bisdimethylaminophosphonous anhydride.

The radio‐oxide is absorbed by the roots of a broad‐bean plant from culture solutions. The level of radioactivity in the plant increases as the solution is absorbed and is higher in the washed roots than in the rest of the plant. The radioactivity of the remaining culture solution decreases as more of it is taken up by the plants showing that the roots selectively absorb the oxide from solution. In this latter respect it differs from the anhydride which is selectively rejected at similar rates of transpiration. The material is absorbed more slowly by plants growing in soil than in sand.

An appreciable part of the oxide absorbed by the roots is given off as vapour by the leaves. The transpired material can be collected and shown to be radioactive and systemically insecticidal. Aphids feeding on treated plants contain radioactive material.

The oxide is less lipoid soluble than the anhydride and does not penetrate as readily into the leaves of the broad bean. Since it is also lost by vaporization from the plants only small amounts are translocated following leaf applications to beans, cabbages and hops.
PETROLEUM OIL FRACTIONS AS PLANT SPRAY MATERIALS THE EFFECT OF REFINING AN OIL UPON ITS DEGREE OF PHYTOTOXICITY
Authors: HERINGA J. W. , SWARBRICK T.
Published: February 2008

Data are presented showing the effect of degree of refining upon the specific gravity, viscosity, unsulphonatable mineral residue (U.R.), refractive index, average molecular weight, group analysis, sulphur content and phototoxicity of two spindle oil distillates in the boiling range 300–390° C.

Cucumber plants proved very suitable for demonstrating differences in phyto‐toxic properties of the oils.

Spindle oils refined to a U.R. of 82 or higher, and a specific gravity of 0.885 or lower, showed no phytotoxicity in the tests on these plants. A fair agreement was found between the results of these tests and the specifications laid down by Dr H. Martin for spray oils.
INVESTIGATIONS OF THE INHIBITORY ACTION OF BACILLUS SUBTILIS ON FUSARIUM UDUM BUTL., THE FUNGUS CAUSING WILT OF PIGEON‐PEA (CAJANUS CAJAN (L.) MILLSP.)
Authors: VASUDEVA R. S. , JAIN A. C. , NEMA K. G.
Published: February 2008

A suitable basic medium for the growth of Bacillus subtilis, particularly in relation to the production of an antibiotic inhibitory to Fusarium udum, is described. Organic nitrogen with carbohydrate and K2HPO4 is shown to be essential for the growth of Bacillus subtilis. Magnesium sulphate, manganese and iron are found to increase the production of the antibiotic. Effects of temperature, period of incubation, aeration, etc., on the production of the inhibitory substance are described. The active principle is adsorbed by soil and to a lesser degree by kaolin. The organic matter and the soluble salts in the soil do not appear to play an important role in the loss of activity of the filtrates during passage through a bed of soil.
A DISEASE OF SCABIOSA CAUCASICA CAUSED BY THE NEMATODE APHELENCHOIDES BLASTOPHTHORUS N.SP.
Authors: FRANKLIN MARY T.
Published: February 2008

Scabiosa caucasica has been found affected by a new species of Aphelenchoides, herein described and named A. blastophthorus. The symptoms of disease are destruction of the inflorescences and distortion of the leaves with reduction of the laminae. Similar symptoms were produced in scabious by experimental infestation. The nematode can infest teazle (Dipsacus fullonum), but has not been found naturally occurring on any host but scabious.
SOME EFFECTS OF A PLANT VIRUS ON NUCLEAR DIVISION
Authors: CALDWELL JOHN
Published: February 2008

This paper records some observations on the effect of the virus of aspermy disease of tomato on the formation of the mega‐ and micro‐spores of the plant. The obvious interference by the virus in the normal meiotic processes suggests that this is the cause of the non‐formation of seed in infected plants. It is suggested that the interference by virus with nuclear divisions may be more widespread and of greater biological significance than is at present realized.
STUDIES ON PLANT GROWTH‐REGULATING SUBSTANCES
Authors: SMITH M. S. , WAIN R. L. , WIGHTMAN F.
Published: February 2008

Three synthetic growth‐regulating substances, α‐(2‐naphthoxy)‐, α‐(2:4‐dichloro‐phenoxy)‐ and α‐(2:4:5‐trichlorophenoxy)‐propionic acids, have been resolved into their (+)‐ and (‐)‐forms. The physiological activity of these isomers and of the racemic compounds has been investigated using the pea curvature and Avena cylinder test methods of assessment.

The (+)‐isomers in each case displayed high activity in both tests, whereas that exhibited by the (‐)‐isomers was negligible. The racemic compounds showed intermediate activity.

The mode of action of aryloxyalkylcarboxylic acids is discussed in the light of the results presented. These considerations suggest the possibility that the activity of the (+)‐isomers might be antagonized by the presence of the corresponding inactive enantiomorphs. Our experiments show that such antagonism does in fact operate.
DRY‐ROT DISEASE OF THE POTATO
Authors: BOYD A. E. W.
Published: February 2008

The standard dry‐rot inoculation technique was employed to demonstrate variation in susceptibility in a number of commercial potato varieties over the whole storage season. Susceptibility is lowest at about normal lifting time and gradually rises. Different rates of seasonal progress in susceptibility between varieties were observed.

A very high peak of susceptibility occurs in immature tubers in the post‐flowering period of plant growth, which, in the variety Doon Star, is in the latter part of August. This is followed by a sudden decrease which reaches a minimum when the haulm is dead. This susceptibility is not due to thinness of skin of the immature tubers but to physiological or chemical changes in the tubers.

Some differences in susceptibility were also observed in different stocks of the same variety, possibly due to soil conditions, but when samples of these stocks were grown on the same soil no clear differences were found in the overall susceptibility, although variations occurred at different sampling dates.
DRY‐ROT DISEASE OF THE POTATO
Authors: BOYD A. E. W.
Published: February 2008

By combining the results of the standard laboratory injection test and a riddle‐abrasion method of inoculation, both carried out at different periods of the year, a susceptibility index for a number of commercial potato varieties grown on the same soil was obtained, using the variety Catriona as a standard. None of the varieties tested was immune from the disease.

The reactions of certain varieties were found to differ in both tests and in a few, e.g. Golden Wonder, this is believed to be caused by differences between ‘physiological’ susceptibility, i.e. that of the tuber flesh, and ‘mechanical’ susceptibility, i.e. where liability to abrasion is also involved.

A method for assessing skin abrasion is described.

The rate of development of rotting was found in some cases to be independent of the final susceptibility index.