bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on watercress chlorotic leaf spot virus and on the control of the fungus vector (Spongospora subterranea) with zinc
Authors: TOMLINSON J. A. , HUNT J. 
Published: February 2008

SUMMARYWatercress chlorotic leaf spot virus (WCLV) caused a yellow leaf spot disease of watercress at Pickering, Yorkshire. The virus was mechanically transmitted to and maintained in Chenopodium quinoa, C. amaranticolor and Petunia hybrida in which it caused systemic symptoms. It could not be mechanically transmitted, however, from infected C. quinoa to Chrysanthemum, Gynura aurantia, potato, tomato, watercress or nine other species of Cruciferae.WCLV could be partially‐purified after extraction in weak (0.05–0.1 M) but not strong (0.5 M) phosphate or tris/HCl buffer after clarification with diethyl ether and acidification to pH 3.9–4.0. Preparations were non‐infective if treated with 5% (vlv) ethanol or n‐butanol or if stored at — 12°C for 1 day or heated for 10 min at 54°C. Preparations were non‐infective after treatment with RNase or proteinase K but not after treatment with DNase.The virus was present in roots of diseased watercress plants which also contained the watercress crook root disease fungus Spongospora subterranea f. sp. nasturtii. Tests showed that WCLV was transmitted by S. subterranea zoospores and that it persisted in the resting spores of the fungus.The crook root disease was controlled by adding 0.3–0.5 μg Zn/ml to the inlet water supply to the crop. The water that had flowed through the crop contained 0.05–0.10 μg Zn/ml. Although this increased the zinc content of the watercress from 8–9 in untreated beds to 16–48 μg Zn/g in treated beds, this was below the tolerance recommended by the Food Standards Committee.A method is described of obtaining accurate dilutions of solutions of zinc sulphate (20% w/v ZnSO4.H2O) in the water supplying the crop using solutions of the red dye Ariavit Amaranth.
Storage of samples infected with lettuce or cucumber mosaic viruses prior to testing by ELISA
Authors: WARD C. M. , WALKEY D. G. A. , PHELPS KATHLEEN 
Published: February 2008

SUMMARYMethods of processing and storing lettuce mosaic and cucumber mosaic virus infected tissues prior to ELISA have been examined. Virus antigen detection was highest in samples homogenised in phosphate inoculation buffer (1% K2HPO4, 0.1% Na2SO3) and stored at either — 20°C or — 196°C. Detection was poor in samples homogenised in phosphate buffered saline prior to storage and in samples of all treatments stored at 4°C. Freeze‐dried leaf segments retained a high concentration of antigen, as did freeze‐dried homogenates of samples prepared in inoculation buffer.Higher levels of antigen were detected in samples stored as whole leaves at 4°C for 24 h before processing, than in samples stored as leaf segments during this period.
Partial purification of hatching activity for Globodera rostochiensis from potato root diffusate
Authors: ATKINSON H. J. , FOWLER M. , ISAAC R. E. 
Published: February 2008

SUMMARYThe potential of several chromatographic methods for isolating hatching factors for potato cyst nematodes from potato root diffusate was investigated using a bioassay based on emergence of juveniles from cysts. Gel filtration provided an overall estimate of molecular weight of 437 Da for the hatching activity and ion exchange chromatography indicated that at least 60% of the recovered activity was anionic in nature.Material less polar than the hatching activity could be removed by passing potato root diffusate through a reversed‐phase Sep‐Pak C18 cartridge and the elutant showed 83.3 ± 4.4% (mean of 32 cysts) of the initial hatching activity. High performance liquid chromatography (HPLC) with a reversed phase, C18 column and gradient elution (0–80% CH3OH in water) confirmed that much of the hatching activity was polar and that it was not retained by this method of separation. A weak anion exchange resin achieved slight retention of much of the hatching activity and an ion pairing reagent lowered the polarity sufficiently to allow some retention in subsequent reversed phase HPLC on a CIS column. Both ion exchange and ion pairing HPLC suggested that hatching activity was not chromatographed as a single compound and indicated that fractions able to influence the nucleolus of the nucleus within the dorsal pharyngeal gland cell did not always show hatching activity.
Inhibition of degreening in the peel of bananas ripened at tropical temperatures
Authors: SEYMOUR G. B. , JOHN P. , THOMPSON A. K. 
Published: February 2008

SUMMARYAn investigation was undertaken to examine the roles of ethylene, oxygen and carbon dioxide in the failure of bananas to degreen at high temperature. Also a comparison was made of the response of bananas and plantains to storage at high temperature.Bananas produced more ethylene at temperatures where they failed to degreen than at those where they turned fully yellow, and supplying high levels of exogenous ethylene to bananas ripening at high temperature did not induce the development of a yellow peel. Isolated peel tissue held, in the presence of ethylene, at 20 or 35°C failed to develop a yellow colouration at 35°C in air or 80% oxygen, while all detached peel tissue held at 20°C degreened. However, when atmospheres were enriched with carbon dioxide degreening of detached peel was suppressed at both 20 and 35°C. In contrast to bananas, plantain fruit degreened more rapidly at 35°C than at 20°C. The way in which high temperatures may inhibit degreening in bananas is discussed.
The importance of technique in establishing biocontrol agents — the moth Carposina autologa on Hakea sericea
Authors: DENNILL G. B. 
Published: February 2008

SUMMARYThe seed attacking moth Carposina autologa was released in South Africa for control of the weed Hakea sericea but established poorly. Altering the release method such that it corresponded more closely to natural infestation and better training and supervision of field workers resulted in a 111 % increase in success of a subsequent release.
Some continuing uncertainties in knowledge of herbicide behaviour in the soil
Authors: HANCE R. J. 
Published: February 2008

SUMMARYRecent developments concerned with the variability in the performance of soil‐ applied herbicides are reviewed with particular reference to phytotoxicity and to factors controlling persistence. It remains questionable that measurements of adsorption and herbicide concentration in the soil solution can adequately predict the phytoxicity of a herbicide in the soil. This is because such an approach ignores the spatial distribution of the herbicide and the parts of the plant through which a herbicide can be taken up. It also ignores the influence of climatic factors on persistence, uptake and plant response. In a general way persistence and the factors which control it are understood but detailed, reliable, quantitative analyses of the phenomena are not yet available. Much remains to be done before the interactions of the soil microflora with its environment and consequent effects on herbicides can be defined. There are still opportunities to improve the precision of use of soil‐applied herbicides based on better comprehension of the processes involved in the expression and duration of phytotoxicity.
Host ranges, symptoms and amino acid compositions of eight potexviruses
Authors: SHORT MARGARET N. , DAVIES JEFFREY W. 
Published: February 2008

SUMMARYThe host ranges, symptom expression and coat protein compositions of eight definitive potexviruses are described and compared. Only limited host range similarity was observed: clover yellow mosaic virus and white clover mosaic virus shared 11 of the 28 host species tested; foxtail mosaic virus and narcissus mosaic virus infected monocotyledons; barrel cactus virus and viola mottle virus had narrow host ranges but had eight of the host species in common. Amino acid analyses of coat proteins showed some similarity among the viruses tested, but little correlation with the different host range types. There was more variation of structurally important amino acids such as lysine, arginine, leucine and proline than might have been expected, but high alanine and low tyrosine, tryptophan, cysteine and methionine were typical of plant virus coat proteins.
The use of water traps for cranefly monitoring: an assessment of operator efficiency
Authors: BLACKSHAW R. P. 
Published: February 2008

SUMMARYUnskilled operators used water traps to monitor cranefly populations in 48 grassland sites in the summer of 1984. For each trap operated the numbers of males and females were recorded and these counts were checked in the laboratory to give estimates of operator error. Operators also recorded the amount of time they spent implementing the scheme. The probability of reporting a correct count for male craneflies was 0.796 and for females 0.846. There was a greater tendency for the male counts to be under‐rather than overestimated, and vice versa for females. Generally, the number of errors made was not related to either the number of craneflies taken or the rate at which they were sorted. Average times were calculated for different aspects of the monitoring system: 37 min for setting up four water traps; 40 min per field per week for servicing traps excluding handling craneflies; 18 flies/min sorting rate. Overall, the mean time spent implementing the scheme in one field was 209 min. It was concluded that operator error can be as important as predictive error in the implementation of a forecasting scheme and that it cannot be assumed that any monitoring system operates with complete accuracy.
A new method for disease‐loss studies used to estimate effects of Pyrenophom teres and Rhynchosporium secalis on winter barley yields
Authors: SHAW M. W. , ROYLE D. J. 
Published: February 2008

SUMMARYIt may be argued that the basic task of yield‐loss studies is to estimate the rate at which a given amount of disease causes a crop to lose yield at each instant during the growing season. This loss rate function can be estimated from detailed data on sets of epidemics and the yields resulting from them in otherwise similar crops. Under certain circumstances, the calculations reduce to regression of yield on integrals of functions of developmental time and disease. Thermal time may form a suitable approximation to developmental time.The technique was tested using 30 plots 12m × 4 m of winter barley cv. Sonja, in which epidemics of Pyrenophora teres and Rhynchosporium secalis developed. An equation describing loss rate due to P. teres throughout the season and R. secalis in spring was successfully developed. The loss rate due to P. teres was greatest later in the season, and disproportionately severe at low disease levels. On the basis of this experiment the proposed technique compares well with alternatives.
The effect of cultivar used as host for Polymyxa gmminis on the multiplication and transmission of barley yellow mosaic virus (BaYMV)
Authors: ADAMS M. J. , JONES P. , SWABY A.G. 
Published: February 2008

SUMMARYA viruliferous isolate of the fungal vector Polymyxa graminis was grown on roots of barley cultivars immune or susceptible to barley yellow mosaic virus (BaYMV). Zoospores or resting spores of the vector produced on different cultivars were then inoculated to a virus‐susceptible test cultivar. Although the vector established in all treatments, transmission of BaYMV was rare and usually nil from immune cultivars; amounts of virus detected serologically in their roots were very low, thus showing that resistance was to virus multiplication. If immune cultivars decrease the virus content of vector populations in the field, this would have important implications for disease control.
Virus diseases of subterranean clover
Authors: JOHNSTONE G. R. , McLEAN G. D. 
Published: February 2008

SUMMARYSubterranean clover (Trifolium subterraneum) is grown as a pasture legume in several temperate regions of the world where the soils are acidic and infertile, and the rainfall is winter dominant and less than 600 mm annually. It is particularly important in southern Australia where more than 16 million ha have been sown with this species as the pasture legume component.Nine viruses have been recorded infecting subterranean clover in the field. These are alfalfa mosaic, bean yellow mosaic (pea mosaic), beet western yellows, clover yellow vein, cucumber mosaic, pea enation mosaic, soybean dwarf (subterranean clover red leaf), subterranean clover mottle and white clover mosaic. In addition there is an important problem referred to as subterranean clover stunt that was assumed to be caused by a virus but whose aetiology is still unknown. The importance of these diseases is reviewed and details on their epidemiologies are outlined together with details on progress towards their control and some comments on matters worthy of attention in the future. Reference is also made to several exotic viruses known to infect subterranean clover experimentally that could possible cause problems if introduced into Australia.
The decimal code for the growth stages of cereals, with illustrations
Authors: TOTTMAN D. R. 
Published: February 2008

SUMMARYThe decimal code for the growth stages of cereals, devised by Zadoks, Chang & Konzak (1974), is reproduced with stylised drawings of selected stages of wheat, barley and oat plants. Expanded definitions of some of the descriptive phrases are designed to assist the application of the code to agrochemical research, development and use in the UK.
Gel formulations for the treatment of pruning wounds.
Authors: CLIFFORD D. R. , GENDLE P. , HOLGATE M. E. 
Published: February 2008

SUMMARYA mixture of carbendazim and triadimefon in an aqueous gel formed from sodium alginate is an alternative to conventional sealants for the treatment of pruning wounds on apple and plum trees. Patterns of movement and persistence of fungicides after application of the gels during dormancy or the growing season are reported. Callus tissue formation is not impaired and treatment does not affect the natural microbial population of the wood. Persistence of fungicides within the wood is insufficient for the formulation to be suitable for a mature wound pathogen treatment but this easily prepared formulation can protect wounds for as long as they are vulnerable to attack by the fresh wound pathogens Nectria galligena and Chondrostereum purpureum.
Laboratory observations on the effect of humidity on the persistence of infectivity of conidia of the aphid pathogen Erynia neoaphidis
Authors: BROBYN PATRICIA J. , WILDING N. , CLARK SUZANNE J. 
Published: February 2008

SUMMARYConidia of the aphid pathogen Erynia neoaphidis on detached bean leaves and glass coverslips maintained at 20°C and at humidities from 40 to 100% r.h. lost their infectivity for pea aphids at a rate dependent on the humidity. Infectivity declined most rapidly in inocula kept on leaves at 70% r.h. and persisted longest in those at 40 and 50% r. h. That of inocula on coverslips declined most rapidly at 77% r.h. and persisted longest in those kept at 40% r.h. Even after 21 days a little infectivity was retained by conidia stored at 50% r.h. on leaves and 40% r.h. on coverslips.
Standard descriptions of growth stages of annual dicotyledonous weeds
Authors: LUTMAN P. J. W. , TUCKER G. G. , BROAD HILARY 
Published: February 2008

SUMMARYFifteen growth stages of annual dicotyledonous weeds are described and illustrated, showing the progression from emergence to senescence. These stages have been agreed following widespread consultation amongst the member organisations of the British Crop Protection Council. Stages are defined in terms of leaf number, plant size and floral development. They are intended for use in the field by farmers, growers and their technical advisers, on herbicide labels and in advisory publications. They are also of value in research, aiding the description of weeds in field and glasshouse experiments.
Improving the biological efficacy of small droplets of permethrin by the addition of silicon‐based surfactants
Authors: ADAMS A. J. , FENLON J. S. , PALMER ANNE 
Published: February 2008

SUMMARYOil‐soluble and oil‐dispersible silicon‐based, non‐ionic surfactants were incorporated in two oil‐based formulations of permethrin. At the optimal concentration of surfactant, 40 μm droplets of the insecticide were twice as effective against whitefly (Trialeurodes vaporariorum) larvae as droplets without surfactant. The addition of a surfactant to a formulation containing 10 g/litre permethrin resulted in a spray mixture which was at least as effective as the same formulation containing 100 g/litre permethrin without surfactant. These improvements in efficacy were not attributable to droplet spread or perimeter on the leaf surface, or to differences in the surface tension of the mixtures. The implications of these results for ultra‐low volume spraying are discussed. A statistical model based on the zero‐cell of the Poisson distribution is described and used to analyse the bioassay results.
Factors affecting the production and motility of zoospores of Polymyxa graminis and their transmission of barley yellow mosaic virus (BaYMV)
Authors: ADAMS M. J. , SWABY A. G. 
Published: February 2008

SUMMARYCultures of Polymyxa graminis were maintained in roots of barley plants grown in sand at different temperatures using Wisconsin soil temperature tanks. At 17 – 20°C, the minimum time from inoculation with cystosori to the production of zoospores from the inoculated roots was 2 – 3 wk. At 11 – 20°C many zoospores were produced but the incubation period was longer at the lower temperatures. Above 20°C little fungal development occurred.The duration of motility of zoospores ranged from c. 1 h to > 24 h. Bovine serum albumen (BSA) prolonged motility but glycine and glucose had no effect or, at higher concentrations, were toxic. Zoospores were rapidly immobilised by zinc ions in solution at or above 10μg/ml.In some experiments BSA added to the zoospore suspension greatly increased transmission of barley yellow mosaic virus (BaYMV) while glucose, glycine and ovalbumen decreased it. When seedlings were incubated with zoospore suspensions for 24 h at different temperatures, BaYMV transmission was high (> 60%) at 10, 15 and 20°C but there was little at 5 or 25°C. In experiments to determine the time taken for zoospore penetration, seedlings were incubated in suspension for different periods of time and then rinsed in zinc sulphate solution to kill free zoospores. Between 3 and 3·5 h was needed for zoospores to establish infection. Transmission occurred equally to plants of various ages between 3 days and 7·5 wk.
The effect of triadimenol on the cytology and growth of sensitive and resistant strains of Ustilago avenue
Authors: HIPPE SIGRUN , GIESEN ULRIKE 
Published: February 2008

SUMMARYTwo triazole resistant mutants of Ustilago avenae and a wild type strain were treated with different concentrations of the fungicide triadimenol in liquid cultures. Growth rates were measured and the morphology of the sporidia examined by light and electron microscopy. After treatment with 1 – 10 μg ml‐1 for 4 days wild type sporidia increased in growth rate, changed from budding to filamentous growth and had considerably thicker cell walls. Their cytoplasm also showed strong degeneration and damage to the cell organelles. The resistant strains were not influenced under these conditions but under longer exposure (14 days) to higher fungicide concentrations (50 to 200 μg ml‐1) similar changes to growth rates, morphology and cell wall thickness also occurred. However, cell disruption only occurred at 200 to 250 μg triadimenol ml‐1 and there were differences in cell wall thickening. One resistant strain (r13) never showed thickening, while in the other (r8), the wall consisted of two distinct layers. The implications of these results are discussed in relation to possible resistance mechanisms.
Bacterial blight of kiwifruit
Authors: YOUNG J. M. , CHEESMUR G. J. , WELHAM F. V. , HENSHALL W. R. 
Published: February 2008

SUMMARYBacterial blight of kiwifruit (Actinidia deliciosa) is caused by Pseudomonas viridiflava. Symptoms are rot of floral buds and flowers, and spots on leaves. Buds and flowers nearest the ground are most likely to be affected. Isolations made from healthy buds, flowers and leaves suggest that the pathogen is an epiphyte on vines throughout the year. Disease incidence fluctuates between seasons, and varies between orchards. A relationship between disease incidence and rainfall in spring is indicated.
A field screening method to evaluate rice breeding lines for resistance to the hoja blanca virus
Authors: ZEIGLER R. S. , RUBIANO M. , PINEDA A. 
Published: February 2008

SUMMARYA method is presented for rearing large colonies of viruliferous Sogatodes oryzicola, vector of the rice hoja blanca virus (RHBV). These colonies were used for field screening up to 10 000 rice breeding lines per season for resistance to RHBV. Uniform infection of check varieties in the field indicated that the method was adequate. Field release of vectors when plants were 14 days old resulted in satisfactory disease incidence, after 21 days, to distinguish lines segregating for resistance from lines uniformly resistant or susceptible. Various sources of resistance identified earlier continued to be resistant under the screening conditions. Progeny of lines identified as non‐segregating resistant continued as non‐segregating resistant. Resistant plants from lines segregating for resistance produced progeny lines that were segregating and non‐segregating. Ratios of resistant to susceptible plants in F1 progeny of three‐way crosses were consistent with earlier observations that RHBV resistance is a dominant character. The susceptibility of the commercial checks indicates that rice production in RHBV areas of tropical Latin America continues to be at risk from the virus. Virus‐resistant commercial cultivars resulting from this method should be available in 2 years.
Light quality effects on the appearance of tillers of different order in wheat (Triticum aestivum)
Authors: CASAL J. J. 
Published: February 2008

SUMMARYPlants of Triticum aestivum cvs Norkin Pan 70, La Paz Inta, Buck Cencerro and Buck Cimarron were grown outdoors in individual pots with two sowing dates and irradiated at the end of the day either with red or far‐red light. In red‐treated plants the number of tillers was close to the potential calculated from the number of leaves on the main shoot but far‐red treated plants produced less tillers. The magnitude of the effect was larger for secondary and tertiary than primary tillers. Thus, the proportion of primary to secondary and tertiary tillers was larger in FR‐treated plants. Leaf sheath and lamina were longer under FR in the second sowing date, possibly due to warmer nights. These responses were greatly affected by the genotype. Significant differences in ear number were not found but in one of the sowing dates red‐light‐treated plants showed a lower grain number and yield than those treated with far‐red.
Field assessments of resistance to the aphids Sitobion avenae and Metopolophium dirhodum in old and modern spring‐sown wheats
Authors: SOTHERTON N. W. , LEE G. 
Published: February 2008

SUMMARYThree ancient varieties of wheat and two modern spring‐sown cultivars were investigated in the field to assess their resistance to the cereal aphids Sitobion avenae and Metopolophium dirhodum; the monitoring of natural populations and detailed observations using clip‐cages were both undertaken.The ancient variety Einkorn showed both antixenotic and antibiotic resistance to S. avenae, and antibiotic resistance to M. dirhodum. The resistance to S. avenae was greater than that to M. dirhodum.The value of Einkorn as a component of a resistance‐breeding programme is discussed with reference to its agronomic and genetic characteristics and with reference to the pest status of cereal aphids.