bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ecology of Erwinia rubrifaciens and the development of phloem canker of Persian walnut
Authors: SCHAAD N. W. , WILSON E. E. 
Published: February 2008

SUMMARYA requisite for development of bacterial phloem canker caused by Erwinia rubrifaciens is the presence of the highly susceptible Hartley cultivar; when interplanted with Hartley, the Franquette and Payne cultivars are sometimes attacked by the disease. The recently developed cultivars, Gustine and Howe, developed active cankers when inoculated, but not as extensive as those in Hartley. The age of the plant part is important in the disease. One‐year‐old Hartley trees and twigs of the current season on mature trees did not develop active cankers. The complete disease syndrome occurs only on trunks and primary (scaffold) branches. Extension of the cankers was most rapid during the summer when the temperature was high. This was correlated with the effect of temperature on growth of the bacterium in culture. At midday in summer the temperature of the cambial area of a shaded trunk was as much as 10d̀F (5.6 d̀C) below ambient temperature but it was commonly a few degrees above ambient at night.Breaks in the thick phelloderm of the trunks and branches are necessary for penetration of the pathogen to the inner bark. Of the several types of breaks commonly occurring, those produced by mechanical harvesting equipment and by sap‐sucking birds were found to be infection sites. Bacteria occur in large numbers in a slimy substance which exudes through cracks and accumulates on the bark of infected trees. They survived for at least 123 days in the exudate and were disseminated laterally as far as 20 ft (6.1 m) in wind‐blown rain. Bacteria were also transmitted from tree to tree in exudate contaminating the pads of mechanical harvesting equipment.
Stabilization, culture and some properties of tulip halo necrosis virus
Authors: MOWAT W. P. 
Published: February 2008

SUMMARYTulip halo necrosis virus, obtained from tulips with leaf necrosis, is very labile in crude sap but can be transmitted consistently by inoculating Nicotiana clevelandii plants with extracts made in pH 8 phosphate buffer containing a stabilizing agent such as 0.2M 2‐mercaptoethanol or 0.01M dithiothreitol. Of the fifteen species in five families of Angiosperms infected by inoculation with sap, few are suitable as sources of inoculum. Cultures of the virus can be maintained in Nicotiana clevelandii kept at 14 or 18d̀C but not at 21d̀C. Infectivity can be assayed in Chenopodium quinoa, in which necrotic local lesions are produced. Stabilized extracts of leaves were infective at a dilution of 1/16 but rarely at 1/32, and infectivity decreased disproportionately with dilution. Infectivity of all extracts was abolished in 10 min at 50d̀C and of some at 45d̀C, but survived when extracts were clarified using diethyl ether or trichlorotrifluoroethane. The virus was not transmitted by the aphid Myzus persicae.
Differences in the probing behaviour of Elatobium abietinum feeding on Sitka and Norway spruces
Authors: PARRY W. H. 
Published: February 2008

SUMMARYThe probing behaviour of Elatobium abietinum (Walk.) on the needles of Norway spruce and Sitka spruce was directly related to the stomatal frequency accompanied by heavy deposition of saliva, and multiple branching and divergence of the salivary sheath, all of which were associated with the impenetrability of the endodermis. On Norway spruce these features were very greatly reduced where there was a higher rate of probing coupled with a higher rate of penetration into the phloem, which was not accompanied by early uptake of phloem sap when compared with aphids on Sitka spruce. These differences in probing behaviour are related to damage symptoms exhibited by the host trees.
A strain of radish mosaic virus occurring in turnip in Yugoslavia
Authors: ŠTEFANAC ZLATA , MAMULA D. 
Published: February 2008

SUMMARYFields of turnip (Brassica rapa L. var. rapa) in Yugoslavia often contained plants infected with radish mosaic virus (RaMV). Yugoslav isolates resemble the type strain in host range, symptoms, physical properties, particle morphology and flea‐beetle transmission and are serologically closely related to the type strain, but did not infect radish and are designated as the European strain. Light microscopy of infected turnip and some other cruciferous species revealed the characteristic inclusion bodies in the cytoplasm.
The effects of soil fumigation and nitrogen fertilizers on nematodes and sugar beet in sandy soils
Authors: COOKE D. A. , DRAYCOTT A. P. 
Published: February 2008

SUMMARYIn fifteen experiments on light land infested with plant‐parasitic nematodes, fumigating the soil during the previous winter with D‐D increased the average yield of sugar‐beet roots from 25 to 36 t/ha; this was more than that obtained with various forms of nitrogenous fertilizers used in amounts up to 250 kg N/ha. Application of 85 kg N/ha increased yields on fumigated plots by 7 t/ha, and there was little benefit from giving more. Fumigation killed 65 % of the Pratylenchus spp., 80% of the Trichodorus spp. and 90% of the Tylenchorhynchus spp. in the top 5 cm of the soil and, at 15–20 cm deep, 90, 93 and 95% of these three genera. The increased yield from fumigant at different sites was not correlated with the initial populations of nematodes. The average increase in yield from fumigation was only poorly correlated with rainfall during May. The increases in nematode populations between April and August depended on rainfall, and were 0positively correlated both with the accumulated rainfall for the 10 weeks before sampling the soil in August and with the rainfall during the week previous to sampling. Fumigation not only improved the health of roots, and so enabled them to use nitrogen more efficiently, but also increased the amount of available nitrogen in the soil and decreased the amount lost by leaching. Injected anhydrous ammonia did not affect the populations of nematodes.
Glandular hairs providing resistance to aphids in certain wild potato species
Authors: GIBSON R. W. 
Published: February 2008

SUMMARYGlandular hairs occur abundantly on Solanum polyadenium, S. tarijense and S. berthaultii. An exudate is discharged from the glandular hair when an aphid mechanically ruptures the cell walls. On contact with atmospheric oxygen, a chemical reaction is initiated in which the clear, water‐soluble material contained in the hair changes to a black insoluble material which is precipitated on the aphid's limbs. This initially impedes its movements and further accumulations eventually stick the aphids to the plant so that they are immobilized and starve to death. In experiments described, about 30 % of infesting aphids were completely immobilized within 24 h. The potential value of this source of resistance to aphids, if incorporated into the cultivated potato, is discussed, especially with reference to the advantages of its being combined with other forms of resistance and to its effectiveness against virus vectors.
Differences in susceptibility to attack by Brevicoryne brassicae (L.) on brussels sprouts
Authors: DUNN J. A. , KEMPTON D. P. H. 
Published: February 2008

SUMMARYThe attack by alate and other forms of Brevicoryne brassicae (L.) and the amount of leaf malformation they caused on each of eighteen varieties or plant breeders' lines of brussels sprout were assessed in both 1967 and 1968 over the first 6 weeks following planting out. The results of the two years agreed closely despite differences in the dates of planting relative to aphid immigration. As a group, the Dutch varieties Roodnerf, Gravendeel, Tribune, Hercules and Castricum Glory were preferred by the incoming alates but suffered less damage than the least preferred inbred line, 3BL, of Cambridge No. 3. Some evidence of antibiosis was obtained, especially from a later experiment with three Cambridge inbred lines. However, in 1969 when there was a high rate of aphid multiplication on six varieties representing sprout types from Holland, Cambridge, Bedford and Ireland, any expression of host non‐preference or antibiosis was soon obscured by the development of large aphid infestations and much damage. Under these circumstances, considerable varietal differences in tolerance to attack were found. Irish Elegance sustained most damage yet its most heavily attacked plants supported little more than half of the aphid numbers of equivalent plants of the most tolerant variety Darkmar 21. The Dutch varieties Vremo Inter and Seven Hills were almost as tolerant as Darkmar 21 and recovered quickly from damage. Darkmar 21 also showed high tolerance to attack in 1970, as did the Dutch varieties Rollo, Roodnerf and Stiekema, when large aphid infestations developed on the eight varieties then grown. Lack of plant tolerance to damage appeared to be associated with incurling foliage, a characteristic of Irish Elegance, Cambridge No. 1 and No. 3.
Studies on a further race (W. 4) of Bremia lactucae Regel
Authors: CHANNON A. G. , HIGGINSON YVONNE 
Published: February 2008

SUMMARYA further race (W. 4) of Bremia lactucae was identified in a sporangial collection from an infected field crop of the cultivar Avondefiance by tests on detached seedlings and leaf disks of various diagnostic lettuce cultivars. Race W. 4 appeared to be unstable, with a similar host range to race W.3, but differed from it in its inability to infect the crisp‐lettuce cultivars Grand Rapids, Calmar, Caravan, Francisco and Great Lakes.Races W. 1, W. 2 and W. 3 were also found in tests starting with the sporangial collection from Avondefiance. Although W. 3 could have been present in small quantities in this original collection, it was considered that W. 1 and W. 2 arose spontaneously from W. 4 during subculturing.A means of eliminating W. 2 from mixtures of W. 1 and W. 2 is described.A laboratory experiment indicated that when competing in a crop of Avon‐defiance or Cobham Green, race W. 2 might predominate over race W. 3.
Resistance to attack by Brevicoryne brassicae among plants of Brussels sprouts
Authors: DUNN J. A. , KEMPTON D. P. H. 
Published: February 2008

SUMMARYBecause they remained almost uncolonized by the cabbage aphid (Brevicoryne brassicae (L.)) throughout the growing season, plants of Brussels sprouts were singled out in each of 4 years, from plots heavily infested with the aphid, as possibly being resistant to attack. Clones of these plants were established from cuttings and tested in a controlled environment by inoculation with B. brassicae and later, in the field, by natural infestation. The tests confirmed that some of the plants were resistant to the aphid, and the most resistant of those from the first year of the work proved at least as resistant as any subsequently found. The resistance was expressed as antibiosis, but in the field host non‐preference was also shown by incoming winged aphids.The possibility that biotypes of B. brassicae might exist, to which the resistant sprout clones were not necessarily resistant, was investigated using B. brassicae collected from sprouts from each of several areas in England. Eight sprout clones, seven of which were known to be resistant, and the other susceptible, to B. brassicae from Wellesbourne were tested with these other B. brassicae. The results showed that biotypes of the aphid, with differing abilities to colonize respective sprout clones, existed in each area, and of the seven sprout clones resistant to the Wellesbourne aphid, only one appeared never to be fully susceptible to one or more of the other biotypes of B. brassicae.
Control of Fusarium solani rot of potato tubers with fungicides
Authors: MURDOCH ANNE W. , WOOD R. K. S. 
Published: February 2008

SUMMARYTecnazene (up to 33 ppm) and dichloran (up to 500 ppm) had little effect on germination of spores or growth of Fusarium solani isolated from and causing a rot of potato tubers; they also did not decrease rotting when applied to wounds later inoculated with the pathogen.Benomyl and thiabendazole (up to 500 ppm) also had little effect on spore germination but did greatly decrease growth at 5 ppm. A pronounced pink coloration developed in cultures growing slowly in the presence of benomyl; a similar though less striking effect appeared in agar cultures containing thiabendazole.Benomyl suspended in water or diluted with Fuller's earth gave good control of rotting when applied to wounds inoculated later with F. solani. Still better control was obtained with thiabendazole; dusts containing 1% a.i. substantially decreased rots and those containing 10 % a.i. gave almost complete control when applied to wounds shortly before inoculation. Thiabendazole was also very effective when used 24 h after inoculation and a fair measure of control was obtained when it was applied 24 h later.Benomyl and thiabendazole placed on apparently intact surfaces of tubers caused tissue 5 mm deep to become toxic to F. solani 10 days later, and, unexpectedly, this tissue prevented spore germination.Fuller's earth alone substantially decreased rotting.The results obtained suggest that dusts containing thiabendazole have some promise for the control of Fusarium rots of potato tubers, especially of early crops.
Chemical control of potato cyst‐nematode in sandy clay soil
Authors: WHITEHEAD A. G. , FRASER JANET E. , STOREY G. 
Published: February 2008

SUMMARYIn sandy clay soil in Bedfordshire, potato cyst‐nematode (Heterodera rostochiensis Woll.) was controlled and yields of Majestic potatoes greatly increased when i‐2g aldicarb, 4‐0 g fensulphothion or 10‐3 g diazinon, disulphoton, ‘Isolan’ (i‐isopropyl‐3‐methyl‐5‐pyrazolyl dimethylcarba‐mate) or thionazin per m2 were incorporated in the top soil before potatoes were planted. Diethyl phosphorothioates controlled H. rostochiensis better than dimethyl phosphates. One hundred and eleven g methyl bromide, 47‐6 g carbon disulphide or 45‐2 g D‐D per m2 applied to the soil and covered with polyethylene sheeting greatly increased the yield of potatoes, but also increased the number of nematodes in the soil. Estimates of the number of larvae able to invade potato roots in treated soil after harvest and of cysts, total eggs or live eggs selected the same range of treatments as effective in controlling H. rostochiensis.
Interference by common leaf saprophytic fungi with the development of Phoma betae lesions on sugarbeet leaves
Authors: WARREN R. C. 
Published: February 2008

SUMMARYWhen sugarbeet leaves were inoculated simultaneously with the parasitic Phoma betae and the saprophytic Aureobasidium pullulans or Torulopsis Candida, the development of expanding lesions caused by P. betae was curtailed. Two other common saprophytes, Sporobolomyces pararoseus and Cladosporium cladosporioides, also decreased numbers and sizes of expanding lesions in the presence of pollen. The numbers of saprophyte cells applied to inoculum areas were similar to those occurring naturally on sugarbeet leaves in the summer.Lesion development was not affected by a mixture of heat‐killed cells of the four saprophytes.
Field experiments on potato aphids and virus spread in South Wales 1966/9
Authors: WEBLEY D. P. , STONE L. E. W. 
Published: February 2008

SUMMARYIn 1966‐9 the spread of leaf roll and severe mosaic (Virus Y) was investigated in seed and ware areas in South Wales. The use of disulfoton granules at planting time greatly reduced the spread of leaf‐roll virus in both areas but had less effect on the spread of severe mosaic. Foliar sprays with formothion did not reduce the spread of either virus. Practical considerations are briefly discussed.
Effect of staking, nitrogen and potassium on growth and development in lesser yams: Dioscorea esculenta
Authors: ENYI B. A. C. 
Published: February 2008

SUMMARYDry‐matter accumulation was greater in staked than in unstaked plants of the lesser yam (Dioscorea esculenta). Staking, N and K application tended to increase the proportion of dry matter diverted into the tubers. Staking was the most important factor in increasing total tuber production, which was one and a half times greater in staked than in unstaked plants. Leaf‐area development was closely and positively related to vine growth, and since staking and N application encouraged vine growth these treatments therefore led to the production of plants with greater leaf area. Leaf‐area duration was increased by staking and N application and was closely and positively related to tuber yield. Staking and N application increased tuber number per plant while K application increased the size of individual tubers. Staking and K application increased bulking rate and both treatments increased the period of bulking by causing earlier tuber initiation.
The effects of windbreaks on the blossom‐visiting fauna of apple orchards and on yield
Authors: SMITH B. D. , LEWIS T. 
Published: February 2008

SUMMARYWindbreaks of coir netting were erected in apple orchards during the flowering period in 1969 and 1970 in an attempt to increase the number of insect pollinators present. Suction traps were used to sample flying insects; insects visiting trees were sampled by examination of flowers. The sheltered zone behind the windbreaks contained more of most species of insects than elsewhere. Increases in final fruit set of approximately 30% in 1969 (cv. Cox's Orange Pippin) and 20 % in 1970 (cv. White Jersey) occurred in trees receiving maximum shelter, and these were due mainly to the increased abundance, and possibly increased activity, of honey bees there. Fruit size was not reduced where yields were increased.
The timing of sprays for the protection of terminal buds on apple shoots from powdery mildew
Authors: BUTT D. J. 
Published: February 2008

SUMMARYPost‐blossom sprays of fungicides, repeated at 10‐day intervals until leader (syn. extension) shoots had stopped producing new leaves, provided the best protection of terminal buds against Podosphaera leucotricha on the apple cv. Lane's Prince Albert. Spraying was most effective in early summer, although many of these buds were not invaded until later, when the rate of shoot growth declined; applications from July to September did not compensate for the enhanced infection which followed interruptions of the post‐blossom programme between late May and early July. This early period was critical because most leaf infections occurred then, and because this phase of the epidemic on foliage determined the eventual intensity of mildew on terminal leaves, and hence the inoculum available for infecting terminal buds. Also, many lateral shoots ceased growth early and their apices were directly protected by sprays applied in June. Applications after early June were too late to protect newly formed fruit buds on spur branches.
Secondary leaf fall of Hevea brasiliensis: factors affecting the production, germination and viability of spores of Colletotrichum gloeosporioides
Authors: WASTIE R. L. 
Published: February 2008

SUMMARYThe optimum temperature for growth and sporulation of Colletotrichum gloeosporioides from Hevea brasiliensis was between 26 and 32 oC, whereas spore germination exceeded 90% between 21.5 and 30.5 oC. Germination decreased in culture after 3 days, and on exposure of spores to sunlight or oven heat (46 oC) for 10 min.Spore viability and germination were sensitive to atmospheric humidity; at 99% r.h. germination was half that at 100% r.h. and was negligible below 97% r.h. Germination decreased by up to 30% after 3 h storage at 80% r.h. Continuous light favoured spore production in vitro, but spores produced in the dark had a higher percentage germination.No differences were detected between the numbers of spores germinating on leaves of different ages, although there were slightly more on susceptible cultivars and in the presence of extracts of uninfected susceptible leaves. Extracts from, infected leaves depressed spore germination, as did concentrations above 5 times 105 spores/ml. The highest % germination was observed when naturally infected leaves were dry‐stored for up to 20 days and then incubated for 2 days in a moist chamber.
Tobacco yellow vein, a virus dependent on assistor viruses for its transmission by aphids*
Authors: ADAMS A. N. , HULL R. 
Published: February 2008

SUMMARYTobacco yellow vein, a disease found in Malawi, is caused by a combination of two viruses transmitted in the persistent manner by aphids. One component, tobacco yellow vein virus (TYVV) is manually transmissible, but aphids transmit it only from plants also containing the other (assistor) component, which is not manually transmissible. Aphids also transmit TYVV from plants containing either of two other assistor viruses ‐ tobacco vein‐distorting and groundnut rosette assistor. A virulent isolate of TYVV infected Soja max, Arachis hypogaea and several solanaceous species. It infected plants already containing tobacco mottle or groundnut rosette viruses but not those containing a mild isolate of TYVV.
The effects of rainfall and shade on the occurrence of three mite pests of tea in Ceylon
Authors: DANTHANARAYANA W. , RANAWEERA D. J. W. 
Published: February 2008

SUMMARYOutbreaks of the red spider mite (Oligonychus coffeae Nietn.), the purple mite (Calacarus carinatus Green) and the scarlet mite (Brevipalpus californicus Banks) of tea were closely associated with the monthly rainfall pattern. Peak numbers occurred during the intermonsoonal dry periods. The relationship between mite numbers and the rainfall pattern suggests that control measures should commence at the end of the first month after the dry season begins. More red spider mites, but fewer purple mites, occurred on tea grown under shaded conditions. Observations on the relationship between scarlet mite numbers and shade were inconclusive. It is suggested that, in addition to direct effects of rainfall and shade, mite numbers are determined by certain biochemical processes that take place within the tea leaves.
Races of Colletotrichum lindernuthianum and implications for bean breeding in Uganda
Authors: LEAKEY C. L. A. , SIMBWA‐BUNNYA M. 
Published: February 2008

SUMMARYNineteen local isolates of the bean anthracnose pathogen have been obtained and tested over the period 1964–70 for pathogenicity on a set of differential cultivars including the sets of four cultivars each used in the alternative systems of Schreiber and Hubberling and of Bannerot and Blondet. The results indicate the existence of a number of races not conforming to those of either system and the ability, when freshly collected, of some isolates with affinities to both α and β races partially to overcome the immunity of the cultivar Cornell 49–242. The implications of the position as now known from these results and a review of the literature for disease‐resistance breeding are discussed. Tests of the Uganda isolates, on a range of other dry bean cultivars, indicate a tendency for α and δ races to be pathogenic on small‐seeded indeterminate viny or indeterminate bush cultivars, whereas β and γ races tend to be pathogenic on larger‐seeded and determinate cultivars.