bluuebunny/crossref_metadata_2025_split huggingface dataset:
D.D.T. Impregnation of Sacks for the Protection of Stored Cereals Against Insect Infestation
Authors: Parkin E. A. 
Published: February 2008

Cotton flour sacks, jute flour sacks, jute bran sacks and jute grain sacks have been impregnated with 1 and 5 % by weight of D.D.T. Treated and untreated sacks, each containing 1 cwt. of a mixture of grain (5 parts) and weatings (1 part), were exposed to severe infestation by adults of Calandra granaria, Tribolium castaneum, Ptinus tectus, Oryzaephilus surina‐mensis and Ephestia elutella. After storage for 15 weeks at a mean temperature of 21.3d̀ C. and a mean relative humidity of 65 %, the numbers of adult insects in each sack were determined by sieving the contents.The results with Ephestia elutella were inconclusive. The results with the four species of beetles showed that the eventual degree of infestation of the contents of the sacks was dependent upon the closeness of weave and the D.D.T. content of the sacking material. Impregnation of sacking with 1 % of D.D.T. should afford adequate protection against insect infestation to clean bagged goods stored in stowages which are not heavily infested. Impregnation with 5 % of D.D.T. should offer a very high degree of protection at all times and can almost entirely prevent infestation, if the treated material is of sufficiently close weave to afford some mechanical hindrance to penetration by insects.
Varietal Resistance of Flax to Disease
Authors: Colhoun John 
Published: February 2008

Field experiments, using contaminated seed, have been carried out from 1941 to 1947 to study the reaction of a wide range of both fibre and oil varieties of Linum usitatissimum to attack by Polyspora Lini Laff., Colletotrichum linicola Pethybr. & Laff., Phoma sp. and Melampsora Lini (Ehrenb.) LéV. The tests made with Colletotrichum linicola were supplemented by direct inoculation experiments with young seedlings grown under greenhouse or laboratory conditions.None of the varieties tested proved to be immune to attack by Polyspora Lini, Colletotrichum linicola or Phoma sp. Herkules, Concurrent, Hindi, La Plata, Saginaw x Ottawa 770 B and Winona x Ottawa 770 B were resistant to the stem‐break and browning phases of attack by Polyspora Lini; Bison, Hindi and La Plata were resistant to attacks by Colletotrichum linicola, while Hindi and La Plata showed some resistance to Phoma sp. Immunity or a ‘high’ measure of resistance to attack by Melampsora Lini was exhibited by Formosa, Stakhanovets, Textilshchik, U.S.S.R. No. 2 (ex Dugejheshchya), Wada, Argentine Selection (C.I. 112), Baladi, Bolley Golden (C.I. 644), Bombay (C.I. 42), Hindi, Italia Roma (C.I. 1005–2), J.W.S. (C.I. 708–1), Koto (C.I. 872), Kenya (C.I. 709–1), La Plata, Newland (C.I. 188), Ottawa 770B (C.I. 355), Pale Blue Crimped (C.I. 647), Tammes Pale Blue (C.I. 333–1), Williston Golden (C.I. 25–1) and C.I. 836.All varieties did not show the same reactions to stem‐break as to the browning phase of attack by Polyspora Lini and similar differences were noted in the case of the uredospore and teleutospore stages of Melampsora Lini. In certain varieties the stems showed a greater resistance to attack by Polyspora Lini or Melampsora Lini than the leaves.Seeds of all varieties tested in the field experiments became heavily attacked with Polyspora Lini (except in La Plata), Colletotrichum linicola and Phoma sp.
Studies in the Diagnosis of Mineral Deficiency
Authors: Goodall D. W. 
Published: February 2008

Material from four fertilizer trials on barley in Hampshire was analysed with the principal purpose of comparing the extent to which the potassium content of different plant organs was diagnostic of potassium deficiency. Samples of older leaf blades and sheaths, young leaves, stems and ears were gathered at the time of ear emergence from each of the 108 plots, and analysed spectrographically for calcium, iron, magnesium, manganese, potassium and sodium.Differences in composition between plants from the different sites were proportionately greater in the older leaf blades than in the other organs for calcium, the young leaves for manganese and sodium, and the older leaf blades and sheaths for potassium. Differences in sodium and manganese content at the different sites appeared to be related to the differences in potassium status.Applications of muriate of potash increased the potassium content of all organs except the ears, and decreased the content of magnesium, manganese and sodium, and of iron at one site. The effect of potassium supply on manganese and sodium content was most marked in the young leaves. The proportional increases observed in potassium content as a result of application of muriate of potash were similar at all four sites, in spite of the fact that responses in growth and yield differed greatly.As between the four sites, the responses to muriate of potash observed in the yields of grain are significantly correlated with the potassium content of the older leaf blades and the stems, and the following tentative limiting values are put forward, above which no increase in grain yield as a result of potassic manuring may be expected:(a) in the older leaf blades at the time of ear emergence 0.92% potassium in dry matter, (b) in the stems at the time of ear emergence 1–01 % potassium in dry matter.
RESOLUTION OF STRAWBERRY VIRUS COMPLEXES: III. THE ISOLATION AND SOME PROPERTIES OF VIRUS 3
Authors: PRENTICE I. W. 
Published: February 2008

Aphids (Capitophorus fragariae Theob.) allowed to feed for several days on a strawberry plant with severe crinkle transmitted two viruses. The isolation and properties of one (virus I) have already been described. The other (virus 3) was separated by transferring the aphids to fresh indicators after 24 hr.Virus 3 was transmitted by aphids which had been allowed to feed on an infected plant for 6 days or more and persisted in the vector for several days. There was some evidence that the virus has a latent period in the vector. The symptoms produced by virus 3 on Fragaria vesca and Royal Sovereign strawberry are described.On Royal Sovereign, viruses 1 and 3 together produced symptoms of severe crinkle and viruses z and 3 together produced yellow‐edge. A form of severe crinkle is thus shown to be caused by a virus complex which can be resolved by means of the vector, and severe crinkle is shown to be etiologically distinct from mild crinkle.
STUDIES IN THE DIAGNOSIS OF MINERAL DEFICIENCY: V. MANGANESE DEFICIENCY IN WHEAT
Authors: GOODALL D. W. 
Published: February 2008

At fourteen sites where winter wheat was growing commercially, twelve of which were known or suspected to be deficient in manganese, a spray of manganese sulphate was applied late in the shooting stage of development, and the effect on yield of grain estimated. Samples of certain organs of unsprayed wheat plants were gathered on three occasions between tillering and ear emergence, and samples of weed leaves on the same occasions and after harvest; these samples were analysed spectrographically for manganese.The results indicate that analysis of the wheat plant can be used to forecast its response to a manganese sulphate spray, and the following tentative limiting values for manganese content are put forward, above which no increase in grain yield as a result of treatment may be expected: (a) during tillering, 34 p.p.m. manganese in dry matter of lower leaf blades; (b) just prior to ear emergence, 36 p.p.m. manganese in dry matter of stems. The highest correlation obtained between response and manganese content was that with the values for stem samples gathered just prior to ear emergence.Analysis of weed samples can only be expected to indicate gross differences in the manganese status of different sites.
EXPERIMENTS WITH INSECTICIDAL SMOKES FOR INDOOR USE
Authors: BUSVINE J. R. , KENNEDY J. S. 
Published: February 2008

Insecticidal smoke generators were tested in the laboratory and in practice. Each generator contained 110–120 g. of crude insecticide, either D.D.T. or benzene hexachloride. Over half the insecticide was evolved unchanged as a smoke of particles less than 1 μ in diameter, by a slow combustion mixture. In the laboratory tests, the generators were used at the rate of one to 1800–2500 cu.ft. (50–70 cu.m.). Benzene hexachloride had a greater initial insecticidal effect and a better residual action up to a week after treatment; thereafter (1 and 6 months) the D.D.T. was more effective. The residual effects of horizontal surfaces were good against bedbugs, but the deposits on vertical surfaces were not highly efficient. Residual action against mosquitoes of vertical surfaces a week after treatment was fair, but effects of inverted surfaces were poor.The deposits of active insecticide on horizontal surfaces were about 15–30 mg./sq.ft.; on vertical surfaces, 3–10 mg./sq.ft.; and on inverted surfaces, 2–6 mg./sq.ft.A field trial was conducted between August and November in kitchens infested by flies and cockroaches. The generators were used at the rate of one per 64 cu.ft. (18 cu.m.). A substantial reduction of flies for 11 weeks was obtained by D.D.T., but for only 2 weeks with benzene hexachloride. Both treatments reduced heavy cockroach infestations to negligible proportions for 2–3 months. There was evidence of some repellent effect.Thermal generators require careful precautions to prevent indirect tainting of food or beverages. They are very wasteful of insecticide especially since two or perhaps three treatments per season might be necessary. This would use twenty times as much insecticide as a spray treatment. On the other hand, labour and equipment costs are somewhat lower, and ease of operation very much greater, with smoke generators.
OBSERVATIONS ON A VIRUS DISEASE OF COWPEA IN TRINIDAD
Authors: Dale W. T. 
Published: February 2008

A mosaic of cowpea and asparagus‐bean (Vigna unguiculata) is common in Trinidad. The same virus sometimes attacks Cajanus indicus, Crotalaria juncea, Glycine max, Phaseolus mungo and P. aureus, usually when growing near to infected cowpeas. Desmodium frutescens, Psophocarpus tetragonolobus, Sesbania speciosa, Vigna vexillata, Phaseolus trinervius and varieties of P. Iunatus are also susceptible to systemic infection. Most of the above give local lesions, which are the only symptoms produced on Canavalia ensiformis and Dolichos lablab. No infections were obtained on Phaseolus vulgaris, or on any plant outside the Leguminoseae.The virus is seed‐borne in asparagus‐bean, but apparently not in tested cowpea varieties. The leaf beetle Ceratoma ruficornis is a vector, and is probably largely responsible for spread in the field; Aphis medicaginis seems unable to transmit the disease. The thermal inactivation‐point of the virus is 66°C., its dilution end‐point 1: 100,000, and longevity in vitro over 20 days.
EFFECT OF PREVIOUS CROPS ON THE INCIDENCE OF EYESPOT ON WINTER WHEAT
Authors: Glynne Mary D. , Moore F. Joan 
Published: February 2008

Surveys of winter wheat from 1939 to 1946 show that eyespot (Cercosporella herpotrichoides Fron.) occurs throughout Britain and that its incidence depends largely on previous cropping and on weather. Examination of 551 crops on land whose cropping for the previous 4 years was known showed that the incidence rose steadily with increasing numbers of preceding wheat and barley crops: where neither crop had been taken for 4 years the proportion of crops with more than 70% infected straws was 2%, rising to 45% where three or four such crops had been taken and the average straws infected rose from 6 to 55%.The percentage infection to be expected in various groups of crops was calculated from previous cropping; it was compared with the actual infection and so used to assess the importance of other factors in determining the incidence of eyespot. High spring rainfall, early sowing and a dense plant increased incidence and low spring rainfall, late sowing and a thin plant reduced it.Eyespot was not usually severe on newly ploughed grassland until the third or fourth crop of wheat, but under very wet conditions it was sometimes severe in the second crop.Oats is much less susceptible than wheat or barley, but some crops were found with a third of their straws infected.A brief survey of winter wheat in Holland suggested possible causes for the rise and fall of eyespot in recent years and for its present lower incidence there as compared with East Anglia.
STUDIES OF THE CLOVE TREE I. SUDDEN‐DEATH DISEASE AND ITS EPIDEMIOLOGY
Authors: NUTMAN F. J. , SHEFFIELD F. M. L. 
Published: February 2008

Sudden‐death disease of cloves has been present and steadily increasing in both Zanzibar and Pemba for many years. The only premonitory symptom is a slight chlorosis followed by thinning of the foliage and reduction of the absorbing system. Death follows after a period, which may vary from only a few days to many months. Death occurs from lack of water caused by the disorganization of the absorbing roots.The outbreaks fall into three classes: (1) the sporadic, which ceases to spread after killing a few trees; (2) the ‘Pemba’ type showing clear peripheral spread; (3) the diffuse epidemic type.In Pemba some 500 small outbreaks are scattered through the clove areas and some seem to be passing from type (2) to type (3). The total number of trees affected there is less than in Zanzibar, where the situation approximates to a single outbreak involving half of the clove‐growing area of the island. The rate of spread of the disease varies, but it is accelerating.Various causes, physical, physiological, and pathological, have been suggested to account for the condition. The epidemiology suggests that all but a pathogenic hypothesis can be discarded. Of the possible pathogens, a virus carried by a lethargic vector is the most probable. Suspicion is attached to a scale insect which is tended and transported by the red tree‐ant, Oecophylla longinoda.
STUDIES ON POTATO VIRUS X I. TYPES OF CHANGE IN POTATO VIRUS X INFECTIONS
Authors: Matthews R. E. F. 
Published: February 2008

In tobacco plants infected with mild strains of virus X, severe strains may arise as mutations which multiply locally.Several strains of virus X gradually lost infectivity for potato on continued culture in other hosts such as tobacco.Strains that are poorly infective or invasive for potato may take considerable time to move into the growing shoot from the tuber in detectable amounts.Pronounced and apparently spontaneous increases in the severity of the strain that dominates in potatoes may occur in field crops.
STUDIES ON POTATO VIRUS X II. CRITERIA OF RELATIONSHIPS BETWEEN STRAINS
Authors: Matthews R. E. F. 
Published: February 2008

The range and type of symptoms produced by strains of virus X are briefly described.Of ten strains examined, six were identical in serological cross‐absorption tests, and two (T.B.R. X and B) differed considerably from the others. The possibility of preparing strain‐specific antisera is indicated.The protection afforded by mild strains against severe strains in tobacco and Datura tatula was complete for all strains tested except T.B.R. X and B, which gave only partial protection. Thus there is a correlation between wide serological differences and a breakdown in the protection afforded in the plant.There was no correlation between type of symptoms caused and serological relationships.There was some evidence to show that strains from the same source were more closely related than strains from different sources.
THE INFECTION OF PLANTS BY VIRUSES THROUGH ROOTS
Authors: ROBERTS F. M. 
Published: February 2008

Roots of young tomato plants became infected when inoculated with tomato bushy stunt, tobacco mosaic, and potato X viruses. Root infections also occurred when these viruses were added to soil or culture solutions in which plants were growing.The viruses were sometimes localized around their initial entry points in roots; sometimes they invaded the root system but not the shoots, and sometimes they produced full systemic infection of roots and shoots. In some experiments, but not all, systemic infections were more frequent when the upper tap root or superficial roots were inoculated than when fibrous roots were inoculated.In both tomato and potato, virus X spread from diseased to healthy plants sharing the same culture solution, if their roots were in contact, but not otherwise. Infection of the roots of potato plants by inoculation, produced only one plant with virus‐infected haulms, although several had infected tubers.
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.