bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of imidacloprid on the sivlerleaf whitefly, Bemisia argentifolii Bellows and Perrring (Homoptera: Aleyrodidae), and whitefly parasitism
Authors: BETHKE JAMES A. , REDAK RICHARD A. 
Published: February 2008

SummaryBioassays were conducted under greenhouse conditions to determine the effect of imidacloprid on adult and nymphal stages of the silverleaf whitefly, Bemisia argentifolii Bellows and Perring, and parasitism by Encarsia formosa (Gahan). A flowable formulation (24Oglitre‐1) of imidacloprid at six rates (0.09, 0.04 and 0.02 g a.i. litre‐1 pot volume for experiments 1 and 2; 0.009, 0.004, and 0.002 g a.i. litre‐1 pot volume for experiment 3) was evaluated. After a 48 h exposure to treated plants, high mortality of adult whitefly (>94%) was observed. Adults exposed to poinsettias treated 150 days earlier also had significantly greater mortality (>79%) than the adults on control plants. When exposed to treated plants for only 6 h, >65% of adults were killed. All three rates of imidacloprid caused >97% mortality of immature whiteflies by day 19. When treated plants were continually exposed to adult whiteflies, immature mortality was 100% for the three higher rates of imidacloprid up to and including 88 days after treatment. During the same time, emerging adults were reduced significantly. Immatures reinfested on plants treated 161 days earlier, incurred 80% mortality at the higher rate 0.09 g a.i. litre‐1 pot volume and 38% mortality at 0.02 g a.i. litre‐1 pot volume. At lower treatment rates, results varied. At 0.009 g a.i. litre‐1 of pot volume, mean percentage whitefly mortality (65%) 25 days after treatment was significantly higher than the controls; however, whitefly mortality at 0.004 and 0.002 g a.i. litre‐1 pot volume was not significantly different from controls or plants treated with the higher rate. Parasitoids could develop to the adult stage on whiteflies infesting imidacloprid treated plants. Parasitism occurred at low levels (< 10%), doe to high levels of whitefly mortality on treated plants. No phytotoxicity was observed for any treatment throughout the length of the trials that lasted through flowering.
An investigation inot the use of multiple site characteristics to predict the presence and infestation level of wireworms (Agriotes sup., Coleoptera: Elateridae) in individual grass fields
Authors: PARKER W E , SEENEY F M 
Published: February 2008

SummarySixty‐two grass fields were sampled in England and Wales over a three year period to assess the level of wireworm population present. Data on site‐specific variables including soil physical characteristics, grass duration, grass genera diversity and other abiotic factors such as field aspect, altitude, and meteorological parameters were abiotic factors such as field aspect, altitude, and meteorological parameters were collected at each site. Only grass duration and soil bulk density showed any association with wireworm infestation stauts when considered as single variates. Data from a sub‐set of 41 fields were used to develop a series of multi‐variate discriminant rules to predit wireworm presence/absece in individual fields. These were vaildated using data from the remaining 21 fields. In general, the rules tended to over‐estimate the number of wireworm‐infested fields by misclassifying uninfested fields as infestes. Multivariate models to predict wireworm populaiton levels in infested fields were also developed using multiple and generalised linear regression. The predictive accuracy of these was poor. Neither the population prediciton models nor the presence/absence rulses accounted fully for the large inte‐field variation in wireworm infestation status.
Development of a dot immunobinding assay to detect Phytophthora spp. in naturally dark‐rooted woody plants
Authors: HAHN RENATE , WERRES SABINE 
Published: February 2008

SummaryAn indirect dot immunobinding assay (DIBA) with a PAb raised against an isolate of P. cinnumomi was evaluated to detect Phytophthora spp. in naturally dark‐rooted woody plants. Screening of different modifications of the procedure were done with root samples of Chamaecyparis lawsoniana non‐infected and infected with P. cinnamomi. With the optimised DIBA procedure, root infection could be diagnosed by a clearly defined halo around the spot and by a colour change in the spot using Fast Red or Fast Blue substrate. Detection of different Phytophthora species in Chamaecyparis plants from commercial nurseries was successful with the optimised procedure.
The effects of cassava mosaic virus disease on yield and compensation in mixed stands of healthy and infected cassava
Authors: OTIM‐NAPE G W , THRESH J M , SHAW M W 
Published: February 2008

SummaryThe effects of cassava mosaic virus disease (CMD) on yield in fully and partly infected stands of cassava were investigated in field trials in Uganda in 1990‐91 and 1991‐92. Three cultivars (Ebwanateraka, Bao and Bukalasa 1 l), each at three levels of cutting infection (O%, 50% and 100%) and harvested 510 and 15 months after planting (MAP) were used in a randomised block design with split‐split plots and four replicates. Moreover, yield and growth data for individual infected and uninfected plants were considered in relation to the health status of their nearest neighbours. In each experiment, fresh tuberous root yields of plants from 100% infected plots gave sigdicantly lower yields than those from 0% or 50% infected plots at each harvest date and the losses were greatest in cv. Bao. Yields of plants from 0% and 50% plots for each of the three cultivars were not significantly different, 10 and 15 MAP. The loss in yield differed between cultivars and harvest dates. Fresh stem, leaf and root yields and the number of tuberous roots were influenced by the health status of the plants harvested and that of their nearest neighbours. Uninfected plants surrounded by infected ones had more roots and heavier total fresh root, stem and leaf weights than those surrounded by uninfected ones. Overall, 26% and 42% compensation was recorded in 1990‐91 and 1991‐92, respectively. The effects of CMD on cassava production and of compensation in mixed stands of infected and uninfected plants are discussed, especially in relation to control strategies such as roguing.
Competitive ability and tolerance of organically grown wheat cultivars to natural weed infestations
Authors: COSSER N D , GOODING M J , THOMPSON A J , FROUD‐WILLiAM R J 
Published: February 2008

SummaryCompetitive ability of a traditional winter wheat cultivar (Maris Widgeon) was compared with two modem cultivars (Hereward and Genesis) when grown organically in each of four seasons in Gloucestershire, UK. In two seasons, cultivars were compared at two sowing dates (September and October or November). Cv. Maris Widgeon was the tallest cultivar and intercepted most photosynthetically active radiation (PAR), particularly if sown early. Cv. Hereward was taller than cv. Genesis when sown early. Cv. Maris Widgeon accumulated most nitrogen and dry matter early in the season (until the end of March) when sown early, but not when sown late. Relative nitrogen and dry matter accumulation by cultivars later in the season depended on season and sowing date. In one season cv. Maris Widgeon had significantly more early season ground cover. Cultivars did not differ significantly in early tiller production. Although most of these indirect measures of competitive ability were greater for the older variety cv. Maris Widgeon, infestation of Veronica spp. was greater in plots of this cultivar than in plots of either one or both of the shorter cultivars in two successive seasons. In the 1993/94 season, the soil seedbank from plots previously cropped with cv. Maris Widgeon produced more seedlings of Sinapis awensis. In the 1994 / 95 season, cv. Maris Widgeon plots contained less weed in terms of ground cover, numbers, dry matter and nitrogen than the other cultivars, and soil sampled from plots previously cropped with cv. Hereward sown late gave rise to larger numbers of weeds than cv. Maris Widgeon. Sowing date affected weed burdens and emergence to a much greater extent than wheat cultivar. In years and sowing date treatments with relatively low weed presence the shorter cultivars tended to yield more than cv. Maris Widgeon. When weed burdens were severe cv. Maris Widgeon yields were equal to or greater than those of either cvs Hereward or Genesis. The results suggest that the traditional tall cv. Maris Widgeon could be used beneficially to tolerate weeds in organic systems when high weed infestations were anticipated, but could not be relied upon to suppress weed development, and in some circumstances could actually encourage certain species.
Identification of the determinants of host resistantce and pathogenicity in interactions between Alternaria linicola Groves & Skolko and Linum Usitatissiumum L. accessions using multivariate analyses
Authors: EVANS N. , MCROBERTS N. , HITCHCOCK D. , MARSHALL M. 
Published: February 2008

SummaryMultivariate analysis of variance (MANOVA) and canonical variates analysis (CVA) were used to examine differences in host plant resistance and pathogen behaviour in interactions between Altemaria linicola and three genotypes of Linum usitatissimum, previously identified as susceptible, moderately resistant and resistant to the pathogen. Significant differences in pathogen development were found among the Linum accessions at 18, 24, and 40 h after inoculation. At 18 h after inoculation attempted penetration by the pathogen was relatively rare on all three accessions and canonical variates analysis revealed that overall differences among accessions resulted from large differences with respect to a small number of variables associated with successful penetration on the most susceptible accession. At later times after inoculation, when attempted penetration was more common, overall differences among accessions were found to result from smaller absolute differences among a group of variables which characterised the early colonisation of the host tissue. The results from these investigations are discussed in relation to recent research on the ecology of the pathogen and the importance of the timing of host responses to infection in determining host plant resistance.
Emergence of temperate pasture grases from different sowing depths: importance of seed weight, coleoptiele plus mesocotyl length and shoot strength
Authors: ANDREWS M. , DOUGLAS A. , JONES A V , MILBURN C E , PORTER D. , McKENZIE B A 
Published: February 2008

SummaryInter‐specific relationships between mean seed weight, coleoptile + mesocotyl (sub‐coleoptile internode) length and width, shoot strength and emergence from different sowing depths were examined for timothy (Phleum pratense L., mean seed weight 0.33‐0.48 mg depending on seed line), cocksfoot (Dactylis glomerata L., 0.65‐0.78 mg), perennial ryegrass (Lolium perenne L., 1.71‐2.19 mg), tall fescue (Festuca arundinucea Schreb., 1.73–2.60 mg), annual ryegrass (Lolium multiflorum Lam., 5.10‐5.20 mg) and prairie grass (Bromus willdenowü Kunth., 10.5–12.2 mg). Across species at 10,30 and 60 mm sowing depths in the field and 10, 15 and 30 mm sowing depths under controlled environment conditions, there was a significant (P < 0.05) positive correlation between emergence % and mean seed weight. Across species at 10–30 mm sowing depth under controlled environment conditions, emergence % was not significantly correlated with coleoptile + mesocotyl length but there were significant positive correlations between emergence % and coleoptile and mesocotyl width: shoot strength increased with increased coleoptile width across species. For seed lines of timothy of different mean seed weight (0.21‐0.81 mg), emergence %, coleoptile + mesocotyl length and coleoptile and mesocotyl width increased with increased seed weight at 10 and 15 mm sowing depth. Shoot strength increased with increased coleoptile width for timothy. For emerged and non‐emerged cocksfoot and timothy seedlings regardless of seed weight, mean coleoptile + mesocotyl length was > 10 mm at 10 mm sowing depth. It is concluded that at 10–30 mm sowing depth, increased emergence % with increased seed weight across species is not due to increased coleoptile + mesocotyl length. It is proposed that increased emergence % with increased seed weight across species at 10–30 mm sowing depths and across seed lines of timothy at 10 mm sowing depth is primarily due to increased coleoptile and mesocotyl width resulting in increased shoot strength and hence an increased ability to penetrate the substrate.
Seasonal variation in the response of Hagberg falling and liquefaciton numbers to propiconazole fungicide in wheat
Authors: KETTLEWELL P S 
Published: February 2008

SummaryThe hypothesis was tested that seasonal differences in the response to propiconazole fungicide of hagberg failling and liquefaction numbers are related to grain drying rate, as indicated by potential evaportranspiration. The response of Hagberg failling and liquefaciton numbers to late‐season applicaitions of propiconazole was calculated using data from a field experiments in each of the years 1981 to 1990 on winter wheat (Triticum aestivum) cv. Agalong grown with similar husbandry at one site. Cumulative potential evapotranspiration was calculated over seven different periods during grain ripening.No visible sprouting occurred in any experiment and Hagberg falling number was above 250 s in nine of the 10 years. Disease severity on the flag leaf was less than 7% in nine of the 10 years, and diseases were generally controlled well by propiconazole. There were no significant relationships between the response of Hagberg falling number and any of the potential evapotranspiration variables. The response of liquefaction number was exponentially related to each of three cumulative potential evapotranspiration variables which covered periods before the estimated date of 40% moisture content. Years with lower cumulative potential evapotranspiration gave the greater responses, but the relationships were considerably influenced by the two lowest potential evapotranspiration years. It was concluded that these data provide indirect evidence that the response of Hagberg falling number (when transformed to liquefaction number) to fungicide is mediated through grain drying rate, and furthermore that the results are compatible with the hypothesis that pre‐maturity alpha‐amylase activity is stimulated by slow grain drying.
A chance field observation and pilor laboratory studies of predation of the New Zealand flatworm by the larvae and adults of carabid and staphylinid beetles
Authors: GIBSON P H , COSENS D. , BUCHANAN K. 
Published: February 2008

SummaryA chance finding in an Edinburgh allotment was made of a stained carabid beetle larva that had eaten Artioposthiu triungulata previously stained red and released into the allotment during a dispersal experiment. In a pilot laboratory study the flatworm was eaten by larval and adult carabid and staphylinid beetles whereas seven other carnivorous species from five arthropod families did not. In another feeding experiment a carabid and a staphylinid larva each ate several specimens of the flatworm and gained tissue weight over 14 days. The conclusion drawn from these preliminary studies and the field observation is that certain carabid and staphylinid beetles are potential predators of A. triangulata.
Nematology: From curiosity to space science in fifty years!1
Authors: WEBSTER JOHN M 
Published: February 2008

SummaryThe young science of nematology has evolved and matured mostly in the last fifty years. This extraordinary growth reflects the agricultural needs of the foundation years, the 1950's and early 1960's, and the influence of scientific discovery and changing philosophies. The crucial role of chemical nematicides in increasing crop productivity was central to nematology's growth, and as other forms of nematode control have emerged so nematology has diversified in its usefulness to society. These changes are described with emphasis on the scientists and research laboratories in the United Kingdom.
Development of a system simulating commercial production conditions for assessing the potential spread of Phytophthora cryptogea root rot of hardy nursery stock in recirculating irrigation water
Authors: PETTITT T R , FINLAY A R , SCOTT M A , VIES E M DA 
Published: February 2008

SummaryA system was developed for monitoring the potential spread of Phytophthora cryptogea root rot of the hardy nursery stock (HNS) species Chamaecyparis lawsoniana, Erica x darlyensis and Calluna vulgaris in recirculating irrigation water on semi‐commercial scale production beds. The spread of disease was monitored by measurements of symptoms and by baiting bioassays. A range of baits was tested and the most sensitive was found to be shoot segments of Lupinus angustifolius. The pathogen spread rapidly throughout the system from infected plants in the recirculating irrigation water. Although the percentage of plants infected was high (in Chamaecyparis 73% in 1994 and 93% in 1995), the percentage of infections actively sporulating at any one sample date was much less (47% in 1994 and 63% in 1995) and shoot symptoms were even less evident (in Chamaecyparis 22% in 1994 and 38% in 1995). In Chamaecyparis the incidence of shoot symptoms was less than expected from results of inoculations of similar plants not irrigated with recirculated water (80% infected, 60% with symptoms). The reason for this difference is not known but it poses a serious threat to the quality of HNS produced using recirculated irrigation water and underlines the need for reliable pathogen control methods.
Determining the effectiveness of grazing and trampling by livestock in transmitting white clover mosaic and subterranean clover mottle viruses
Authors: MCKIRDY S J , JONES R A C , SIVASITHAMPARAM K. 
Published: February 2008

SummaryGlasshouse and mini‐sward experiments were done to determine the relative roles of grazing and trampling by livestock in transmitting white clover mosaic (WC1MV) and subterranean clover mottle (SCMoV) viruses between clover plants in pastures. Wounding due to grazing was simulated by repeatedly cutting plants with serrated scissors (glasshouse) or mowing (mini‐swards), while wounding due to trampling was simulated by repeatedly bashing plants with the flat end of a wooden hammer handle (glasshouse) or rolling (mini‐swards). In glasshouse experiments, cutting was more effective than bashing in transmitting WC1MV to white clover (Trifolium repens) plants but cutting and bashing transmitted it to subterranean clover (T. subterraneum) plants at similar rates. In an experiment with white clover mini‐swards, mowing was more effective than rolling in transmitting WC1MV, and when both were combined, initially spread exceeded that obtained when the spread from mowing and rolling alone was added together. In glasshouse experiments, bashing was more effective than cutting in transmitting SCMoV to subterranean clover plants. In one experiment, neither mowing nor rolling spread SCMoV in mini‐swards of subterranean clover. When transmission to subterranean clover cultivars which were ‘susceptible’ or ‘moderately susceptible’ to SCMoV was compared in glasshouse experiments, repeated bashing spread the virus more slowly to the ‘moderately susceptible’ cultivars. When mixed with ruminant saliva, infective sap containing WC1MV or SCMoV was still infective to clover plants after 4 wk storage at room temperature. When infective sap was allowed to dry naturally on a metal surface, SCMoV still infected clover plants when the dried sap was taken up in tap water after 4 but not 14 days, while WC1MV was infective after 24 h but not 4 days.These results suggest that grazing and mowing are more effective than trampling at transmitting WC1MV to white clover plants in pastures, while trampling is more effective at spreading SCMoV to subterranean clover. However, both transmitted WC1MV to subterranean clover at similar rates. Possible reasons for these differences are discussed in relation to differences in clover plant morphology and virus‐specific factors.
The use of S1 nuclease treatment of hybrid PCR products for the differentiation between PVY isolates
Authors: ROSNER ARIE , SPIEGEL SARA , MASLENIN LUDMILA , LEVY DAVID 
Published: February 2008

SummaryA new strategy based on treating PCR hybrids with S1 nuclease was used to differentiate between two PVY isolates. Mixed denatured and annealed hybrid PCR products of two PVY isolates including a tested strain and a reference N strain were treated with S1 nuclease. Single‐stranded mismatched regions were revealed by the S1 nuclease cleavage, yielding a characteristic pattern of bands in polyacrylamide gel by which virus isolates could be matched. Sequence analysis of the relevant PCR products revealed that only part of the mismatched regions were cleaved by the S1 nuclease. Still, the distinct pattern of degradation products enabled the differentiation between the PVY isolates. The general application of this procedure for strain differentiation is discussed.
Observations on patterns of granular fertiliser deposition beside hedges and its likely effects on the botanical composition of field margins
Authors: TSIOURIS S. , MARSHALL E J P 
Published: February 2008

SummaryPatterns of granular fertiliser deposition differed markedly between a pneumatic boom applicator and a spinning disk machine, both of which were tractor‐mounted. The pneumatic applicator gave relatively even distribution across the boom width. A spinning disk gave more variable deposition and significant amounts were spread further than the expected 12 m overlapping pattern. When operating with a deflector plate on the spinning disk, significant amounts of fertiliser were also spread further than the expected 6 m. However, when operating next to a hedge, there was evidence of fertiliser concentration at the base of the hedge and prevention of granules passing through to adjacent habitat. A peak concentration of up to 150 kg ha‐1 of fertiliser was deposited at the hedge/field edge interface.In a tray experiment on seedling competition and establishment, there was no evidence of nitrogen fertiliser effects, at rates found in the field, on early plant establishment or species diversity. However, in a competition experiment with established plants of four grass species grown in pots, the nitrophilous species Bromus sterilis was able to increase growth at increasing nitrogen level, at the expense of slow‐growing Brachypodium sylvaticum and Anthoxanthum odoratum. Whilst hedges may buffer fertiliser contamination of habitats adjacent to agricultural fields, deposition of concentrated nitrogen fertiliser beside the hedge is likely to encourage the growth of nitrophilous plant species. In the short term, this may not affect botanical composition or diversity, but to reduce the likely long‐term adverse effects of fertiliser misplacement, we recommend that farmers are encouraged to use pneumatic fertiliser applicators and to introduce vegetation buffer strips at field edges.
An ultrastructural study of bruising in stored potato (Solarium tuberosum L.) tubers
Authors: EDGELL T. , BRIERLEY E R , COBB A H 
Published: February 2008

SummaryPotato tubers of the cultivar Pentland Dell were investigated for ultrastructural changes following impact. Studies were carried out on tubers after 12 and 24 wk of storage using a falling bolt delivering 0.7 J of energy. Ultra‐thin sections were examined by light and transmission electron microscopy. Tubers stored for 12 wk exhibited no visual bruise formation, whereas visible bruising resulted following impact of tubers stored for 24 wk. An ultrastructural sequence of events during bruising was established as (1) a collapse of intracellular compartmentation, (2) increased ribosomal and mitochondrial abundance within the cytoplasm, (3) increased density of cytoplasm adjacent to the cell wall and surrounding amyloplasts, and (4) the development of melanin in bruised cells. These observations are discussed in relation to tuber turgor and physiology during storage.