bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between powdery mildew infection, green leaf area and grain yield of barley
Authors: CARVER T. L. W. , GRIFFITHS ELLIS 
Published: February 2008

SUMMARYBarley plants (cv. Julia), grown in a greenhouse in large boxes of John Innes compost at a spacing equivalent to 300 plants/m2, were exposed to powdery mildew from growth stage (G.S.) 2 (Feekes scale) until maturity. Treatment with ethirimol was used to provide five different epidemic patterns, viz. (i) no mildew, (ii) early mildew, (iii) late mildew, (iv) continuous mildew and (v) continuous mildew but delayed by seed dressing.None of the treatments affected the number of spikelet primordia differentiated on primary shoots, nor were the numbers and sizes of leaves affected.From graphs of mildew and green leaf area (GLA), plotted from G.S. 2 to G.S. 10.5, areas under the curves were determined. There was a strong negative correlation (r= ‐0.926) between areas under the mildew and GLA curves and it was also clear that reduction in GLA lagged behind disease. Grain yield was strongly correlated with total area under the GLA curve (r= 0.994 for primary shoots and 0.986 for tillers). For values of GLA at specific growth stages the best correlations were found at G.S. 9 (r= 0.967 for primary shoots and 0.992 for tillers). The correlation between total yield of primary shoots and area under the mildew curve was also high (r= 0.953) but for mildew estimates at specific times only those at G.S. 7 were significant (r= 0.980); at G.S. 10.5 there was no significant correlation.It may be postulated from the data that retranslocation of stored photosynthate, produced before anthesis, plays an important role in grain filling and that mildew post anthesis may have little effect on yield. The implications of the results are discussed in relation to methods of loss appraisal and strategies for mildew control.
Field resistance in cowpea, Vigna unguiculata to the cowpea moth, Cydia ptychora
Authors: EZUEH M. I. , TAYLOR T. AJIBOLA 
Published: February 2008

SUMMARYField evaluation of 26 selected cowpea cultivars showed that several of them had good levels of resistance to Cydia ptychora; TVu 946, Adzuki, ‘Vita 5’ and Igbirra were the most resistant. Percentage seed damaged by the larvae was positively correlated with days to 50% flowering (r= 0.39*), days to 50% pod ripening (r= 0.48*) and weight of 100 seeds (r= 0.56**). All four cultivars were early maturing, had semi‐determinate or determinate plant types and carried their pods above the leaf canopy.No single morphological character could be related to the degree of seed damage but some association with phenological characteristics was indicated. Earliness, determinacy and uniform pod maturity were important plant characters associated with the expression of field resistance. Even if these characters are not causative, they provide a rational basis for screening of a large germplasm to identify or synthesise materials with greater resistance to this moth.
The biological bases of resistance in cowpea to the cowpea moth, Cydia ptychora (Lepidoptera: Olethreutidae)
Authors: EZUEH M. I. 
Published: February 2008

SUMMARYIntensive greenhouse screening using potted plants demonstrated a high level of resistance in the wild cowpea, Vigna unguiculata (ssp. mensensis), to the cowpea moth, Cydia ptychora. Two closely related cvs (TVu 946 and TVu 2994) also showed some resistance. Further investigations in the laboratory and in the greenhouse indicated that resistance was due mainly to oviposition preference and to antibiosis. Pods of the wild cowpea, and those of cvs TVu 946 and TVu 2994, were not attractive to egg‐laying females whereas no oviposition preference was seen among the genetically improved cultivars. Pronounced antibiosis was detected in the wild cowpea, and to a lesser extent in the closely related cvs, when pods were infested with first‐instar larvae. Fecundity of females was also significantly reduced. These effects were thought to be partly due to nutritional deficiencies in the resistant cvs but there may also be an antibiotic factor in the wild cowpea progenitor. Apparently, pod‐wall thickness was not related to resistance although differences in successful penetration of pods by larvae were observed.
A rapid method to estimate the resistance of cold stored carrot roots to Botrytis cinerea
Authors: HARDING V. K. , HEALE J. B. 
Published: February 2008

SUMMARYInoculating whole carrot roots at 4°C with mycelial/agar discs of the grey mould fungus Botrytis cinerea gives a measure of their resistance and hence storage potential to this pathogen, but results are not obtained for at least 33 days. In the present investigation a more rapid method was used which involved inoculating root slices with spore suspensions containing 5 × 103–5 × 106 spores/cm3 at 24°C. Resistance was assessed visually and by a chitin estimation 48 h after inoculation.Both methods were used to measure the resistance of cold stored carrot roots during two storage seasons, 1976/77 and 1977/78. In each season there was a particular inoculum level which most clearly recorded the increasing susceptibility of roots with time in store. In 1976/77 this was 1 × 105 spores/cm3 whereas in 1977/78 it was the lower inoculum concentration of 5 × 104 spores/cm3, suggesting the roots were generally more susceptible in 1977/78 than the previous season. This was in accord with the results from the whole root method of assessment. A chitin estimation proved to be the more sensitive method of assessment for inoculum potential experiments.
The effect of seed and stem base spray treatment with iprodione on white rot disease (Sclerotium cepivorum) in autumn‐sown salad onions
Authors: ENTWISTLE A. R. , MUNASINGHE H. L. 
Published: February 2008

SUMMARYIprodione applied to seed at 250 g a.i./kg controlled white rot in autumn‐sown salad onions until July the following year, and reduced losses during the winter caused by Botrytis spp. At 25–150 g a.i./kg seed, iprodione controlled autumn and spring infections but it was less effective later in the summer.Treatment of autumn‐sown onions at 50 g a.i./kg seed followed in March by a single stem base spray at 0.031 g a.i./m row (total rate c. 2.4 kg a.i./ha) gave complete control; seed treatment at 25 g a.i./kg followed by a stem base spray at 0.125 g a.i./m row (c. 4.5 kg a.i./ha) was equally effective.Four stem base sprays of iprodione at 0.075 g a.i./m row/spray (9 kg a.i./ha) applied in spring to plants raised from untreated seed, controlled spring and summer infections but yields were low because of losses caused by infection in the previous autumn. A single stem base spray of iprodione at 0.125 g a.i./m row applied in spring to plants raised from thiophanate‐methyl treated seed at 125 g a.i./kg gave complete control and high yields.
Purification and some properties of Tephrosia symptomless virus
Authors: BOCK K. R. , GUTHRIE E. J. , FIGUEIREDO GINA , WOODS R. D. 
Published: February 2008

SUMMARYTephrosia symptomless virus (TSV), isolated from Tephrosia villosa, is widely distributed in coastal districts of Kenya. The virus was readily transmitted by inoculation of sap, but not by Aphis craccivora or Apion sp. (Curculionidae) or through soil. Host range was very restricted and it infected only 10 of 70 species tested in one of nine plant families; susceptible species were confined to five genera within the Papilionaceae. The virus was cultured, propagated and assayed in soybean.TSV remained infective after 10 min at 85°C, 3 wk at 20°C and 26 wk at ‐12°C; crude infective sap of Glycine max retained infectivity when diluted 10‐6 but not 10‐7.Virus was purified from systemically infected soybean by clarifying sap extracted in 0.06 m phosphate buffer containing 0.001 m EDTA and 0.1% thioglycollic acid (pH 7.5) with equal volumes of 1:1 n‐butanol/chloroform followed by two cycles of differential and one of sucrose density gradient centrifugation. Purified preparations contained c. 33 nm isometric particles. TSV contained RNA and one protein of molecular weight 1.53. 106 and c. 42 000, respectively. Analytical centrifugation indicated a single component with a sedimentation coefficient (s.20, w) of 127 S; in Cs2SO4 and CsCl isopycnic gradients a single virus band formed; buoyant density in CsCl was 1.361.TSV was not related serologically to any of 44 viruses in nine plant virus groups but it resembled the tombusviruses and other ungrouped viruses such as carnation mottle in some of its properties.
The effect of oxamyl on the growth of peas attacked by pea cyst nematode
Authors: GREEN C. D. , WILLIAMSON KATHERINE , DENNIS E. B. , McBURNEY T. 
Published: February 2008

SUMMARYOxamyl treatment at drilling greatly increased the growth of the plants, the yield and quality of the peas harvested, in soil infested by small or large numbers of Heterodera goettingiana. Treated plants were continuing to set pods when non‐treated plants were senescing. Rhizobium nodulation, sap nitrate and tissue nitrogen content were increased in treated plants. Oxamyl applied to growing plants reduced later nematode invasion and enabled root nodulation to proceed with an increase in tissue nitrogen but no increase in yield. Oxamyl applied at drilling in April was inactive against invasion by H. goettingiana in June, which enabled the nematode to multiply equally in treated and non‐treated plots. The most economic treatments were at the smallest rates, giving the greatest increase in yield/kg of oxamyl applied.
Seed survival and periodicity of seedling emergence in twelve weedy species of Compositae
Authors: ROBERTS H. A. , NEILSON JUNE E. 
Published: February 2008

SUMMARYAchenes of 12 species of Compositae were collected in each of 3 years and mixed with the top 7.5 cm of sterilised soil which was confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Seedling emergence was recorded for 5 yr and the numbers of viable seeds remaining then determined. Emergence of Arctium lappa, A. minus, Picris hieracioides, Taraxacum officinale, Sonchus arvensis and S. asper was mainly in spring. Seedlings of Chrysanthemum segetum, Lapsana communis, Anthemis cotula and Sonchus oleraceus were often most numerous in spring but also emerged at other times, while Matricaria matricarioides and M. recutita showed no consistent seasonal pattern of emergence. Except for C. segetum and A. cotula, in which there was evidence of innate dormancy imposed by the seed coat, the numbers of seedlings were greatest in the first year and thereafter decreased approximately exponentially from year to year. Few viable seeds of A. lappa or A. minus remained after 5 yr and those of T. officinale, P. hieracioides and S. arvensis accounted for less than 1.5% of the seeds sown. Seed survival was greatest in the annual weeds and ranged from 2.1% (S. asper) to 8.6% (M. matricarioides) after 5 yr.
Wound‐healing in carrot roots in relation to infection by Mycocentrospora acerina
Authors: LEWIS B. G. , DAVIES W. P. , GARROD B. 
Published: February 2008

SUMMARYA period at 25 °C or 15 °C in a humidity approaching saturation before storage at 2 °C accelerated wound repair, diminishing subsequent infection by Mycocentrospora acerina in proportion to the period of treatment up to 48 h. The total number of localised lesions was reduced as well as the proportion which subsequently became progressive. Healing involved the accumulation of antifungal substances on the wound surface; patches of oily conglomerates were fungicidal and the remainder of the surface was strongly fungistatic. Only a small proportion of the chlamydospores germinated after wounds had been healed for 48 h.
Components of resistance to Cercospora arachidicola and Cercosporidium personatum in groundnuts*
Authors: NEVILL D. J. 
Published: February 2008

SUMMARYThe reactions of four groundnut cultivars to inoculation with two leaf spot pathogens (Cercospora arachidicola and Cercospodirium personatum) were investigated. Resistant cultivars showed longer latent periods, reduced sporulation and less defoliation; however, none of the cultivars was resistant to both pathogens. Numbers of lesions, time to leaflet loss and the percentage of spores which produced lesions were influenced by the concentration of C. personatum inoculum applied to the leaves and there were significant cultivar differences in lesion numbers at the lowest inoculum level. Only the first two characters were affected by applied spore concentration in the study with C. arachidicola. Generally it was found that lower inoculum levels gave a better separation of cultivars.The level of resistance was similar to that found in the slow resting reaction of cereal crops and should be useful in a groundnut breeding programme.
Resistance and susceptibility to colour forms of the aphid Sitobion avenue in spring and winter wheats (Triticum aestivum)
Authors: LOWE H. J. B. 
Published: February 2008

SUMMARYGlasshouse assessments of resistance to S. avenae in 29 entries of wheat and two of rye were made by releasing half‐grown aphids on randomised plants at the stem extension phase of growth. Wheat cvs Kador, Amigo, Highbury and Lutescens 1377 were resistant and cvs Sentry and Talavera de Bellevue partially resistant. Cv. Klein Acero, a breeding line TB68/6/10 and Lerma Rojo selections 197 to 200 were highly susceptible to S. avenae although the latter are moderately resistant to greenbug (Schizaphis graminum) (Starks & Merkle, 1977). The rye cultivars were susceptible to 5. avenae and no cultivar was found to be resistant to Metopolophium dirhodum.Clonal stocks of S. avenae, differing in colour, varied in their ability to form large populations on susceptible cultivars, and hence in their differentiation of susceptible from resistant wheat. No clone was detected with specific ability to attack the resistant cvs Kador and Amigo.
The susceptibility of Myzus persicae and Brevicoryne brassicae to 14C‐phorate in artificial diets
Authors: GALLEY BY D. J. , GOHAIN RUMA 
Published: February 2008

SUMMARYColonies of Myzus persicae and Brevicoryne brassicae were established on artificial diets and the honeydew produced by them collected on aluminium foils. The diets were later exchanged for others containing a range of 14C‐phorate concentrations. The honey‐dew produced while feeding on the treated diets was collected separately and mortalities were recorded. The diets, aphids and their honeydew were subsequently analysed.About 1.6% of the doses applied initially were found in the diets at the end of the bio‐assay period. Thin‐layer chromatography of diets containing LC50 concentrations of insecticides showed that phorate and its metabolites were present in similar proportions. The LC50 values were 15.5 nM and 277 nM phorate equivalents for B. brassicae and M. persicae respectively.
Field evaluation of 4‐n‐butyl‐1,2,4‐triazole for the control of leaf rust of triticale*
Authors: THAPLIYAL P. N. , SINHA A. P. 
Published: February 2008

SUMMARYSevere epidemics of triticale leaf rust were controlled by a single treatment with 4‐n‐butyl‐1,2,4‐triazole (triazbutyl) as a foliar spray or as broadcast application on soil followed by irrigation. A single foliar spray of triazbutyl at 0.5 litre a.i./ha approached the control obtained by 1.0 litre a.i./ha. Effective control was obtained by spraying 10 days before or 10 days after the rust appearance but later spray applications were less effective.
Tests for transmission of cherry leaf roll virus using Longidorus, Paralongidorus and Xiphinema nematodes
Authors: JONES A. T. , McELROY F. D. , BROWN D. J. F. 
Published: February 2008

SUMMARYThe ability of 10 nematode species to transmit three strains of cherry leaf roll virus (CLRV) was tested by three methods: (1) virus‐infected source plants and virus‐free bait plants were grown concurrently in nematode‐infested soil, (2) as for (1) but virus source plants were removed before bait plants were planted, and (3) nematodes were extracted from soil after access to virus source plants, and were added to pots containing bait plants. The occurrence of galls on roots showed that nematodes fed both on source and on bait plants in all experiments and, in some experiments, CLRV was detected by direct assays (slash tests) of Longidorus elongatus, L. leptocephalus and Paralongidorus maximus. Although the nematodes readily transmitted control viruses, for which they are known to be vectors, CLRV was detected by root assays in only a few bait plants exposed to L. elongatus, L. macrosoma, Xiphinema diversicaudatum or L. leptocephalus + X. vuittenezi in tests by method 1. The recovery of CLRV in these tests is interpreted as being due to contamination.These results add to the increasing circumstantial evidence against the involvement of nematodes in the transmission of CLRV. Other possible mechanisms of spread are discussed.
Effects of some systemic imidazole and triazole fungicides on white clover and symbiotic nitrogen fixation by Rhizobium trifolii
Authors: FISHER D. J. , HAYES ANN L. 
Published: February 2008

SUMMARYEffects of prochloraz, imazalil, diclobutrazol, triadimefon and propiconazole were studied. Compared with most systemic fungicides previously tested they were all relatively toxic to R. trifolii on agar. Effects of soil residues of the compounds on the growth and nitrogen fixing capacity of white clover were measured. The lowest concentration of the fungicides used was that which would be present if all the active ingredient from a single application remained unchanged and evenly distributed in the top 5 cm of soil. This concentration of diclobutrazol decreased the size and weight of 11‐wk‐old clover plants. The rate of nitrogen fixation was reduced by twice this concentration and root nodulation by four times this amount. None of the other fungicides had any significant effect.The possibility of field application of diclobutrazol to cereals causing damage to clover crops is discussed. It is questionable whether harmful soil residues will ever accumulate from normal usage of the fungicide but exceeding the recommended rate of application, or application to cereals undersown with clover, might cause undesirable effects on the clover.
A small‐scale screening technique for evaluating fungicides against Phytophthora palmivora pod rot of cocoa
Authors: McGREGOR A. J. 
Published: February 2008

SUMMARYPlots of clonal Trinitario cocoa were sprayed with fungicides in the field. Ripe pods were harvested from the trial plots and artificially inoculated with Phytophthora palmivora using various techniques, the most suitable of which proved to be the zoospore spot method. Percentage infection results from the spot inoculation tests agreed well with the field percentage infection results and it was concluded that field spraying followed by zoospore spot inoculation of detached pods is a suitable preliminary screening technique for fungicides. Three systemic fungicides metalaxyl, aluminium tris (ethyl phosphonate) and DPX‐3217 in a mixture with captafol and copper oxychloride were compared with the protectant cuprous oxide. Metalaxyl was found to be the most effective of the systemic fungicides and when applied at the rate of 0·44 g ai/ha every 8 wk it gave a similar reduction in percentage infection to 4 weekly applications of cuprous oxide at the rate of 4·4 kg Cu++/ha during the wetter part of the year when pod rot is most severe.
Compensation in grain yield components in a panicle of rainfed sorghum
Authors: HAMILTON R. I. , SUBRAMANIAN BALA , REDDY M. NARAYANA , RAO C. HANUMANTHA 
Published: February 2008

SUMMARYIn a field experiment with rainfed grown sorghum hybrid CSH‐6, various proportions of spikelets from the apex, base or random regions of the panicles were removed at the time of anthesis and the yield compensation in grain number and grain size within a panicle was investigated. The distribution of grain number and grain yield in a control panicle from apex to base was parabolic while grain size showed a progressive linear decrease. Full grain yield compensation occurred due to an increase in grain number and size when the panicles lost up to 20% of their portions at the base or at random. No grain number compensation was, however, recorded at the apical region. Irrespective of the number of spikelets retained, the size of grains in the upper part of the panicle was always larger than those in the lower part.The grain number compensation, which occurred when spikelets were removed at the time of anthesis and the decreasing grain size from apex to base of the panicle would suggest hormonal involvement in the determination of potential grain number and size.
Secondary host preferences and reproductive activity of the bird cherry‐oat aphid, Rhopalosiphum padi
Authors: LEATHER S. R. , DIXON A. F. G. 
Published: February 2008

SUMMARYOf 15 species of grass, including cereals, alate exules and emigrants of Rhopalosiphum padi preferred to colonise Lolium perenne. Emigrants colonised cereals twice as readily as alate exules. Apterous exules also preferred L. perenne to cereals. Although small when reared on L. perenne, R. padi was more fecund per unit weight than on any of the other grasses tested. On the later growth stages of Dactylis glomerata and L. perenne, R. padi developed faster and were more fecund than on Phleum pratense at the same growth stages. At low temperatures R. padi were more fecund on P. pratense than on L. perenne and D. glomerata and vice versa at high temperatures. The secondary host preferences and reproductive activity of R. padi are discussed in relation to possible suitable hosts for viviparous overwintering and the pest status of this aphid in Britain.
Some effects of insecticide deposit patterns on the parasitism of Trialeurodes vaporariorum by Encarsia formosa
Authors: PERERA P. A. C. R. 
Published: February 2008

SUMMARYThe functional response of Encarsia formosa parasitising Trialeurodes vaporariorum on Phaseolus vulgaris was a typical type II functional response (Holling, 1959) where, with increasing host density, the numbers of hosts parasitised by a single parasitoid show a negatively accelerating rise to an upper plateau. A mean maximum parasitism of 6.6 per female per 24 h reached at host densities near 80 larvae per leaf was observed. When presented with insecticide (‘Pynosect 30 ULV’) deposits, the parasite's search pattern changed, conforming to a typical Sigmoid functional response curve. With a uniform cover spray deposit of 27.6 × 10‐7 ml/cm2 searching began only at host densities of c. 80 larvae per leaf and the mean maximum parasitism was only 1.5 per female per 24 h. When the insecticide deposit of 27.6 × 10‐7 ml/cm2 was in the form of discrete groups of 100 μm droplets, searching began at host densities of c. 40 larvae per leaf but the mean maximum parasitism was low at 2.2. However by using the same discrete deposit pattern but reducing the deposit level to 2.65 × 10‐7 ml/cm2 it was possible to obtain the same high mean maximum parasitism as with the untreated control.
Effect of nitrogen nutrition on Fusarium wilt of tomato plants
Authors: SARHAN A. R. T. , BARNA B. , KIRÁLY Z. 
Published: February 2008

SUMMARYThe role of nitrate‐nitrogen (NO3‐N) in relation to the development of tomato wilt caused by Fusarium oxysporum f. sp. lycopersici R1 was studied. Plants receiving 284 μg/ml nitrogen in the nutrient solution exhibited the same severe wilt symptoms as the control plants in soil. Disease decreased with increasing nitrogen levels (420, 630 and 1050 μg/ml). Apparently, the plants were also less susceptible to the disease when the concentration of nitrogen was 70 μg/ml, i. e. below the optimal level (284 μg/ml).Protein content in tissues of plants grown with different amounts of nitrogen was also determined. High nitrogen levels, which decreased disease severity, increased the protein content in leaf tissues. Of 17 amino acids only proline content increased with increasing nitrogen supply. High doses of NO3–N decreased the phenol content and the activity of peroxidase in stem and leaf tissues of tomato plants. It is suggested that phenolic compounds and the activity of peroxidase are not significant in the resistance of tomato to Fusarlum wilt associated with high nitrogen supply.