bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cultural and insecticidal control of Thrips tabaci on onions in the Sudan
Authors: KISHA JENNIFER S. A. 
Published: February 2008

SUMMARYOnion thrips (Thrips tabaci) is the major pest of onions in the Sudan. In the Gezira Scheme onions are normally transplanted between October and January when the thrips population is very low. Later, thrips commence to breed. Early transplanted onions were well established before infestations became severe and, without the need for insecticidal control, produced significantly higher yields. Onions transplanted later, when thrips began to multiply, produced lower yields.Depending on the duration and intensity of infestation three to five sprays applied at fortnightly intervals were required to control thrips on the late transplanted crop. The effect of spray frequency on the development and yield of onions was investigated and the response found to be solely due to the extent of thrips control achieved. The toxicant itself had no effect on growth. Although the leaves were unaffected by the various treatments, spraying when most thrips were present increased fresh and dry leaf weights, bulb weight and, in the Hudeiba cultivar, the proportion of flowering plants.With the late‐transplanted crop, light infestations led to yield losses of at least 39% whilst severe thrips attacks reduced the crop by 57%.
Role of weed grasses in the etiology of ergot disease in wheat
Authors: MANTLE P. G. , SHAW S. , DOLING D. A. 
Published: February 2008

SUMMARYForty isolates of the ergot fungus Claviceps purpurea collected from nineteen gramineous host species were used to inoculate male‐sterile wheat. The isolates segregated into highly and weakly infective groups. The marked pathogenicity, on wheat, of the fungal strains occurring on certain grass species has been correlated with distinctive patterns of alkaloids within the sclerotia.Analysis of the alkaloid content of 241 samples of naturally occurring ergot sclerotia from twenty gramineous host species has confirmed the existence of host restricted strains characterized also by their particular spectra of alkaloids.Similarity of the alkaloid spectra of ergot sclerotia from blackgrass (Alopecurus myosuroides) and wheat, ease of cross‐infection from blackgrass to wheat and an association between blackgrass infestation and the occurrence of ergot sclerotia in surveyed wheat crops have confirmed the hypothesis that the presence of this early flowering weed grass increases the risk of high levels of ergot infection in wheat.
Laboratory rearing of the mushroom phorid Megaselia halterata (Diptera: Phoridae)
Authors: RICHARDSON P. N. , HESLING J. J. 
Published: February 2008

SUMMARYA technique used for 3 yr to produce 15 000–20 000 nematode‐free adult Megaselia halterata/v/k is described and its potential for future mass‐production of nematode‐parasitised flies, for use in biological control, is assessed. Gravid female phorids preferred to oviposit in compost in which mushroom mycelium had grown for 7–12 days. At 20 ± 1 °C flies began to emerge 24 days after adults of the previous generation had been released on the compost. By day28, 88% of the total population had emerged.In laboratory experiments using different densities of parental flies, fly yield per female was highest when 200 flies infested each 1 kg of compost. At higher densities, competition between larvae affected survival of larvae and pupae, and probably resulted in the mean egg content of emerging flies being reduced by as much as 16‐4%. Theoretically, 250 kg compost should yield 1 150 000 phorids.
Development of the Dutch elm disease epidemic in southern England, 1971‐6
Authors: GIBBS J. N. 
Published: February 2008

SUMMARYThe current epidemic of Dutch elm disease was studied by recording the fate of individual hedgerow elms (Ulmus procera) in five plots in the West Midlands, and by analysing data from successive Forestry Commission surveys of non‐woodland elms in 234 plots in southern England.Ninty‐five percent of the individual trees died between May 1972 and September 1975. The average infection rate (r) was found to be 1 ‐35 during the period when the proportion of disease, x, increased from 0–16 to 0–42. In the plots of the main survey the average infection rate was 0–65 and the cumulative loss increased from 6 to 62% between 1971 and 1976, with little evidence that the course of the epidemic was influenced by variations in the weather from year to year. These infection rates are as high as those recorded in Dutch elm disease epidemics elsewhere in the world. The infection rate in English elm was higher than in either the wych elm or the heterogeneous ‘smooth‐leaved elm’. The study of English elm in four geographical areas of southern Britain showed that there was an initial drop in infection rate until x = 0–12, when a steady infection rate obtained in all four areas, ranging from 0–56 in the Midlands to 0–76 in the south‐east. It is concluded that the epidemic is likely to continue at a high rate until most non‐woodland elm have died. Most trees which survive are likely to be smooth‐leaved elm in East Anglia.Few communities in southern England have been able to practice vigorous sanitation control programmes, but data from two, in East Sussex and Brighton, are analysed and the effect on disease progress discussed.
Methods used to study Pythium oligandrum, an aggressive parasite of other fungi
Authors: Deacon J. W. , Henry Christine M. 
Published: February 2008

ABSTRACTIsolates of Pythium oligandrum Drechsler and P. acanthicum Drechsler behaved similarly in a range of experiments and in a manner consistent with mycoparasitism. They grew on cellulose in association with some fungi ‐ notably Botryotrichum pilulferum Sacc. & March. and Phialophora radicicola Cain var. radicicola (IMI 187786) ‐ and markedly reduced cellulolysis by these species; however, they had little effect on cellulolysis by Gaeumannomyces graminis (Sacc.) Arx & Olivier var. graminis and made little growth on cellulose in the presence or absence of this fungus.Pythium oligandrum and P. acanthicum also grew rapidly across plates of potato‐dextrose agar precolonised by Phialophora radicicola var. radicicola, whereas isolates of P. echinulatum Matthews, P. mamillatum Meurs, P. megalacanthum de Bary, P. spinosum Sawada and P. ultimum Trow did not grow under these conditions. Precolonised agar plates were therefore used as a selective medium to isolate Pythium oligandrum and similar fungi from soils. For this, small pieces of soil organic matter were transferred to precolonised agar plates and incubated for 4–6 (‐12) days, when the presence of P. oligandrum or similar fungi was assessed by their production of spiny oogonia across the host colony. The technique proved successful in isolating these fungi from a wide range of cultivated soils, even if the soils had been stored air‐dry. However, boiled hemp seeds buried in soil and subsequently transferred to precolonised agar plates usually gave rise to phytopathogenic rather than mycoparasitic pythia.Pieces of wheat straw precolonised by P. oligandrum decomposed at the same rate as virgin straws or straws precolonised by P. ultimum or Mucor hiemalis Wehmer, when all were buried in nitrogen‐supplemented soil. However, different cellulolytic fungi appeared to colonise straws in these respective treatments, Fusarium spp. being less common and Stachybotrys atra Corda more common in the presence of P. oligandrum than in its absence. When subsequently opposed to P. oligandrum on agar plates, Fusarium spp. appeared to be parasitised by this fungus and made very little growth across the agar, whereas S. atra grew through the colony of P. oligandrum and was clearly unaffected by the presence of this fungus.Our results demonstrate the widespread occurrence of P. oligandrum in cultivated soils in Britain and also suggest that this species might influence the activities of other soil fungi.
Studies on the lenticel development, surface microflora and infection by common scab (Streptomyces scabies) of potato tubers growing in wet and dry soils
Authors: ADAMS M. J. , LAPWOOD D. H. 
Published: February 2008

SUMMARYThe mechanisms of control of potato common scab (Streptomyces scabies) by irrigation were investigated in 5 years by studying the growth and surface microflora of young potato tubers developing in wet or dry soils. Direct examination of the tuber surface by light or scanning electron microscopy showed that the newly formed internodes near the apex, which carry stomata, had a very sparse microflora. In dry soil the older internodes, which carry lenticels at a susceptible stage, were increasingly colonised by actinomycete hyphae and discrete, although sometimes large, bacterial colonies. In wet soil, actinomycetes were rarely seen on tuber surfaces but bacteria were generally scattered over them, differences not always shown by isolation from periderm pieces onto water agar.When dry scab‐infested soil was wetted, scabs did not subsequently develop on the two youngest tuber internodes (A‐1, A‐2), which may be an example of disease escape rather than inherent resistance of the stomata. The scab control achieved in wet soil was probably caused by some form of microbial antagonism, but whether through competition or antibiosis was not established.
An investigation into inter‐plot interactions, in experiments with mildew on barley, using balanced designs
Authors: JENKYN J. F. , BAINBRIDGE A. , DYKE G. V. , TODD A. D. 
Published: February 2008

SUMMARYSerial designs, balanced for effects of neighbours, were used in 1975–1977 to investigate interactions between plots of spring barley given different treatments for the control of powdery mildew (Erysiphe graminisDC. f. sp.hordeiMérat). Differences in amounts of disease, between similarly treated plots, could be related largely to the treatments applied to the neighbouring plots and to wind directions. Amounts of disease in plots were usually increased if the upwind neighbour was untreated but untreated plots themselves were also affected by neighbours, having least disease where the upwind neighbour was sprayed early.Differences in mildew due to treatment were reflected in grain yield. Yields also provided evidence of interactions between plots. Interference, as well as altering the average response to treatments, can also contribute to variability in experiment results and lead to substantial losses in efficiency. The yields in 1975 and 1976 provided strong evidence of profiles of fertility. In the analyses, adjustment by covariates, employed to allow for these profiles, gave substantial net gains in accuracy.
Observations on the cabbage stem flea beetle, Psylliodes chrysocephala, on winter oil‐seed rape in Cambridgeshire
Authors: ALFORD D. V. 
Published: February 2008

SUMMARYThe biology of the cabbage stem flea beetle, Psylliodes chrysocephala (L.) (Coleoptera: Chrysomelidae), on winter oil‐seed rape crops was studied in Cambridgeshire from 1974 to 1978, with particular reference to autumn and winter activity. The timing of adult invasion of crops in the autumn and subsequent attack on plants by larvae showed considerable variation from year to year, being influenced mainly by temperature. Also, early‐germinating crops tended to be invaded earlier than later‐germinating ones. Egg development, which was closely correlated with temperature, required an accumulated sum of 240 day oC above 3.2 oC (calculated from daily mean temperatures). Monitoring adult activity, and consideration of temperature data, allowed dates of egg hatch to be predicted. The usefulness of this information for accurately timing chemical sprays against the pest is discussed.
Studies of halo‐blight seed infection and disease transmission in dwarf beans
Authors: TAYLOR J. D. , DUDLEY C. L. , GRAY) LORNA PRESLY (née 
Published: February 2008

SUMMARYThe transmission of Pseudomonas phaseolicola from plant to seed was mainly by the penetration of bacteria from external pod lesions to the underlying seeds. There was no evidence for translocation of bacteria from other parts of the plant to the seed, and symptomless pods contained only healthy seeds. Although a small proportion of infected seeds showed obvious symptoms of infection, the majority showed either slight symptoms, which could be detected only by careful observation, or were symptomless. In tests of disease transmission from seed to seedling, seeds with slight symptoms, or those which were symptomless were responsible for 35% and 52% respectively of the total disease transmission compared to 13% for obviously infected seeds. The viability of bacteria in seed stored under relatively uncontrolled conditions (10–27 d̀C) declined by a factor of 250 per annum over the first 3 yr with extrapolation predicting effective extinction after c. 5 yr. The pathogen survived longer under controlled conditions (7–10 d̀C and 45–50% r.h.) but no viable bacteria were detected in seed stocks which were 10‐yr‐old and with one exception 6‐yr‐old stocks were also free of the pathogen.
The biology of the ground beetle Harpalus rufipes in a strawberry field in Northumberland
Authors: LUFF M. L. 
Published: February 2008

SUMMARY Harpalus rufipes (Degeer) was studied in a strawberry plot in Northumberland from 1973 to 1978 by pitfall trapping, and in the laboratory. Adults were active from April until November. Overwintered male beetles predominated at the beginning of each season until May, followed by overwintered females in June and July. Newly emerged, mainly female, beetles were active from August onwards. Overwintered females matured during early summer and laid eggs in August with a fecundity of 10–15 eggs/female. In the laboratory about 30% of beetles survived from one breeding season to the next.First‐ and second‐instar larvae were caught in pitfall traps in autumn; in the laboratory they made approximately vertical burrows in which they stored seeds taken from the soil surface. Third‐instar larvae fed on these seeds and were not active on the surface. Preferred seeds were those of grasses and Chenopodium album L. Larvae were usually aggregated in the soil at densities of 3–20/m2.
Effects of Pythium species on the growth of apple and their possible causal role in apple replant disease
Authors: SEWELL G. W. F. 
Published: February 2008

SUMMARYSeveral lines of circumstantial evidence collectively indicated that poor early growth of apple (‘replant disease’) might be associated with the effects of soil‐borne pythiaceous fungi. This hypothesis was supported by pathogenicity tests. All isolates tested of P. sylvaticum and certain isolates of seven other Pythium spp. significantly reduced the growth of apple seedlings. The growth reductions caused by certain Pythium isolates were of comparable magnitude to the growth increases occurring after chloropicrin‐fumigation of apple orchard soils. The Pythium isolates most virulent to apple were of low virulence to a clonal cherry rootstock.Reappraisal of the nature of the disease as a non‐specific soil malaise is consistent with established features of the pathology of Pythium spp. The disease, however, is an ill‐defined ‘poor growth phenomenon’ with no diagnostic symptoms and conclusive evidence that Pythium spp. are widely causal is likely to be elusive.
Studies on the epidemiology of Alternaria brassicicola in Brassica oleracea seed production crops
Authors: HUMPHERSON‐JONES F. M. , MAUDE R. B. 
Published: February 2008

SUMMARY Alternaria brassicicola lesions present on overwintered leaf litter of Brassica oleracea seed production crops produced high concentrations of spores in the spring, these were able to initiate new infections on foliage and subsequently on inflorescences and pods. A vertical disease gradient developed in maturing crops, the lowest pods becoming infected first and infection spreading slowly upwards. Spores were produced abundantly after 20 h leaf wetness at a mean temperature of 13°C or more. Their release was stimulated by a fall in relative humidity but inhibited at a constant high relative humidity resulting in a daily cycle in air spore concentrations with minimum numbers occurring in the early morning and maximum numbers in the early afternoon. For most of the growing season spore movement was restricted to within the crop, however, massive release of spores and subsequent distribution over a wide area occurred when the crop was cut and later threshed. Using semi‐selective agar traps spores released at these times were detected up to 1800 m downwind of the parent crop and were instrumental in infecting nearby young crops destined for seed production in the following season.
Pathogenic variability of downy mildew (Sclerospora graminicola) on pearl millet. II. Statistical techniques for analysis of data
Authors: BALL SARAH L. , PIKE D. J. 
Published: February 2008

SUMMARYDifferent cultivars of pearl millet were exposed to infection by asexual propagules ofSclerospora graminicolain Polythene tunnels. Subsequent incidence of disease was measured on one‐month old seedlings. The data consisted of binomial proportions based on differing total numbers of seedlings. It is shown how to utilise the logit link in the GLIM statistical package for analysis to compare variety performances. In addition the possibilities of interplot interference and intraplot variation were investigated using GLIM. Interplot interference occurred infrequently and did not affect the rank order of the cultivars in terms of their response to the fungus infection. Intraplot variation was also shown to be non significant in spite of proximity of some plants to the disease spreader plants. Once these potentially confounding phenomena were eliminated the cultivars could be compared directly with impunity. GLIM was also used to confirm that the type of symptom expression was a stable feature of each host genotype.
Chemical treatments for control of decay in pruning wounds
Authors: MERCER P. C. , KIRK S. A. , GENDLE P. , CLIFFORD D. R. 
Published: February 2008

SUMMARYWound treatments were evaluated, in the laboratory and the field, for their effect on beech and poplar tissue (phytotoxicity) and on the growth and colonisation pattern of micro‐organisms. Three types of treatment were examined: a physical barrier or sealant, a sealant plus fungicide and a fungicide alone. Greatest phytotoxicity was shown by materials normally employed as timber preservatives and the least by sealants. Generally colonisation by fungi and bacteria was little delayed by most treatments with the exceptions of Santar (sealant plus mercuric oxide) and Australian Arborseal (sealant plus captafol). However, colonisation by basidiomycetes was generally delayed by treatment, but its overall intensity was reduced only by Santar and Lac Balsam (sealant). Some treatments had a selective effect on the species of micro‐organisms colonising a wound ‐ thus wounds treated with carbendazim derivatives were most likely to be colonised by basidiomycetes and Alternaria spp. Treatment with Santar discouraged most micro‐organisms with the exception of Phoma spp.No sealant provided a visually intact cover for longer than 12 months: even wounds with apparently intact cover occasionally had fruit bodies of decay fungi present on them. The chemicals triadimenol, triadimefon, carbendazim and thiophanate methyl were still present in fungicidal amounts in wounds up to at least 157 days. Both Santar and triadimenol prevented the growth of Trametes versicolor from inoculum plugs in wounds of apple trees.
Ecology of nematophagous fungi: distribution and habitat
Authors: GRAY N. F. 
Published: February 2008

SUMMARYA survey of 161 samples of soil and plant material collected from sites throughout Ireland has shown that nematophagous fungi exist in a wide range of habitats. 205 isolations were made consisting of 11 endoparasitic and 20 predatory species. The commonest endoparasites and their frequency of occurrence were Myzocytium spp. (9·3%), Acrostalagmus obovatus (6·8%) and Harposporium anguillulae (6·2%). Predators were equally abundant, the commonest being Dactylella bembicodes (8·7%), D. mammillata (6·8%) and D. ellipsospora (6·2%). Arthrobotrys oligospora and A. musiformis both had a highly restricted distribution. Adhesive knobs and constricting rings were significantly more abundant than the other trapping mechanisms.All the samples were classified into one of 10 broad habitat types. Of these temporary agricultural pasture, coastal vegetation and coniferous leaf litter had the greatest percentage of sites from which nematophagous fungi were isolated. A number of species showed distinct habitat associations, in particular Arthrobotrys robusta, A. musiformis and Dactylella cionopaga.
The use of polyethylene bags in the culture and study of Striga spp. and other organisms on crop roots
Authors: PARKER C. , DIXON N. 
Published: February 2008

SUMMARYA technique is described by which root parasites such as Striga and Orobanche species may be grown on the roots of suitable host plants growing on a layer of glass‐fibre filter paper in a flattened, standard polyethylene bag. The single‐bag units are compact, inexpensive, simple to set up and allow repeated observation without damage. Some other potential uses of the technique are described.
The effect of leachates from grass trash on establishment of ryegrass
Authors: MARSHALL A. H. , NAYLOR ROBERT E. L. 
Published: February 2008

SUMMARYThese experiments have shown that whilst leachates from grass trash produced by killing grass with glyphosate can significantly affect germination and seedling growth of both perennial and Italian ryegrass on germination paper and on inert media, they had no effect when added to seeds on soil. This suggests that these leachates are unlikely to inhibit germination in direct drilled sowings in the field unless seeds are sown in direct contact with grass trash and in conditions of sufficient moisture availability to enable production of the leachates.Comparisons of the effect of leachates from grass killed with herbicides or by drying, both before and after passing through a soil column further confirmed this and suggested that the effect of these leachates could partly though not wholly be attributed to herbicide residues on the trash.Glyphosate was less toxic to germination than paraquat. However on sandy soils, glyphosate residues could still cause a reduction in germination. Surface trash produced by spraying with glyphosate had no effect when seeds were sown at a depth of 1 cm, again confirming that seeds must be in close proximity to grass trash before germination and establishment is reduced.
Laboratory tests on mating competition between thiotepa‐sterilised and normal males of the potato moth, Phthorimaea operculella (Lepidoptera: Gelechiidae)
Authors: NABI M. N. , HARRISON R. A. 
Published: February 2008

SUMMARYMale potato moths less than 24‐h‐old were sterilised in fumigation chambers in the laboratory with one of three concentrations of thiotepa 0·05, 0·075 and 0·1 g at either 25 or 30°C. Sterile males were associated with untreated virgin males and virgin females in the ratios of 1:1:1, 2:1:1, 4:1:1 and 1:0:1. The sterile and normal male contingents were placed with a single female. The percentage of egg hatch after mating decreased with the increase of concentration and the sterile male ratio. Sterile males were competitive in mating and their longevity was not adversely affected in comparison to the control groups.
Biological treatments for the control of decay in tree wounds.: Laboratory tests
Authors: MERCER P. C. , KIRK S. A. 
Published: February 2008

SUMMARYNon‐decay fungi and bacteria which had been isolated from pruning wounds of beech (Fagus sylvatica) were examined for their ability to check the growth of decay fungi in a number of laboratory tests. Several fungi and bacteria inhibited growth although the degree of inhibition varied to some extent with the test. The most consistently antagonistic fungi were Trichoderma spp., especially an isolate of T. viride. The most antagonistic bacteria were Bacillus spp.