bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some observations on assessing Phoma betae infection of sugar‐beet seed
Authors: GAMBOGI P. , BYFORD W. J. 
Published: February 2008

SUMMARYNear‐ultraviolet or ‘black’ light applied continuously from the start of incubation, facilitates tests for Phoma betae on sugar‐beet seed by stimulating the production of pycnidia and restricting mycelial growth of P. betae and other fungi. Pretreatment of the seed with dilute sodium hypochlorite decreases the number of seeds with P. betae by removing superficial infection, but some of this is of significance in the field. Rubbing beet seed also decreased counts of P. betae in the laboratory and increased field emergence, primarily by removing the fungus.Griseofulvin sprayed on beet‐seed plants either 2 wk or 2 days before harvest significantly decreased seed infection with P. betae, but not to a level at which further seed treatment could be omitted.
Chemical treatment and inoculation of hardwood stumps for control of Armillaria mellea
Authors: RISHBETH J. 
Published: February 2008

SUMMARYThe type of chemical treatment used to control regrowth from hardwood stumps affects their colonization by fungi. Since such stumps often act as sources of infection for Armillaria mellea this may have important consequences. Ammonium sulphamate generally favours growth of species causing rapid decay, some of which compete well with A. mellea, whereas 2,4,5‐trichlorophenoxyacetic acid tends to promote growth of Chondro‐stereum purpureum which is replaced by A. mellea. The former treatment is recommended for situations where serious damage from A. mellea seems likely to occur, because the best hope of control is to ensure rapid killing of stump roots.Prompt colonization of stumps was obtained by inoculating the cut surface with spores of a wood‐rotting fungus and then treating it with 40% ammonium sulphamate. In birch stumps jointly inoculated with Coriolus versicolor and A. mellea the amount of wood occupied by the latter after 4 yr was greatly reduced by comparison with controls inoculated with A. mellea alone. Stump inoculation might be worth developing for use in valuable plantations and other intensively managed areas such as parks and gardens, especially where measures such as stump excavation are impracticable.
Growth and development of soyabean cv. TK5 as affected by tropical daylengths, day/night temperatures and nitrogen nutrition
Authors: HUXLEY P. A. , SUMMERFIELD R. J. , HUGHES A. P. 
Published: February 2008

SUMMARYTwo experiments were done in Saxcil growth cabinets in order to investigate the effects of climatic factors and nitrogen nutrition on the growth, reproductive development and seed yield of soyabean cv. TK5. In the first, plants were grown to maturity in eight environments comprising all combinations of two short daylengths (11 h 40 min and 13 h 20 min), two day (27 and 33oC) and two night (19 and 24oC) temperatures. In the second, day temperature was kept at 33oC but the night temperature was varied (19 and 24oC) as was the mineral nitrogen supply (20 and 197 ppm N) to plants which were either inoculated or not with an effective single strain of Rhizobium.Taller, more branched, later flowering plants were produced in the longer daylength but seed yield was hardly affected because the components of yield did not all respond similarly. In the higher day temperature treatments seed yield per plant was reduced by half because all yield components were adversely affected ‐ pods per plant by 34 %, mean seed dry weight by 24 % and seeds per pod just slightly. There was a marked effect of the higher night temperature which promoted early vegetative growth, induced early flowering and although the number of pods per plant was, overall, reduced by 48 %, seed yield per plant was little affected as mean seed dry weight was increased by 37 % and the number of seeds per pod was also increased slightly.Prior to flowering, nodulated plants obtained about two thirds of their total nitrogen requirement via direct uptake and one third through the symbiotic system. Vegetative dry weight and plant nitrogen content were increased by the higher mineral nitrogen level and, although height was slightly diminished, more branches were produced. Seed yield, however, was only slightly increased.These experiments have shown that night temperature is an environmental factor of major importance for the growth of this soyabean cultivar. They have provided, also, a more rational basis for interpreting seasonal variations in growth and seed yield of soyabean in the tropics where, clearly, day and night temperature effects can override those of daylength and nitrogen nutrition.
The spread of Phoma exigua within the potato crop
Authors: LOGAN C. 
Published: February 2008

SUMMARYThe incidence of gangrene that developed in tuber samples harvested in a systematic way from potato crops planted with surface sterilized gangrene‐free seed surrounding a small plot planted with gangrene‐affected seed showed that in two out of the three years marked outward spread of Phoma exigua var.foveata occurred in an uneven manner to about 4 ft (1–2 m) from the central plot. The occurrence of var. foveata was restricted to the immediate area in and around the gangrene infection locus whilst P. exigua var. exigua was more widely and evenly distributed throughout the experimental area.The incidence of infection in and around the central plot varied from year to year and it is suggested that the main method of spread of var. foveata inoculum is by rain splash. Infection by both fungi appeared to be influenced in a similar manner in all three seasons.
Influence of crop background on natural enemies of aphids on Brussels sprouts
Authors: SMITH JUDITH G. 
Published: February 2008

SUMMARYThe most abundant natural enemies of aphids on Brussels sprout crops were Syrphidae, different species being attracted differentially to weedy or weed‐free plots according to whether they were more host‐plant‐orientated (e.g. Melanostoma spp., Platycheirus spp.) and thus affected directly by the background, or more aphid‐orientated (e.g. Syrphus balteatus) and so less affected by background than by aphid numbers. Oviposition by Melanostoma spp. was usually much greater in weedy sprout crops than on sprouts in bare soil, and their eggs were also very abundant on weeds. Eggs of other syrphid species were scarcer on weeds. In contrast to Melanostoma, Platycheirus spp. usually oviposted preferentially on sprouts growing in bare soil. Oviposition by S. balteatus was in response to aphid abundance and thus tended to become greater on sprouts in bare soil. Notably more adults of non‐aphido‐phagous Syrphidae were caught over weedy than over non‐weedy Brussels sprout plants. Anthocoris nemorum nymphs and adults were very common on sprout plants and weeds in the weedy crop but were scarce on sprouts in bare soil; A. nemorum oviposited on white and yellow charlock (Raphanus raphanistrum and Sinapis arvensis) occasionally.Parasitism of Brevicoryne brassicae by Diaeretiella rapae appeared to be related to aphid numbers and was only indirectly influenced by the crop background.Field experiments with green and brown cloth backgrounds showed that some syrphids were attracted to green; A. nemorum was relatively scarce over both artificial backgrounds.It is concluded that decreased natural enemy action is partly responsible for the initially greater abundance of B. brassicae in a weed‐free crop of Brussels sprouts than in a weedy crop.
New virulence gene combinations in British isolates of Bremia lactucae
Authors: CRUTE I. R. , DAVIS ANNE A. 
Published: February 2008

SUMMARYIsolates of Bremia lactucae made in 1974 from new Dutch‐bred lettuce cultivars carrying the R gene combinations 3, 4, 7 or 3, 4, 7, 8 proved to have the V gene combination 1, 3, 4, 5, 6, 7, 8 predominant. An isolate obtained from cv. Larganda (R2, 7) was found to overcome all ten R genes identified in lettuce cultivars to date and could be designated V 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. The virulence combinations 3, 7, and 2, 3, 7 have not previously been reported in British B. lactucae collections although the former has been found in Holland and both occur in Sweden. The practical implications of these findings are discussed.
Ultrastructural changes in leaf cells of poplar naturally infected with poplar mosaic virus
Authors: ATKINSON M. A. , COOPER J. I. 
Published: February 2008

SUMMARYIn poplar (Populus x euramericana cv. Robusta) infected with poplar mosaic virus, rod‐shaped, virus‐like particles (c. 13 nm in diameter) occurred singly or in loose bundles in the cytoplasm of cells in palisade and mesophyll tissue and in vascular parenchyma. The cell walls had local overgrowths consisting of membranous elements (vesicles and/or tubules) in a loosely fibrillar matrix. Accumulations of endoplasmic reticulum with enlarged cisternae occurred near cell nuclei.We are indebted to Mr A. G. Mackay, Bryant and May (Forestry Ltd) for supplying the poplar material and we acknowledge technical assistance from Mrs D. McCall. The work was supported financially by the Natural Environment Research Council.
Observations of life‐cycle, population development and vertical distribution of Longidorus macrosoma on raspberry and other crops
Authors: COTTON J. 
Published: February 2008

SUMMARYHigh population densities of Longidorus macrosoma were recorded in the field under raspberry, blackcurrant and cherry, and low densities under grass and alternating spring barley and fallow. Comparison of population development in the field within and between the rows of raspberry and under fallow, suggested that multiplication and development of the nematode was related to the availability of growing host roots, but the nematode was unable to complete its life‐cycle within 1 yr. The nematode was distributed to at least 60 cm depth in association with raspberry. In glasshouse pot tests, the nematode took at least 1 yr to complete its life‐cycle on raspberry and was unable to do so during the period of the experiment on ryegrass and in fallow soil.
Some effects of leaf posture on photosynthesis and yield in wheat
Authors: AUSTIN R. B. , FORD M. A. , EDRICH J. A. , HOOPER B. E. 
Published: February 2008

SUMMARYCanopy enclosures were used to study the photosynthesis of two winter wheat genotypes with contrasting leaf posture (E, erect; L, lax). Over the grain filling period, the net carbon dioxide fixation during the daytime was nearly always greater in E than in L. In general, a greater proportion of the fixation took place in the lower leaves of E than L.Because of the slower senescence of its lower leaves, the leaf area index of E was slightly but consistently higher than that of L and this appeared to account, in part, for the difference between the genotypes in canopy photosynthesis. However, during June and early July, when the leaf area indices were above three, the more uniform distribution of light in the canopy of E than in that of L appeared to be a cause of its higher rate of photosynthesis.Over the grain filling period, more dry matter was lost from the stems of L than from those of E. It is suggested that the shortfall of assimilate for grain filling was met, at least in part, by translocation of materials from the stems and that their greater depletion in L made up for the lower contribution from current assimilation in this genotype.
Studies on plant growth‐regulating substances. XLIII. 2 ‐Chloro ‐3 ‐phenoxypropionitriles
Authors: KEMP M. S. , RIUS‐ALONSO C. , WAIN R. L. 
Published: February 2008

SUMMARYA number of ring substituted 2‐chloro‐3‐phenoxypropionitriles have been prepared and their plant growth‐regulating activity has been assessed in the wheat coleoptile, pea segment and pea curvature tests, and also by spray treatments on tomato and dwarf French bean plants. The activities of these compounds are compared with those of previously studied 2‐chloro‐3‐phenylpropionitriles and the results are discussed in terms of chemical structure/biological activity relationships and mode of action.
Infection of ryegrass plants with ryegrass mosaic virus decreases numbers of the mite vector
Authors: GIBSON R. W. 
Published: February 2008

SUMMARYFewer of the eriophyid mite Abacarus hystrix, vector of ryegrass mosaic virus (RMV), were found on RMV‐infected field plants of Italian ryegrass (Lolium multiflorum cv. S. 22) than on healthy plants. In glasshouse experiments, mites multiplied similarly on healthy and infected plants until disease symptoms developed; afterwards, they did not multiply as rapidly on infected plants and appeared to disperse from them more than from healthy ones, thus encouraging disease spread.
A comparative study of the infection of perennial ryegrass by Fusarium nivale and F. culmorum in sterilized soil
Authors: HOLMES S. J. I. 
Published: February 2008

SUMMARY Fusarium nivale and F. culmorum were frequently found in association with damaged perennial ryegrass.In glasshouse experiments using sterilized soil the pathogenicity of F. nivale isolates varied greatly, but those which were pathogenic reduced seedling emergence and damaged established young plants.All the F. culmorum isolates tested significantly reduced the emergence of S321 perennial ryegrass seedlings, but none had any effect on the growth of established seedlings.Combined inoculations with both Fusarium species further reduced seedling emergence but resulted in less damage to established seedlings than was obtained with F. nivale alone.
Chemical suppression of the symptoms of two virus diseases
Authors: TOMLINSON J. A. , FAITHFULL E. M. , WARD C. M. 
Published: February 2008

SUMMARYCarbendazim applied at the rate of 2 g per plant to the roots of tobacco (Nicotiana tabacum cv. White Burley) plants before infection with tobacco mosaic virus (TMV) caused very considerable reduction in the severity of disease symptoms in systemically infected leaves but did not affect their virus content. Leaves of untreated, infected plants had a greatly reduced chlorophyll content 100 days after infection whereas the chlorophyll content of leaves of infected plants treated with carbendazim was similar to that of normal uninfected leaves. Carbendazim had no effect on the infectivity of TMV in vitro or on the local lesion reaction of N. glutinosa plants when inoculated with TMV.Carbendazim was applied to lettuce cv. Cobham Green at a total rate of o‐i g per plant before and after they were infected with beet western yellows virus and the plants were then grown on in the field. At harvest time (50 days after infection) almost all the treated virus‐infected plants were of a normal green appearance, whereas the untreated controls were almost all very severely yellowed and unmarketable.
Studies on the mechanisms of barley seed deterioration
Authors: HARRISON J. G. , PERKT D. A. 
Published: February 2008

SUMMARYDecline in vigour and viability of barley seeds during storage at room temperature depended on elapsed time and on seed moisture content and was associated with an increase in fungal contamination. Aspergillus repens, Penicillium cyclopium and Fusarium culmorum each became dominant within certain moisture ranges but other evidence indicated that they were not the primary causes of deterioration.Respiration rate, dehydrogenase and diastase activities of germinating deteriorated seeds were less than those of non‐deteriorated controls, and the integrity of cell membranes was affected. The principal site of deterioration which affected seedling growth lay in the embryo.
Weed competition in drilled summer cabbage
Authors: ROBERTS H. A. , BOND W. , HEWSON R. T. 
Published: February 2008

SUMMARYIn four field experiments in different years with summer cabbage drilled in May, naturally‐occurring weed populations of 50–540 plants per m2 reduced the yield of marketable cabbage by 47–100% from that of weed‐free crops. Species composition of the weed population and the rate of emergence and early growth relative to that of the crop were important factors in determining the extent of yield loss. If weeds were removed no later than about 3 wk after 50 % crop emergence and the crop was subsequently kept clean there was no yield loss. If the crop was kept clean without soil disturbance for the first 2 wk or longer, weeds that established after this did not affect yield. There was thus no ‘critical period of weed competition’ and a single weeding 3 wk after 50% crop emergence gave yields similar to those of crops kept weed‐free throughout.
Estimating sib percentages from small samples of F1 hybrid populations
Authors: FREEMAN G. H. , JOHNSON A. G. 
Published: February 2008

SUMMARYPlant breeders raising Fx hybrid populations cannot usually grow more than about 300 plants from one seed lot. If not more than k sibs are observed in a random sample of size N, they then need to estimate the probability that the proportion of sibs in the population is at most p. For sample sizes of not more than 300 this note describes the required statistical procedure which, though not new, may be unfamiliar to plant breeders.
South American leaf blight of Hevea brasiliensis: spore dispersal of Microcyclus ulei
Authors: CHEE K. H. 
Published: February 2008

SUMMARYTrapping of ascospores and conidia of Microcyclus ulei among young trees of Hevea brasiliensis in Trinidad from May 1973 to May 1975 snowed that ascospores occurred throughout the year whilst conidia were present only during the wet season. Peak ascospore concentrations occurred in August and November during the wet season, the latter peak being more marked and the former coinciding with the period of maximum conidium liberation.In dry weather the number of ascospores increased during the night to a maximum at 06.00 h, and decreased to a low level during the day. On rainy days heavy ascospore discharge also occurred during the day. Ascospore concentration decreased significantly after dawn on sunny days whilst on overcast days the concentration remained high most of the day. Conidium production was highest around 10.00 h and decreased towards the evening to a low level during the night, reaching a minimum at 07.00 h.
The influence of leaf surface roughness on the spreading of oil spray drops
Authors: BOIZE L. , GUDIN C. , PURDUE G. 
Published: February 2008

SUMMARYThe effect of surface roughness of leaves on the retention and spreading of oil drops is considered. Three types of roughness have been recognized. Leaf hairs and protruding or recessed veins underlying the cuticle constitute a macroscopic roughness. Microscopic roughness is determined by epidermal cell size and arrangement, which influence the geometry of the grooves between these cells. Ultra‐microscopic roughness is determined by the size, shape and organization of the epicuticular wax system. The effect of environmental conditions on surface roughness is also considered and the significance of the spreading of spray drops is discussed in relation to the application of pesticides.
Ear and flag leaf photosynthesis of awned and awnless Triticum species
Authors: OLUGBEMI L. B. , BINGHAM J. , AUSTIN R. B. 
Published: February 2008

SUMMARYThe net photosynthetic rates of ears and flag leaves of awned and awnless wheats were measured by infra‐red gas analysis in a controlled environment experiment. At 107 W m‐2 the rates of net photosynthesis of the ears of two awned Triticum aestivum lines were two to three times greater than those of their isogenic awnless counterparts. The net rates of photosynthesis of the flag leaves of all four lines were, however, similar. Net photosynthetic rates of ears of T. durum and T. turgidum, which have much larger awns, were considerably higher than those of T. aestivum. Between 70 and 90% of carbon‐14 assimilated by the flag leaves and by the ears of T. aestivum was translocated to the grains, with no effect of awns in this respect.In a glasshouse experiment with detached shoots the contributions of the component organs to gross photosynthesis were determined by carbon‐14 labelling. Ears of awnless lines of T. aestivum contributed about 10% to the photosynthesis of the organs above the node of the penultimate leaf and awns increased this to about 18%. Fixation by awned ears of T. durum and T. turgidum was 21–29% and of this 78–86% was contributed by the awns. In both experiments the contribution of the flag leaf to shoot photosynthesis was greater in T. aestivum than in the other species.
The influence of climate on the incidence and severity of some tropical crop diseases
Authors: Waller J. M. 
Published: February 2008

ABSTRACTAgriculture in tropical countries produces many of the world's most valuable crops, but productivity is limited by a multiplicity of different diseases, many of which have been inadequately studied. Certain characteristics of tropical climates have a fundamental influence on the incidence and severity of many of these diseases. The main seasonal variations which control crop growth and disease epidemiology depend on differences in moisture availability rather than daylength and temperature differences. Marked dry seasons hinder the survival of many pathogens outside hosts unless they can produce drought‐resistant spores. In many tropical areas continuous cropping throughout the year is possible, enabling disease epidemics to continue without interruption over long periods.Much agriculture in the tropics is at fairly high altitudes enabling temperate crops to be grown, but low temperatures may present special disease hazards. Violent storms are a feature of many tropical climates and have been implicated in the spread of many bacterial diseases. Drought is a factor which influences the severity of many root diseases. The various effects which moisture, as rain or dew, temperature and cropping cycle can have are illustrated by discussion of sigatoka disease of bananas (Mycosphaerella musicola Leach), South American leaf blight of rubber (Microcyclus ulei (R. Henn.) Arx) and coffee berry disease (Colletotrichum coffeanum Noack).
Sources and inheritance of resistance to downy mildew of the pea, Peronospora pisi
Authors: Matthews P. , Dow K. P. 
Published: February 2008

ABSTRACTSix hundred and one lines from the John Innes Pisum germplasm collection were surveyed for resistance to downy mildew (Peronospora pisi). Potential sources of resistance were identified in forty‐seven lines. Using the inoculation methods described resistant varieties/lines showed no evidence of infection.Isolates from recent outbreaks in the United Kingdom when screened against a representative test array of resistant and susceptible lines showed no evidence for a race structure in Peronospora pisi, although differences were found in overall virulence.The inheritance of resistance was studied in F2 and F3 families. Under the test conditions adopted the results obtained suggest that resistance may either be determined by a single dominant gene or by two recessive genes, but the lack of concordance between F2 and F3 segregation patterns was a disturbing feature despite careful control of experimental conditions. This, coupled with difficulties in obtaining large F3 families presents considerable problems in interpretation.It is proposed that inbred lines of JI 411 Cobri and JI 399 Cennia be adopted as standards.