bluuebunny/crossref_metadata_2025_split huggingface dataset:
The control of coffee rust in Kenya by fungicides
Authors: RAYNER R.W. 
Published: February 2008

SUMMARYThe results are reported of a series of four factorial field trials carried out at Ruiru, Kenya, to determine the effect on the control of coffee rust (Hemileia vastatrix B. et Br.) of the main variables associated with the application of copper fungicides, i.e. concentration, volume per acre, leaf surface to which applied, time of application, and types of fungicide and application used.Rust control increased with log concentration, there being evidence for a linear relationship. As neither asymptotic nor optimal values occur the optimum for commercial practice must be determined by economics and possible phytotoxic effects.Control also increased with volume per acre, but adjusting the amount of spray residue via concentration was more effective and less wasteful of fungicide than via volume. Upper‐surface application was as effective as lower in one trial at all concentrations, and in another at the higher concentrations. It is considered that liberation of fungicide from upper surface residues by rain, and the presence of thick aggregations of these residues may be of importance for rust control.Differences in rust control following the use of three spraying machines were correlated with the differences in amount of spray residue on the leaves, there being a linear relation to log residue. For the same rust control, a mist‐blower with swirl‐plate atomisation required the greatest expenditure of fungicide per acre and a pneumatic hand‐sprayer, closely approached by a mist‐blower with spinning‐cage atomisation, the least. However, to obtain as heavy residues and as good rust control as with the hand‐sprayer, higher concentrations were necessary. At the same copper content of spray fluid no differences in rust control by Burgundy mixture, cuprous oxide (as ‘Perenox’) and copper oxychloride (as ‘Blitox’) were found. Some observations on the fungicides fermate, cuprous oxide in oil and captan were made. Captan did not increase foliage density. Evidence that this is directly influenced by copper sprays is presented.For reducing the amount (but not the percentage) of rust attack March and April sprays were most effective, January least, and October was intermediate. The earlier sprays reduced the effect of later ones. Reduction of inoculum in January to March did not reduce the July‐August rust peak. The implications are discussed.
Thysanopteran populations overwintering in hedge bottoms, grass litter and bark
Authors: LEWIS T. , NAVAS D. E. 
Published: February 2008

SUMMARYA qualitative and quantitative survey was made of thysanopteran populations overwintering in hedge bottoms, grass litter and bark. The sampling methods used are described. The most common thrips found in these habitats were grass‐infesting species, particularly Aptinothrips rufus (Gmelin) in litter and Limothrips cerealium Hal. in bark. L. denticornis Hal. occurred in both, but preferred litter, whereas Chirothrips manicatus Hal. was almost entirely confined to dead grass inflorescences and litter. Populations were generally more dense in litter than in bark, bark with the most crevices containing most thrips. None of the populations examined showed a significant decline during the winter. Possible predators of thrips were collected from bark. L. cerealium aggregated in bark crevices of suitable width, and touch was probably more important in the selection of crevices than light. In thick pine bark, this species seemed to penetrate into the deeper layers to spend the most severe winter months.
The behaviour and control of the blackcurrant gall mite Phytoptus ribis (Nal.)
Authors: SMITH B.D. 
Published: February 2008

SUMMARYBy placing groups of potted blackcurrant bushes at weekly intervals in a plantation infested with Phytoptus ribis during 1959, 1960 and 1961 it was shown that the maximum rate of mite emergence and infestation coincided with the blossom period and that approximately half of the total infestation took place at this growth stage.Effective migration continued for 12–14 weeks and during the early part of this period the rates of emergence and infestation were directly affected by temperatures below 50° F. Temperatures above 50° F., particularly towards the end of the migration period increased the rate of desiccation of the old buds and forced mites to emerge.When lime sulphur was placed, by hand, in all new leaf axils at weekly intervals, on bushes where there were large mite infestations, complete control was achieved, but this was not found where all the old wood or all infested buds were covered with lime sulphur. These investigations indicate that, for commercial control, repeated treatments must be made especially during the blossom period.Single applications of 1% lime sulphur with a wetting agent were made at various developmental stages on blackcurrants at Long Ashton in 1961 and the percentage reduction of infestations of the blackcurrant gall mite estimated. The most effective were those during the blossom period and particularly where they coincided with the periods of greatest mite emergence and penetration of new axillary buds. Applications were made from the first open flower stage until early June; some control, although progressively decreasing, was given by applications made up to 6 June. More than one spray was necessary for adequate commercial control.Two commercial wettable sulphur powders, applied at the first open flower stage and again 2 weeks later, were found to be approximately as effective as lime sulphur. A wetting agent was used in all the sprays but at half the concentration with the wettable powders.Thiodan did not appear to provide a better control of the gall mite than lime sulphur when two applications of each were made with a wetting agent. Three applications gave better results than two and the addition of a wetting agent was of great importance: where none was used an increase of infestation resulted after three applications, whilst a 94.1% reduction was achieved by three applications of 1% lime sulphur with 0.025 dinonyl sodium sulphosuccinate (0.0125% active ingredient). Hand lances using high volumes of liquid were used throughout.
A method of assessing caterpillar populations on large forest trees, using a systemic insecticide
Authors: SATCHELL J. E. , MOUNTFORD M. D. 
Published: February 2008

SUMMARYA method is described of obtaining estimates of numbers of leaf‐feeding caterpillars on oak trees which might be applied to other large, irregularly‐branched forest trees. A systemic insecticide was introduced to tree boles through cuts in the bark, and poisoned larvae were collected on sheets as they fell off the foliage. Larvae remaining on the trees were subsequently sampled and included in the population estimate. Apart from the cuts, which eventually callused over, the method did not injure the trees.
A study of the absorption of 14C‐labelled DDT from water by fish
Authors: HOLDEN A. V. 
Published: February 2008

SUMMARYThe distribution of DDT in brown trout poisoned by low aqueous concentrations of a labelled form of the insecticide has been studied. A direct‐mount technique for determining the carbon‐14 activity extracted from various organs is described.The DDT was rapidly removed from the water by the fish and by detritus, and relatively high concentrations were found in all organs and tissues examined. Storage occurs principally in the stomach, pyloric caeca, intestine, spleen, muscle and skin. The concentrations found in lipid extracts from the various organs generally showed much more uniformity than concentrations in terms of unit weight of tissue. It is suggested that the concentration of DDT present in the lipids may determine the toxicity to fish, thus explaining the greater susceptibility to DDT of fish in poor condition or of low fat content. DDT extracted from ovaries and testes indicates the possible danger to reproduction.The use of static water for fish toxicity tests involving insecticides is criticized.
The infection of strawberry and raspberry fruits by Botrytis cinerea Fr.
Authors: JARVIS W. R. 
Published: February 2008

SUMMARY Botrytis cinerea occurs abundantly throughout the year as a saprophyte and facultative parasite on a wide variety of plant materials in raspberry and strawberry plantations. Despite high concentrations of airborne spores at the time of fruit development, relatively few infections have resulted from penetration of fruit surfaces following the germination of spores in drops or films of water, uninfluenced by the presence of necrotic tissues. The majority of fruit infections are initiated from mycelium growing saprophytically in contiguous plant material or from spores germinating in solutions trapped between such material and the fruit surface.Dry spores of B. cinerea on the surface of strawberry fruits do not readily germinate in a saturated atmosphere but germinate rapidly in a water film. Although ripe and unripe fruits differ markedly in susceptibility, fruit maturity induces only small differences in the rates of spore germination. Field observations suggest that water films generally do not persist on the surface of the fruit long enough for the post‐germination infection process to be completed. Such films, however, may persist much longer when trapped between floral parts, and spores germinating there are able to initiate infections almost as soon as the buds open. The process may be accelerated by the presence of necrotic tissue, for example, in flowers damaged by frost. Mycelium infecting floral parts may subsequently invade the proximal end of both strawberry and raspberry receptacles. This mycelium may remain quiescent until the fruit ripens; consequently infected fruit may escape notice during picking and marketing.Some methods of supplementing fungicidal control measures by reducing the incidence of sources of infection are suggested.
The cumulative action of insecticides on adult mosquitoes
Authors: HADAWAY A.B. , BARLOW F. 
Published: February 2008

SUMMARYDDT, dieldrin, γ‐BHC, malathion, diazinon and Sevin were all cumulative to some extent in their action on adult mosquitoes, Aedes aegypti. Mosquitoes receiving a sublethal dose of each insecticide were more susceptible to it 48 hr. later than were untreated mosquitoes from the same population. The greatest effect was obtained with dieldrin; the least with γ‐BHC.
‘Eyespot’, a foliar disease of bananas caused by Drechslera gigantea (Heald & Wolf) Ito
Authors: MEREDITH D. S. 
Published: February 2008

SUMMARYThe external symptoms of a hitherto undescribed leaf‐spot disease of young Lacatan bananas are described. The name ‘eyespot’ is suggested since the mature lesion has a white or grey centre and a narrow, well‐defined, brown border. Drechslera gigantea (Heald & Wolf) Ito was consistently isolated from eyespot lesions and, in pathogenicity tests, conidia of the fungus caused typical spots to develop within 48 hr.Conidia of D. gigantea germinated after 30–60 min. in a film of water on the leaf surface, one to five germ tubes being produced from each terminal cell. After 12 hr., germ tubes were up to 75 μ long and swollen at the tip into appressorium‐like bodies. Penetration of the host occurred within 24 hr. Similar stages in the infection process were observed on naturally infected leaves. Sometimes, one conidium caused two distinct lesions as a result of bipolar germination and infection.Air‐borne conidia of D. gigantea were caught by means of a Hirst spore trap. They displayed regular diurnal periodicity, being maximal between 08.00 and 14.00 hr. E.S.T. and practically absent at all other times. Conidia were violently discharged under drying conditions. Highest conidium concentrations were recorded after rain. In the vicinity of the trap, the major source of conidia was Bermuda grass (Cynodon dactylon L.) which was bearing zonate eyespot lesions caused by D. gigantea.This appears to be the first record of D. gigantea in Jamaica. In addition to Musa spp., the grass Anthephora hermaphrodita (L.) Kuntze is now added to Drechsler's host list for D. gigantea.
Experiments on the use of ethyl mercury phosphate and other materials for treating sugar‐beet seed
Authors: BYFORD W. J. 
Published: February 2008

SUMMARYSteeping sugar‐beet seed in ethyl mercury phosphate solution controlled Pleospoya betae and increased the emergence of seedlings in the field more than did ‘short‐wet’ fungicide treatments, spraying EMP solution on to the seed, or steeping in other fungicides.
Further studies of green petal and other leafhopper‐transmitted viruses infecting strawberry and clover
Authors: POSNETTE A. F. , ELLENBERGER CHRISTINA E. 
Published: February 2008

SUMMARYStrawberry green petal, clover witches' broom, stolbur and Delphinium yellows viruses were distinguished from one another and from aster yellows, tomato big bud (lucerne witches' broom) and cranberry false blossom viruses by vector species, host range, host symptoms and reactions to heat in vivo. Euscelis plebejus (Fall.) leafhoppers transmitted green petal virus from, but not to, strawberry plants. Aphrodes bicinctus (Schrank) was an efficient vector and is probably chiefly responsible for green petal disease in strawberry crops.Green petal virus did not protect clover plants from the effects of witches' broom virus, but the latter seemed to interfere with the transmission of green petal virus by E. plebejus. The witches' broom virus also retarded the development of E. plebejus vectors and apparently reduced their longevity. This virus was not transmitted by A. bicinctus.Strawberry plants did not become infected with stolbur virus, but did with Delphinium yellows virus, which caused a bronze‐leaf‐wilt syndrome indistinguishable from that caused by clover witches' broom virus. Stolbur and Delphinium yellows viruses both killed clover; stolbur was occasionally transmitted by E. plebejus and frequently by A. bicinctus, neither of which transmitted Delphinium yellows. Cuscuta campestris Yunck. transferred Delphinium yellows virus from Vinca rosea L. to strawberry and V. Yosea but not to clover or aster; only a single white clover plant was infected by Macrosteles sexnotatus (Fall.). Delphinium yellows virus was inactivated in V. Yosea plants kept at 42°C. for 3 weeks, whereas green petal virus was not, although virus‐free cuttings were propagated from heat‐treated plants.
Withertip disease of limes (Citrus aurantifolia) in Zanzibar
Authors: WHEELER B. E. J. 
Published: February 2008

SUMMARYIn field trials aimed at developing a successful control for withertip disease of limes, applications of fungicides containing phenylmercuric salts, copper, captan, zineb and nickel were compared. Of these, the organo‐mercurial fungicides were the most effective. A light mineral oil as a carrier for this type of fungicide proved less satisfactory than water.Timing of the spraying programme should be determined by two particular periods of flowering—that associated with showers at the end of August and that with the vuli rains (November‐December). These flowering periods provide the greater part of the crop in the following year.The number of spray applications necessary to obtain good disease control was found to depend mainly on rainfall during periods of new growth. In one trial, however, regular applications every 5th day, irrespective of rainfall, gave good control.
The ameliorating effect of zinc on symptoms of phyllody virus (strawberry green‐petal) in white clover
Authors: CARR A. J. H. , STODDART J. L. 
Published: February 2008

SUMMARYWater‐culture experiments with six concentrations of zinc between a trace and 20 p.p.m. showed that the symptoms of clover phyllody were ameliorated by zinc. The proportion of symptomless flower‐heads increased with higher concentration, and when pollinated these set viable, virus‐free seed. Infected plants produced approximately twice as many inflorescences as uninfected plants at each concentration, but the addition of zinc decreased the number produced. Leaf‐bronzing typical of the phyllody syndrome was greater in infected plants and increased with higher concentration, but necrotic spotting attributable to zinc toxicity was more marked in uninfected plants. Zinc at 20 p.p.m. was generally toxic. The dry weight of shoot and root decreased at the higher levels of zinc, and at a lower level with infected than with uninfected plants. Zinc content of root and shoot increased with greater concentrations in the culture solution, being higher in the roots of infected plants than of uninfected ones but less in the shoots. Stolons of infected plants bearing symptomless inflorescences reverted to the full phyllody condition when transplanted into normal soil.The relationship of zinc to normal metabolic processes in the host, including earlier work on hormone levels, is discussed. It is considered that the technique would be of practical value to the legume breeder.
Some new equipment for routine assessment of levels of soil infestation by the potato‐root eelworm, Heterodera rostochiensis Woll
Authors: FIDLER J. H. 
Published: February 2008

SUMMARYIn the examination of a soil sample for the cysts of potato‐root eelworm subjective errors are liable to occur at three particular stages of the technique, especially when large numbers of samples are being examined as a routine. Three pieces of equipment have been developed to mechanise these stages as far as practicable: (1) A centrifugal divider was adapted to obtain mechanically a uniform aliquot subsample from the full soil sample taken from the field; (2) A turntable was developed so that if cyst numbers are large the total may be estimated without picking off all the cysts present; (3) A magnetic stirrer was used to ensure that a reliable aliquot subsample is taken from the suspension of eggs for counting in the Fenwick slide. The inherent errors associated with each of these stages of the technique are examined.
The effect of environment, and nutrition of pathogen and host, in the damping off of seedlings by Rhizoctonia solani
Authors: SHEPHARD M. C. , WOOD R. K. S. 
Published: February 2008

SUMMARYTwo isolates of Rhizoctonia solani which differed in their pathogenicity toward lettuce and cauliflower seedlings were obtained. Each was highly pathogenic toward one host and almost non‐pathogenic to the other. Mineral nutrition of the host, illumination and temperature had little effect on pathogenicity, although very different types of plants were produced. A resistance that developed rapidly with age depended on adequate nutrition and active growth of the seedlings. The nutrition of the fungus, its vigour, and the quantity of inoculum were important in establishing infection, but did not affect the pathogenicity to resistant hosts. High relative humidity reduced the resistance of cauliflower seedlings to the lettuce isolate and also increased the pathogenicity of the lettuce isolate to this host.Pathogenicity depended mainly on intrinsic properties of the host and isolate, and environmental factors were rarely of more than secondary importance in determining whether or not an isolate would attack a particular host plant.
Withertip disease of limes (Citrus aurantifolia) in ZanzibarII.
Authors: WHEELER B. E. J. , PICKARD J. A. , MARTIN J. T. 
Published: February 2008

SUMMARYMature leaves from trees of lime (Citrus aurantifolia) given one small‐volume application of phenylmercuric nitrate showed a deposit of 0·68 p.p.m. mercury compared with 3·99 p.p.m. on similar leaves which were completely wetted. Repeated applications of the fungicide resulted in a build‐up of mercury on both mature and young leaves. Small amounts of mercury were found in new shoots which developed after spraying. Assessments of small‐volume spray deposits using Saturn Yellow as a fluorescent tracer showed good correlation with the analytical values.Lime fruits produced during an intensive spraying programme using small‐volume applications of phenylmercuric nitrate, and harvested 3 months after the last application, showed a mercury content of 0·04 p.p.m., distributed between the peel (65%) and pith (35%). Juices prepared in the laboratory from these fruits and those extracted commercially from fruits similarly sprayed were substantially free from mercury. Fruits picked immediately after one full‐coverage application of phenylmercuric nitrate or acetate showed mercury contents of 0·10‐0·18 p.p.m. The implications of these results are discussed.
Tomato seed germination and emergence at controlled soil‐moisture tensions from 0·5 to 20 cm. mercury
Authors: HACK H. R. B. 
Published: February 2008

SUMMARYA method of controlling the tension (hydrostatic head)—and hence soil moisture—in seed emergence tests, using porous ceramic plates, is described. In the compost employed emergence was good at 2 cm. mercury tension but severely retarded at 1 cm. mercury. This small difference in tension was associated with a large difference in the soil pore space occupied by air. Tensions below 1 cm. mercury would be expected in seed boxes watered according to customary practice. The results are discussed in the light of reports on gaseous diffusion in porous media and on gas balance in soil at different tensions. The need for ensuring an adequate distribution of pores large enough to be filled with air at the low tensions found in seed boxes is indicated.
The effect of weather on emergence and take‐off of overwintering Limothrips cerealium Haliday (Thysanoptera)
Authors: LEWIS T. 
Published: February 2008

SUMMARYThe temperature threshold for take‐off of Limothrips cerealium is 18·4° C., but a temperature‐dependent development period is necessary before thrips are ready to fly in spring. In April and May 1960 this ranged from 4 days at 25° C. to 42 days at 10° C. Thrips hibernating on the warm southern side of trees are therefore ready to fly sooner than those on the cooler northern side.Overwintering thrips were observed emerging from pine bark and their take‐off was recorded by a suction trap. Most thrips emerged when the sun shone on the bark and they usually took off a few minutes later, after combing and flexing their wings.Temperature was the most important single factor influencing take‐off: apparent temperature thresholds for take‐off ranged from 14° C., using air temperature, to 19° C., using bark temperature. These arbitrary values, which were only reflexions of the real temperature threshold, indicated the importance of standard procedures for measuring temperatures, and were a guide to expected behaviour in the field. Take‐off was not retarded by temperatures up to 35° C.Low light intensity reduced take‐off 1–2 hr. before sunset, but in spring the temperature often fell below the take‐off threshold before this. Relative humidity and wind speed were less important, and take‐off occurred at humidities from 27 to 53% and wind speeds from 2·5 to 4·5 m.p.h. Sultry weather was not a necessity for spring flight.
Azobenzene derivatives as seed treatments
Authors: FOX H. M. , GEOGHEGAN M. J. , SILK J. A. , SUMMERS L. A. 
Published: February 2008

SUMMARY4‐Amino‐4′‐hydroxyazobenzene and particularly some of its ring‐substituted derivatives are efficient seed protectants for the control of Pythium ultimum on peas. They are also active against Tilletia caries on wheat, but are ineffective against four other seed‐ or soil‐borne pathogenic fungi. A possible mode of action of the compounds is suggested. Mammalian toxicity data for 4‐amino‐4′‐hydroxyazobenzene and its 3′,5′‐dimethyl and 2,3′,5′‐trimethyl homologues are included.