bluuebunny/crossref_metadata_2025_split huggingface dataset:
The behaviour of populations of potato cyst eelworm Heterodera rostochiensis Woll. Towards resistant potato varieties derived from Solarium tuberosum ssp. andigena Juz & Buk
Authors: BROWN E. B. 
Published: February 2008

SUMMARYMany populations of Heterodera rostochiensis mostly from the main potato growing areas of England and Wales, were tested with eelworm‐resistant potato varieties (andigena hybrids). Except in the Eastern Region, where resistant varieties were planted alongside commercial varieties in infested fields, tests were done in pots inoculated with a standard number of cysts extracted from a single soil sample from each field. The tests showed that England and Wales could be divided into areas according to the percentage of cysts(< 10%, 11–70%,> 70%) produced on the resistant compared with a commercial non‐resistant variety. On the peat soils of the East Anglian fens and in Bedfordshire, Essex and Kent (area A) most populations produce few cysts on resistant varieties. In much of the East Midlands and Yorkshire (area D), populations produce many cysts on resistant varieties which behave much as ordinary susceptible potatoes. Populations in the rest of England and Wales (areas B, C) vary and in many districts every field must be tested separately.If the pathotypes occurring in Britain had separate origins in South America, the present distribution in England and Wales is probably due to chance introductions dispersed with seed and following the patterns of trade in seed potatoes. As all commercial varieties, before the release of eelworm‐resistant ones, were about equally susceptible to the different pathotypes, the varieties themselves probably played little part in determining the present distribution of pathotypes.
Methods for assessing the tolerance and resistance of different types of cocoa to cocoa swollen‐shoot virus
Authors: KENTEN R. H. , LEGG J. T. 
Published: February 2008

SUMMARYDifferent types of cocoa were compared for their resistance to infection and tolerance of infection with the virulent strain A of cocoa swollen‐shoot virus, inoculated either by mealybugs or manually. The method of infection did not affect the ranking of the cocoa types for resistance, except at high percentages of infection, or for tolerance. In comparison with other methods, manual inoculation simplifies the screening of cocoa types for resistance and tolerance to virus infection, and provides a more sensitive test for resistance.
The fumigant effect of metaldehyde on slugs
Authors: HENDERSON I. F. 
Published: February 2008

SUMMARYThe fumigant effect of metaldehyde on slugs is confirmed and shown almost certainly to be caused by impure metaldehyde breaking down to the volatile parent monomer, acetaldehyde. Acetaldehyde was slightly more toxic to Agriolimax reticulatus than to Arion hortensis.
Changes in the resistance of tobacco leaf to Erysiphe cichoracearum DC. induced by topping, cytokinins and antibiotics*
Authors: COLE J. S. , FERNANDES DESIRÉE L. 
Published: February 2008

SUMMARYTreatments that produced different rates of growth in attached tobacco leaves and leaf discs, also affected the growth of powdery mildew on them.Topping (removal of flower head) increased the resistance of upper leaves, and attached leaves of topped and intact plants were more susceptible than leaf discs from them incubated on water.Hyphal growth increased on leaf discs incubated on water at increasing light intensities, as did dry and fresh mass of healthy discs. On kinetin, dry and fresh mass also increased with light intensity but hyphal growth decreased slightly. Discs incubated at all light intensities on kinetin had less hyphal growth than those on water at the lowest intensity (< 50 lx).Floating leaf discs on chloramphenicol at 500 μ/ml restricted fungal growth but not quite as much as kinetin (10 μ/ml); kinetin inhibited the fungus in the presence of chloramphenicol. Actinomycin D (2.μ5 μ/ml) and puromycin (5.0 μml) had little effect on the fungus.
Observations on the infection and rotting of apples var. Bramley's Seedliong by Diaporthe perniciosa
Authors: AYUB A. NAWAWI BIN HOJI , SWINBURNE T. R. 
Published: February 2008

SUMMARYIn N. Ireland Diaporthe perniciosa March is a common inhabitant of the dead wood of Bramley's Seedling apple trees, and its pycnospores, extruded throughout the growing season, are responsible for fruit infections which result in stalk‐end rots during storage.Pycnidia were produced in culture only after exposure to light, near‐UV radiation being particularly favourable. The carbon source in the medium influenced pycnidia production: high yields were obtained where mannitol was used. Only a‐spores germinated under the conditions tested, giving optimum germination at 25 d̀C. in a water film. No germination occurred at less than 98% R.H. Germ tubes and hyphae developed appressoria after germination on artificial surfaces but on apple skin most spores produced only a protuberance from which penetration hyphae developed directly. The cuticle and epidermal cells of apples of all ages were penetrated within a few days of inoculation. Intact surfaces and lenticels were penetrated equally. Susceptibility to further rotting increased with age of the fruit. Apples loaded with spores early in the season rotted later than similar apples loaded just before picking. Polygalacturonase was detected in sap expressed from rotted apples of various ages, the level of activity being correlated with the susceptibility of the fruit.
Pathogenic behaviour of Cephalosporium maydis and C. acremonium
Authors: SABET K. A. , ZAHER A. M. , SAMRA A. S. , MANSOUR I. M. 
Published: February 2008

SUMMARY Cephalosporium maydis infects young maize plants easily, but as plants age fewer are infected and none after approx. 50 days from sowing. The mesocotyl and seminal, fibrous and adventitious roots are attacked, especially when there is damage or much inoculum. Most penetration occurs where roots are elongating and emerge from the mesocotyl or from fibrous roots. At first the fungus grows superficially on roots, producing hyphae with short, brown, thick‐walled, and swollen cells. After penetrating, the fungus spreads towards the xylem, where it grows slowly at first but after 5 weeks grows faster upwards. C. acremonium causes black‐bundle disease of maize. It seems to infect plants growing in unfavourable conditions but the details remain uncertain. The percentage of plants infected was not related to the amount of inoculum and the fungus may not be a primary parasite. The sterile culture filtrate of the fungus produces vascular discoloration and wilt of maize seedlings.
Spraying bananas in Fiji to control black leaf streak disease
Authors: FIRMAN I. D. , HOSKIN P. 
Published: February 2008

SUMMARYThree sprays, maneb in water applied by hydraulic knapsack sprayer and maneb in an oil/water emulsion or an oil/water emulsion alone applied by mistblower were compared for the control of black leaf streak disease of banana caused by Mycosphaerella sp.Although there were no differences in yield in the ‘plant’ crop, maneb, especially as a water‐based spray, resulted in much better disease control and leaf survival. Oil seemed to have an adverse effect on fruit quality but not on plant growth.Since it is unlikely that oil alone will adequately control the disease in ratoon crops fungicides may be necessary.
The effects of soil sterilants on the cereal cyst‐nematode (Heterodera avenae Woll.), take‐all (Ophiobolus graminis Sacc.) and yields of spring wheat and barley
Authors: WILLIAMS T. D. , SALT G. A. 
Published: February 2008

SUMMARYIn a 3‐year field experiment on sandy loam at Woburn, methyl bromide, chloropicrin, D‐D mixture, dazomet, formalin and mercury salts were applied in the first year only, or in the first and second years, before drilling spring wheat. In the third year, their residual effects on spring barley were measured. All sterilants except mercury decreased cereal cyst‐nematode (Heterodera avenae) numbers and take‐all (Ophiobolus graminis) incidence, and increased crop yields in the year they were applied. Dazomet gave the best control of H. avenae in the first year and controlled O. graminis best in both years of application. In the third year, O. graminis increased in all plots previously treated (except after two successive D‐D treatments), but H. avenae increased only after formalin. Two formalin applications more than trebled the H. avenae egg count by the end of the third year and depressed the yield of barley. Two successive applications of chloropicrin gave the best nematode control.Other fungus diseases, Fusarium foot rot, Pythium root rot, eye‐spot (Cercosporella herpotrichoides Fron.) and sharp eye spot (Rhizoctonia solani Kühn), were uncommon and sterilants had no detectable effects on them. The largest aggregate straw yield (3‐year total) was obtained from two applications of dazomet, but the best yields after treatment in the first year only were given by D‐D and methyl bromide.
Observations on the effects of distribution and numbers of slug pellets on the catch of slugs
Authors: WEBLEY D. 
Published: February 2008

SUMMARYThirty comparisons were made of the catch of different numbers of slug pellets and the effect of meteorological factors on them. Ten pellets/2 1/2 ft (0.75 m) gave the greatest catch although, economically, the best treatment was from two to five pellets for Agriolimax reticulatus; for Arion hortensis and Milax budapestensis the return per pellet was low. Throughout the year only 16.6% of the catch variance was removed by meteorological factors.
Seasonal and geographical variation of powdery mildew on susceptible cereal cultivars, 1958‐68
Authors: DOLING D. A. , SAUNDERS P. J. W. , DOODSON J. K. 
Published: February 2008

SUMMARYAnnual patterns of mildew on winter and spring barley, wheat and oats at NIAB trial sites for 1958‐68 are reported. High intensities of mildew were preceded by early infections, particularly at sites where both winter and spring crops were infected early. Relative earliness and severity of infections in all six crops of cereals were generally similar at any site. This pattern was repeated within denned mildew ‘regions’, i.e. north, east and west. Sprowston (Norfolk) was atypical of the eastern sites, showing patterns of mildew infection more characteristic of sites in the west, where mildew values were 50 % higher than elsewhere.Dates of first visible infection became later further eastwards and northwards, particularly in winter cereals. This suggested the possibility of dispersal of inoculum by prevailing winds to the north, north‐east and east, or a similar progression in climatic factors favourable to mildew development.Estimates of loss of potential yield in the trial plots of sites in each region and over the whole country were calculated for winter wheat, spring barley and spring oats using the formulae of Large and Doling, for which supplementary confirmation was provided.
Pre‐selection for Phytophthora cactorum (Leb. &Cohn) Sehroet. resistance in apple seedlings
Authors: WATKINS R. , WERTS JULIE M. 
Published: February 2008

SUMMARYInoculation of apple seedlings at the two‐leaf stage with a Phytophthora cactorum zoospore suspension provided a rapid method of pre‐selecting for collar rot resistance, since the susceptible plants died within 2 weeks of inoculation while the resistant plants continued to grow satisfactorily. The presence of the resistance gene Pc was not alone sufficient to explain the observed segregation.
Quantitative isolation of Verticillium spp. from soil and moribund potato haulm
Authors: ISAAC I. , FLETCHER P. , HARRISON J. A. C. 
Published: February 2008

SUMMARYA technique to isolate a high proportion of the propagules of important Verticillium spp. from soils is described with modifications for quantitatively distinguishing between the microsclerotial and conidial fractions of V. dahliae and estimating the microsclerotial population and its viability in dried potato stems.In pots, soil populations of V. dahliae with less than c. 40 propagules/g failed to induce disease in potato plants; with larger populations there was some relation between disease severity and fungal population. In soils artificially infested with V. dahliae (c. 50000 propagules/g dried soil) the viable population decreased within 6 months to c. 100 propagules/g and then remained stable for more than a year. From fields in South Wales and East Anglia large populations of V. nigrescens and V. lateritium and small populations of V. dahliae were obtained.
Association between the potato cyst‐nematode, Heterodera rostochiensis Woll., and Verticillium dahliae Kleb. in the early‐dying disease of potatoes
Authors: HARRISON J. A. C. 
Published: February 2008

SUMMARYInvestigation of a possible association between Verticillium dahliae and H. rostochiensis (pathotype E, British notation) was based on field observations and an examination of disease development in single‐stemmed potato plants grown in pots. An association was found in the distribution of the nematode and the fungus in the field, and the disease was far more severe with a combined infection than with either pathogen alone. Studies on leaf‐area development and yield reduction suggest there is synergism between fungus and nematode, the reductions produced by the combined infection exceeding the sum of those produced by either pathogen alone. Fungal mycelium and the extent of host colonization by V. dahliae were greatly increased by the presence of the nematode. The possible benefits to V. dahliae in the fungus‐nematode complex are discussed.
Serological relationships of some viruses from cocoa (Theobroma cacao L.) in Ghana
Authors: KENTEN R. H. , LEGG J. T. 
Published: February 2008

SUMMARYStrains A and Anibil of cocoa swollen‐shoot virus are serologically closely related. They are more distantly related to strain M and cocoa mottle‐leaf virus (Kpeve isolate), which are distantly related to one another. Strains A and Anibil protected against one another in cocoa seedlings, but no protection was found with any other combination between these four virus isolates. All mealybug‐transmitted cocoa viruses in West Africa are probably best considered as strains of cocoa swollen‐shoot virus.
Testing the effects of liquid eradicants on emergence of Anobium punctatum (Deg.)
Authors: TAYLOR JEAN M. 
Published: February 2008

SUMMARYA laboratory method is described for evaluating the effectiveness of insecticides in preventing the emergence of furniture beetles (Anobium punctatum (Deg.)). Composite blocks of Scots pine were prepared consisting of an untreated core containing larvae and two treated outer veneers from which all solvent had evaporated and through which beetles had to emerge.Dieldrin and gamma‐BHC prevented emergence of beetles, dieldrin being the more effective material. The following did not prevent emergence at the concentrations tested: pentachlorophenol, zinc naphthenate, polychlor‐naphthalene, copper‐chrome‐arsenate, tri‐butyltin oxide.
The toxicity of some soil‐applied systemic insecticides to Aphis gossypii (Horn. Aphididae) and Phytoseiulus persimilis (Acarina: Phytoseiidae) on cucumbers
Authors: BINNS E. S. 
Published: February 2008

SUMMARYTests with potted cucumber plants confirmed that granular or soil drench treatments applied against Aphis gossypii Glover may limit the performance of a predaceous species introduced to control another pest. Soil applications of thionazin, methomyl, demeton‐S‐methyl and aldicarb in equal amounts caused deaths, in descending order of toxicity, of the predatory mite Phytoseiulus persimilis Athias‐Henriot. This effect was not demonstrated for pirimicarb, menazon or isolan on whole plants at rates up to 10 mg a.i. nor in laboratory tests on detached plant portions. Methomyl and thionazin, but not aldicarb, were relatively more toxic to P. persimilis than to its prey, Tetranychus urticae Koch. Some survival of P. persimilis occurred on plants treated with demeton‐S‐methyl, but this material was inferior to pirimicarb in both selectivity and persistence. Pirimicarb offers practical control of A. gossypii on cropping cucumbers, without phytoxicity or residues, when applied at 125 mg a.i./plant. It is therefore preferable to other aphicides for use on cucumbers during propagation or cropping, especially where the favoured means of control of T. urticae is by introductions of P. persimilis. Qualitative evidence of in vitro tests suggested that those systemic materials which affect P. persimilis do so by ‘food‐chain’ toxicity, but that vaporization from the leaf may also be a factor.
Effects of soil fumigation on soil nitrogen and on disease incidence in winter wheat
Authors: EBBELS D. L. 
Published: February 2008

SUMMARYWinter wheat was grown in soil fumigated with D‐D, 85% dazomet dust or formalin, and top‐dressed with o or 125 kg nitrogen/ha. Six weeks after fumigation, there was much more ammonium nitrogen in fumigated than in unfumigated soil. Nitrate was also more after fumigation with dazomet, but less after D‐D and formalin. After 5 months, only D‐D plots had less nitrate and more total mineral nitrogen than unfumigated plots.Take‐all (Ophiobolus graminis) was less prevalent in the first crop after dazomet or formalin, but was more prevalent in the second crop than after other treatments. Eyespot (Cercosporella herpotrichoides) was decreased only by formalin and only in the first crop after applying it. Fumigation had little effect on the incidence of other diseases recorded or on grain yield, except that yields were light on D‐D plots in the first crop after fumigation, when ears were severely deformed.
Reproduction of Lumbricillus rivalis (Levinsen) in laboratory cultures and in decaying seaweed
Authors: KIRK R. G. 
Published: February 2008

SUMMARYThe cocoon production of 144 Lumbricillus rivalis cultured in pairs at 10 ± 1 °C was high over the first 2 weeks of breeding activity and then declined, chiefly because of high mortality. Cocoon deposition lasted for between 1 and 16 weeks, eight pairs of worms producing cocoons for 9 weeks and one pair for 16 weeks. During the total period of cocoon deposition over 9000 eggs (mean 17·4 per cocoon) were deposited.Two decaying wrack bed populations of L. rivalis showed a low level of cocoon and egg production in autumn, rising to an annual maximum in late winter/early spring. In these populations the mean egg content varied seasonally from 17·1 to 47·8 eggs per cocoon.When cocoons in the laboratory were transferred from the site of deposition to incubation dishes 31% hatched, but those left in the substrate showed a 92% hatch. In the naturally occurring populations 19% of the cocoons detached from seaweed fronds hatched, but 62% of those left in situ.Eggs and worm embryos developed to relatively late stages in most cocoons, whatever the rate of hatching; development often continued for up to 2 months after deposition without hatching.Over 50% of the fertile eggs in cocoons from decaying wrack hatched and developed to 5 mm worms.
Some hosts and properties of dahlia mosaic virus
Authors: BRUNT A. A. 
Published: February 2008

SUMMARYDahlia mosaic virus (DMV) infected twenty‐five of the eighty‐five plant species from four of eighteen families inoculated, but only dahlias were found naturally infected. DMV infected fourteen members of the Solanaceae, Amaranthaceae and Chenopodiaceae, and eleven of twenty‐nine Compositae. Verbesina encelioides was the best plant for diagnosis, assay and source of virus. Systemically infected hosts contained ovoid intracellular inclusions 2–5–10 μm in diameter which were shown by electron microscopy to consist of a finely granular, vacuolated matrix containing numerous virus particles. V. encelioides sap was sometimes infective after dilution to 1/2000 but not 1/3000, after heating for 10 min to 75 °C but not 80 °C, and after 4 days at 18 °C or 32 days at 2 °C. Sap from infected dahlia, Zinnia elegans or Ageratum houstonianum rapidly became non‐infective, but extracts made with 0·05 M sodium thioglycollate or 0·03 M sodium diethyldithiocarbamate remained infective for 24–48 h at 18 °C. Some purified preparations remained infective for up to 3 years at 2 °C.DMV was best purified from V. encelioides by one or more cycles of differential centrifugation, followed by density‐gradient centrifugation and further concentration. Composition, molarity, and pH of the extracting buffer had little effect on yield of virus. Best yields were obtained from extracts stored with 8‐5% (v/v) n‐butanol at 2 °C for 10–14 days. Purified preparations were infective at dilutions up to 1/5000, had ultraviolet absorption spectra typical of a nucleoprotein (Å 260/280 = 1·47), probably contained DNA, and had a single sedimenting component having isometric particles c. 50 nm in diameter with a sedimentation coefficient of 254 S. The cryptogram of DMV is (D)/*:*/(16):S/S:S/Ap.DMV is serologically closely related to cauliflower mosaic virus, but the viruses are distinct pathogens. The two viruses have similar properties, size, shape and other characteristics, and together with at least three others form a small but apparently homogeneous group of aphid‐borne viruses.
Field experiments on the resistance of cocoa to cocoa swollen‐shoot virus
Authors: LEGG J. T. , KENTEN R. H. 
Published: February 2008

SUMMARYProgenies from crosses between different Upper Amazon cocoa types and between Upper Amazon and Amelonado were compared for their field resistance to infection with cocoa swollen‐shoot virus (CSSV) virulent strain A. Among the intra‐Amazon progenies, those from crosses of Scavina, Iquitos and Nanay groups showed most resistance. Progenies from crosses within these groups may have sufficient resistance to be of immediate practical value in reducing crop losses in areas where CSSV is widespread. Some Nanay progenies were more resistant than others and this provides scope for improvement by breeding. Progeny of crosses between Upper Amazon and Amelonado parents were less resistant than those from intra‐Amazon crosses.The present results confirm those previously obtained in gauze‐house tests on young plants.
Effects of light and temperature on symptom development and virus content of tobacco leaves inoculated with potato mop‐top virus
Authors: HARRISON B. D. , JONES R. A. C. 
Published: February 2008

SUMMARYNecrotic spots or small rings develop after 3–4 days in leaves of Nicotiana tabacum cv. Xanthi‐nc inoculated with potato mop‐top virus and kept at 14 °C in continuous light (4320 lux); a series of concentric necrotic rings of increasing diameter then form at 2‐ to 3‐day intervals around each initial lesion. Successive rings take longer to appear when either the light intensity or the photoperiod is decreased. Virus accumulation is much decreased and lesions rarely develop either at 14· in darkness or at 22° in light. Virus accumulates rapidly when plants are transferred from these conditions to 14° in light (4320 lux), and necrotic spots or rings develop whose size depends on the interval between inoculation and transfer, and on the conditions during this period. In such plants, necrosis seems to occur only when conditions become favourable for virus synthesis, it is confined to recently infected cells and it does not prevent virus spread to further healthy cells. From the sizes of the necrotic rings, the virus is estimated to invade tissue in light (4320 lux) at c. 38 μm/h at 22° and c. 16 μm/h at 14°. Invasion in darkness at either temperature is very slow.Necrotic rings develop, and the rate of virus accumulation increases when inoculated plants are transferred from 22° in light (4320 lux) to 14° in darkness, but no lesions appear when the order of the treatments is reversed. The process of lesion formation thus includes an early phase requiring light and a later phase requiring low temperature. The light‐requiring phase takes about a day at 14° but less at 22°. The later phase takes about 2 days in light (4320 lux) or 3 days in darkness.