bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serological and biological characterisation of isolates of barley yellow dwarf virus in Sweden in 1983
Authors: EWEIDA M. 
Published: February 2008

SUMMARYIn 1983, cereal plants showing symptoms of barley yellow dwarf virus (BYDV), collected from 15 localities in Sweden, were tested for BYDV using enzyme‐linked immunosorbent assay (ELISA). Antisera against two Swedish isolates of BYDV were used, a mild isolate (27/77) transmitted specifically by Sitobion avenae and a severe one (39/78) transmitted mainly by Rhopalosiphum padi. No virus was detected in 57 of 607 plants of oats and barley tested. Of the 550 plants in which virus was detected, 366 were infected with viruses similar to isolate 27/77, 116 with viruses similar to 39/78 and the remaining 68 reacted strongly with both antisera. When tested, the latter isolates were shown to be mixtures.Thirty‐nine selected samples were also tested with antisera against the USA isolates RPV, RMV, MAV and PAV, and for transmission by S. avenae and R. padi. Twenty‐six of these samples were transmitted specifically by S. avenae, one was transmitted only by R. padi and the remaining 12 samples were shown to be infected with a mixture of an S. avenae‐specific isolate and one transmitted mainly by R. padi. Antisera against PAV and MAV each detected all isolates tested and the results were very similar to those with the antisera to the 39/78 and 27/77 isolates, respectively. None of the field isolates reacted with antisera against RMV or RPV.It was concluded that 1983 was an epidemic year for BYDV in Sweden and that isolates specifically transmitted by S. avenae predominated. Symptoms of infection by these isolates on oat plants ranged from mild to severe.
Immunity from raspberry vein chlorosis virus in raspberry and its potential for control of the virus through plant breeding
Authors: JENNNINGS D. L. , JONES A. T. 
Published: February 2008

SUMMARYThe apparent immunity of five cultivars of red raspberry and two of black raspberry from graft inoculation with raspberry vein chlorosis virus (RVCV) was established or confirmed. The segregations obtained from selfs and crosses with infectible cultivars of four of the red raspberry cultivars and the black raspberry cultivar Cumberland indicated that the apparent immunity was not determined by a single major gene. The range in severity of the symptoms expressed in the segregates suggested either that sensitivity to infection is under separate genetic control, or that immunity and sensitivity are opposite expressions of a character which varies continuously rather than discontinuously. Nevertheless, although the precise mechanism of immunity remains unclear, the high proportion of immune segregates obtained in crosses indicated that breeding for immunity from RVCV is feasible and offers the best prospect for control of the virus.
Apparatus for determining oxygen in small gas samples
Authors: BANKS NIGEL H. 
Published: February 2008

SUMMARYA simple modification to an electronic O2 analyser is described which enables accurate determination of O2 in small gas samples. The response to O2 concentration is linear over the range 0–21% by volume and as little as 0.07 μl of O2 can be detected. Analysis of a 25 μl sample takes 25 s.
Observations on the number of cereal aphids on the soil in relation to aphid density in winter wheat
Authors: SOPP P. I. , SUNDERLAND K. D. , COOMBES D. S. 
Published: February 2008

SUMMARYThe numbers of cereal aphids on the soil surface was assessed by soil samples and by counting the numbers captured in pitfall traps. A relationship was found by both methods between the density of aphids on the plants and the numbers of aphids on the soil. This relationship indicated that a higher proportion of the aphid population was on the soil surface at the lower densities on the plant. Reasons for this relationship are suggested and discussed.
Bacterial soft rot of tomato in plastic greenhouses in Crete
Authors: MALATHRAKIS N.E. , GOUMAS D.E. 
Published: February 2008

SUMMARYDuring recent years a new disease has been noticed on tomatoes grown in Polythene greenhouses in Crete. Early symptoms are yellowing of the lower leaves, and a yellow brown discoloration of the pith and stem xylem. As leaves wilt and die there is progressive yellowing towards the top of the plants. A progressive disintegration of the cortical tissues follows which results in a soft rot and a longitudinal splitting of the stem running mainly upwards. Soft rot of the fruits rarely appears. Severely infected plants may wilt and die, but other less affected plants often survive and yield normally. Very vigorous plants grown under humid conditions are more susceptible. Often more than 20% of the plants are infected. Isolations were made from stem (xylem, cortex and pith), from leaf xylem and from fruits of infected tomato plants collected throughout the island from 1979 to 1985. Bacteria of the genus Erwinia and Pseudomonas were consistently isolated. On the basis of physiological and biochemical characters of 49 representative pathogenic isolates, 22 were identified as Erwinia carotovora subsp. carotovora, 10 as Erwinia carotovora subsp. atroseptica, four as Pseudomonas viridiflava and 13 as Pseudomonas fluorescens biotype I. All disease symptoms were reproduced when artificial inoculations were made with the above isolates in the laboratory (20°C and 100% r.h.) on 3–4 week tomato plants and in a commercial greenhouse on 4–5 months tomato plants. Bacteria used for inoculations were reisolated. Results indicated that the disease symptoms as described may be caused by four different bacteria species.
The influence of mixed cropping on the control of potato bacterial wilt (Pseudomonas solanacearum)
Authors: AUTRIQUE A. , POTTS M. J. 
Published: February 2008

SUMMARYExperiments with bacterial wilt (Pseudomonas solanacearum) race 3 showed that the practice of intercropping potato with maize or haricot beans markedly reduced the incidence and rate of disease development in the potato crop. This reduction in disease was considered to be an effect of the increased distances between individual potato plants, their spatial arrangement and the presence between potato plants of root systems of other plant species, all of which resulted in a reduction in plant‐to‐plant transmission, via the roots. The lower potato plant population associated with intercropping resulted in a slower rate of inoculum build‐up in the soil and the presence of an intercrop further markedly reduced the inoculum build‐up. Where farmers retain tubers for seed, but where roguing of diseased plants is not practised, the isolation of plants through intercropping was considered to facilitate an efficient selection of healthy tubers.
Properties of a new strain of tobacco streak virus from Clematis vitalba (Ranunculaceae)
Authors: RANA G. L. , KRAJAČIĆ M. , ŠTEFANAC ZLATA , PLEŠE NADA , RUBINO LUISA , MILIČIĆ D. 
Published: February 2008

SUMMARYA distinct strain of tobacco streak virus (TS V/Cle), isolated in Yugoslavia from wild Clematis vitalba showing chlorotic spots or yellow netting of the leaves and from many symptomless shrubs, is described.TSV/Cle was seed transmitted in C. vitalba (70%), and in the experimental hosts Chenopodium quinoa (80%), Nicotiana benthamiana and N. megalosiphon. It was also detected in the pollen of infected C. quinoa. Purified virus preparations mostly contained quasi‐spherical particles measuring 24–26 × 28, 26–28 × 28–30 and 28–31 × 32–36 mn, and sedimented in sucrose density gradient and analytical centrifugation as three components with sedimentation coefficients of 76S, 87S and 98S. The virus contained a single polypeptide species of mol. wt of c. 25 000. Unfractionated TSV/Cle preparations contained four RNA species with mol. wts, estimated by gel electrophoresis in agarose, of 1.1 × 106, 0.9 × 106, 0.7 × 106 and 0.3 × 106. In comparative experiments, TSV/Cle differed from four reference strains of TSV (TSV/B, TSV/HF, TSV/RN, and TSV/Ro) in host range and in symptoms induced in some common hosts. In agar gel double diffusion tests it was more closely related to TSV/B and TSV/M (SDI = 5) than to TSV/HF (SDI = 7), TSV/RN (SDI = 7) or TSV/Ro (SDI = 5–8). Immunoelectrophoresis experiments clearly distinguished TSV/Cle from the reference strains. TSV/Cle strain was detected in C. vitalba plants from distant and climatically different regions in Yugoslavia.
Effects of 2,4‐D butyl vapour on the growth of six crop species
Authors: BREEZE V. G. , WEST CAROLINE J. 
Published: February 2008

SUMMARYSix species of crop plants (tomato, lettuce, clover, cabbage, sunflower and field bean) were exposed to concentrations of 2,4‐D butyl in the range 3–50 ng/litre, for 3.5 h, using an air‐flow system. Symptoms of phytotoxicity were recorded during the following 4 wk, after which the plants were harvested. Sunflower and field bean were found to be most sensitive, with tomato, lettuce and cabbage less affected and clover least sensitive, on the basis of weight. Small tomato plants were more sensitive than ones approximately twice the weight. A 50% reduction in dry weight was caused by a 3.5h exposure to less than 3 ng/litre 2,4‐D butyl for sunflower, compared with over 50 ng/litre for clover. The ranking of sensitivities did not agree with reports based on liquid doses of 2,4‐D, especially for field bean, which was found to be more sensitive than previously thought.
Germination and effect of reduced humidity on expression of pathogenicity in Verticillium lecanii against the glasshouse whitefly Trialeurodes vaporariorum
Authors: DRUMMOND J. , HEALE J. B. , GILLESPIE A. T. 
Published: February 2008

SUMMARYFifteen isolates of the entomopathogenic fungus Verticillium lecanii, from various hosts and locations, were bioassayed in the laboratory at 19 ± 1°C and > 95% r.h. against fourth instar scales of Trialeurodes vaporariorum. Highly pathogenic isolates generally originated from whitefly; however, there was no correlation between conidiospore size or germination rate on agar, and pathogenicity. LT50 values ranged from 5.7 to > 9 days and LC50 (7 days) from 1.3 × 105 to 4.2 × 107 spores/ml. The effect of periods in low humidity (70% r.h.) following 16 or 96 h at > 95% r.h. after immersion of whitefly scales on tomato leaf discs in a suspension of 1 × 106 spores/ml, was compared for five isolates. Progressively longer periods at 70% r.h. following 16 h at > 95% r.h., reduced significantly (P < 0.001) the pathogenicity of all isolates. In these conditions isolate A was least affected by low‐humidity transfer. The high pathogenicity of isolate A was associated with its more rapid development on the host cuticle during the first 16 h in high humidity. When inoculated whitefly scales were transferred to 70% r.h. after a preliminary 96 h incubation in high humidity, all five isolates achieved a higher level of pathogenicity compared with their transfer to low humidity after 16 h high humidity. Thus the screening of V. lecanii isolates in limiting humidity conditions provided a more critical assessment of their pathogenicity and of their potential success in whitefly control relevant to the glasshouse environment.
A column elutriator for extracting cyst nematodes and other small invertebrates from soil samples
Authors: WINFIELD A. L. , ENFIELD M. A. , FOREMAN J. H. 
Published: February 2008

SUMMARYA column soil elutriator (the Wye Washer) for extracting cyst nematodes and other small invertebrates from soil samples is described. Laboratory tests have shown the new equipment to achieve extraction rates equal to or better than existing techniques and to offer operational advantages also. Soil in quantities of up to 1 kg may be processed without drying or subsampling, the equipment can be left unattended once set to work, and can be used to extract a range of target organisms. There is only one working part (a valve) and no electrical parts, but water use and price is high. The Wye Washer is now used in the advisory entomology laboratory at Wye as the standard equipment for extracting cysts of Heterodera and Globodera, for eggs of cabbage root fly (Delia radicum) and for cocoons of black currant leaf midge (Dasineura tetensi).
The effect of inoculating flowers and developing fruits with Botrytis cinerea on post‐harvest grey mould of red raspberry
Authors: WILLIAMSON B. , McNICOL R. J. , DOLAN ALISON 
Published: February 2008

SUMMARYRaspberry flowers were inoculated in the glasshouse and field with dry conidia of Botrytis cinerea and the fruits derived from them subjected to post‐harvest rot tests at c. 20°C and high humidity. Apparently healthy fully‐ripe picked fruits derived from inoculated flowers developed grey mould faster than those from non‐inoculated flowers in all tests.In the glasshouse experiments, fruits from inoculated tightly closed flower buds rotted more slowly than those from inoculated open flowers or those at later developmental stages. Fruits from inoculated whole flowers rotted more rapidly than those from emasculated flowers; the addition of pollen to emasculated flowers had little effect on post‐harvest grey mould.In the dry summer of 1984 no fruits in the field from inoculated whole flowers rotted before ripening, but in the wet season of 1985 pre‐harvest grey mould was common and the surviving healthy fruits rotted in c. 1 day after picking.Only minor differences were detected in host susceptibility to post‐harvest grey mould in both glasshouse and field tests, the ranking of genotypes varied depending on whether or not flowers had been inoculated. The susceptibility of pistils of 40 Rubus genotypes to infection was examined 7 and 28 days after inoculation of stigmas with dry conidia. Conidia germinated on the stigmas and produced hyphae which grew through transmitting tissues of the styles to infect carpels symptomlessly in 17 red raspberries, one blackberry, two Rubus spp. and one hybrid. No germination occurred on stigmas of cv. Carnival and New York Selection 817.
The invertebrate population and response to pesticide treatment of two permanent and two temporary pastures
Authors: CLEMENTS R. O. , BENTLEY B. R. , NUTTALL R. M. 
Published: February 2008

SUMMARYDuring 1979 and 1980 the herbage yields of two permanent pastures and two temporary swards were compared. All four swards received 250 kg N/ha per yr. The invertebrate population of all four swards was studied. Pot‐worms (Enchytraeidae) and some species with long life cycles, e.g. wireworms (Agriotes spp.) were more numerous in the permanent swards, but aerial species were more numerous in the temporary swards. A range of pesticide treatments was applied. At one temporary sward site, application of the broad‐spectrum pesticide aldicarb increased total annual yield of herbage by 16% in 1979 and 33% in 1980. Insecticide application at the same site resulted in no increase in herbage yield in 1979 and 12% yield increase in 1980. At the other three sites no significant increases in total annual yield were recorded in either year, but there were significant responses at one harvest or more at every site.
Effects of ethylene and acetylene on mango fruit ripening
Authors: MEDLICOTT A. P. , SIGRIST J. M. M. , REYNOLDS S. B. , THOMPSON A. K. 
Published: February 2008

SUMMARYMangoes (var. Tommy Atkins) were exposed to ethylene and acetylene over a range of concentrations at high humidity for 24 h at 25°C, then ripened in air alone. Ripeness was assessed after 4 and 8 days by analysis of texture, colour development, soluble solids and acid contents.Ethylene in air at concentrations of 0.01 ml litre‐1 and above or acetylene at 1.0 ml litre‐1 were found to initiate ripening. Treatment with 0.01 ml litre‐1 acetylene resulted in limited softening but had no effect on the other ripening changes analysed. Individual ripening processes responded differently to treatment: texture changes were most rapidly affected, while the rate of acidity losses was often reduced in ethylene treated fruits. Acetylene‐treated fruits at concentrations of 0.01 and 0.1 ml litre‐1 showed delayed ripening when compared to those treated with either 1.0 ml litre‐1 acetylene or ethylene. Increased acetylene concentrations of 2.0 ml litre‐1 gave a similar response to 1.0 ml litre‐1, although in some instances there were indications of inhibitory effects.
The effect of temperature on the rate of sprout growth and development within stored onion bulbs
Authors: BREWSTER J. L. 
Published: February 2008

SUMMARYIn order to understand better the effects of storage temperature on the time to visible sprouting in stored onions, sprout growth was measured by regularly dissecting samples from bulbs stored at 1, 10, 15 or 25°C for 243 days. The dry‐weight of the shoot or sprout within stored onion bulbs increased exponentially with time. The rate of increase of sprout dry weight, as well as the rate of leaf initiation by the shoot apex was faster at 17° than at 10 or 25°C, and almost zero at 1°C. The rate of loss of dry weight from storage tissue was similar at 17°C and 25°C but slower at 10°C and slower still at 1°C.
Dangers in testing statistical hypotheses
Authors: COUSENS ROGER , MARSHALL CHARLES 
Published: February 2008

SUMMARYMost experiments are intended for the estimation of the size of effects rather than for the testing of a hypothesis of whether or not an effect occurs. Hypothesis testing is often inapplicable, is over‐used and is likely to lead to misinterpretations of results. The two types of error possible in hypothesis testing are discussed. Whereas Type I error is usually examined as a matter of course, Type II error is almost always ignored. Investigations in which zero differences are important should recognise the possibility of Type II error in their interpretation. A nonsignificant result should not be interpreted as evidence of a lack of effect. Statistical significance is not synonymous with economic or scientific importance. The importance of choosing the most appropriate design is emphasised and some suggestions are made as to how important sources of error can be avoided.
Field screening for resistance to barley net blotch
Authors: SKOU J. P. , HAAHR V. 
Published: February 2008

SUMMARYInoculation with barley net blotch from infested straw debris was compared with that from diseased plants after sowing infected grains. The straw debris had a high, uniform inoculation potential which gave an early, continuing infection and easily reproducible results that were effective for screening barley cultivars in the field for resistance against a natural population of the pathogen. Further, it minimises an eventual influence from other leaf pathogens coming from the surroundings.Irrigation was decisive for the success of the method ‐ especially in the initial phase. Ten m separation with an immune crop was insufficient to completely prevent infection in the uninoculated plots.The tested 25 cvs were differentiated in six categories of resistant and susceptible on the basis of disease development and final level of attack. None of them was free of symptoms. The most resistant cvs kept a constant, low level of attack during the whole growing season, whereas the most susceptible cvs showed an early and rapidly increasing attack. Intermediate cvs were characterised with more or less slow increase of the attack. The size and proportion of the brown necrotic spots and the surrounding yellow halo varied greatly from one cultivar to the other.The grain yield reduction was due solely to an effect on the thousand grain weight which decreased linearly with the squared point score for net blotch. Further, the disease affected the quality of the grains as less nitrogen was transported from straw to grain in the severely diseased plants.
The importance of understanding host plant phenology in the biological control of Acacia longifolia*
Authors: DENNILL G. B. 
Published: February 2008

SUMMARYIn order to assess the effect of an introduced gall wasp on the weed Acacia longifolia, it was necessary to study the vegetative growth and reproductive potential of uninfested trees. The growth of branches on uninfested trees was studied over one year. The results yielded a growth phenology which is notably different from the growth phenology of A. longifolia described by Milton (1980). Milton (1980) observed no flushing, but a gradual increase and decline in growth during spring and late summer, respectively. The present study showed distinct flushing, and a marked lack of growth during spring. Examination of the effect of reproduction on the vegetative growth of A. longifolia explains the disparity. A. longifolia reproduces during spring. Comparison of phyllode addition during spring with pod production for three successive years at one site, and for two years at another, shows that phyllode addition is low during years of high pod production, and vice versa. Between trees, phyllode addition is also inversely related to pod production within a reproductive season. Because the present growth phenology was done in a year of high pod production, growth during spring was negligible, in contrast with Milton's (1980) phenology which was done in a year of low pod production and high phyllode addition. Depending on the year in which the plant was studied, its reproductive potential and vegetative growth could have been under‐ or overestimated by as much as 62% and 90%, respectively. This study shows that the phenology of weeds with an annual cycle needs to be examined for at least two years in order not to under‐ or overestimate their reproductive or growth potential. This is especially important when assessing the efficacy of biological control agents.
Effects of osmotic priming and ageing on the germination and emergence of carrot and leek seed
Authors: DEARMAN JANE , BROCKLEHURST P. A. , DREW R. L. K. 
Published: February 2008

SUMMARYCarrot and leek seed was osmotically primed in polyethylene glycol solution (273 g/kg water and 342 g/kg water respectively) for 10, 14 or 17 days before accelerated ageing for 0, 24, 48, 72 or 96 h. Priming reduced the germination time compared with non‐primed seed. Accelerated ageing increased germination and emergence times and decreased percentage germination and emergence to a greater extent for the primed seeds than for non‐primed seeds in both species.Primed and dried but non‐aged seed from both species was stored at 10°C for 12 months. There was no loss of viability and improvements in germination time due to priming were maintained throughout the storage period for all the priming treatments in leek, and for the 10 and 14 day priming treatments in carrot. Carrot seed primed for 17 days lost some viability after 12 months storage compared with non‐stored seed.
Virus content of leaves of cassava infected by African cassava mosaic virus
Authors: FARGETTE D. , THOUVENEL J‐C. , FAUQUET C. 
Published: February 2008

SUMMARYAfrican cassava mosaic virus (ACMV) was detected in cassava leaves by ELISA. Some normal constituents of cassava leaves interfered with virus detection but leaf extracts of Nicotiana benthamiana did not. The symptom pattern was determined early in the growth of a leaf and subsequently changed little. ACMV was found only in the yellow or yellow green areas of the mosaic pattern. Virus content of the leaves increased with increasing symptom intensity, but decreased with leaf age and ACMV was not detected in mature leaves. Most whiteflies were found on young growing cassava leaves and the number decreased progressively with leaf age. This distribution will aid both the acquisition and inoculation of the virus.