bluuebunny/crossref_metadata_2025_split huggingface dataset:
The competitive effects of volunteer barley (Hordeum vulgare) on the growth of oilseed rape (Brassica napus)
Authors: LUTMAN P. J. W. , DIXON F. L. 
Published: February 2008

SummaryThe effects of competition from volunteer barley (Hordeum vulgare) on the growth and yield of oilseed rape (Brassica napus) were investigated in four experiments over three seasons. The growth of rape in the autumn was reduced by 50 ‐ 91 % by competition from 400 barley plants m‐2. A lower barley density of 200 plants m‐2 had less effect but still reduced growth of rape by 65 ‐ 81% in two of the experiments and 25 ‐ 40% in the other two. During winter and spring the barley decreased in vigour and in the spring the rape started to recover, especially on the early drilled (23 ‐ 30 August) plots. The rape sown in mid‐September recovered less quickly. In Experiment 3, herbicides applied in November to control barley did not result in increased growth of rape in winter but led to greater recovery in spring. The barley died during the winter in Experiments 2 and 4, even in the absence of herbicides. Despite the marked effects of barley on the growth of rape in the autumn, yields on plots that had previously contained 200 barley plants m‐2 were reduced by a maximum of only 16% in three of the experiments. In Experiment 3, where the barley was most competitive, this density and 400 plants m‐2 lowered yields by 39% and 78%, respectively. Where a herbicide was used in November to control the barley these yield losses were reduced to 5%. In many rape crops the cost of herbicide treatment would be greater than the financial returns from the expected increase in yield resulting from the control of weeds. Possible reasons for the small loss in yield of rape from barley densities that had substantial effects on the growth of rape in the autumn are discussed.
Effects of treating seed potatoes with trace elements on sprouting and microbial spoilage during storage under tropical conditions
Authors: SHASHIREKHA M. N. , NARASIMHAM P. 
Published: February 2008

SummaryAttempts were made to extend the storage life of seed potatoes by treating them with trace elements as antimicrobial and antisprouting agents. In tests to measure the growth of Fusarium oxysporum, and Erwinia carotovora pv. carotovora it was found to be decreased more by iron, copper and zinc than by boron, manganese and molybdenum. Dipping seed tubers in aqueous solutions of trace element salts decreased both sprouting and microbial spoilage during storage at ambient conditions. Field testing at the end of storage proved that treating seed potatoes with ferrous sulphate did not decrease the yield of tubers or increase their iron content. It is suggested that trace elements may be used to extend the storage life of seed potato tubers, in tropical conditions.
Effect of soil compaction on growth, yield and light interception of selected crops
Authors: ASSAEED A. M. , McGOWAN M. , HEBBLETHWAITE P. D. , BRERETON J. C. 
Published: February 2008

SummaryThe response of spring barley (Hordeum vulgare, cvs Carnival and Atem), faba beans (Vicia faba, cv. Maris Bead), sugar beet (Beta vulgaris, cv. Monoire), forage maize (Zea mays, cv. Leader), forage peas (Pisum sativum, cv. Poneka) and white turnip (Brassica campestris, cv. Barkant) to topsoil compaction was investigated in a three year trial. Soil compaction was induced by tractor wheeling after crop sowing.Compaction reduced leaf area and dry matter accumulation in all crops in every season. Yield of barley was reduced by 29%, 27% and 40% in 1984, 1986 and 1987 respectively. Yield of maize, peas and turnip decreased by 33%, 14% and 13% in 1986 and 25%, 16% and 19% in 1987. Yields of beans and sugar beet were decreased by 34% and 35% respectively in 1984.Light interception was decreased in all crops in all three years of study but, with the exception of maize in 1987, the efficiency of conversion of radiant energy to dry matter was not significantly affected by soil compaction. It is concluded that reduced dry matter production and yield due to soil compaction was more a consequence of reduced light interception because of restricted leaf area development rather than as a result of an impaired ability of crops to utilise intercepted radiant energy.
The use of chlorophyll fluorescence in assessment of low temperature hardiness in blackcurrant (Ribes nigrum L.)
Authors: BRENNAN R. M. , JEFFERIES R. A. 
Published: February 2008

SummaryThe effect of freezing stress on chlorophyll fluorescence was examined in leaves of five genotypes of blackcurrant (Ribes nigrum L.). Minimum fluorescence (Fo), variable fluorescence (Fv) and the time for Fv to decay to half its maximum value (q1/2) all varied between genotypes. Freezing stress significantly reduced Fo in all genotypes, but the effect of freezing stress on Fv was non‐significant. Freezing stress significantly increased q1/2, but the effect varied significantly between genotypes. The increase in q1/2 induced by freezing stress was greatest in the cultivar Baldwin and least in the accession Ri‐74020‐6. The effects of freezing on chlorophyll fluorescence, particularly q1/2, corresponded to the susceptibility of the genotypes to spring frosts. It is concluded that chlorophyll fluorescence can provide a rapid screening technique for assessing frost hardiness in blackcurrant.
Low‐ethylene storage of apples cv. ‘Cox's Orange Pippin’: effects of ‘Rapid CA’ and ultra‐low oxygen
Authors: STOW J. , GENGE P. 
Published: February 2008

SummaryThree methods of reducing ethylene accumulation in the flesh of apple fruits cv. ‘Cox's Orange Pippin’ during controlled atmosphere storage were compared with one another and with a control. They were: (a) rapid establishment of storage conditions, (b) treatment with 5% CO2 for 15 days prior to long‐term storage, and (c) lowering storage O2 from 1.25% to 0.75%. In all cases ethylene was either allowed to accumulate or maintained below 1 μl litre‐1. When ethylene was removed from the storage atmosphere all three methods reduced internal ethylene concentrations.Although the firmness of fruits from two orchards was affected differently by ethylene removal, the effects on the retention of flesh firmness by ethylene removal and storage in 0.75% O2 were generally additive.No adverse effects of storage in 0.75% O2 were observed.
The effect of introducing the aphid‐pathogenic fungus Erynia neoaphidis into populations of cereal aphids
Authors: WILDING N. , MARDELL SUSAN K. , BROBYN PATRICIA J. , WRATTEN S. D. , LOMAS JANET 
Published: February 2008

SummaryThe aphid‐pathogenic fungus Erynia neoaphidis, as dried fungus‐infected aphids, was applied to caged plots of winter wheat infested with cereal aphids at two sites, one in Hertfordshire and the other in Hampshire, in 1983. In each trial, the fungus became established in the aphid populations in the treated plots even though conditions were drier than average and therefore sub‐optimal for fungus spread. Treatment applied in the third week of June increased the proportion of infected aphids more than that applied two weeks later at one site, and the early application was the only treatment to have an obvious effect at the other. In spite of the observed effect of treatments on the proportion of infected aphids, the fungus failed to reduce the numbers of aphids relative to those in untreated plots, chiefly because in these plots many aphids were killed by fungi of the same species as that introduced and other related species from natural sources. Artificial introduction of E. neoaphidis acts too slowly and unpredictably to be likely to form a practical alternative to conventional insecticides for cereal aphid control.
Studies on the toxicity of insecticidal drift to the first instar larvae of the Large White butterfly Pieris brassicae (Lepidoptera: Pieridae)
Authors: SINHA S. N. , LAKHANI K. H. , DAVIS B. N. K. 
Published: February 2008

SummaryThe toxicity (LD,) of eight insecticides to 2–day‐old first instar larvae of Pieris brassicue was determined by topical application. On this basis, the insecticides could be ranked in ascending order viz. dimethoate > pirimicarb > phosalone > endosulfan > fenitrothion > pirimiphos‐methyl > fenvalerate > diflubenzuron. Relative to endosulfan, dimethoate and pirimicarb were 30–25 times less toxic while at the other extreme, fenvalerate (x 12) and diflubenzuron (x 26) were much more toxic to the larvae of P. brassicae.A methodology was developed for examining the effects of spray drift through bioassay using these 2–day‐old larvae. Six field trials with commercial formulations were carried out in which variables other than the insecticide and wind speed were held constant as far as possible. Phosalone (700 g active ingredient ha) produced no effect beyond 1 m downwind at low wind speed (2 m s); at high wind speed (4 m s‐1). larval mortality (5.3%) was recorded up to 2m. Fenitrothion (1050 g a.i. ha‐1) at moderate wind speed (3 m s‐l) caused mortality up to 4 m while fenvalerate (30 g a.i. ha‐l) at the same wind speed affected larvae up to a distance of 8 m. Diflubenzuron at a very low dosage (6.5 g a.i. ha‐1) also produced effects up to 8 m. At the maximum approved dosage (100 g a.i. ha‐1), and at high wind speed (4.25 m s‐l), diflubenzuron killed 8.4% of the larvae at 16 m distance.At wind speeds of 2 ‐ 3.5 m s‐1, spray deposits on the upper surfaces of water sensitive papers were high at 0 m and declined exponentially with distance. At higher wind speeds (4 ‐ 4.25 m s‐I) turbulence produced irregular deposits. Deposition on lower surfaces was much lower than on upper surfaces but the trends with distance and wind speed were the same.The exponential relationships between mortality and distance, and drift deposition and distance, were examined. The results are discussed with respect to laboratory toxicities, application rates, wind speeds and ecological factors.
A comparison of inoculation techniques for assessment of germplasm susceptibility to Karnal bunt (Tilletia indica) disease of wheat
Authors: WARHAM ELIZABETH J. 
Published: February 2008

SummaryThree inoculation techniques for Karnal bunt (Tilletia indica) disease of wheat were compared: 1) boot inoculation ‐ injection of inoculum with a hypodermic syringe into the boot; 2) spray inoculation ‐ inoculum sprayed at growth stages between heading and anthesis, and 3) cotton wool inoculation ‐ small pieces of cotton wool saturated in inoculum placed either inside the floret or between the spikelet and rachis. Each inoculation technique was assessed using susceptible cultivars to determine the optimum inoculum concentration, the ideal plant growth stage and the humidity requirements for successful infection.Boot inoculation did not require high humidity and gave reliable infection with low secondary sporidia concentrations (1000–10 000/ml). The ideal plant growth stages for inoculation were early‐boot and mid‐boot. Spray inoculation required high secondary sporidia concentrations (50 000/ml) and 48 h of high humidity, but infection was initiated over a range of growth stages throughout heading and anthesis. Cotton wool inoculation gave low levels of infection at growth stages throughout heading and anthesis, even with high secondary sporidia concentrations (100 000/ml).
Effects of fungicides applied to seed potato tubers at harvest or after grading on fungal storage diseases and plant development
Authors: CARNEGIE S. F. , RUTHVEN A. D. , LINDSAY D. A. , HALL T. D. 
Published: February 2008

SummaryAn assessment was made over 3 years of the efficacy of thiabendazole, 2–aminobutane and a formulation of a mixture of thiabendazole and 2–aminobutane in controlling gangrene, skin spot and dry rot when applied either at harvest or after grading at different dates during the storage season.After harvest applications, the incidence of gangrene was least on tubers treated with the mixture and generally greatest with thiabendazole. When applied after grading the efficacy of the fungicides was not affected by date of grading. Although 2–aminobutane applications at harvest or after grading were equally effective in controlling gangrene, thiabendazole and the mixture were less effective after grading where gangrene was prevalent in a stock. Thiabendazole and the mixture gave good control of dry rot when applied at harvest but were less effective when applied after grading, particularly late in the storage season. Dry rot was sometimes more prevalent on tubers fumigated with 2–aminobutane, especially those treated after grading. Skin spot was more effectively controlled by the mixture and 2–aminobutane than by thiabendazole but, with applications after grading, the efficacy of all fungicides declined the later the date of grading.Plants grown from tubers treated with the mixture or its 2–aminobutane glycollate constituent exhibited characteristics associated with genetic variation.
Virus content of seed potato stocks produced in a unique seed potato production scheme
Authors: WILSON C. R. , JONES R. A. C. 
Published: February 2008

SummaryWestern Australia has a unique seed potato production scheme which has remained virtually unchanged for more than 60 years, consisting of summer plantings of predominantly one cultivar in wind‐exposed coastal swamplands. No rotation is used and the scheme relies on natural winter flooding and ‘grazing’ by sheep to eliminate unharvested tubers. Stocks are recycled every year with only limited inputs of pathogen‐tested seed tubers in recent times. Virus spread in the crop is controlled by selecting large tubers for planting, roguing, aphicide application and growing season inspections. Potato viruses X and S were commonly detected in old seed stocks produced by this scheme attaining 100% infection in some. Both viruses were less frequently found in newly introduced seed stocks. By contrast, potato virus Y was never detected and potato leaf roll virus rarely found.
Resistance to potato virus Y and potato virus X in Solanurn brevidens
Authors: GIBSON R. W. , PEHU E. , WOODS R. D. , JONES M. G. K. 
Published: February 2008

SummaryAlthough Solanum brevidens could be infected with potato virus X (PVX), potato virus Y0 (PVY0) and PVYN, no symptoms of infection were apparent and tests by double antibody sandwich ELISA, electron microscopy and sap transmission to local lesion test plants indicated that the titres of PVX were less than a tenth of those of PVY0 and PVYN were less than a hundredth of those in infected plants of PDH40, a susceptible dihaploid clone of S. tuberosum cv. Pentland Crown. Furthermore, PVY0‐ and PVYN‐ infected leaves of S. brevidens were a poor source of inoculum in aphid transmission tests. The possibility of a common mechanism and genetic basis of resistance to PVY, PVX and potato leaf roll virus in S. brevidens is discussed.
Studies on Artioposthia triangulata (Dendy) (Tricladida: Terricola), a predator of earthworms
Authors: BLACKSHAW R. P. 
Published: February 2008

SummaryObservations had linked the disappearance of earthworms from a grass field to the presence of Artioposthia triangulata. An experiment demonstrated that this land planarian could severely and quickly reduce numbers of four earthworm species. Two different approaches to sampling A. triangulata were investigated on a grassland site. The first used four different trap types (wood, ceramic tile, ‘corriboard’ plastic and 5 mm polystyrene beneath a ceramic tile) measuring 15 cm x 15 cm which were compared over a period of 18 wk. The second used one, or two, applications of dilute formalin solution to quadrats followed by counting the residual planarians by hand‐sorting the soil beneath the quadrat to a depth of 30 cm. The polystyrene traps were the most effective for detecting the presence of A. triangulata. No planarians were ever found by hand‐sorting after two formalin applications and it was concluded that formalin sampling provided a good estimate of the population density. Counts under traps were not related to absolute estimates of population densities so polystyrene type traps should only be used for detection of the planarians. A multiple regression relationship of A. triangulata weight over time in 5% formalin is presented and allows the original liveweight to be calculated from the weight in preservative. Planarian and earthworm population densities in eight fields were sampled and the planarians were found to be randomly distributed. Counts of planarians in 0.25 m2 quadrats were not related to numbers of earthworms but overall field population densities were. It is concluded that A. triangulata is a severe threat to the earthworm populations of Northern Ireland.
Responses of Schizaphis graminum (Homoptera: Aphididae) to leaf excision in resistant and susceptible sorghum
Authors: MONTLLOR C. B. , CAMPBELL B. C. , MITTLER T. E. 
Published: February 2008

SummaryGreenbugs, Schizaphis graminum (Rondani), were reared on intact and excised leaves of varieties of sorghum which differed in their suitability as hosts for this aphid. Aphids grew poorly on intact leaves of three resistant varieties, but grew well on excised leaves of the same varieties. Leaf excision did not affect aphid growth on three susceptible varieties. By electronically monitoring the feeding behaviour of aphids on two resistant and one susceptible variety, significant differences were found in many parameters between aphids assayed on excised vs. intact leaves of only the resistant varieties. Aphids on excised leaves of the resistant varieties, and on excised or intact leaves of the susceptible variety, made fewer probes to the phloem, spending more time ingesting from phloem during each probe, compared to aphids on intact resistant plants. There was a higher level of free amino acids in excised leaves of all varieties, but aphid growth and feeding behaviour improved as a result of excision only on resistant varieties. This observation, coupled with the fact that intact plants of all varieties have similar amino acid levels, indicates that these nutrients are not of primary importance in sorghum suitability to the greenbug. Other explanations for the aphids' responses to excised leaves are discussed.
Ingestion of Pythium spp. by larvae of the fungus gnat Bradysia impatiens (Diptera:Sciaridae)
Authors: GARDINER R. B. , JARVIS W. R. , SHIPP J. L. 
Published: February 2008

SummaryMycelium, oospores and zoospore cysts of Pythium spp. were fed to larvae of the fungus gnat Bradysia impatiens. The fungal structures were all ingested and provided a complete nutritional source for the insect's development from egg to adult. Mycelium seemed the major source of food as only empty fragments were found either in the digestive tract or in larval faeces. Oospores appeared intact and were viable both during passage through the tract and when expelled. Germination of oospores was normal. Most encysted zoospores also survived passage through the gut, although some appeared damaged. After transferring recently‐fed larvae to a new food source, oospores were still detected in the digestive tract 48 h later. These results show that the larval stage of B. impatiens may serve as an important vector for Pythium spp.
Effect of moisture stress, plant population density and pathogen inoculation on charcoal stalk rot of sorghum
Authors: PANDE S. , MUGHOGHO L. K. , KARUNAKAR R. I. 
Published: February 2008

SummaryThe effects of moisture deficit stress, plant population density and pathogen inoculation technique on charcoal stalk rot in the sorghum hybrid CSH 6 were studied in the 1980–81 and 1981–82 post‐rainy seasons at three locations in India. Incidence and severity of charcoal rot caused by Macrophomina phaseolina were compared in three plant population densities, subjected to different moisture stress regimes created by withholding irrigation at various plant growth stages. Natural infections were compared to artificial inoculation with M. phaseolina. Combinations of moisture stress, plant population and inoculation treatments were compared to identify the combination most likely to develop maximum disease. Lodging, the first external symptom of charcoal rot, was significantly correlated with other disease symptoms used to measure charcoal rot, such as soft stalk, number of nodes crossed by M. phaseolina infection, root damage and plant senescence. In both seasons the highest incidence of lodging occurred when moisture stress was induced at the ‘flag leaf visible in the whorl’ growth stage. The greatest incidence of the disease was recorded in the highest plant population (266 700 plant ha‐) at all three locations. No significant differences were found between artificially and naturally inoculated treatments. The maximum number of lodged plants was found at a density of 266 700 plants ha‐1 when moisture stress was induced at the ‘flag leaf visible in the whorl’ growth stage.
Interaction of post harvest disease control treatments and gamma irradiation on mangoes
Authors: JOHNSON G. I. , BOAG T. S. , COOKE A. W. , IZARD M. , PANITZ M. , SANGCHOTE S. 
Published: February 2008

SummaryThe effects of gamma irradiation and disease control treatments on disease severity and post harvest quality of several mango cultivars were investigated.In mangoes cv. Kensington Pride, irradiation doses ranging from 300–1200 Gy reduced disease, but the level of control was not commercially acceptable. Hot benomyl immediately followed by irradiation provided effective control of anthracnose (Colletotrichum gloeosporioides) and stem end rot (Dothiorella dominicana) during short‐term storage (15 days at 20°C). The effects of the two treatments were additive.Satisfactory disease control was achieved during long term controlled atmosphere storage when mangoes were treated with hot benomyl followed by prochloraz and then irradiated. Effects of fungicide treatment and irradiation were additive. Fungicide, or irradiation treatments alone, were unsatisfactory.Irradiation of cv. Kensington Pride at doses in excess of 600 Gy caused unacceptable surface damage (i.e. lenticel spotting, surface discolouration and retardation of degreening) which was particularly severe after long‐term controlled atmosphere storage.In a separate short‐term storage trial, several other mango cultivars were assessed. Hot benomyl followed by prochloraz controlled anthracnose on all cultivars and stem end rot on some. Irradiation at 600 Gy contributed only minor improvements to disease control. The severity of surface damage that developed following irradiation and fungicide treatment varied with cultivars.
Assessment of UK hops for the occurrence of hop latent and hop stunt viroids
Authors: BARBARA D. J. , MORTON A. , ADAMS A. N. 
Published: February 2008

SummaryThe occurrences and distributions of hop stunt (HSVd) and hop latent (HLVd) viroids were assessed by a nucleic acid hybridisation assay, using samples from 476 commercial hop plantings in the UK. These samples represented about half of the UK production.HLVd was detected in c. 17% of the samples, with infection in different cultivars ranging from 0% to 89%. This viroid was found in all cultivars sensitive to Verticillium wilt except cv. Sunshine, an old cultivar grown on only one farm in the UK. Two minor wilt‐tolerant cultivars were also found to be infected at low frequencies, but the main commercially‐important wilt‐tolerant cultivars were all uninfected. A high proportion of the nuclear stock mother plants in the “A +” house at the Institute of Horticultural Research Dept of Hops Research, Wye College were infected. Circumstantial evidence, based on the planting dates of infected gardens, suggests that infection became established in the hop propagation system during the late 1970s and that there was a major increase in the prevalence of HLVd as a result. Whether this contamination of propagating material arose because of spread from long‐standing infections or because the viroid was newly introduced into the UK, is not known.All samples were also tested for HSVd but this viroid was not detected in any UK hop material.