bluuebunny/crossref_metadata_2025_split huggingface dataset:
Verticillium wilt of tomatoes—further experiments on the role of pectic and cellulolytic enzymes
Authors: BLACKHURST FRANCES M. , WOOD R. K. S. 
Published: February 2008

SUMMARYAn isolate of Verticillium albo‐atrum virulent on tomato produced polygalacturonase abundantly in suitable culture media. Secretion was greatly stimulated by pectic substances, and by organic, as compared with inorganic sources of nitrogen. Degradation of polypectate by culture filtrates decreased sharply when only about 25% of available glycosidic linkages had been hydrolysed.Cellulase (Cx) activity of culture filtrates was relatively much lower and no cellulase (Cx) activity was detected.The fungus produced pectic and cellulolytic enzymes when grown on sterilized pieces of tomato stem.Culture filtrates liberated reducing groups from insoluble plant material and there was some evidence that this depended on the activity of pectic enzymes.Polygalacturonase was strongly adsorbed by plant material but was eluted readily with O·2M‐NaCl.When dilute solutions of polygalacturonase were taken up by tomato cuttings only a relatively small proportion could be recovered from the tissues by treatments which removed enzyme adsorbed by plant tissue. This indicates inactivation of the enzyme by living pieces of stem, but extracts from healthy and infected stems did not inactivate polygalacturonase in vitro.Polygalacturonase was detected in extracts from the stems of root‐ and shoot‐inoculated plants. It was shown that the activity in these extracts was of the order to be expected from the activity of filtrates from cultures on media suitable for production of polygalacturonase.In all respects tested, the material from resistant Loran Blood and susceptible Ailsa Craig plants reacted in the same way with pectic and cellulolytic enzymes.
Some factors affecting the transmission of sugar‐beet mosaic and pea mosaic viruses by Aphis fubue and Myzus persicae
Authors: COCKBAIN A. J. , GIBBS A. J. , HEATHCOTE G. D. 
Published: February 2008

SUMMARYAlate Aphis fabae were often less efficient vectors than Myzus persicae of pea mosaic virus and sugar‐beet mosaic virus. Flight‐mature A. fabae rarely transmitted these viruses unless they had either flown (tethered) or fasted for several hours before feeding on infected plants; by contrast, flight‐mature M. persicae transmitted either virus before flying or fasting, though more frequently afterwards. There was little difference in the infectivity of the two species after they had flown and then fed for a short time on infected plants.Aphids flown for 1–5 hr. and then allowed a short feed on infected plants transmitted only slightly more often than aphids flown for 15 min., but they remained on the host plants longer. After flying for 15–60 min., many A. fabae settled permanently on broad bean plants, and a few on sugar‐beet plants, but most M. persicae flew off after feeding on these plants for a few hours.Many flight‐mature alatae of both species probed briefly before flying from a plant for the first time; more M. persicae than A. fabae transmitted after such pre‐flight probing on infected plants.The infectivity of flying or fasting alatae, and fasting apterae, decreased at similar rates. The rate of decrease was accelerated as the temperature rose, and few aphids transmitted after 30 min. at temperatures above 30 °C.PMV and SBMV, but not henbane mosaic virus, were transmitted more often by alatae than by apterae. The species of plant (broad bean or sugar beet) on which aphids developed did not affect their ability to transmit PMV or SBMV.
The uptake of hexoestrol by the roots of plants and its retention when applied to the foliage as a spray
Authors: GLASCOCK R. F. , HEWITT E. J. 
Published: February 2008

SUMMARYBecause of possible dangers to health arising from the use of oestrogens on fattening cattle, the uptake of tritium‐labelled hexoestrol by plants through their roots and its retention when applied in a spray has been investigated. Uptake through the roots was between 0·06 and 0·4% of that given, depending on root medium and species; uptake period had little effect. Hexoestrol was strongly adsorbed on the sand in which the plants were grown and much of it was transformed to unidentified compounds both in the nutrient medium and in the plants. The small amounts absorbed through roots were apparently translocated to foliage. When the hexoestrol was applied as a spray from 3 to 70% of it was retained depending on the interval between application and taking of samples, and on whether the leaves remained dry, or were sprayed with water periodically to simulate rain. About half of the hexoestrol applied as a spray was transformed to other chemical forms within a few hours. When the plants were cut the amounts present in later growth were negligible. There appears to be no danger to animal or human health in eating plants grown in soil containing hexoestrol. Although the amounts remaining on plants after surface contamination were appreciable this source is unlikely to be dangerous in practice.
The accuracy of the rating method for determining leaf area
Authors: HUMPHRIES E. C. , FRENCH S. A. W. 
Published: February 2008

SUMMARYThe errors involved in determining leaf area of intact potato plants by rating, i.e. by visual comparison with pictorial standards, are considered.The true area was consistently underestimated but, while the error in estimating areas of single leaves may be large, it is only about 7% for the total area of a large sample of leaves.It is shown that errors may arise from peculiarities in the standard pictures.The standards increased in size logarithmically but further work is necessary to see if this is the best arrangement.
Factors affecting the growth of carnation plants from shoot apices
Authors: STONE OLWEN M. 
Published: February 2008

SUMMARYCarnation plants were grown from shoot apices ranging from 200 μ to 1 mm. in length, derived from plants of different ages, at all times of the year. Tips grew best in small tubes on a simple nutrient medium, supported on wicks of ashless filter paper. The presence of rooting hormone in the medium was essential during the early stages of culture. Rooting was affected by the size of the tips and the time of year at which they were excised. Rooting of tips after heat treatment of the parent plants differed with variety, and virus infection also affected the rooting of some varieties.
The use of baits treated with α‐chloralose to catch wood‐pigeons
Authors: MURTON R. K. , ISAACSON A. J. , WESTWOOD N. J. 
Published: February 2008

SUMMARYWood‐pigeons were induced to take wheat, barley, oats, peas and beans when these were spread on fields where the birds were feeding. When these foods were scattered on pastures in winter (January‐March) they were taken in preference to the pigeons' normal food of clover. These results are discussed in relation to food preferences and the role of a ‘search image’ in the feeding behaviour of the species.Cereal and pea baits containing 1·5% by weight of α‐chloralose were laid on a variety of feeding grounds used by wood‐pigeons during the periods 27 October 1959 to 21 March 1960 and 4 November 1960 to 18 June 1961. In a total of thirty‐four such trials 1408 birds were narcotized. Of these 57% were wood‐pigeons and 20% were legally protected or game species. Using cereal baits the risk to species other than wood‐pigeons was lowest on pasture, where 74% of the birds caught were wood‐pigeons, 5% were game species and less than 1% were protected birds.Of the narcotized wood‐pigeons, 81% recovered unharmed, and partridges and pheasants had similar recovery rates. Only 38% of the stock‐doves recovered and the small finches (including house and tree sparrows) also had a low recovery rate of less than 50%. Baits normally disappeared within about I week. In a few cases they persisted for longer periods, the maximum being 31 days. Uneaten baits were lost through settlement in the soil, germination and ploughing operations. Birds were captured throughout the whole period during which bait was available.Three trials using peas treated with 1·5% by weight of a‐chloralose were conducted between 7 November 1961 to 22 January 1962. Thirty‐nine wood‐pigeons and thirty‐one game birds were narcotized and captured but no small protected birds were affected. The recovery rates of the captured birds were similar to those narcotized by using cereal baits. The method is much cheaper than control by shooting or nest destruction.The method of using stupefying baits is potentially a valuable means of wood‐pigeon control but further field tests are necessary. Only baits such as peas and beans are at present suitable as these appear to be too large to be eaten by the small protected species.
Toxicological studies on a beetle,Alphitobius laevigatus(F.)
Authors: HEWLETT P. S. 
Published: February 2008

SUMMARYA series of experiments was done, in each of which a toxicant solution was applied to the mesoscutella of the beetles, to their hind coxae, and to both sites. An equation derived by Plackett & Hewlett (1952) was used to interpret the results; this equation assumes parallel probit‐log‐dose lines for single applications to the respective sites, and allows for the possibility that the amount of toxicant reaching the site of action is not directly proportional to the dose (here the volume of solution) put on the sites of application; by contrast the equation for similar action considered by Finney (1952) in effect assumes proportionality. Apart from one experiment with allethrin, the former equation fitted the data satisfactorily.Forn‐valone, the joint action of the doses was interpretable on the assumption that the amount ofn‐valone acting was proportional to the volume of solution raised to the power of 0.76, a value significantly below unity(P< 0·001). The corresponding value for DDT was 0·89, but this was not significantly below unity (P= 0·12). The values for dieldrin and allethrin were 0·99 and 1·04, also not significantly different from unity.
Some effects of pancreatic ribonuclease and kinetin on tomato aucuba mosaic virus
Authors: DAFT M. J. 
Published: February 2008

SUMMARYLesion production by tomato aucuba mosaic virus was inhibited when the surfaces of infected Nicotiana glutinosa leaves were treated with pancreatic ribonuclease. Application of the enzyme shortly after inoculation with the virus produced the greatest effect, When incorporated with the inoculum the inhibitory action of the enzyme was found to depend on the relative concentration of the virus, the concentration of the enzyme and possibly on the enzyme activity.Floating leaves of N. glutinosa on solutions of kinetin before inoculation with tomato aucuba mosaic virus slightly increased the number of local lesions produced, whereas floating on solutions containing P‐indoleacetic acid decreased the number. These effects could not be attributed to altered leaf ribonuclease activity.Spraying N. glutinosa leaves 4 days before and 5 days after inoculation significantly increased lesion production. Spraying kinetin on to infected N. tabacum leaves increased the amount of infective virus produced. This stimulatory effect on lesion formation and on virus production is probably linked with the age of the leaf. Treatment with kinetin delayed the ageing of the detached leaves and greatly lessened the movement of cytidine, uridine, uracil and ribonucleic acid to the petiole.
Control of sugar‐beet downy mildew (Peronospora farinosa) by sprays
Authors: BYFORD W. J. , HULL R. 
Published: February 2008

SUMMARYNo fungicide tested gave more than partial control of sugar‐beet downy mildew in root crops or steckling beds and even frequent spraying beginning shortly after seedling emergence rarely did more than halve the incidence. This degree of control is not adequate for commercial use on root crops, but is helpful on steckling beds in conjunction with other control measures.
Wilt of lucerne caused by species of Verticillium
Authors: HEALE J. B. , ISAAC IVOR 
Published: February 2008

SUMMARYAll isolates of Verticillium albo‐atrum from lucerne are virulently pathogenic to this host, whereas V. dahliae is only slightly pathogenic. Isolates of both fungi from other crop plants do not produce symptoms when inoculated into lucerne, suggesting a degree of specialization in the ‘lucerne strains’ of V. albo‐atrum and V. dahliae. However, both these strains can infect broad bean, strawberry, Italian clover (Hedy‐sarum coronarium) and pea, while V. albo‐atrum may also attack potatoes and runner beans. V. albo‐atrum spreads rapidly underground from diseased to healthy lucerne plants, particularly when they are closely planted. Resting mycelium remains viable for 9 months in pieces of moribund lucerne buried 12 in. in soil, for 7 months at 6 in. and for only 5 months at the surface. V. albo‐atrum spreads from buried infected lucerne debris to the adjacent soil and can be re‐isolated for up to 9 months from 12 in. and for 5 months from 6 in. levels. In pot experiments a correlation was found between the speed of symptom development and the number of conidia in contact with the root system.Isolates of the fungus from lucerne can infect a number of common weeds (Plantago lanceolata, Polygonum persicaria, Sinapis arvensis, Rumex obtusifolius, Solanum nigrum, Papaver rhoeas, Capsella bursa‐pastoris, Senecio vulgaris and Anthemis cotula) and the fungus is still pathogenic to lucerne when re‐isolated.Field observations in Norfolk show that harvesting machinery may be the carrier of both the initial infection and the later spread throughout the crop. The incidence of disease increases with the age of the stand; a significant decrease of dry‐weight yield of diseased lucerne occurs during the second harvest year: this often necessitates the ploughing‐in of badly wilted crops before they reach their third harvest.
Studies on the chemical control of Phytophthora palmivora (Butl.) Butl. on Theobroma Cacao L. in NigeriaV.
Authors: HISLOP E. C. 
Published: February 2008

SUMMARYA pneumatic knapsack sprayer, a motorized shoulder‐mounted mist‐blower and an automatic tractor‐mounted mist‐blower have been compared for efficacy in controlling black‐pod disease of cocoa and for cost of operation. Preliminary evaluation of these machines was carried out using fungicide/dye mixtures applied to artificial paper‐covered pods. Fungicide deposits for different methods of spraying were determined from the simple colorimetric estimation of the dye. On the basis of these tests three blocks of Amazon cocoa were sprayed with cuprous oxide during the black‐pod season of 1962. Both knapsack machines gave good control of the disease but the cost of spraying with the mist‐blower was three times that for the more simple machine. The tractor‐mounted machine was expensive to use and gave poor disease control. It is suggested that the use of mist‐blowers might be economic only in areas where labour is expensive or scarce, and where yields and black‐pod losses are high.
The epidemiology of tomato mosaic
Authors: BROADBENT L. , COOPER A. J. 
Published: February 2008

SUMMARYTomato plants (vars. Moneymaker and Minimonk) inoculated at the cotyledon stage with tomato mosaic virus (TMV) developed about half as much root as did healthy plants, by the time the first trusses were flowering. Although infected plants recovered to some extent, their roots remained 10–25% smaller. Infection at the flowering of the first truss reduced the size of root system by about one‐third after 6 weeks, but the plants then recovered. Infection at later stages of growth did not significantly affect root growth. There was no significant relation between the dry weight of the root system and the fresh weight of the top including fruit.Moneymaker and Potentate tomato plants, sown in November, March, June and September, showed similar seasonal changes in the volume of fruit produced weekly, whether or not the plants were healthy or infected with TMV. Infected plants always produced less than healthy ones, but the decrease varied with time of year and age of plant, being greatest in spring and in young plants; the decrease remained fairly steady in older plants. The initial period of acute decrease in volume of fruit production was greater when ovary swelling began early in the year than when it began later. Fewer fruits were produced by infected plants than by healthy ones, except during the winter in var. Moneymaker. During the winter and spring, mean fruit size was decreased by TMV, and was unaffected or increased during the summer and autumn, especially in older plants.
The influence of seedling competition on the amount of loose smut (Ustilago nuda (Jens.) Rostr.) appearing in barley crops
Authors: DOLING D. A. 
Published: February 2008

SUMMARYA thoroughly mixed seed sample of Herta barley produced different percentages of smutted ears when grown at several centres throughout the country. From an analysis of the data it was concluded that crop density was not a major factor affecting this variation.The effects of time of sowing, seed size and seed rate on the smut intensity were also examined.By varying the seed rate, differences in the amount of smut were obtained. An examination of the number of infected and non‐infected plants and tillers established from each 100 seeds sown and of the tillering capacity of infected and non‐infected seedlings at each seed rate showed that the differences in smut intensity were the result of competition for establishment between the two kinds of seedlings.
‘Lyamungu dieback’ of arabica coffee in Tanganyika
Authors: BURDEKIN D. A. , BAKER R. M. 
Published: February 2008

SUMMARYCoffee trees suffering from Lyamungu dieback showed restricted vegetative and fruit growth, leading to death. Both chemical and visual estimations of starch reserves in woody tissue demonstrated that affected trees had lower reserves than healthy trees. The starch deficit appears to be a causal factor in the condition. It is suggested that this deficit may be caused by an imbalance between crop and vegetative growth, associated with low soil fertility.
The effect of planting date and spacing on the incidence of groundnut rosette disease and of the vector, Aphis craccivora Koch, at Mokwa, Northern Nigeria
Authors: A'BROOK JOHN 
Published: February 2008

SUMMARYAt Mokwa in Northern Nigeria early planting and close spacing increased the yield of groundnuts and decreased rosette incidence. With late planting, increasing the plant population reduced both the rosette incidence and the number of aphid‐infested plants. It is suggested that winged Aphis craccivora Koch bring the virus into the crop, and that spacing and planting date affect rosette incidence because of the influence of groundcover on the optomotor landing response of the winged aphids.
Studies on sharp eyespot disease of cereals II. Viability of sclerotia: persistence of the causal fungus, Rhizoctonia solani Kühn
Authors: PITT D. 
Published: February 2008

SUMMARYSclerotia of Rhizoctonia solani survived for long periods in the laboratory. When left undisturbed in the soil, 79% of buried sclerotia survived for a period of 6 months. Sclerotia retained their infectivity towards seedling wheat plants throughout all viability tests.Sclerotia germinated readily in response to various stimuli and were able to regerminate at least ten times: it is considered that this property enhances their survival value.Although wheat stem isolates decomposed cellulose in pure culture and competitively colonized certain types of cellulose in soil, they were ineffective in colonizing cereal straws in the soil. The pathogen quickly died out in artificially infested soil and showed only limited survival in naturally infected cereal straw buried in soil. In pot experiments the pathogen persisted parasitically under a number of crops.
Organophosphorous and carbamate insecticides as soil treatments for the control of wireworms
Authors: GRIFFITHS D. C. , BARDNER R. 
Published: February 2008

SUMMARYLaboratory methods are described for testing soil insecticides against wireworms, and the results obtained with some organophosphorus and carbamate compounds tried as possible alternatives to chlorinated hydrocarbons are reported. The most promising compounds in the laboratory tests were thionazin, O‐ethyl S‐p‐tolylethylphosphonodithioate (Bayer 38156) and fenthion. These were tested in a small‐plot field trial with cereals, on land severely infested with wireworms: the compounds were applied to the soil as sprays at 2·7 lb./acre active ingredient before the crop was drilled. Fenthion was ineffective, but thionazin and Bayer 38156 each increased yields significantly and the increases were associated with diminished wireworm populations.
Natural mortality of eggs of the black bean aphid, Aphis fabae Scop., on the spindle tree, Euonymus europaeus L
Authors: WAY M. J. , BANKS C. J. 
Published: February 2008

SUMMARYEgg mortality of Aphis fabae Scop, ranged from 18 to 73% on individual bushes of Euonymus europaeus L. at different sites in Hertfordshire during the winters of 1958—59 and 1959‐60. Field and laboratory experiments indicated that the average mortality is unlikely to exceed about 40% and is probably relatively unimportant in limiting subsequent increase to pest density. Winter temperatures in. Southern England do not harm eggs except perhaps at hatching time. Some eggs are destroyed by Anthocoridae and by birds. Others either fail to develop, or develop fully but fail to hatch, even when the weather is apparently favourable and natural enemies are absent.
Studies on Septoria on celery seed
Authors: MAUDE R. B. 
Published: February 2008

SUMMARYStudies of the relationship between the viability of Septoria on celery seed and the ability of the seed to give rise to infected plants have enabled the effectiveness of various fungicides against celery blight to be readily assessed by tests of treated seed. Seed of differing degrees of infectivity was obtained by storage over a period of 14 months or by various seed disinfection treatments.The germination of spores derived from infected seeds was determined by streaking them on agar and the viability of the ‘total’ fungus (spores and mycelium within the seed) was assessed by inserting seeds into slits in celery petioles. The ability of the seed to give rise to infected seedlings was determined by sowing the seed on compost in seed boxes and retaining glass covers on the boxes for 14 days after seedling emergence.Using the three tests concurrently on stored seed it was shown that the decline in the viability of the ‘total’ fungus was similar to that of the spores and was reflected in the decline in seedling infection. It was thus concluded that tests of the viability of spores from infected seed would indicate the ability of such seed to give rise to infected seedlings and that spore germination tests could be used for assessments of the effectiveness of seed treatments.By this means it was shown that soaking diseased seeds in 0·2% thiram suspension for 24 hr. at 30° C. eliminated infection.
Methods of reducing variability in the results of glass‐slide spore‐germination assays of fungitoxicity
Authors: FRICK E. L. 
Published: February 2008

SUMMARYWhen conidial spores of Venturia inaequalis (Cooke) Wint. were germinated on glass, in distilled water only, very little variation was found, but addition of copper sulphate produced a marked variation, particularly between slides.An examination of the standard cleaning technique showed its inadequacy to produce a chemically clean surface, but the introduction of a cleaning method based on permanganic acid led to a very marked decrease of the total variation.When copper sulphate was applied as a deposit, with various wetting agents, to slides cleaned by this method, there was no appreciable reduction in the variation. When the wetting agent was applied with the spore suspension, however, a marked reduction was obtained, but the total variation was further reduced to an acceptable level only when the toxicant was applied in the nutrient solution in which the spores were suspended.A modification of a commercial inverted microscope, to facilitate counting, is described.