bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some variants and possible errors in the test‐tube dilution and slide‐germination methods for laboratory testing of fungicides
Authors: McIntosh A. H. 
Published: February 2008

SUMMARYA method is given for moulding uniform Perspex (polymethyl methacrylate) cavity slides, which are quickly made, almost unbreakable and without joints; they can withstand strong alkalis, but not strong acids or solvents, and are useful for spore germination tests of water‐soluble fungicides. When the drops of spore suspension‐fungicide mixture in the cavities of these slides or of Böttcher's glass cavity slides are enclosed by cover‐slips, there is no meniscus effect, and in tests of long duration the same spores can be counted repeatedly.In such tests, errors may arise from sorption of the fungicide on the surfaces of pipettes and tubes (dilution stage) and on slides and cover‐slips (incubation stage); and from changes in the volume of the drops (incubation stage).Ions of many metals may be lost by sorption, and the losses are often greater on soft than Pyrex glass. Hg was lost rapidly. In a three‐stage serial dilution of HgCl2 solution in soft glassware from 60 to 1.0 p.p.m. of Hg, the loss in strength was 27%. More Hg was lost from HgCl2 than from phenyl mercuric acetate solutions. The losses on glass or Perspex slides with cover‐slips from solutions containing 1.0 p.p.m. of Hg (but no spores in suspension) were 30–35% in 15 min. and 61–74% in 24 hr. with HgCl2, but only 5–10% on glass and 35–37% on Perspex slides in 24 hr. with phenyl mercuric acetate. Increase in temperature (10–25% C.) slightly increased the loss from HgCl2 but not from phenyl mercuric acetate solutions. Perspex slides, which were used repeatedly for tests of water‐soluble mercury compounds and washed in distilled water after each test, eventually became toxic to conidia of Botrytis fabae Sardiña.When the slides, with drops, are placed in moist chambers for incubation, some evaporation is unavoidable because the air close to them is not initially saturated with water vapour. When the chambers were pre‐cooled or pre‐warmed, so that the temperature of the air in them was uniform, the loss from 0.30 ml. drops in cavity slides was not serious (about 8%, with or without cover‐slips, in 48 hr. at 10 or 25% C.). But when the temperature was not uniform, the possibilities of change in drop volume were much greater: in 48 hr., the volume of open drops could decrease by evaporation (44% loss at 10° C.) or even increase slightly by condensation (3% gain at 25° C.). When spores have to be counted on several occasions, the evaporation losses may be more serious.
Chocolate spot of beans (Vicia faba L.)—interactions between phenolase of host and pectic enzymes of the pathogen
Authors: DEVERALL B. J. , WOOD R. K. S. 
Published: February 2008

SUMMARY Botrytis fabae and B. cinerea, pathogens which cause ‘chocolate spot’ of beans (Vicia faba L.) produced polygalacturonase abundantly in media containing pectic substances or soluble cellulose derivatives; only filtrates from cultures grown on poly‐pectate had pectinesterase activity and even this was relatively low. B. cinerea filtrates from media containing cellulose had appreciable cellulase (Cx) activity, but did not degrade insoluble wood cellulose; B. fabae filtrates were inactive in both respects. Cultures of both fungi on certain types of media readily macerated sections of bean stems and caused them to become brownish black in colour.Filtrates from cultures of both fungi had considerably lower polygalacturonase activities when leaf extracts were present in otherwise suitable media.The latent phenolase present in water extracts of leaves was activated by poly‐pectate, polygalacturonic acid, pectin and carboxymethylcellulose. Activation was most rapid near pH 4.5 and was negligible at pH 5.5 which was the optimum value for sodium dioctyl sulphosuccinate, one of the best activators so far described. Solutions of the polymers could be diluted with no great effect on activations.Lesions are produced more readily on old than on young leaves, and extracts of old leaves discolour more rapidly than do extracts of young leaves when exposed to activated phenolase from bean leaves. This is because young leaves contain some system which retards the development of the coloured products which are normally produced following the oxidation of phenols.Water extracts of bean leaves inactivate the polygalacturonase of both fungi. The polygalacturonase of B. fabae differed from that of B. cinerea in being rapidly inactivated after filtrates had been diluted with water, and by being inactivated quickly by cyanide. B. fabae polygalacturonase was inactivated relatively quickly by products formed after oxidation of dihydroxyphenylalanine, but was less affected when catechol was used; B. cinerea behaved in the opposite way.The mechanisms by which both fungi cause lesions on bean leaves are discussed in the light of the results summarized above.
Fruit‐spot (‘speckle’) of Jamaican bananas caused by Deightoniella torulosa (Syd.) Ellis
Authors: MEREDITH D. S. 
Published: February 2008

SUMMARYUsing an automatic volumetric spore trap, variation in the atmospheric spore content of Deightoniella torulosa (Syd.) Ellis, the cause of banana fruit ‘speckle’, has been studied in a banana plantation during the period September 1960‐February 1961. Dry weather was characterized by relatively low daily mean spore concentrations of 50–200 spores/m.3of air. Much higher concentrations (2000–7000 spores/m.3) were recorded shortly after rainfall or periods of under‐tree irrigation.Considerable reduction in concentration occurred after the removal from the plantation of decaying leaves and other banana ‘trash’, such tissues being the major source of inoculum of D. torulosa. Similarly, spore counts in trash‐free plantations were consistently lower than those in ‘dirty’ ones. Although the evidence is not conclusive, since it was not possible to provide controls, it seems likely that good plantation hygiene is a major factor in reducing the air spore content of the fungus.In the plantations, the large conidia of D. torulosa have a short air‐borne phase, probably because sedimentation and/or deposition rates are high. This results in relatively short horizontal dispersal distances.
Germination and penetration studies on coffee rust (Hemileia vastatrix B. & Br.)
Authors: RAYNER R. W. 
Published: February 2008

SUMMARYSpore dispersal, germination, penetration and incubation‐period studies on coffee rust (Hemileia vastatrix B. & Br.) in Kenya, East Africa, are described.Evidence is produced that air‐borne spores may be trapped effectively on the upper surfaces of leaves, thence to be liberated and transported to the undersurfaces of other leaves by rain splash.Germination requires liquid water and was observed to occur in 2.6–4.7 hr‐(medians) at 23° C., the minimum being 1 hr. Appressoria were formed in 6.5–8.5 hr. (medians) with a 5.3 hr. minimum. Germination is inhibited by light and in the field by the rapid evaporation of water droplets on the lower leaf surface which occurs during daylight. Light inhibits the growth of germ tubes that are less than 30 μ long and reduces rate of growth if they are longer; appressoria may continue to form.In the field, appressorium formation and infection can occur between 10 p.m. and 8 a.m. If coffee trees are wet at dusk or rain falls before midnight, infection is probable and it is proposed that the number of occasions this occurs be used to forecast the severity of the annual rust maximum.The median incubation period throughout the year varied from 4 to 7 weeks, increasing with low temperatures and dry conditions. A multiple regression of mean maximum and minimum temperatures on incubation period gave fair agreement between observed and computed values for Ceylon and Mysore. Susceptibility and incubation period were strongly affected by coffee variety and rust biotype, but not by age of leaf or crop size.
Field observations on the control of blossom beetles (Meligethes aeneus F.) and cabbage‐seed weevils (Ceuthorhynchus assimilis Payk.) on mustard‐seed crops in East Anglia
Authors: WINFIELD A. L. 
Published: February 2008

SUMMARYField trials on the control of blossom beetles (Meligethes aeneus F.), and cabbageseed weevils (Ceuthorhynchus assimilis Payk.) were carried out in East Anglia during 1958 and 1959, and twenty‐six commercial crops of Trowse mustard (Brassica juncea Coss) were surveyed during the summer of 1959. The development of a Trowse mustard plant, and damage by adult and larval blossom beetles are described. Methods for assessing the damage done by both blossom beetles and seed weevils are discussed, and a preliminary attempt has been made to differentiate the effects of the two pests on the yields of seed.It has been confirmed that DDT is unsatisfactory for the control of seed weevils; two carefully timed applications of dieldrin will probably give an economic control of both blossom beetles and seed weevils. Spraying usually gave increased yields of seed, sufficient to cover the cost of treatment, but a single spray was not persistent enough to give a good control of the damage by adult and larval blossom beetles, and at the same time to control the damage by seed weevil larvae. A single spray applied during May, when the population of adult blossom beetles was rising, did not prevent later adults or larvae from causing damage. A single spray applied shortly before flowering began allowed the early immigrant adults to cause damage but gave some control of the larvae. The infestation of pods by seed weevil larvae was best controlled by a spray during the early‐flowering period. Because of the risk of harming bees and other beneficial insects it is unlikely that a spray during the blossom period could at present be recommended as a routine for all mustard crops.
Comparison between malathion spraying and lindane‐whitewash mixture for controlling Ephestia elutella (Hübn.) in warehouses
Authors: ARMSTRONG MARGARET T. 
Published: February 2008

SUMMARYProvisional estimates of the total numbers of adult Ephestia elutella emerging from warehouse rooms of about 4000 cu.ft. were between 228,300 and 509,300 in ‘moderately infested’ rooms and 1,670,000 in a ‘heavily infested’ room.Moths caught on commercial fly‐papers are a useful index to the emergence date of adult E. elutella.A trial in a Liverpool warehouse in 1958 showed that lindane in a commercial whitewash mixture, applied to walls and ceilings to produce an initial deposit of 40 mg. γ‐BHC/sq.ft., will remain effective against E. elutella between May and December. To obtain this deposit it was necessary to apply over twice this dosage. Very few active moths were seen and a negligible larval migration took place from trap bags which had been the only foodstuffs stored there.Observations over the same period in a warehouse which had been treated commercially at a heavy dosage, in December 1957, showed similar results.Cage tests in the laboratory and in the field indicated that malathion water‐dispersible powder, applied at an initial deposit of 162 mg. malathion/sq.ft., would theoretically be as satisfactory as lindane‐whitewash mixture. In warehouses, however, the former was not so effective as the latter, probably because of the marked fumigant effect of gamma‐BHC.There were indications that lindane‐whitewash mixtures alone might control infestations of endemic E. elutella in fully loaded rooms.
Studies on Gloeosporium musarum Gke. & Massee causing storage rots of Jamaican bananas
Authors: MEREDITH D. S. 
Published: February 2008

SUMMARYIn several commercial‐scale experiments, bunches of bananas were treated by immersing for approximately 1 min. in 2% Shirlan WS and then rinsing in water. Reports obtained after ocean transportation and subsequent ripening of fruit in England indicated that this treatment effected poor or no control of fruit‐rot caused by Gloeosporium musarum Cke. & Massee. Possible reasons for this are discussed in relation to earlier laboratory trials.
Potato haulm resistance to Phytophthora infestans
Authors: LAPWOOD D. H. 
Published: February 2008

SUMMARYReasons were sought for the difference in haulm resistance to potato blight (Phytophthora infestans (Mont.) de Bary) of four potato varieties. Up‐to‐Date produced more foliage than King Edward, Majestic and Arran Viking and a denser canopy which prolonged periods of high relative humidities, and lowered mid‐day temperatures by a few degrees. When field conditions favoured infection, the fungus spread in all varieties, but most extensively in King Edward and least in Arran Viking. Infections developed first, mainly in the lower crop canopy, then the middle and finally in the upper canopy, with lesions on leaves and leaflets distributed similarly on all varieties.The fungus advanced at the same rate in leaf laminae of all the varieties, but not in petioles, which were girdled more rapidly in Up‐to‐Date and King Edward than in the other two and consequently led to the collapse of more leaves.Majestic and Arran Viking are more resistant than Up‐to‐Date and King Edward in the field, because their leaves are infected more slowly early in the blight attack and die more slowly after infection.
An attempt to increase yield by controlling leaf‐area index
Authors: WATSON D.J. , FRENCH S.A.W. 
Published: February 2008

SUMMARYPrevious work showed that the leaf‐area index (L) of kale crops in their later stages of growth can be much above the optimum for dry‐matter production, which was between 3 and 3.5. When L was held close to 3.5 during July‐September 1955, by repeated thinning of plants, the total yield of dry matter including thinnings was increased by about 6%. When thinning was more severe yield was not increased. In a similar period in 1956, thinning that held L between 3.5 and 4 or between 3 and 3.5 did not increase total yield of dry matter, because in this year optimal L was much higher than before. The explanation of the seasonal variation in optimal L is not known.
Studies on plant growth‐regulating substances XVI. The auxin‐activity of ω‐(N,N‐dimethylthiocarbamoylthio)alkanecarboxylic acids, and their β‐oxidation within plant tissues
Authors: GARRAWAY J.L. , WAIN R.L. 
Published: February 2008

SUMMARYMembers of the homologous series (CH3)2NC(S)S(CH2)nCO2H n= 1–6, were prepared and their plant growth‐regulating activities were examined in three different tests. Derivatives of some of these acids with methyl groups in the fatty acid chain were also studied. The metabolism in wheat and broad‐bean plant tissues of two of the homologues were investigated, the products of metabolism being identified by chromatography. All results are shown to be consistent with the theory that the fatty acid chain in this series of compounds becomes degraded in the plant by β‐oxidation.
Seed transmission of Didymella stem‐rot of tomatoes
Authors: MAUDE R.B. 
Published: February 2008

SUMMARYIn studies on seed transmission of Didymella stem‐rot of tomatoes in the outdoor crop, heavily infected seed was sown in the glasshouse in January, March and April and the surviving plants were subsequently planted in the field. 50% of the plants grown from the January sowing became infected and a few of them first showed symptoms after planting in the field. On the other hand only 9 and 5%, respectively, of the plants from the other two sowings became infected, none of them after field planting. No infection occurred on plants raised in soil in which infected seeds had previously been sown. Lesions arising from seed‐borne infection occurred on the cotyledons or hypocotyl and could be distinguished by their position on the mature plant from those resulting from other sources.
Experiments with slug baits in South Wales
Authors: WEBLEY D. 
Published: February 2008

SUMMARY0.025% endrin and 0.05% Rogor (dimethoate), when incorporated in standard metaldehyde and bran slug baits did not increase the catch of slugs. Both insecticides in bran biscuits acted as repellents.The addition of 1 part of 50% Sevin (I‐naphthyl‐N‐methylcarbamate) to 40 parts of the standard metaldehyde and bran mixture improved the catch by 15%. Arion hortensis did not appear to be attracted to metaldehyde to the same extent as Agriolimax reticulatus and Milax budapestensis and the latter species responded more when the nights were warm.Meteorological observations suggest that in the autumn and winter months more slugs are trapped when the night air temperature and the morning relative humidity are high. The age of the biscuits, the grass minimum temperature and the mean night air temperature accounted for 70% of the variance of the catch of metaldehyde biscuits.
Some properties of the virus causing ‘woodiness' of passion fruit in Western Nigeria
Authors: MARTINI C.K.H. 
Published: February 2008

SUMMARY‘Woodiness’ of passion fruit (Passiflora edulis Sims.) in Kenya and Australia is considered to be caused by cucumber mosaic virus. A virus from similarly affected vines in Western Nigeria is transmissible by sap inoculation and by Aphis gossypii Glover, as is cucumber mosaic virus and the ‘woodiness’ virus in Kenya and Australia, but its apparent restriction to the genus Passiflora, the shape of its particles and the manner of transmission by aphids suggest that it is a distinct virus for which the name passion fruit mosaic virus is proposed. Chenopodium amaranticolor Coste & Reyn. produces countable local lesions when inoculated with preparations purified and concentrated by heat clarification and high‐speed centrifugation. Salt concentrations that are tolerated by other plant viruses seem to inactivate passion fruit mosaic virus.
Studies of pelargonium leaf curl virus
Authors: HOLLINGS M. 
Published: February 2008

SUMMARYA virus consistently isolated from pelargoniums showing symptoms of leaf curl infected fifty‐four out of ninety‐nine plant species by sap inoculation. The virus was cultured in Nicotiana clevelandii, and assayed in Chenopodium amaranticolor, Gomphrena globosa or Phaseolus vulgaris; C. amaranticolor, P. vulgaris and Antirrhinum majus produced diagnostic symptoms. During the summer, the virus could not be isolated from pelargoniums, when they show no symptoms, although it is readily transmissible between other plants at all times. Pelargoniums proved immune to infection between March and September, but were readily infected during the winter by sap inoculation from N. clevelandii though not from infected pelargoniums, in which the virus titre is very low. Many infected pelargoniums no longer contained the virus after being grown for a summer in a warm glass house, and plants grown for 4 weeks at 37° C. in a heat chamber were freed from virus.Leaf curl virus was not transmitted by handling, plant leaf or root contact, or by the cutting knife, nor when healthy and infected pelargoniums were exposed together outdoors. Experiments did not detect any virus transmission through the seed or soil, nor by four species of aphid or the glasshouse whitefly.Infectivity was destroyed by heating infective sap for 10 min. at 90° C. and, often, at 85° C.; expressed sap was still infective after dilution to 1:100 (pelargonium) or 1:40,000 (N. clevelandii), and infectivity persisted for at least 21 days in sap at c. 18° C. and more than 3 years at 0° C.The virus was fairly stable in vitro and could be partially purified and concentrated in several ways: the butanol‐centrifugation method proved best. Specific antisera were made by intramuscular injection of such preparations into rabbits, and were successful in tests by precipitin tube, micro‐precipitin drop and gel‐diffusion methods. Electron micrograms of virus preparations contained icosahedral particles about 28 mμ diameter. The virus produced one, two or more distinct light‐scattering zones when centrifuged to equilibrium in density‐gradient sucrose columns; these zones were associated with maximum serological activity, infectivity, and concentration of particles.Leaf curl disease seems to spread slowly in Britain and is not a threat to commercial cultivation of pelargoniums; it can be controlled by selection of material for propagation, or heat treatment of any badly‐affected varieties.
Dispersal of conidia of Cordana musae (Zimm.) Höhnel in Jamaican banana plantations
Authors: MEREDITH D.S. 
Published: February 2008

SUMMARYThe air in several Jamaican banana plantations was sampled from July 1960 to September 1961, using an automatic volumetric spore trap. Conidia of Cordana musae, a banana leaf pathogen, display regular diurnal periodicity, the peak concentration of conidia per m3. of air normally occurring near 07.00 hr. The period of most rapid liberation corresponds with that of rapidly increasing temperature and decreasing R.H. Relatively low daily mean conidium concentrations (< 20 per m3.) were recorded in St Catherine where the incidence of Cordana leaf spot was low. Appreciably higher counts were obtained at Bodles where the trap was operated close to diseased plants. With few exceptions, nights when humidity exceeded 95% R.H. for less than 5 hr. were followed on successive days by concentrations lower than c. 25 conidia per m3. Rainfall and irrigation, resulting in longer periods of high R.H. at night, were usually followed by markedly higher concentrations (50–400 conidia per m3.). The highest hourly estimate recorded was c. 4000 conidia per m3.
Etiology of a gall disease of cocoa in Ghana caused by Calonectria rigidiuscula (Berk. & Br.) Sacc.
Authors: BRUNT A. A. F. , WHARTON A. L. 
Published: February 2008

SUMMARYA form or strain of Calonectria rigidiuscula (Berk. & Br.) Sacc. has been shown to be the cause of a gall disease of cocoa (Theobroma cacao L.) in Ghana. Galls were formed only when the pathogen was inoculated into buds, and the disease is not systemic.Seed is highly susceptible to infection, symptoms usually appearing 12–14 days after inoculation, and a rapid seed inoculation method for testing the pathogenicity of isolates from gall tissue is described. Galls on trees may not develop until many months after inoculation and the full extent of the latent infection period is not known.Using the same methods of inoculation, the disease could not be reproduced by isolates of the same fungus commonly associated with the disease‐complex referred to as ‘cocoa dieback’.
Fungicidal activity and chemical constitution XI*. The activity of n‐alkyl guanidine acetates
Authors: BYRDE R.J.W. , CLIFFORD D.R. , WOODCOCK D. 
Published: February 2008

SUMMARYThirteen n‐alkyl guanidine acetates were prepared and tested against conidia of Venturia inaequalis. Maximum fungistatic activity was associated with a chain length of 12–15 carbon atoms. Selected members of the series were also tested against conidia of Nectria galligena and in a greenhouse assay against apple mildew, caused by Podosphaera leucotricha. These fungi proved in general more tolerant of the guanidines than was V. inaequalis, but were markedly checked by the n‐dodecyl homologue (dodine acetate).For comparison, ten n‐alkylamine hydrochlorides were also tested against V. inaequalis, and found to be generally less toxic.