bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
STUDIES OF FLUCTUATIONS IN INSECT POPULATIONS XII. FURTHER EVIDENCE OF PROLONGED LARVAL LIFE IN THE WHEAT‐BLOSSOM MIDGES
Authors: BARNES H. F. 
Published: February 2008

Contarinia tritici emerges the same year as the larvae are in the wheat ears and up to 3 years later. Its parasites emerge up to 2 years after the larvae are in the wheat ears, but never the same year. This indicates that the supernumerary generation of C. tritici that occurs on couch grass in August and September may be expected to be free from parasites and so constitutes a dangerous source of replenishment of the pest.Emergence of Sitodiplosis mosellana can take place after the larvae have been in the soil up to twelve winters. Most of any one year's larvae do not necessarily emerge as midges after one winter, although usually this is so. Any one year's flight is probably a composite one derived from several previous generations of this one‐generation‐a‐year gall midge.
INSECTICIDES FOR PREVENTING BARNACLE SETTLEMENT
Authors: WAUGH G. DUNCAN , HAWES F. B. , WILLIAMS F. 
Published: February 2008

During the summer of 1950 experiments were made to test the use of insecticides for preventing the fouling of oyster spat collectors by the barnacle Elminius modestus.The insecticides used were DDT, BHC (benzene hexachloride‐γ‐isomer) and dieldrin (hexachloro‐epoxy‐octahydro‐dimethano‐naphthalene), made up as 5% solutions and tested on egg‐box collectors and quarry tiles. The tiles were used for frequent observations on settlement.When the solutions were sprayed on to the surfaces, in sufficient quantity to give a covering of 200 mg./ft.2 of active insecticide, none of them interfered with either barnacle or oyster settlement.When the test surfaces were dipped in the solutions, DDT and BHC prevented barnacle settlement almost completely, while dieldrin reduced it by approximately 50%. Settlement of Ostrea edulis was also reduced on the treated surfaces.Urea‐formaldehyde resins made up as varnishes, to which DDT or BHC had been added, were also tested. A varnish incorporating 20% by weight of DDT provided an effective anti‐fouling compound which lasted at least 3 months and completely prevented barnacle settlement.The possibility of insecticides dissolving into the water and inhibiting barnacle growth on adjacent surfaces is discussed.
RESOLUTION OF STRAWBERRY VIRUS COMPLEXES
Authors: PRENTICE I. W. 
Published: February 2008

Strawberry virus 4 produces vein chlorosis and necrosis on strawberry (var. Royal Sovereign) and slight chlorotic spotting on wild strawberry (Fragaria vesca L.). No vector is known. Virus 5 produces leaf curling and vein necrosis on Royal Sovereign and F. vesca. It is transmitted by strawberry aphids (Pentatrichopus fragaefolii Cock.) which have fed on an infected plant for 1 hr. or more and persists for about 1 hr. in the vector.The names strawberry mottle, mild yellow‐edge, crinkle, vein chlorosis and leaf‐curl virus are proposed for strawberry viruses 1, 2, 3, 4 and 5 respectively.
THE PENETRATION OF THE INSECT CUTICLE BY DDT AND RELATED COMPOUNDS
Authors: ARMSTRONG G. , BRADBURY F. R. , BRITTON H. G. 
Published: February 2008

The penetration of pp‐DDT and some related compounds into grain weevils has been studied by a micro‐analytical technique.Grain weevils were exposed to filter papers, impregnated with the chemical under test, for periods varying from a few hours to several days. The chemical removed by washing the insects with cold methanol, which was not expected to dissolve anything which had penetrated below the wax layer of the epicuticle, was described as being ‘outside’ the insect; that which remained was extracted with ether after grinding the insects with anhydrous sodium sulphate and recorded as being ‘inside’ the insect. By plotting the amounts ‘inside’ and ‘outside’ after varying times of exposure a picture of the rate of penetration of these compounds was obtained.The results are discussed in relation to similar curves published earlier for isomers of benzene hexachloride. The major difference revealed is the very slow penetration of pp‐DDT compared with γ‐BHC. This is ascribed to the vapour effect of γ‐BHC which has a vapour pressure much greater than that of pp‐DDT.
OBSERVATIONS ON APPLE CANKER
Authors: BYRDE R. J. W. , CROWDY S. H. , ROACH F. A. 
Published: February 2008

Sodium pentachlorophenate and phenyl mercury chloride have been tested as eradicant sprays against apple canker. Trials with inoculated shoots showed that neither of these sprays would affect an established leaf‐scar canker. Both chemicals checked sporulation of Nectria galligena on cankers but phenyl mercury chloride was the more effective and reduced sporing up to 18 months after application.The incidence of leaf‐scar infection was diminished by treatments reducing sporulation, such as spraying with phenyl mercury chloride or the removal of diseased material from the tree. Bordeaux mixture used as a protectant winter spray was ineffective in reducing leaf‐scar infection.
Studies On Plant Growth‐Regulating Substances
Authors: WAIN R. L. , WIGHTMAN F. 
Published: February 2008

The physiological activity of all the mono‐, di‐ and trichloro‐phenoxyacetic acids has been investigated using the pea curvature and Avena cylinder tests. The highest activity was shown by the 4‐chloro‐, 2:4‐dichloro‐ and 2:4:5‐trichloro‐ acids, though the 2‐ and 3‐chloro, 2:3‐, 2:5‐ and 3:4:dichloro‐ and the 2:3:4‐trichloro‐ derivatives were appreciably active in both tests. Significant activity was also shown in either one or both tests by the 2:6‐dichloro‐, 2:3:5‐, 2:3:6‐ and 3:4:5‐trichloro‐ acids.The activity of such compounds is considered in relation to two recent theories which attempt to relate capacity to induce a growth response with the position of substituents in the aromatic ring. It is concluded that neither theory can satisfactorily explain the relative activities of these compounds for all types of growth response.
STUDIES ON A CANKER DISEASE OF CYPRESSES IN EAST AFRICA, CAUSED BY MONOCHAETIA UNICORNIS (COOKE & ELLIS) SACC
Authors: JONES D. RUDD 
Published: February 2008

A canker disease of cypresses, caused by Monochaetia unicornis, was first observed in Kenya in 1942. Outbreaks appear to have followed a spread from south‐east to north‐west, the direction of the south‐east monsoon, and the disease has now been recorded in nearly all the cypress‐growing areas of Kenya, Tanganyika and Uganda, in Southern Rhodesia and the Union of South Africa. The oldest known infections occurred in 1937.The fungus grows in the bark and sapwood, forming cankers which spread rapidly up and down the stem or branch, more slowly round, frequently causing girdling. Cankered trees produce large amounts of resin and a periderm may be initiated in advance of the fungus. Infections occur most commonly at main branch crotches, but cankers also start at the tree collar, on the stem and at minor branch crotches.The fungus exists in nature in three strains having differing levels of virulence, growth rate in culture, size of acervuli and conidia, and retention of viability in conidia. The distribution of one strain appears to be limited by ecological conditions.Acervuli ripen and conidia are liberated from 3 to 8 weeks after the start of the rains. Infections start during the rains and misty weather, the slimy spores being dispersed for short distances only. Conidia may retain their viability for up to 28 months.The local spread of the disease in Kenya has been traced and differing levels of virulence east and west of the Great Rift valley, associated with differences of climate, have been observed.Trees 2 years old are the most susceptible and older trees are only infected in the rapidly growing parts. Cupressus macrocarpa is more susceptible than C. lusitanica, the latter species being heavily infected only where it is growing close to diseased C. tnacrocarpa.Occlusion of cankers occurs in both species but is more effective in halting the spread of the fungus in C. lusitanica.It is suggested that the disease originated from a single focus and may represent the mutation of a strain of Monochaetia unicornis parasitic on cypresses from a strain only parasitic on an indigenous host, Juniperus procera. The fungus may, however, have been imported from abroad.
OBSERVATIONS ON FUNGICIDE CONTROL OF WITCHES‘ BROOM, BLACK‐POD AND PINK DISEASE OF THEOBROMA CACAO
Authors: THOROLD C. A. 
Published: February 2008

Spraying experiments were started in Trinidad in 1940 and continued in Nigeria in 1950 to determine the control of certain cacao diseases obtainable by relatively frequent applications of copper fungicides, and also to test modified procedures designed to reduce spraying costs.It was found that a spray applied only to the cropping regions of the trees reduced pod losses, which may include Phytophthora and Diplodia infections in addition to witches' broom disease (Marasmius perniciosus).Experiments in Trinidad on witches' broom disease showed that monthly applications of 1% Bordeaux mixture reduced the incidence of both vegetative brooms and affected pods. The number of cushion brooms was not reduced; there was an apparent increase associated with spray applications to one particular cacao clone (ICS 4). There was no apparent advantage when the interval between spray applications was reduced to 1 or 2 weeks, because vegetative brooms occurred in spite of such frequent applications. However, if pod losses can be controlled directly, the occurrence of vegetative brooms would be unimportant.Pink disease (Corticium salmonicolor) was completely controlled by applications of Bordeaux mixture. It appeared that there was at least a 12 months' residual effect from spraying.Experiments were carried out in Nigeria on the control of black‐pod disease (Phytophthora palmivora), using carbide Bordeaux, prepared by adding solid calcium carbide to 1% copper sulphate solution. Satisfactory disease control was obtained with applications at intervals of 1–4 weeks. Perenox (0.1%) was less effective than carbide Bordeaux. Knapsack spraying failed to protect all pods more than 7 ft. from the ground.In Fernando Po, where Bordeaux mixture is used for the control of black‐pod disease, two to four applications are made per season. Black‐pod control is almost universal on plantations in Fernando Po, where there are consequently relatively few sources of infection.
QUANTITATIVE STUDIES ON THE TRANSMISSION OF CABBAGE BLACK RING SPOT VIRUS BY MYZUS PERSICAE (SULZ.)
Authors: HAMLYN BRENDA M. G. 
Published: February 2008

Factors affecting the transmission of cabbage black ring spot virus by Mysus persicae (Sulz.) were studied quantitatively using the local lesions produced on tobacco leaves. Aphids prevented from feeding for 15 min. or more, before feeding for a few minutes on an infected plant, caused more infections than unfasted aphids. Fasted aphids acquired virus from infected plants in feeding times as short as 10 sec., and infected healthy plants in test‐feeding times of 5 sec. Increasing test‐feeding times to 30 min. increased the numbers of infections. Increasing infection‐ feeding times from 10 sec. to 5 min. had little effect, but increasing to more than 5 min. greatly reduced the number of transmissions. This reduction was partly offset if the aphids were prevented from feeding continuously while on the infected plants. With undisturbed infection‐feeding periods of 15 min. or longer, previously fasted aphids caused no more infections than unfasted aphids.Infective aphids lost their ability to produce lesions more rapidly when feeding than when fasting.Winged and wingless aphids were equally efficient vectors.
THE SYSTEMIC INSECTICIDAL ACTION OF SODIUM FLUOROACETATE AND OF THREE PHOSPHORUS COMPOUNDS ON THE EGGS AND LARVAE OF PIERIS BRASSICAE L.
Authors: DAVID W. A. L. , GARDINER B. O. C. 
Published: February 2008

Four compounds, bisdimethylaminophosphonous anhydride (anhydride), bis(dimethylamino)fluorophosphine oxide (oxide), diethyl paranitrophenyl phosphate (E600) and sodium fluoroacetate (acetate), previously shown to have systemic insecticidal activity against aphids, have now been tested against the eggs and larvae of Pieris brassicae L.The anhydride proved to have very little toxic action on Pieris, but the other three compounds showed both contact toxicity and systemic insecticidal action when taken up by the roots of cabbage plants from solution and from soil. The acetate, but more especially the E600, also showed systemic action following application to the leaves.In all cases the order of decreasing toxicity was E600 > acetate > oxide > anhydride. E600 is the only compound which is outstandingly toxic to Pieris eggs and larvae. It has the added interest that when watered on to the roots of cabbage plants it kills larvae in egg batches on the leaves. Death takes place at the stage when the larvae are biting through the shells. The oxide and acetate proved to be surprisingly innocuous.Unless it is felt to be too poisonous E600 is worthy of consideration as an insecticide against Pieris eggs and larvae, since it is highly effective as a contact insecticide and also has some systemic action.
THE INFLUENCE OF INFECTION WITH NOSEMA APIS ON THE ACTIVITIES AND LONGEVITY OF THE WORKER HONEYBEE
Authors: HASSANEIN M. H. 
Published: February 2008

Infection of the adult worker honeybee with Nosema apis reduces or obviates brood feeding and causes her to commence foraging earlier than a healthy bee. The length of foraging activity and the total length of life of infected bees is reduced.In colonies infected with N. apis the rate of brood rearing is severely depressed during April, May and June, the degree of depression being proportional to the percentage infection.Infection decreases during July, August and September, and consequently the rate of brood rearing increases, but the resulting addition in foraging population is usually too late to increase the honey crop.