bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population studies on the active stages of the black bean aphid, Aphis fabae Scop., on its winter host Euonymus europaeus L
Authors: WAY M. J. , BANKS C. J. 
Published: February 2008

SUMMARYAutumn populations of Aphis fabae Scop, on the primary host Euonymus europaeus L. were little affected by natural enemies, most of which had begun to hibernate before the aphid populations developed.The size of the population in spring was usually determined by the number of overwintering eggs on a bush. The fundatrices hatched about 3–6 weeks before natural enemies became common. The growth of large A. fabae populations was first halted by the effects of intra‐specinc competition, notably by the production and departure of emigrant alatae and by adult apterae reproducing more slowly. Later, natural enemies, especially Adalia 2‐punctata (L.), Syrphidae and the parasite Trioxys sp. (near angelicae), multiplied and accelerated the decline in the aphid populations, which usually disappeared in June leaving many immature natural enemies. Larval A. 2‐punctata began to eat parasitized aphids and cannibalized other larvae and pupae.The small populations of A. fabae that develop from few overwintering eggs are at greater risk from natural enemies than are large ones. Intraspecific competition still slowed population increase, because most aphids remained crowded on the few originally colonized twigs. Such populations produced very few emigrant alatae before they were exterminated by the combination of T. angelicae with specific and non‐specific predators. Adult Cantharidae killed many of the aphids, especially in hedgerow habitats, where they were abundant.Coccinellidae, Anthocoridae and syrphid larvae, and the adults of nonspecific predators, notably Cantharidae, prevented recolonization of E. europaeus throughout July and August. Leaves of E. europaeus may remain physiologically suitable for A. fabae throughout July but begin to deteriorate in August when A. fabae kept on them become less fecund.Experiments using exclusion techniques provided evidence that natural enemies which attack A. fabae on E. europaeus and on summer hosts cause the common 2‐year cycle of aphid abundance.Individual E. europaeus differ consistently in the extent to which they are colonized by A. fabae. Conditions are discussed that should govern the choice of E. europaeus bushes on which the A. fabae populations can be used as sensitive indicators of later crop infestations.
Hatching of the winter eggs of the fruit‐tree red spider mite (Panonychus ulmi (Koch))
Authors: LIGHT W. I. ST G. , JOHN MARGARET E. , GOULD H. J. , COGHILL K. J. 
Published: February 2008

SUMMARYObservations on the hatching of winter eggs of Panonychus ulmi (Koch) from apple orchards in England over the 5 years 1962‐6 are described. Differences of 2–3 weeks between orchards in the date at which 50% hatch was reached were quite common and this was out of step with petal fall in the majority of orchards. There was a continuous range between early and late hatching populations and a tendency for the populations to hatch in the same order every year. In 1966 populations on Cox's Orange Pippin hatched earlier than those on Worcester Pearmain but the difference was unlikely to be of practical importance. Neither recording accumulated day degrees for populations hatched out‐of‐doors nor hatching in an incubator after chilling was considered to give a sufficiently reliable forecast of 50% hatch but observations in 1966 suggested that this might be predicted from the total eggs hatched in an incubator expressed as a percentage of total healthy eggs.
The control of strawberry‐seed beetle (Harpalus rufipes Deg.); with observations on the damage it causes and that by linnets (Carduelis cannabina cannabina (L.))
Authors: FRENCH N. , JOHN MARGARET E. , MORETON B. D. 
Published: February 2008

SUMMARYIn a laboratory trial, the previous diet of strawberry‐seed beetles influenced their choice of food. The beetles generally preferred crushed oats to chicken pellets or bran though they fed more often on ripe strawberries than on the other foods. Baits of crushed oats containing malathion and fenitrothion (each at 0·15% active ingredient) and 0·1% a.i. of aldrin were eaten when strawberries were also available. In field trials, beetle mortality ranged from about 30% in small enclosed plots to about 90% in large field plots. Malathion bait remained effective for 5–7 days under wet conditions and 10–12 days under dry. Fenitrothion and aldrin baits were effective for 2–3 weeks. Observations made after using fenitrothion baits suggest that they are not a danger to wild life. In a survey of forty‐seven commercial crops linnet damage was found in thirty‐five crops and seed‐beetle damage in three crops. Linnet damage was most severe in unstrawed maiden crops.
Some effects of spraying with thiabendazole on the susceptibility of sugar beet to yellowing viruses and on their vector, Myzus persicae (Sulz.)
Authors: RUSSELL G. E. 
Published: February 2008

SUMMARYIn a field experiment fewer sugar‐beet plants became infected with aphid‐transmitted yellowing viruses in plots that had been sprayed with solutions of thiabendazole lactate than in water‐sprayed plots, after exposure to natural infestation with aphids. Subsequent glasshouse tests showed that foliar sprays of o·o1 % thiabendazole lactate in water significantly reduced the proportion of inoculated sugar‐beet plants which became infected with beet yellows virus (BYV) or beet mild yellowing virus (BMYV) after inoculation with viruliferous Myzus persicae (Sulz.). This effect on virus transmission was not apparently due to a direct insecticidal action of thiabendazole, because adult aphids usually survived equally well on sprayed and unsprayed plants. Treatment of test plants with thiabendazole did not affect the transmission of beet mosaic virus to them by M. persicae. The fecundity of M. persicae was greatly reduced by transferring them to plants which had been sprayed with thiabendazole or by spraying them with thiabendazole before transfer to unsprayed plants. The fertility of adult Aphis fabae Scop, was also reduced by spraying with thiabendazole. The mechanisms whereby thiabendazole affected fecundity of aphids and transmission of viruses are not understood.
The relationship between leaf blotch caused by Rhynchosporium secalis and losses in grain yield of spring barley
Authors: JAMES W. CLIVE , JENKINS J. E. E. , JEMMETT J. L. 
Published: February 2008

SUMMARYTwo methods were used to investigate the loss in grain yield associated with specific levels of leaf blotch. Yields from plots sprayed with fungicide were compared with those from unsprayed plots and yields of varieties of different susceptibility to the disease were compared with one another. A disease assessment key is presented, which was used to assess the percentage laminar area of the top two leaves affected by the disease. A linear relationship between disease on the upper two leaves and yield was established. Results from nine trials showed a consistent relationship between the disease level, at growth stage 11·1 (Feekes scale), and loss in yield. The loss in yield expressed as a percentage of the yield of an uninfected crop was equivalent to approximately two‐thirds of the percentage of the flag‐leaf area visibly infected, or one‐half of the infected area on the second leaf. The predicted loss in yield is the average of these two estimates.
Experiments using sterilized apple‐leaf discs to study the mode of action of urea in suppressing perithecia of Venturia inaequalis (Cke.) Wint.
Authors: ROSS R. G. , BURCHILL R. T. 
Published: February 2008

SUMMARYLaboratory experiments using sterilized apple‐leaf discs showed that treatment of leaves with urea during the early stages of perithecial initiation induced a high nitrogen content of the leaves, which prevented further development of perithecia although mycelial growth was unaffected. Treatments applied at a later stage of fungal development inhibited both perithecial and mycelial growth.Some of the bacteria isolated from urea‐treated leaves in the field restricted perithecial development, particularly when applied in the first month after inoculation with suspensions of conidia from sexually compatible strains of the fungus. One isolate, a Pseudomonas sp., was shown to be important in the decomposition of apple leaves.
Methods of measuring the prevalence of pathogenic fungi on potato tubers
Authors: HIDE G. A. , HIRST J. M. , SALT G. A. 
Published: February 2008

SUMMARYMethods are described whereby the prevalence of pathogenic fungi on seed potato tubers can be measured quickly and quantitatively. Eye‐bearing plugs of tuber tissue, 8 mm diameter by 10 mm long, are excised, incubated over water at 15 °C for 5 days and then examined microscopically. The occurrence of fungi and macroscopic tuber symptoms are recorded directly on punched tape and tabulated by computer.
Freckle disease of banana in Hawaii caused by Phyllostictina musarum (Cke.) Petr
Authors: MEREDITH D. S. 
Published: February 2008

SUMMARY‘Freckle’ (‘black‐spot’ disease) of bananas is common on leaves and fruit of Dwarf Cavendish and other varieties in Hawaii, especially after rainy periods. On fruit, symptoms may appear 2–4 weeks after the bunch has opened, and become more severe as maturity is approached. The disease is usually confined to older leaves on affected plants. Freckled tissue contains numerous pycnidia of Phyllostictina musarum and disease was experimentally induced by inoculating leaves and fruit with conidia of this fungus. This appears to be the first record of successful inoculation with P. musarum.Conidia of P. musarum germinate after 3–6 h in a film of water on banana peel, appressoria being formed after 18–30 h. Penetration of the epidermis occurs 24–96 h after inoculation, and is brought about by an infection hypha which grows from the appressorium. The progressive increase in severity of freckle as fruit matures is due to repeated infection by further conidia of P. musarum, rather than to enlargement of original infections. Some banana clones, including Gros Michel, appear to be resistant to the fungusDispersal of P. musarum conidia immediately after discharge from the pycnidium is chiefly by rainwater and dew. Secondary infections contribute greatly to the total number of infections. Conidium dispersal by water often results in the development of characteristic patterns of spotting, chiefly in the form of streaks or circular areas, coinciding with the directions of movement of rainwater and dew. Large numbers of conidia of P. musarum are washed on to fruit in rainwater and dew running from diseased, overhead leaves.
Laboratory tests of fungicides against Peronospora parasitica (Pers. ex Fr.) Fr
Authors: CHANNON A. G. , FAULKNER) RUTH J. HAMPSON (née 
Published: February 2008

SUMMARYMethods were investigated of culturing Peronospora parasitica on detached cotyledons in plastic box moist chambers in constant‐temperature cabinets. Light was essential and a temperature of 15 °C was most suitable for infection and survival of cotyledons. Using such cotyledons the protectant and eradicant actions of various fungicides against P. parasitica were compared with those of zineb. Captafol, Daconil 2787, dichlofluanid and propineb were markedly superior to zineb as protectants, being highly effective at 0·025 % a.i. None of these compounds (at 0·2 % a.i.) checked fungal development when applied 5 h after inoculation, during which time the fungus had penetrated the cotyledons, and it was concluded that the fungicides had thus no internal effect. Internal fungistasis was shown, however, by a maneb‐nickel sulphate fungicide and also by nickel sulphate. The latter (at 0·4% NiSO4.6H2O) gave some disease control when applied up to 72 h after inoculation and appeared to be translocated within the tissue of the cotyledon.
Effects of cultural treatments on the incidence of, and damage done by, tomato brown root rot
Authors: LAST F. T. , EBBEN MARION H. , ROTHWELL J. B. , JONES D. A. G. 
Published: February 2008

SUMMARYIn soils naturally infested with Pyrenochaeta lycopersici, which usually occurs as a grey sterile fungus (GSF), symptoms of brown root rot (BRR) developed sooner and more extensively in the second year of cropping than in the first. The amount of BRR attributable to corkiness increased as plants aged but, at comparable stages of cropping, decreased in the second and third seasons, an effect associated inversely with the severity of early GSF attack. The larger amount of corkiness, 33 compared with 18 %, on two batches of plants in 1965, each with 53 % end‐of‐season BRR, was also attributed to a less severe early GSF attack on the former than on the latter, growing in soils unsteamed for 1 and 3 years respectively.The incidence of BRR decreased with increasing depth in infested soils but increased on plants grown in plots with partially sterilized topsoil.Partially sterilizing soils at the G.C.R.I. and Fairfield E.H.S. decreased the incidence of BRR and increased crop weights from about the second month of picking, but fruit quality was poorer. Seasonal yields from plants in untreated soil progressively decreased relatively to those from repeatedly steamed plots, from 93 to 65 % in successive years at Fairfield and from 65 to 56 and 43 % at the G.C.R.I. Steaming done in 1963 and 1964 temporarily retarded GSF attack in 1965 with corresponding yield increases.Increasing the amounts of sterilized propagating soil surrounding roots at planting from 0·4 to 1·01 per plant increased yields by c. 0·4 kg/plant, this being a relatively large increase for plants in infested soil, where this treatment significantly delayed the early incidence of BRR near stem bases.Grafting commercially acceptable scions to rootstocks that tolerated colonization by GSF (‘resistant’ rootstocks), temporarily checked growth, delayed picking and decreased fruit quality. Usually grafted plants, irrespective of soil treatment, yielded at least as much fruit as ungrafted plants in steamed soil. In one of five comparisons, soil steaming increased yields of grafted plants. When testing the effects of previous cropping it seemed that populations of GSF increased similarly in soils planted with grafted and ungrafted plants.In addition to GSF attack, roots at Fairfield E.H.S. were often colonized by Colletotrichum coccodes, microsclerotia (= black dots) being more numerous as plants aged. Although significantly more black dot developed on GSF‐resistant rootstocks grown in untreated soil than on those grown in steamed soil, the differences were not associated with effects on yield. C. coccodes colonized GSF‐susceptible and ‐resistant roots equally.
Effects of plant growth regulators and other compounds on flow of latex in Hevea brasiliensis
Authors: ABRAHAM P. D. , BOATMAN S. G. , BLACKMAN G. E. , POWELL R. G. 
Published: February 2008

SUMMARYEighty‐nine compounds have been tested for their ability to promote the flow of latex from Hevea brasiliensis after tapping. The twenty‐four substances which showed significant activity were: twelve chloro‐ and fluoro‐phenoxy alkylcarboxylic acids substituted in the 4‐, 2, 4‐ and 2, 4, 5‐ positions, two chlorinated benzoic acids, α‐ and β‐naphthaleneacetic acid, 3‐indolylacetic acid, 2‐methoxy‐4‐diethylamino‐6‐isopropylamino‐1, 3, 5‐ triazine (methoxy‐ipazine), N,N‐diallyl‐α‐chloroacetamide (CDAA), 1,1′‐dimethyl‐4,4′‐bi‐pyridilium‐2A (paraquat), neomycin, dichloro‐m‐xyienol, and phenyl mercury acetate and chloride. Despite the many replications the high variability of the yield data does not allow of a precise classification of the relative activities. The most active compounds were 2, 4‐dichloro‐5‐fluorophenoxyacetic acid and 2, 4, 5‐trichlorophenoxyacetic acid (2, 4, 5‐T), although 2, 4‐dichlorophen‐oxyacetic acid (2, 4‐D) gave increases in yield comparable to those of 2, 4, 5‐T in some of the trials.
The analysis of grain yield of wheat in terms of photosynthetic ability and efficiency of translocation
Authors: LUPTON F. G. H. 
Published: February 2008

SUMMARYA technique, using 14CO2, for measuring the rate of photosynthesis and the distribution of synthesized carbohydrate in the same plant, applied to wheat plants at intervals from 10 days before anthesis until the plants were no longer green, showed that the rate of photosynthesis by the leaves and ears decreased steadily; it was much less for ears than for leaves. The proportion of carbohydrate translocated to the grain was very small at and before anthesis, but increased rapidly afterwards.Integration of these data provided estimates of yield based on physiological components which showed good agreement with measured yields at harvest, though varietal differences in observed yield could not be explained.An experiment in which ears were removed from plants 7 days after anthesis showed that photosynthetic activity was not limited by the size of the ‘sink’ to which photosynthates were translocated.
Hatching agents for the potato cyst‐nematode, Heterodera rostochiensis Woll
Authors: CLARKE A. J. , SHEPHERD AUDREY M. 
Published: February 2008

SUMMARYOf 444 compounds tested for their ability to stimulate eggs of Heterodera rostochiensis to hatch, forty‐five did so to varying extents. Many compounds that hatched H. schachtii Schm. eggs did not hatch H. rostochiensis eggs. The most effective compounds with H. rostochiensis were picrolonic acid, anhydro‐tetronic acid and vanadates. Tests with analogues of picrolonic and anhydro‐tetronic acids suggested some structures that may be concerned in hatching H. rostochiensis and H. schachtii. The simple analogues hatched the eggs of H. schachtii but not those of H. rostochiensis. Suitably placed polarisable atoms seemed to be an essential feature. Picrolonic acid contains pairs of polarizable atoms, about 4 and 6·7 Å apart, that may respectively be associated with the hatching of H. schachtii and H. rostochiensis. Other features of the more active hatching agents were a cis and co‐planar arrangement of the two polarizable atoms with respect to the rest of the molecule. The function of hatching agents is discussed.
Some hosts and properties of bulbous iris mosaic virus
Authors: BRUNT A. A. 
Published: February 2008

SUMMARYIris mosaic virus (IMV) was the only virus isolated from forty‐six bulbous iris plants of twenty‐two cultivars tested; it was common also in Iris danfordiae and I. reticulata but was not detected in any of fifty‐two rhizomatous iris plants with mosaic symptoms. IMV was transmitted to healthy irises with difficulty by mechanical inoculation but was transmitted efficiently by Myzus persicae.IMV infected eight of forty‐six plant species inoculated mechanically with partially purified virus preparations. Characteristic local lesions without subsequent systemic infection were produced in Amaranthus caudatus, six Chenopodium spp., and Tetragonia expansa; of these, C. quinoa and T. expansa were the best indicator and assay hosts.The virus was moderately stable in vitro and, unlike some similar filamentous viruses, was best purified by differentially centrifuging infective sap clarified with n‐butanol. Partially purified preparations from several hosts were infective, produced one specific light‐scattering zone after centrifuga‐tion in sucrose density‐gradient columns, were antigenic and contained particles of 760 mμ model length. IMV was not serologically related to any of nine similar aphid‐transmitted, filamentous viruses.
Studies of the seed‐transmission of tobacco ringspot virus
Authors: OWUSU G. K. , CROWLEY N. C. , FRANCKI R. I. B. 
Published: February 2008

SUMMARYSome factors influencing the transmission of tobacco ringspot virus (TRSV) by seed of soybean, Glycine max (L.) Merr. cv. Lincoln, have been studied.The age of a plant at the time of infection was the most important factor determining the amount of infected seed produced. The inability of TRSV to infect maturing embryos was not due to slowness of virus movement within the host. TRSV was consistently found in the embryo and perisperm tissues of infected seeds but not in the testa.All attempts to control seed‐transmission of TRSV in soybean failed. Storage for 7 months, and heat‐treatment of seed at temperatures near the thermal inactivation point of the virus, failed to inactivate TRSV in infected seeds. Spraying of TRSV‐infected plants with 2‐thiouracil and 8‐azaguanine had no effect on host infection and did not prevent seed‐transmission.
Changes in the microbial population of apple leaves associated with the inhibition of the perfect stage of Venturia inequalis after urea treatment
Authors: CROSSE J. E. , GARRETT CONSTANCE M. E. , BURCHILL R. T. 
Published: February 2008

SUMMARYTreatment of detached apple leaves in October with urea induced a rapid and prolonged increase in the microbial populations present in the leaves during the winter. These effects were accompanied by a major shift in the population balance from a predominantly Gram‐positive, chromogenic type of microflora to one dominated by Gram‐negative and non‐chromogenic organisms. Fluorescent pseudomonads became particularly numerous in the urea‐treated leaves and many were found to suppress the development in vitro of Venturia inaequalis. An organism forming yellow colonies, possessing exceptional activity against the scab fungus, which was also found in urea‐treated leaves, was shown to be a Gram‐negative, peritrichous bacterium.No antagonistic organisms were isolated from untreated control leaves, but many were found–usually chromogenic forms–which appeared to stimulate the scab fungus in vitro. Treatment with urea accelerated the decomposition of the leaves and suppressed the development of V. inaequalis in the portions of the laminae which remained structurally intact until the following spring.Many of the effects of urea were enhanced by the addition of glucose, streptomycin, or a suspension of a Pseudomonas sp. isolated from leaves during the winter. Streptomycin alone reduced the total numbers of microorganisms in the leaves but increased the proportion of Gram‐negative organisms: this was associated with diminished ascospore production in the spring.There was no direct evidence that the antagonistic flora stimulated by urea was responsible for the inhibition of V. inaequalis, and alternative explanations are suggested.