bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparison of sampling methods for bibionid larvae (Diptera: Bibionidae) in grassland
Authors: BLACKSHAW R. P. , D'ARCY‐BURT S. 
Published: February 2008

SUMMARYThree extraction methods were compared for the recovery of bibionid larvae from grassland soil samples. Only wet‐sieving followed by flotation in a saturated salt solution yielded bibionids. No larvae were recovered either with modified Tullgren funnels or by slow immersion of soil cores into a saturated salt solution. The efficiency with which larval bibionid populations can be estimated is poor. Generally, smaller cores yielded more larvae per volume of soil. Most bibionids were found in the top 4 cm of soil. It is concluded that 10 cm diameter and 6–8 cm deep soil cores are an acceptable compromise between efficiency and sampling effort but sample size will largely be determined by the resources available for processing of samples.
Susceptibility of western flower thrips, Frankliniella occidentalis (Pergande) to fumigation with methyl bromide
Authors: MACDONALD O. C. 
Published: February 2008

SUMMARYAll life stages of the western flower thrips (Frankliniella occidentalis Pergande) were tested for their response to the fumigant methyl bromide and dose response curves were established. Pseudo‐pupae were the most tolerant stage with a calculated LD99 of 53.1 mg litre“1 h at 15oC with a gas concentration of 13.5 mg litre”1, but no survivors were found in any test above a concentration time product of 40 mg litre“1 h. Standard 4 h fumigations achieving a CTP of 54 mg litre”1 h that are used to control other pests are therefore likely to give very high levels of control of western flower thrips.
Epidemiological studies on the stunt disease of highbush blueberry
Authors: TOZZP D C MAESO , RAMSDELL D. C. , TABOADA O. , LEE I ‐M , DAVIS R. E. 
Published: February 2008

SUMMARYPopulation levels of Scaphytopius spp., possible sharpnosed leafhopper vectors of blueberry stunt disease (BBSD), were monitored during 1989,1990 and 1991, using yellow sticky traps and a D‐Vac power aspirator. Scaphytopius magdalensis (Prov.), S. frontalis (Van D.) and 5. acutus (Say) had two population peaks, one after the petal fall stage and a larger second peak in late Summer to early Autumn. Healthy cv. Bluecrop highbush blueberry (Vaccinium corymbosum L.) plants were placed under stunt‐diseased bushes in the field for 2‐wk periods during 1989 and 1990. These plants and some of the leafhoppers trapped during 1990 and 1991 were tested for mycoplasma‐like organism (MLO) infection with a DNA probe that detected BBSD‐associated MLO. The percentage of plants and the number of Scaphytopius spp. that were MLO‐positive tended to follow the same bimodal distribution found in the population studies. BBSD transmission tests were performed with Scaphytopius spp. collected from the field. Stunt‐related MLO transmission was achieved with S. magdalensis, S. acutus and 5. frontalis.
Multiplication and distribution of iris severe mosaic virus in secondarily‐infected iris bulbs after stress induced by heat and wounding
Authors: VLUGT CORNELIA I M VAN DER , LOHUIS HENDRICUS , DIJKSTRA JEANNE , MARQUART ARNOUD , GOLDBACH ROB W. , BOONEKAMP PIET M. 
Published: February 2008

SUMMARYIn freshly‐lifted iris bulbs infected with iris severe mosaic virus (ISMV), virus was not always detected in the basal plate and rarely in bulb scale tissue. After exposing the bulbs to stress (wounding or high‐temperature treatment) the sensitivity of virus detection was enhanced. The improved detection of viral antigen after local stress (wounding) coincided with an increase of viral RNA synthesis. When general stress (high‐temperature treatment) was applied, the virus could be reliably detected in the basal plate, and usually in vascular bundles and surrounding tissue. Virus was detected in the upper part of the bulb scale when such tissues were detached from the basal plate. Thus, virus must have been present in the scales in localised spots, albeit at a very low concentration, and multiplication is likely to be the main factor involved in the improved sensitivity of viral detection. The distribution of ISMV in the bulb after local or general stress treatment is discussed.
Characterisation and serology of virus‐like particles associated with faba bean necrotic yellows
Authors: KATUL UNA , VETTEN H. J. , MAISS E. , MAKKOUK K. M. , LESEMANN D‐E , CASPER R. 
Published: February 2008

SUMMARYA disease showing chlorosis, leaf rolling and stunting in Vicia faba and other legumes was observed in West Asia and North Africa during 1987–1988. The putative causal agent could not be transmitted mechanically, but could be transmitted by aphids, most efficiently by Acyrthosiphon pisum, in the persistent manner. Further studies revealed isometric virus‐like particles (VLPs) closely associated with the disease, although their infectivity could not be demonstrated by membrane feeding. These particles, measuring c. 18 nm in diameter and containing a capsid protein of about 22 kDa and ssDNA of about 1 kb, are hereafter designated faba bean necrotic yellows virus (FBNYV). A high proportion of circular nucleic acid molecules of about 0.9 kb were visualised by electron microscopy. Hybridisation analysis of cloned viral DNA suggests that the circular genome is larger than 1 kb and consists of several components of similar size. An antiserum produced against FBNYV was used in ELISA, immunoelectron microscopy (IEM) and Western blot experiments for virus detection in aphids and field samples and for serological comparison with other viruses. Weak heterologous reactions between FBNYV and subterranean clover stunt virus (SCSV) were detected in IEM, but could not be confirmed in ELISA or Western blots. No serological relationship to banana bunchy top virus (BBTV) was detected. Using a direct tissue blot immunoassay (TBIA), FBNYV was detected in vascular tissue of infected faba bean leaves and stems.
A model of the competitive relationships between R. cochinchinensis and Z. mays
Authors: BRIDGEMOHAN PURAN , McDAVID CHARLES R. 
Published: February 2008

SUMMARYAn understanding of the competitive relationship between weed and crop can be used in assessing what physiological aspects of the association can be exploited in the control of the weed. Field and greenhouse studies were conducted with Z. mays L. and Rottboellia cochinchinensis (Lour.) W D Clayton using a modified replacement series model in which the overall weed crop density in each treatment was maintained as a constant, but the proportion of the two species varied. The results indicated that the crop had greater competitive ability (Kmr) than the weed even at increasing weed densities. Under field conditions, the values of the Plant Relative Yield (PRY) indicated that severe specific competition was occurring and suggested that some environmental factor was limiting, while the Relative Yield Total (RYT) suggest that either the crop and the weed were exploiting the resources in mutual antagonism or that allelopathy was occurring. The limiting environmental factor that both species exploited in mutual antagonism in the field was light under conditions of adequate soil moisture and nutrients.
Inbred line versus Ft hybrid breeding in swedes (Brassica napus L. var. napobrassica Peterm)
Authors: BRADSHAW J. E. , WILSON R. N. 
Published: February 2008

SUMMARYIn 1989 seven F[hybrid swedes were produced in polythene tunnels. The female parent was an inbred line derived from cv. Ruta 0tofte, and made self‐incompatible with an S‐allele introduced by backcrossing. Three more hybrids were produced in 1990 in a similar way with an inbred line from cv. Criffel as female parent. In trials in Dundee over the period 1990 to 1992, better parent heterosis for dry matter yield in the hybrids ranged from 1.9% to 19.2%. There was no such heterosis for dry matter percentage nor for mildew resistance.The highest yielding hybrid was the one between the Criffel line and an inbred line from cv. Magres. It averaged 9.9% heterosis over the two years 1991 and 1992, outyielded seven commercial cultivars, but had a lower yield (12.3 t/ha) than an F6 line SS5 (13.3 t/ha) derived from the cross between the Criffel and Magres lines by pedigree inbreeding with selection.It is concluded that high yielding heterotic F/s should be the starting point rather than the finishing point of swede breeding programmes, and that research into breeding methods should concentrate on improving the efficiency of pedigree inbreeding following hybridisations, rather than on ways of producing Fj hybrids.
Comparative studies of light leafspot (Pyrenopeziza brassicae) epidemics on the growth and yield of winter oilseed rape
Authors: JEFFERY D C , JENKINS P D , JONES D GARETH 
Published: February 2008

SummaryComparisons of epidemics of light leafspot of differing duration and time of initiation were made in two experiments using a single cultivar of Brassica napus. Fungicide was applied before introduction of disease to prevent infection or some time after inoculation to stop further disease development. In the first experiment, substantial reductions in green leaf area and total plant dry‐matter were found at flowering when disease was introduced in the autumn or in January. Plant dry weight at maturity was also greatly reduced in these treatments. The detrimental effect of an epidemic initiated in the autumn was avoided to a large extent if fungicide application began in February. Epidemics initiated in March had only small effects on final dry‐matter yield. Seed yield was negatively correlated with the length of the epidemic. In a second experiment, early epidemics initiated in the autumn were halted after different time intervals. Commencing fungicide application even as early as December failed to prevent some loss of dry weight at flowering. At maturity, however, dry weight and seed yield were reduced significantly when fungicide application was delayed until February. Failure to control the disease resulted in a 46% loss of seed yield.
Amplification of plasmid DNA to detect plant pathogenic mycoplasmalike organisms
Authors: GOODWIN P H , XUE B G , KUSKE C R , SEARS M K 
Published: February 2008

SummaryThe polymerase chain reaction (PCR) was employed to develop a specific assay for plant pathogenic mycoplasmalike organisms (MLOs). A cloned fragment of a plasmid from a severe strain of western aster yellows (AY)‐MLO was sequenced to identify oligonucleotide primers for PCR. Amplified DNA fragments of the predicted size were obtained from DNA extracted from plants and insects infected with pear decline MLO, beet leafhopper‐transmitted virescence agent, elm yellows MLO and several AY‐MLO strains. No amplification occurred from healthy leafhopper or plant DNA. The PCR‐based assay was over 500 times more sensitive than a _tilized_tion‐based assay which _tilized a cloned AY plasmid fragment as a probe. With the PCR‐based assay, MLOs could be detected using DNA samples of leafhoppers that were only crushed and boiled in buffer. Amplification of the target DNA was confirmed by digestion of the PCR product with Mbo I which yielded predicted sized fragments for all MLO strains except Bradford AY and eastern AY. Sequencing the PCR product from elm yellows and eastern AY‐MLOs revealed greater than 90% homology, and the failure to restrict the PCR product with Mbo I was due to a single base change in the restriction endonuclease site. The ability of the assay to detect a wide range of MLOs with minimal sample preparation and high sensitivity will be useful in epidemiological studies of MLO‐caused diseases.
Effect of dinitroaniline herbicides on rhizobia, nodulation and N2(C2H2) fixation of four groundnut cultivars
Authors: DURGESHA M 
Published: February 2008

SummaryField, greenhouse and laboratory investigations were conducted to determine the effect of four dinitroaniline herbicides on rhizobia, nodulation and nitrogen fixation of four groundnut cultivars. Benefin, dinitramine and nitralin used at recommended levels decreased nodule dry weight, nitrogenase activity and total nitrogen of groundnut tops and pod yield in three cultivars Kadiri 71‐1, Kadiri‐2, ICGS‐11 and not for a fourth cultivar, Kadiri‐3 of groundnut (Arachis hypogaea L.), but fluchloralin used at the recommended level increased the nodulation rate, nitrogenase activity and total nitrogen of groundnut tops and pod yield compared to untreated plants. Studies were conducted in vitro to determine the relative toxicity of the herbicides on four Rhizobium strains isolated from the nodules of four cultivars of groundnut. It was found that various strains of rhizobia differ in their sensitivity to different rates of the herbicides tested. Carbon dioxide exchange rate (CER) of all the cultivars which received herbicide treatment was measured at different time intervals to determine the relationship between photosynthesis and inhibition of nodulation. The lack of adverse effect on the CER of four cultivars when treated at recommended concentrations indicated that nitrogen fixation was affected in cultivars Kadiri 71‐1, Kadiri‐2 and ICGS‐11 due to inhibition of nodulation.
Biochemical and bioassay analysis of resistance of potato (Solanum tuberosum L.) cultivars to attack by the slug Deroceras reticulatum (Muller)
Authors: JOHNSTON K A , PEARCE R S 
Published: February 2008

SummaryA method is described for using young field slugs Deroceras reticulatum (Muller) in a bioassay study of biochemical resistance of potato (Solanum tuberosum L.) cultivars to slugs. Tuber parts or an artificial diet were provided as food sources. Comparisons were made of feeding, survival and weight gain between the susceptible cultivar Maris Piper and the resistant cultivar Pentland Dell. Biochemical analyses were made of these two cultivars and the resistant cultivars Stormont Enterprise and Majestic. Comparisons of tuber sections and peelings as food sources indicated factors affecting growth were located in the surface layers of the tubers. Phenolics and glycoalkaloids were concentrated in the surface layers but the amounts were similar in the susceptible and resistant cultivars and the bioassays indicated that neither acting alone could explain resistance. The amounts and distribution of free amino acids also did not correlate with resistance although when supplied in the artificial diet they partly inhibited feeding. Proteinaceous inhibitors of slug gut proteolytic enzymes were present throughout the tubers but were not concentrated in the surface layers and the amounts were similar in the different cultivars thus they too did not explain the difference in susceptibility between the cultivars. Bioassays using acetone extracts (low molecular weight substances) and acetone powders (high molecular weight substances) either alone or in combination indicated that the resistant cultivar Pentland Dell contained a high molecular weight substance which together with a low molecular weight substance from either the same cultivar or the susceptible Maris Piper could confer resistance. Bioassays using protein extracts supplied in the presence or absence of chlorogenic acid indicated that this mechanism could comprise enzymic oxidation of phenolics. Assays of phenolase confirmed this since activity was highest in the outer layers of the tubers and was highest in the three resistant cultivars. Thus the chief resistance factor identified was high phenolase activity acting rapidly on phenolics when the slug first bites the tuber surface. The quantity of phenolics per se did not control the resistance. Thus while phenolics must be available, resistance is compatible with low blackening on cutting the tuber.
In vivo use of extracts from Ocimum gratissimum and Cymbopogon citratus against Phytophthora palmivora causing blackpod disease of cocoa
Authors: AWUAH R T 
Published: February 2008

SummaryCrude steam distillate from Ocimum gratissimum sprayed onto infection courts on detached cocoa pods moments after inoculation with Phytophthora palmivora completely inhibited the pathogen and blackpod lesion development on 75% of the infection courts. Disease suppression obtained with the extract was comparable to that obtained with a 2% Kocide 101 suspension. In the field, the O. gratissimum extract also suppressed lesion development although to a significantly lower (P = 0.05) extent in comparison with Kocide 101. Blackpod lesion expansion rates of 3.80, 3.56, 2.71 and 0.78 cm/day, respectively, were associated with pods treated in the field with C. citratus extract, tap water, O. gratissimum extract and 2% Kocide 101. The extract from Cymbopogon citratus was also ineffective on detached pods. Sporangia of P. palmivora from sporu‐lating blackpod lesions on both detached and non‐detached pods lost their infectivity within 1 h of treatment with the O. gratissimum extract. This effect was superior to that obtained with Kocide 101. Fungitoxicity of the extract on pods, however, was lost within 3 h of application. Thus, despite its in vivo effectiveness as an eradicant, the O. gratissimum extract, in its present form, has limited utility as a protectant fungicide.
Incidence of potato virus Y infection in seed and ware tubers of the potato cv. Record
Authors: BARKER HUGH 
Published: February 2008

SummaryThe incidence of potato virus Y (PVY) infection was assessed in samples of potato tubers, cv. Record, taken from Scottish seed stocks and English ware crops grown from some of these seed stocks. PVY was readily detected by ELISA of tuber sprouts. PVY‐infected tubers were found in 10 seed stocks of 84 tested. The mean level of virus infection was 0.23%, 0.76% and 0.56% in Super Elite, Elite and AA stocks respectively. In 46 commercial ware crops grown from some of these seed stocks, a substantial proportion of the harvested tubers in all but one of the crops were infected with PVY, the mean percentage of infected tubers was 58.5%. Ware crops grown from seven seed stocks in which PVY had been detected (mean 6.2% infection in seed) contained a mean of 70% infected tubers, compared with 56% infection in crops grown from 39 stocks in which PVY was not detected in the seed tubers. The predominant PVY strain detected in the ware crops was the veinal necrosis strain (PVYvn).
A field evaluation of different criteria for determiningthe need to treat winter wheat against the grain aphid Sitobion avenae and the rose‐grain aphid Metopolophium dirhodum
Authors: OAKLEY J N , WALTERS K F A 
Published: February 2008

SummaryThe economics of control of grain aphid (Sitobion avenae) and rose‐grain aphid (Metopolophium dirhodum) were investigated in a series of experiments carried out across England in 1988 and 1989. Sprays of pirimicarb or dimethoate were applied at three growth stages and yield effects measured. Aphid infestations were determined by a range of different methods, to evaluate the value of each for decision making.Aphids overwintered in crops in mild conditions in both seasons, resulting in early population build‐up and decline in many cases. Aphicide sprays applied during the booting stage increased average yields by 0.26 t/ha. Profitability of the treatment strategies considered was not greatly enhanced by selective spray application related to aphid assessment at this stage. Delaying decision making to the flowering or grain‐filling stages resulted in reduced profitability. A poor correlation between aphid numbers and crop yield response to sprays was found. This was shown to be due to differences in subsequent aphid population development and in aphicide efficacy. Grain quality was affected only by high aphid infestations which caused large yield reductions.
Predicting leatherjacket population frequencies in Northern Ireland
Authors: BLACKSHAW R P , PERRY J N 
Published: February 2008

SummaryAnnual surveys of leatherjacket (Tipula spp. larvae) were made in Northern Ireland to provide warning of the likelihood of damage to spring sown cereals after grass. A climate‐based multiple regression model was developed to estimate mean annual populations. Ades distributions were fitted to the annual data of leatherjacket counts to provide common estimates of parameters r and r. These values were then held constant to provide yearly estimates of A, the third parameter. The relationship between A and the sample mean was established so that a frequency distribution could be generated for any estimated mean population density. The ability of these models to predict leatherjacket frequency distributions was validated by using weather data for 1985–1988 to predict the number of fields with populations in excess of thresholds of 0.5,0.75 and 1 times 105ha‐1. It is concluded that the predictions were of sufficient accuracy to substitute for the annual leatherjacket survey.
Evaluation of fungicides applied to soil to control naturally‐occurring take‐all using a balanced‐incomplete‐block design and very small plots
Authors: BATEMAN G L , HORNBY D , PAYNE R W , NICHOLLS P H 
Published: February 2008

SummarySix sterol biosynthesis‐inhibiting fungicides representing several combinations of properties were applied to soil to control naturally‐occurring take‐all (caused by Gaeumannomyces graminis var. tritici) in winter wheat in field experiments in two successive years. The average take‐all severity category was never more than moderate in the different clay‐loam and sandy loam sites used in each year. At each site in each year there were six treatments and an untreated control in an arrangement based on a balanced‐incomplete‐block design for six treatments in 10 blocks each with three treatments. Each block had three treated plots and a control plot and was paired with the complementary block of three treatments (plus control) to form a complete replicate, of which there were 30 per site.Take‐all assessments in June or July showed that after incorporation into the seed bed (at 2 kg ha“1and sometimes at 1 kg ha”1) in autumn, two non‐volatile, strongly lipophilic compounds, nuarimol and triadimenol, with good intrinsic toxicity to the take‐all fungus and slow rates of degradation, partially controlled take‐all. However, another compound, flutriafol, with similar properties to nuarimol and triadimenol, controlled take‐all less. Two slightly volatile, strongly lipophilic compounds, flusilazole and penconazole, with good intrinsic activity, were less effective (at 2 kg ha‐1). A volatile, less lipophilic compound, PP 969, with less intrinsic activity, also partially controlled take‐all, but only after application as a drench in the spring (2 kg ha‐1). The most effective treatments were generally more effective the greater the level of disease (as indicated by assessments of disease in control plots), especially in spring assessments of disease.Although flutriafol did not perform as expected, it still seems reasonable to conclude that the requirements for a soil‐applied fungicide to control take‐all are likely to be: (i) good intrinsic fungitoxicity, (ii) some mobility in soil water (i.e. not strongly lipophilic), and (iii) season‐long persistence.