bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of tobacco mosaic virus infectivity by the fungus Thielaviopsis basicola (Berk. &Br.) Ferr
Authors: HARPAZ I. , BAR‐JOSEPH M. , SELA I. 
Published: February 2008

SUMMARYThe presence of an inhibitor of tobacco mosaic virus (TMV) infection was demonstrated in extracts of Nicotiana glutinosa infected with the fungus Thielaviopis basicola. The inhibitor was shown to spread systemically in the infected plant. It was found to be heat‐stable, but rapidly lost its activity upon dilution or dialysis. The inhibitor does not act directly on the virus and lacks the power to decrease infectivity of virus already present in the cells.A similar inhibitor was extracted from the fungal body, differing only slightly from the one extracted from fungus‐infected plant tissue.
The effect of temperature on loose smut of wheat (Ustilago nuda)
Authors: DEAN W. M. 
Published: February 2008

SUMMARYIn experiments made in controlled‐temperature rooms on the wheat variety Kota, inoculated with two races of Ustilago nuda (Jens.) Rostr., maximum smut development occurred at 23 °C; at 20 ° and 15 °C the incidence and extent of smutting was reduced. An even greater reduction occurred when seedlings were grown at 6 °C for 2 months. No marked effect of temperature on mycelial development within the spike was observed until the ear emerged, when the mycelium in many of the ears of plants subjected to the lower temperatures failed to sporulate. The date of sowing in the field influenced disease development, presumably through the period of exposure to winter temperatures. Variety Little Club inoculated with race C3 showed a similar but less marked response to cold‐treatment.
The persistence in soil of the fungicidal seed dressings captan and thiram
Authors: GRIFFITH R. L. , MATTHEWS S. 
Published: February 2008

SUMMARYThe persistence in soil of captan and thiram was investigated by means of a technique in which the fungicidal content of soil was assayed by incubating plugs of soil containing fungicide on agar plates seeded with spores of Myrothecium verrucaria and measuring the diameter of the zone of fungal inhibition that was produced. When the fungicides were well distributed in soil they showed extremely low persistence, both fungicides having a half‐life of between 1 and 2 days. In contrast, when the fungicides were added to soil in the form of dressings on the surface of glass beads they persisted well in soil, little change from their initial concentration occurring even after 21 days.These results suggest that captan and thiram persist far longer in soil when localized in high concentrations than when uniformly distributed through soil. If a glass bead is regarded as a reasonable simulation of a seed these results help to explain the effectiveness of these fungicides as seed dressings despite their apparently low persistence in soil.
Fungicidal activity and chemical constitution
Authors: BYRDE R. J. W. , FIELDGATE DIANA M. , JORDAN V. W. L. , WOODCOCK D. , CARTWRIGHT J. 
Published: February 2008

SUMMARYSix 4‐(1‐phenylalkyl)‐, eight 4‐(1‐cyclohexylalkyl)‐, seven 4‐(1‐cyclo‐pentylalkyl)‐ and seven 4‐(1‐cyclobutylalkyl)‐2,6‐dinitrophenols, together with some derivatives, were tested against the powdery mildews of apple (caused by Podosphaera leucotricha) and blackcurrant (caused by Sphaerotheca mors‐uvae) in the greenhouse and in field trials, against rose mildew (caused by S. pannosa) in the field, and against Venturia inaequalis in spore germination tests. Highest activity in the greenhouse was shown by members of the cyclobutyl series with 4–6 carbon atoms in the alkyl group. No phytotoxicity on healthy foliage occurred with any compound in these series.
The nature of the microbial stimulus affecting sporophore formation in Agaricus bisporus (Lange) Sing
Authors: HAYES W. A. , RANDLE PHYLLIS E. , LAST F. T. 
Published: February 2008

SUMMARYAn apparatus is described in which pure cultures of Agaricus bisporus were maintained on composted media in filtered atmospheres free from (a) noxious concentrations of carbon dioxide, and (b) contaminating microorganisms. When grown on compost alone, cultures of A. bisporus did not produce sporophores. Their formation was however stimulated by a covering layer of an unsterilized mixture of peat and chalk (=‘casing’ soil). Autoclaving or fumigating ‘casing’ with propylene oxide decreased populations of contaminating bacteria and prevented sporophore formation.Populations of micro‐organisms isolated from unsterile ‘casing’ contained bacteria which when added to pure cultures of A. bisporus stimulated fruit‐body formation. Numbers of these stimulators increased when cultured on a carbon‐free liquid medium exposed to atmospheres with ethanol, ethyl acetate and acetone or containing the volatile metabolites of A. bisporus. The ability to utilize these volatile chemicals was exploited in a selective technique for isolating sporophore stimulators where aqueous suspensions of mixed bacterial populations were exposed to atmospheres of these materials for 5 days, before aliquots were added to agar media subsequently gelled.The stimulatory bacteria were identified as, or closely related to, Pseudomonas putida.
Properties of some defective strains of tobacco mosaic virus and their behaviour as affected by inhibitors during storage in sap
Authors: KASSANIS B. , Woods R. D. 
Published: February 2008

SUMMARYFrom the type strain of tobacco mosaic virus, defective strains were isolated that produced chlorotic or ringspot type symptoms in tobacco and were difficult to transmit without carborundum in the inoculum. Their concentration was less than 0–1 μg/ml of sap instead of the usual 2 mg/ml with the type strain. Phenol extracts of infected leaves were a little more infective than extracts in buffer, whereas phenol extracts of leaves infected with type strain were very much less infective than extracts in buffer. Electron microscopy of infective sap rarely showed any virus particles, but preparations concentrated by ultracentrifugation contained virus particles, many of which were broken or seemed inadequately assembled.Changing the ambient temperature at which infected plants were kept from 20 to 35°C did not increase the amount or improve the appearance of the virus. Some of the strains were inactivated during heating for 10 min between 70 and 80 °C.Undiluted sap lost its infectivity in 3 days at 20 °C, as did the type strain when diluted to 0–1 μg/ml in sap from healthy leaves. This is because substances that inhibit infection were produced by microbes in the sap. The ability of sap from healthy leaves to inhibit infection increased by more than twenty‐five times when left 3 days at 20 °C. Infectivity of appropriate mixtures of type strain and aged sap was restored by diluting them in buffer. Sodium azide at 0·02% in sap prevented formation of the inhibitor. The infectivity of the defective strains increased when inoculated together with the type strain.
Chemical control of root disease of Douglas–fir seedlings in relation to fungus and nematode populations
Authors: BLOOMBERG W. J. , ORCHARD W. R. 
Published: February 2008

SUMMARYSeed treatment with thiram reduced post–emergence damping–off, while fumigating forest nursery soils with methyl bromide or DD improved Douglas‐fir seedling emergence, shoot and root growth, and decreased the incidence of root disease.At an old site, where corky root develops, the benefits from these fumigants were associated with fewer (a) Xiphinema bakeri and (b) isolates of Cylindrocarpon radicicola.At a new site, decrease in Fusarium root rot and increase in shoot growth were related to reduction of populations of Paratylenchus and Pratylenchus, respectively. In unfumigated soils, Fusarium oxysporum was isolated from diseased and healthy roots.
The phenology of skin spot (Oospora pustulans Owen &Wakef.) and other fungal diseases of potato tubers
Authors: HIDE G. A. , HIRST J. M. , MUNDY E. J. 
Published: February 2008

SUMMARYUnderground stems and roots of the potato varieties King Edward and Majestic became more severely infected by Oospora pustulans (skin spot) as the growing season advanced. Tubers became infected at their initiation in June and July but the proportion of infected eyes usually increased during both the growth of the crop and bulk storage. Some buds on tubers in bulk stores died in December, but few were killed until after January, when attacks increased until by March about a quarter of Majestic eyes were usually dead. Boxing (chitting) not only prevented most eyes from dying but also prevented much skin spotting on tubers. At High Mowthorpe, Majestic seed unboxed or boxed in March yielded, respectively, 3 and 1 ton/acre less than seed boxed by January. Early boxing increased the yield of seed–sized tubers but did not affect the infection of progeny tubers. Dipping Majestic seed tubers in organo–mercurial fungicide and then boxing soon after lifting decreased their infection by O. pustulans; it also lessened infection on plants they produced and increased the yield of progeny seed–sized tubers. However, dipping, even in successive years, had little effect on the infection of progeny tubers by O. pustulans. Rhizoctonia solani and Helminihosporum atrovirens became increasingly prevalent on tubers during growth after July and during bulk storage. H. atrovirens was decreased by early boxing or dipping tubers in fungicide. Verticillate conidiophores often grew on incubated tuber plugs but their prevalence was affected by past storage.The results suggest that some of the benefit for chitting may be from disease control, it was not possible to measure the extent to which benefits from chitting depend on effects on disease or on the physiology of the tuber.
Infection of the flowers and seed of parsnip by Itersonilia pastinacae
Authors: CHANNON A. G. 
Published: February 2008

SUMMARYSeeding parsnip plants on four commercial holdings in Essex showed not only the root cankers and leaf spots associated with infection by Itersonilia pastinacae, but also extensive lesions on the petioles and necrosis of the inflorescences. These last‐named symptoms were proved to be caused by I. pastinacae which could also be found on some of the seeds. Seed infection, though largely superficial, was sometimes more deep‐seated. It could be eliminated by soaking the seed in an aqueous suspension of 0·2% thiram at 30 °C for 24 h.Heavily infected seed gave a low percentage of seedlings bearing cotyledon lesions: it is uncertain whether hypocotyl lesions, which also occurred, were caused directly by the fungus.An outdoor test failed to show that infected seed gave rise ultimately to roots bearing Itersonilia cankers: the significance of this and other possible sources of infection is discussed.
Phytoalexin production by leaves of Pisum sativum in relation to senescence
Authors: BAILEY J. A. 
Published: February 2008

SUMMARYA sterile culture nitrate of Penicillium expansum was shown to induce pisatin synthesis in pea leaf discs. The amount of pisatin produced by pea leaves was shown to decrease as they underwent senescence. N6‐benzyladenine delayed senescence, and at the same time maintained the production of pisatin at a high level. In darkness, leaf discs maintained on either benzyl‐adenine solution or distilled water produced greater amounts of pisatin than leaf discs which were not treated in this way. Benzyladenine also increased pisatin production by leaf discs kept in the light. The relevance of these results to disease resistance and possible mechanisms involved are discussed.
The stimulating effect of some fungicides on Glomerella cingulata in relation to the control of coffee berry disease
Authors: NUTMAN F. J. , ROBERTS F. M. 
Published: February 2008

SUMMARYThe non‐parasitic strain of Colletotrichum coffeanum Noack which colonizes the maturing wood of Coffea arabica produces its perfect stage (Glomerella cingulata) on the branches. Assessments of the relative abundance of this in relation to preceding rainfall have shown that for unsprayed branches, but rarely for sprayed ones, the correlation is negative and highly significant. Various fungicides stimulate G. cingulata greatly, and this stimulation persists for many months. One other saprophytic component of the micro–flora is similarly stimulated, but with two others all the fungicides used depress sporulation. It is suggested that when the main source of infection of coffee berries is the pathogenic conidia from the wood, the mechanism of long–term control by early–season sprays may lie partly in this stimulation of some fungal competitors of the pathogen.
Seasonal differences in the pattern of assimilate movement in branches of Coffea arabica L
Authors: CANNELL M. G. R. , HUXLEY P. A. 
Published: February 2008

SUMMARYAt Ruiru, Kenya, 14CO2 was fed to single leaves at different distances from the apex on branches of mature fruiting and non‐fruiting trees of Coffea arabica on six occasions from the Short Rains (November) 1966 to the Long Rains (April‐May) 1967. The location of 14C‐labelled assimilates in the treated branches was determined 26 h later by autoradiography. The direction of movement of labelled assimilates indicated large seasonal differences in the relative sink strengths of the shoot tip, fruit and trunk‐root systems.On vegetative trees the sink strength of trunk‐roots was much smaller, as compared with the shoots, at the beginning of the Long Rains than at the end of the previous Short Rains or in the intervening dry season. Assimilate use by growing fruits did not alter the pattern of distribution of assimilates to the other sinks at the end of the Short Rains, but it did restrict assimilate movement to both shoot tips and trunk‐roots at the_ beginning of the Long Rains. In the dry season, virtually all assimilates were utilized by growing fruits when these were present. Vegetative secondary shoots provided assimilates to growing fruits and trunk‐roots at the end of the Short Rains and in the dry season. Some practical implications are noted.
Estimation of yield in wheat from measurements of photosynthesis and translocation in the field
Authors: LUPTON F. G. H. 
Published: February 2008

SUMMARYThe rate of photosynthesis of ears, flag leaves and second leaves of two varieties of wheat, and the proportion of synthesized carbohydrate translocated from them to the grain, were determined in the field using 14CO2. The relationship of rate of photosynthesis to changes in age and in incident radiation was expressed by parameters determining hyperbolic functions. These were combined with empirical equations describing the increase with age in the proportion of photosynthate stored in the grain, to form a mathematical model by which yield was determined from physiological parameters. This model gave estimates of yield in reasonable agreement with measured values.
Experiments with CCC on wheat: effects of spacing, nitrogen and irrigation
Authors: HUMPHRIES E. C. , BOND W. 
Published: February 2008

SUMMARYIn experiments with spring and winter wheat at Rothamsted and Woburn during 4 years CCC increased yield at close spacing (4 in) (10 cm) more than at usual spacing (8 in) (20 cm), but there was no interaction between spacing and yield.Some experiments tested up to 2·4 cwt/acre (300 kg/ha) N to see whether yields continued to increase with more than usual amounts of N, when CCC prevented lodging. There was no evidence of this.When a short dry spell occurred at ear emergence, yield of spring wheat was increased by 6 cwt/acre (750 kg/ha) by CCC and 10 cwt (1250 kg) by irrigation. CCC probably improves yield in these conditions because the larger root system it causes enables more ear‐bearing shoots to survive.CCC increases yield in two ways, either by increasing ears or grain per ear. In an unlodged crop CCC usually makes the grains smaller, but by preventing lodging it can also increase size. Usually CCC decreases the leaf area per shoot. The flag leaf may be smaller, unchanged or larger than those of untreated plants. There was no obvious connexion between flag‐leaf area and grain yield; when CCC decreased flag‐leaf area duration by 25 %, grain yield was unchanged.The results suggest that using CCC gives a more than even chance of a profitable yield increase.
A laboratory method for studying the biology and control of pests in mushroom compost
Authors: WYATT I. J. 
Published: February 2008

SUMMARYA Petri dish technique, devised by Eger (1960, 1962) for studying mycelial growth through mushroom compost and casing material, has been modified for pest investigations. The method provides a sensitive test for phytotoxic and insecticidal action of applied chemicals, and experiments are described which indicate that thionazin is a suitable insecticide for use against Heteropeza pygmaea Winnertz (Dipt.: Cecidomyiidae). Examples are also given of the use of this method in the study of the biology and population dynamics of paedogenetic Cecidomyiidae.
Factors involved in resistance to blight (Phytophthora infestans (Mont.) de Bary) in potatoes and assessment of resistance using detached leaves
Authors: MALCOLMSON JEAN F. 
Published: February 2008

SUMMARYIn leaves of potatoes inoculated with Phytophthora infestans early in the growing season, more but smaller lesions with later onset of sporulation and fewer sporangia developed than on those inoculated later. None of these factors was uniform on detached leaves of all clones, so could not be used separately to forecast field resistance satisfactorily; when considered together, a reasonable prediction was feasible. With some clones, tests of detached leaflets gave a better indication of behaviour in the field than laboratory tests of whole plants.
Host/parasite relations up to the time of tuber initiation in potato plants infected with Verticillium spp
Authors: HARRISON J. A. C. , ISAAC I. 
Published: February 2008

SUMMARYThe growth pattern of potato plants, infected with V. albo‐atrum and V. dahliae, was studied, using growth‐analysis techniques, during the initial stages of development up to tuber initiation.During the first 5–6 weeks of growth the morphology of the infected plants was not affected, but the distribution of dry weight materials between various plant organs and the growth rates of the whole plants were affected much sooner. In contrast to healthy plants, those infected exhibited lower specific leaf areas, higher leaf weight ratios and higher leaf area ratios, and, under dry conditions, lower relative growth rates and lower unit leaf rates. Thus during the incubation phase of the disease, although effects of infection are not immediately apparent, Verticillium pathogens have a considerable influence upon the development of the host.
Dew and the growth of the uredospore germ tube of Puccinia graminis on the wheat leaf
Authors: BURRAGE S. W. 
Published: February 2008

SUMMARYWater droplets simulating dew, formed on wheat leaves held in a condensation chamber, appeared first on the leaf hairs and coalesced into lines along the ridges of the leaf surface in close proximity to the stomata. On leaves thus wetted, germ tubes from uredospores of Puccinia graminis showed a thigmotropic response, growing at right angles to the ridges: when they reached the stomatal region the penetration of the stoma may be further assisted by chemotropic or hydrotropic attraction.Studies on plastic surfaces showed that germ‐tube growth took place only between and not within water droplets.
Inoculum sources for coffee berry disease*
Authors: GIBBS J. N. 
Published: February 2008

SUMMARYIsolates of Colletotrichum spp. from coffee berries and bark in Kenya fell into four categories, distinguishable by their cultural characteristics on agar. Three of these proved non‐pathogenic; the fourth invariably infected both wounded and unwounded berries and caused coffee berry disease.The sporulating capacity on bark of the various Colletotrichum strains showed peaks in the periods before both the long and the short rains. The pathogenic strain made up only a very small proportion of the whole Colletotrichum complex on the bark and its sporulating capacity never exceeded twenty spores/cm2/h. By contrast, a green berry with an active coffee berry disease lesion produced 5×104conidia/h and an infected ripe berry twice as many.It is concluded that in any year, regardless of cropping pattern, diseased berries are likely to play an important role in the development of coffee berry disease.
Early‐season sprays for the control of coffee berry disease*
Authors: GRIFFITHS E. , GIBBS J. N. 
Published: February 2008

SUMMARYBock (1963) showed that in the years 1956‐60 early season sprays achieved good control of coffee berry disease (CBD) in East Rift areas of Kenya. In recent years, however, this spray programme has given erratic and often very poor results. In field experiments in 1966 yields of main (late) crop were increased from 151 to 652 kg/ha by early season sprays but in 1967 practically no control of the disease was achieved. Of the fungicides examined captafol was superior to copper; ‘Tuzet’, the best antisporulant, gave the poorest control. Analysis of the data indicates that this large seasonal variation depends on the very different inter‐relationships between rainfall, cropping pattern and timing of sprays which obtained in the 2 years.The hypothesis that early‐season sprays achieve control of CBD mainly by reducing the sporulating capacity of the maturing bark is questioned. The view is put forward that the protectant action of these sprays has been underestimated.
Control of survival of Ophiobolus graminis between consecutive crops of winter wheat
Authors: SCOTT P. R. 
Published: February 2008

SUMMARYUnder a glasshouse crop of red clover, Ophiobolus graminis (Sacc.) Sacc. in artificially colonized straws survived for longer on the soil surface than when buried, and for much longer when suspended above the soil; survival in buried straws was somewhat more prolonged in fallow soil than under clover. In field experiments with consecutive crops of winter wheat, under‐sowing with red clover was not effective in reducing the incidence of take‐all, possibly because of above‐ground survival of the pathogen in unploughed straw. Early rotavation, however, significantly reduced disease incidence, probably because of enhanced microbial activity and competition for nitrogen in the well‐aerated compost of soil and stubble.
Investigations on chemical control of zebra disease in Agave hybrid no. 11648
Authors: PEREGRINE W. T. H. 
Published: February 2008

SUMMARYIn laboratory, greenhouse and field experiments, mancozeb and copper compounds controlled the leaf‐spot phase of zebra disease caused by Phytophthora arecae, one of the pathogens responsible for this serious disease in Tanzania's high‐yielding Agave hybrid no. 11648. As the copper compounds were phytotoxic, Dithane M‐45 (Mancozeb) is recommended as a protectant during the rainy season.
Effect of CCC and glycine betaine on growth and growth‐substance content of primary leaves of dwarf Frenchbean (Phaseolus vulgaris L.)
Authors: WHEELER A. W. 
Published: February 2008

SUMMARYCCC (2‐chloroethyltrimethylammonium chloride) decreased growth of primary leaves and stem internodes above the hypocotyl of dwarf French bean, probably because it decreased the amount of auxin produced by interaction between tryptophan and phenolic esters in the primary leaves. Growth of leaves was less affected than that of stems, and the gibberellin content of the primary leaves, previously shown to be associated with their expansion, was unaffected by CCC. CCC delayed death of the primary leaves, the breakdown of chlorophyll, and the increase in auxin associated with death of bean leaves. CCC had less effect on the growth of leaf discs, probably because they are not sites of growth‐substance production. Glycine betaine, a quaternary ammonium compound similar to CCC, did not affect growth of bean plants, their metabolism of growth substances or the longevity of their primary leaves, but inhibited growth of leaf discs, probably directly.