bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of fungicides and insecticides applied to spring barley sown on different dates in 1976‐79
Authors: JENKYN J. F. , PLUMB R. T. 
Published: February 2008

SUMMARYFactorial experiments in 1976–1979 investigated the effects of sowing date, fungicides (ethirimol seed treatments and tridemorph sprays) and insecticides (phorate applied to the soil, and menazon or dimethoate sprays) on powdery mildew, aphids, barley yellow dwarf virus (BYDV) and grain yield of spring barley (cv. Julia in 1976 and 1977; cv. Wing in 1978 and 1979). Late sowing usually increased the severity of powdery mildew, numbers of aphids and incidence of BYDV and generally decreased yield. Responses to pesticides were commonly greater on the late‐sown than on the early‐sown barley. Response to fungicides are principally attributed to the control of powdery mildew (Erysiphe graminis f. sp. hordei; the target species) but responses to insecticides cannot be attributed to virus control and seem unlikely to be due solely to control of aphids, whose numbers were relatively small. There were some effects of fungicides on aphids and insecticides on mildew, but they were inconsistent and too small to affect crop protection strategies.
Studies on fast and slow growing Rhizobium spp. nodulating Cqjanus cajan and Cicer arietinum
Authors: BROMFIELD E. S. P. , RAO J. V. D. K. KUMAR 
Published: February 2008

SUMMARYFast and slow growing Rhizobium spp. isolated from Cajanus cajan and Cicer arietinum were compared in terms of colony characteristics, utilisation of carbon sources, acid production, symbiotic effectiveness and nodulating competitiveness.Fast growing isolates from C. cajan and C. arietinum formed 3–6 mm diameter colonies on yeast‐extract mannitol agar after 4 days and were unlike the slow growers which produced colonies of c. 1 mm diameter after 7–10 days at 28 °C. The fast growing Rhizobium spp. from C. cajan utilised a wider range of carbon sources than the slow growing isolates from this host. Fast and slow growing strains from C. arietinum were able to utilise most of the carbon sources tested suggesting that the slow growers possessed glycolytic pathways similar to those in other fast growing species of Rhizobium. In culture, slow growing isolates from C. cajan produced a near‐neutral to alkaline reaction (pH 66·7‐5) whereas the fast growers from this host and both fast and slow growing isolates from C. arietinum produced an acidic reaction (pH 4·4–5·6). These data are discussed in the context of Norris' (1965) evolutionary concept of the Leguminosae. Under glassshouse conditions, fast and slow growing strains isolated from C. cajan and C. arietinum were equally effective on their respective hosts.In competition with slow growing rhizobia, half of the fast growers formed more than 70% of the nodules on C. cajan grown in sand. In all but one instance similar results were obtained when plants were grown in soil. With C. arietinum grown in sand or soil, all fast growing isolates from this host formed more than 85% of the nodules in competition with slow growing strains.
An attachment to a tractor‐mounted seed‐spacing drill for applying granular formulations to small field‐plots
Authors: THOMPSON A. R. , PERCIVALL A. L. , EDMONDS G. H. , LICKORISH G. R. 
Published: February 2008

SUMMARYTractor mounted equipment is needed to deliver granular formulations of pesticides accurately to the soil in small‐plot trials in a manner comparable to commercial equipment. Inexpensive units incorporating a belt unit mechanism were designed and fitted to a Mk II Stanhay S‐870 Precision Seed‐Spacing Drill. The individual delivery belts were driven through a continuously‐variable reduction gearbox by the main drive shaft of the drill and pre‐weighed amounts of granules were placed along the belts. Insecticides and dose patterns could thereby be changed readily from plot to plot.In field assessments of uniform doses of fuller's earth granules delivered to single row, 4·8 and 10·3 m plots, the mean weights recovered were 94–98% of the target doses, S.E.'s being ±2% of the means. When 16‐fold, exponentially‐increasing doses were delivered, the weights recovered were generally within 10% of the target dose at any point within 0·2 m from the start and 0·3 m from the finish of the plot. The performance of uniform doses of carbofuran (on sand) and chlorfenvinphos (on Spanish Silical) against cabbage root fly on radish in 15 m plots showed that errors in loading were insignificant compared with the variability in pest infestation on the field plots. With doses increasing exponentially by c. 12‐fold applied to similar plots, the percentage of carrots or radish undamaged by carrot fly and cabbage root fly increased from 40–60% to 85–99·3%, the relationship between the log‐log proportion of undamaged roots and log‐dose being linear.The equipment allows free‐flowing, granular pesticide products to be applied to small plots of a wide range of row‐crops much more accurately than has hitherto been possible. A work rate of 24 plots h‐1 was achieved by a team of two technicians and a tractor driver.
The efficiency of visual assessment of grain yield and its components in spring barley rows
Authors: ISMAIL A. B. , VALENTINE J. 
Published: February 2008

SUMMARYThe efficiency of visual assessment for grain yield and its components in spring barley rows was examined using a number of assessors. In 20 out of 28 combinations of assessor and character, only 20 or less lines were needed to be retained from the set of 99 lines to save at least 50% of the best 10 lines. Assessments of tillers/row and to a lesser extent 1000‐grain weight were generally more effective than assessments of yield/row and grain/ear. The low effectiveness of assessment of grains/ear was attributed to inadequate sampling of ears. Four out of five assessors showed bias towards assessment of tillers/row, the most easily assessed character, in their assessments of yield/row.Experienced barley workers were more successful in their assessments than others less familiar with the crop. Specially developed keys, aimed at making visual assessment more objective, generally had only small positive effects on the efficiency of assessment. Repeated assessments of characters by some assessors were consistent.It was concluded that visual assessment rather than direct measurement should be recognised as a basic tool of breeding in the early generations, using a large number of lines as a ‘safety net’ allowing the loss of some of the best lines.
The efficiency of visual assessment for yield and its components in winter oat rows
Authors: VALENTINE J. , ISMAIL A. B. 
Published: February 2008

SUMMARYThe efficiency of visual assessment of grain yield and yield components in 0–75 m rows of winter oats was, in general, moderately high. Only eight or less lines were needed to be saved in six out of eight cases to retain at least 50% of the best four lines from the set of 40 lines. Assessments of yield/row and tillers/row were more effective than assessments of grains/panicle and 1000‐grain weight on the basis of the proportion of variation accounted for by regression of visual assessment on actual performance. An experienced oat breeder was more successful in his assessment than another assessor unfamiliar with the crop. Assessments of yield/row by the experienced assessor were apparently biased towards assessments of grains/row as the single most easily assessed character, while the assessor unfamiliar with the crop attempted to take tillers/row and 1000‐grain weight into account in his assessments. Implications to a winter oat breeding programme are indicated.
Interactions between seed priming treatments and nine seed lots of carrot, celery and onion. I. Laboratory germination
Authors: BROCKLEHURST P. A. , DEARMAN JANE 
Published: February 2008

SUMMARYSamples of three seed lots of each of three cultivars of carrot, celery and onion were primed in polyethylene glycol solution for 2 weeks at 15 °C. Priming reduced the mean germination times (recorded at 15 °C) of all seed lots (compared to the untreated control) by 3–4 days in carrot, 6–10 days in celery and 3–5 days in onion. The largest reductions in mean germination time occurred in the slowest‐germinating seed lots. There were highly significant interactions between priming and cultivars, and between priming and seed lots within cultivars for each species.Drying back the primed seeds at 15 °C increased the mean germination times (compared to primed seed which had not been dried) by 0·6 day in carrot and 1·4 days in celery, and there was no interaction with cultivars or seed lots. The corresponding increase for onion was either 1·0 or 1·8 days, according to the cultivar, but this variation was largely attributable to differences in time taken for the dried seeds to re‐imbibe. Seeds dried back at 30 °C germinated 0·2·0·7 day (depending on the species) later than those dried at 15 °C.Percentage germination was not affected by either priming or drying back. Priming reduced the spread of germination times in all cultivars. For primed and dried‐back seed, the spread of germination times was larger than that of primed seed in certain cultivars, but was always smaller than that of untreated seeds.
Biological control of Dutch elm disease by Pseudomonas species
Authors: SCHEFFER R. J. 
Published: February 2008

SUMMARYAntagonism of a selected group of bacteria against Ophiostoma (=Ceratocystis) ulmi, the Dutch elm disease pathogen, was determined on agar media. Four promising bacterial isolates, all fluorescent Pseudomonads, were used for field experiments and for further tests on in vitro antagonism against several fungi. It was shown that only slight differences existed in antagonism against different O. ulmi isolates. Also Ceratocystis fagacearum and C. fimbriata were inhibited similarly to O. ulmi.In field experiments bacteria were applied to elm trees by low pressure injection or by injection with a specially developed ‘gouge‐pistol’. Elms treated only with bacteria remained healthy throughout two growing seasons. Elms inoculated with O. ulmi developed severe Dutch elm disease symptoms. Trees, inoculated first with O. ulmi and treated subsequently with bacteria also developed severe Dutch elm disease symptoms. Trees treated with bacteria first and inoculated subsequently with O. ulmi showed significantly fewer symptoms, especially those where treatments were carried out with the gouge‐pistol.
Pathogenicity studies on isolates of Leptosphaeria maculans from brassica seed production crops in south‐east England
Authors: HUMPHERSON‐JONES F. M. 
Published: February 2008

SUMMARYOut of 117 isolates of Leptosphaeria maculans collected from a range of brassica seed crops in south‐east England, 26 were virulent when tested on cabbage cv. January King. Of these, 24 were isolated from oil‐seed rape (Brassica napus) and the remainder from a swede (B. napus) and a cabbage (B. oleracea) seed crop. Virulent strains were derived from infected stems and from single ascospores of the sexual state present on diseased stubble. In glasshouse tests virulent isolates were not host‐specific and caused severe cankers on cabbage, kale, swede, turnip and oil‐seed rape; under field conditions, ascospores originating from diseased oil‐seed rape stubble produced severe cankers and high levels of seed‐borne infection in eight horticultural and vegetable brassica hosts (B. napus, B. campestris and B. oleracea). Virulent and non‐virulent types could be distinguished by certain cultural characteristics. On nutrient agar virulent types grew slowly, irregularly and quickly staled whereas non‐virulent types grew rapidly, regularly and did not stale. The latter also produced a yellow‐brown pigment in liquid culture. The potential for cross‐infection of virulent strains originating from oil‐seed rape to other brassica seed crops has serious implications for disease incidence on forage and vegetable brassica seed crops.
Factors affecting aphid acquisition and transmission of soybean mosaic virus
Authors: SCHULTZ GERALD A. , IRWIN MICHAEL E. , GOODMAN ROBERT M. 
Published: February 2008

SUMMARY Myzus persicae transmitted soybean mosaic virus (SMV) most efficiently following 30 or 60 s acquisition probes on infected plants. There were no differences in susceptibility to SMV infection of soybean plants 1 to 12 wk old, but symptoms were more severe in plants inoculated when young than when old. Soybeans inoculated between developmental stages R3 and R6 only showed yellowish‐brown blotching on one or more leaves. There were no observable differences in the time of appearance or type of symptoms shown by soybean seedlings inoculated either by sap or by aphids; infected plants became acquisition hosts for aphids 5–6 days after inoculation. There was no change in the efficiency with which M. persicae transmitted SMV from source plants up to 18 wk after inoculation. M. persicae transmitted SMV from leaves of field‐grown soybeans when plants were inoculated at developmental stages V6, R2, and R3 and tested as sources 57–74 days after inoculation but not from plants inoculated at R5 and tested as sources 14 to 32 days after inoculation. M. persicae acquired SMV from soybean buds, flowers, green bean pods, and unifoliolate, trifoliolate, and senescent leaves. Middle‐aged and deformed leaves were better sources of the virus than buds, unfolding and old symptomless leaves. The results are being incorporated into a computer model of SMV epidemiology.
Effect of nutritional stress on control of Longidorus elongatus by nematicidal chemicals
Authors: ALPHEY T. J. W. 
Published: February 2008

SUMMARYStudies were made to determine the effect of starvation on the susceptibility of Longidorus elongatus to nematicidal chemicals. In vitro studies, using stylet protraction as a measure of susceptibility, showed that the EC50 for nematodes exposed to oxamyl for 5 min was 6‐5 μg cm‐3 for starved nematodes and 7‐7 μg cm‐3 for well‐fed specimens. In pot studies aldicarb and oxamyl, applied at half the normal commercial rates, decreased the numbers of starved, but not of well‐fed, L. elongatus. In a field study aldicarb, oxamyl and the fungicide quintozene decreased the numbers of starving and well‐fed L. elongatus. Oxamyl was more effective than aldicarb and the numbers of L. elongatus were decreased more in plots previously fallowed than in those cropped with a grass/clover mixture. A significant interaction between oxamyl treatment and initial crop was found. Starved L. elongatus appear to be more susceptible to carbamate nematicides than well‐fed ones. Quintozene decreased numbers of L. elongatus more, and for a longer period of time, than either of the systemic nematicides. The mode‐of‐action of the nematicidal chemicals is discussed.
A controlled environment study of the effect of leaf physiological age on the movement of apterous Myzus persicae on sugar‐beet plants
Authors: JEPSON P. C. 
Published: February 2008

SUMMARYApterous Myzus persicae were found to move frequently from leaf to leaf on sugar‐beet plants in controlled environment conditions. It is suggested that aphid movement can be related to changes in the rate and content of translocate flow during leaf development. These changes make newly‐emerged leaves nutritionally favourable to colonising aphids and make expanding leaves slowly wane in favourability during the process of ‘sink to source’ conversion leading to aphid dispersal from the leaf. Variation in temperature was not found to alter the rate of aphid movement or the period (measured in thermal time) that aphids spent on particular leaves. However, the lower temperature was found to increase the rate of aphid development, aphid size and fecundity; these effects could also be due to nutritional factors.This dispersal behaviour may be a tactic to maximise food intake by a polyphagous aphid and increase the probability that nymphs are deposited on nutritionally‐favourable leaves. The implications of the interleaf dispersal of apterous M. persicae for within‐ and between‐plant spread of beet yellows virus (BYV) and beet mild yellowing virus (BMYV) are discussed.
Overwintering of Venturia inaequalis the causal agent of apple scab in relation to weather
Authors: JEGER M. J. , BUTT D. J. 
Published: February 2008

SUMMARYApple leaves collected at East Mailing and bearing colonies of Venturia inaequalis were exposed outdoors from November 1978 to May 1979 at 12 United Kingdom sites. Pseudothecial development and abundance were recorded from samples returned to East Mailing every 2 wk. Pseudothecia matured most rapidly with high rainfall in November and high temperatures in spring. Mature pseudothecia were most abundant with low temperatures in November and low rainfall in spring. In 1979‐80 a cross‐over experiment, in which scabbed leaves spent either November‐January or February‐April at a common site, and the other half of the winter at one of five sites, demonstrated the separate effects of weather following leaf‐fall and in the spring. Equations for forecasting the time to pseudothecial maturity, but not the numbers of mature pseudothecia, were obtained.Experiments in controlled environments demonstrated the importance of low temperature and high moisture for initiation and early development of pseudothecia, but a controlled increase of temperature in the spring did not result in faster rates of maturation compared with lower temperatures outdoors. Ascospore production from leaves kept in controlled environments in spring was consistently lower than from leaves kept outside.
Double resistance by citrus green mould Penicillium digitatum to the fungicides guazatine and benomyl
Authors: WILD B. L. 
Published: February 2008

SUMMARY In vitro dosage response data with different isolates of Penicillium digitatum and the fungicide guazatine indicated an approximate 10‐fold shift in tolerance when compared with wild type strains. ED50 values for resistant strains were approximately 0.5 μg/ml compared to approximately 0.05, μg/ml for the wild type strains. Colony growth of guazatine resistant isolates on selective media containing carbendazim showed that they were also resistant to the benzimidazole group of fungicides. In vivo tests in inoculated oranges with strains previously characterised by in vitro tests confirmed resistance to guazatine and benomyl. A combined treatment of these fungicides at 400 /μ/ml and 500 μg/ml respectively, which normally gives protection against decay, also failed to provide adequate mould control. Growth and pathogenicity of the resistant strains in these tests in oranges were indistinguishable from that of wild type strains.
The response of eggs of the white potato cyst nematode Globodera pallida to diffusate from potato and mustard roots
Authors: FORREST J. M. S. , FARRER LINDA A. 
Published: February 2008

SUMMARYBrief exposure of eggs of Globodera pallida to potato root diffusate not only initiated hatching but also caused the majority of unhatched juveniles to respond more rapidly to subsequent treatment with diffusate. Eggs previously exposed to diffusate had a peak hatch after 1 or 2 days compared with 4 days for untreated eggs. Mustard root diffusate prevented hatch, and further stimulation with potato root diffusate was necessary to re‐initiate it. Eggs previously treated with potato root diffusate for 24 h were much more sensitive to drought than untreated eggs. These results are discussed in relation to the theory that potato root diffusate alters the permeability of the eggshell as an initial step in the hatching process.
Seed survival and periodicity of seedling emergence in eight species of Cruciferae
Authors: ROBERTS H. A. , BODDRELL JUNE E. 
Published: February 2008

SUMMARYSeeds of eight species of Cruciferae were collected, usually in each of 3 years, and mixed with the top 7‐5 cm of sterilised soil confined in cylinders sunk in the ground outdoors and cultivated three times yearly. The seedlings emerging were recorded for 5 yr and the numbers of viable seeds remaining then determined. Emergence of Alliaria petiolata was almost entirely restricted to February and March. That of Erysimum cheiranthoides, Lepidium campestre, Sinapis arvensis and Raphanus raphanistrum took place mainly in March and April, but seedlings continued to appear until late autumn. Some seedlings of Arabidopsis thaliana, Cardamine hirsuta and Sisymbrium officinale appeared in spring, but most did so in summer (C. hirsuta and S. officinale) or early autumn (A. thaliana). Seed survival in A. petiolata was of short duration and there were few seedlings after the second year, whereas 18% of the seeds of R. raphanistrum were still present and viable after 5 yr. Seed survival at this time for the other six species ranged from 1 ‐6% (C. hirsuta) to 6‐1% (S. arvensis).
A comparison of methods for evaluating seed quality in carrots (Daucus carota)
Authors: GRAY D. , STECKEL JOYCE R. A. 
Published: February 2008

SUMMARYComparisons of embryo length, ISTA (International Seed Testing Association), cold (10 oC), controlled‐deterioration, and slope tests for estimating seedling size variability and percentage seedling emergence were made using eighteen stocks of carrot seeds.The coefficient of variation (C.V.) of seedling weight was closely correlated with the C.V. of embryo length (r = 0–87 D.F., 16) and also with the C.V. of root length from the slope test (r = 0–63 D.F., 16).Poorer estimates of percentage seedling emergence were obtained from the cold test in all three sowings (correlation coefficients were between 0–65 and 0–70 D.F., 16) compared with the ISTA, controlled deterioration, and slope tests. For these three tests the correlation coefficients varied between 0–80 and 0–87 (D.F., 16) for all sowings.The embryo test is a rapid (1 man hour per seed lot) and accurate method of assessing potential variability between seed lots. The slope test could provide a less labour demanding method of assessing potential variability than the embryo length test though the results would not be available immediately. However, the slope test could also provide as good an estimate of seedling emergence in the field as the ISTA or controlled‐deterioration tests.
Laboratory evaluation of resistance to pesticides in the phytoseiid predator Typhlodromus pyri from English apple orchards
Authors: KAPETANAKIS E. G. , CRANHAM J. E. 
Published: February 2008

SUMMARY Typhlodromus pyri, reared on plate cultures and fed on pollen of Vicia faba, were bioassayed using a taped‐slide technique. Mite stocks from isolated unsprayed orchards were used to establish base‐line susceptibility to azinphos‐methyl, parathion, carbaryl and permethrin. Stocks from English orchards with a spray history of organophosphates and carbaryl showed resistance of 4 to 6x to azinphos‐methyl, c 50 x to parathion, >20x to carbaryl, and no resistance to permethrin. An orchard population derived from T. pyri imported from New Zealand in 1977 responded similarly. In other tests, mites exposed to spray residues on glass and on apple leaves were killed by lower concentrations than in taped‐slide tests (glass < apple leaf < taped‐slide technique); but for all three assay techniques the resistance factors to azinophos‐methyl and carbaryl, comparing two stocks, were similar. All stocks from sprayed orchards were resistant to both azinphos‐methyl and carbaryl, suggesting cross‐resistance; and resistance to both these pesticides appeared to be stable in the field when selection pressure was relaxed. The results are discussed in relation to earlier work on T. pyri and two other resistant orchard‐inhabiting phytoseiid species.