bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Samples 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

Antagonism 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

Out 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

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

Studies 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

Apterous 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

Apple 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

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

Brief 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

Seeds 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

Comparisons 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

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.
Effects of spur blight (Didymella applanata) and premature defoliation on axillary buds and lateral shoots of red raspberry
Authors: WILLIAMSON B. , DALE A.
Published: February 2008

Nodal lesions typical of natural infections of Didymella applanata were produced on young raspberry canes when wounded petioles were inoculated with mycelium. The buds which developed in the axils of these inoculated petioles were smaller and less likely to produce lateral shoots than those in the axils of delaminated or undamaged petioles, but only when the petioles were inoculated in the field before the end of July. This effect was more pronounced in cv. Mailing Jewel than in cv. Glen Clova which suggests that the latter is more tolerant of D. applanata.

Sprays to control D. applanata in the cropping region of canes will probably be effective in Scotland only if applied before the end of July.
Further evidence on the nature of the dependence of carrot mottle virus on carrot red leaf virus for transmission by aphids
Authors: WATERHOUSE P. M. , MURANT A. F.
Published: February 2008

Preparations were made from chervil plants doubly infected with carrot mottle virus (CMotV) and its helper virus, carrot red leaf (CRLV), on which it depends for transmission by the aphid Cavariella aegopodii, by the procedure developed previously for CRLV. The preparations contained 25 nm isometric particles which were indistinguishable from those of CRLV but possessed aphid‐transmissible infectivity of both viruses and manually transmissible infectivity of CMotV. Only one sedimenting and buoyant density component was detected. The manually transmissible CMotV infectivity was resistant to freezing and to organic solvents, treatments that destroyed the CMotV infectivity in extracts from singly infected plants. The aphid‐transmissible CMotV infectivity in preparations from CRLV/ CMotV‐infected plants, and that in extracts from CRLV/CMotV‐carrying C. aegopodii, was abolished by treatment with CRLV antiserum but not with normal serum. These results show that transmission of CMotV by C. aegopodii is dependent on the packaging of its RNA in coats composed partially or entirely of CRLV particle protein.

The aphid Myzus persicae does not transmit CRLV or CMotV from plants mixedly or singly infected with these viruses but it is a vector of beet western yellows virus (BWYV) and potato leafroll virus (PLRV) and it transmitted CMotV from plants that also contained either of these viruses. This suggests that the coat proteins of BWYV and PLRV can substitute for that of CRLV in packaging CMotV nucleic acid and thereby confer on it their own vector specificities.
The relationship of potato yield with and without nematicide to density of potato cyst nematodes, lobodera rostochiensis and G. pallida
Authors: BROWN E. B.
Published: February 2008

Trials relating response to nematicide to potato cyst nematode density were conducted initially in the West Midlands and later in other Regions. Thirteen trials, only three of which were within the intensive potato growing areas, conformed to a general pattern with yield losses being largely recouped by nematicide treatment. Five trials, four within the intensive areas, gave no correlation between potato yield and nematode density and an unpredictable response to nematicide. The control of the nematode appeared to be poorer in the latter trials but other factors affecting yield and nematode multiplication may have been involved. It is speculated the main factor might be interaction with fungal organisms e.g. Rhizoctonia or Verticillium.

Evidence is presented to show that on several trials the nematicide has an effect other than by controlling potato cyst nematodes.

Yield losses caused by potato cyst nematodes are more variable than previous work indicated, probably due to varietal, seasonal or environmental influences.
The use of water and some inorganic salt solutions to advance sugar beet seed. I. Laboratory studies
Authors: DURRANT M. J. , PAYNE P. A. , MCLAREN J. s.
Published: February 2008

The emergence of sugar beet seedlings is often slow or irregular and insufficient plants may be established for the crop to yield fully. Treating the seed prior to sowing, such that the subsequent germination percentage is not reduced but germination is more rapid and better synchronised should be beneficial. A series of laboratory experiments was made to investigate seed treatment procedures involving water and various inorganic salt solutions. Many treatment combinations were identified which gave faster germination without decreasing germination percentage and left the seed dry and intact and suitable for sowing with conventional precision drills. No treatment was found which ‘primed’ the sugar beet seed and the term seed ‘advancement’ describes, more accurately, the effects observed. There was little difference in the performance of seeds optimally treated with water or some salt solutions generating an osmotic potential of between about –10 and –20 bars. However, the use of salt solutions, although more complicated, was preferred to water as inadvertent germination during treatment was less likely. The optimum treatment for the one bulk of sugar beet seed studied was, firstly, to wash the seeds for 3.5 h with water, then after air‐drying, to moisten them on filter paper dampened with –15 bar (0–34 M) sodium chloride solution for 6 days at 15oC followed by a final wash and air‐drying.
The use of water and some inorganic salt solutions to advance sugar beet seed. II. Experiments under controlled and field conditions
Authors: DURRANT M. J. , PAYNE P. A. , MCLAREN J. s.
Published: February 2008

The effect of seed advancement on the early growth of sugar beet was determined in two experiments made under controlled conditions and eight field experiments made between 1974 and 1978. The experiments in the growth room suggested that seed advancement increased the rate of emergence and seedling dry weight over a wide range of soil moisture contents but seedling numbers were only greater under sub‐optimal moisture conditions. Similarly, in most field experiments, seed advancement resulted in more rapid emergence and larger seedlings. In four field experiments, seed advancement gave up to 16% more plants, and in three experiments a significant increase in final sugar yield of up to 0–7 t h‐1 was detected. The plants were hand‐singled to a uniform stand and had the crops been drilled to a stand, some yield responses would have been larger. Seed advancement did not decrease the plant stand or final yield in any experiments.

Results in 1977 and 1978 provided some evidence that seed advancement may help reduce the damage caused by field mice and the number of plants which bolt and, by making emergence more rapid, be particularly beneficial on soils prone to slumping or capping. There might, however, be a slightly increased risk of frost injury if advanced seed is used for early sowings.
Ontogenetic interactions between photosynthesis and symbiotic nitrogen fixation in pigeonpea
Authors: LUTHRA Y. P. , SHEORAN I. S. , SINGH RANDHIR
Published: February 2008

Total nodule nitrogenase activity (TNA, μmols ethylene plant‐1 h‐1) in pigeonpea (Cajanus cajari) increased with plant growth to reach maximum at flowering (75 days after sowing), decreasing thereafter until maturity (120 days after sowing). However, specific nodule nitrogenase activity (SNA, μmols ethylene g‐1 nodule fresh wt h‐1) reached its maximum earlier (45 days after sowing). The rate of photosynthesis and shoot and nodule respiration followed a similar pattern to TNA. However, higest rates of root respiration were observed at flowering and again immediately before final harvest. 14CO2 feeding studies showed that assimilates produced in leaves before flowering were retained in the vegetative parts. Assimilates produced after flowering were exported to the reproductive structure at the expense of the nodules. It is suggested that the decreased availability of photosynthate to nodules decreased nitrogen fixation.
The influence of wheat growth stage on yield reductions caused by the rose‐grain aphid, Metopolophium dirhodum
Authors: HOLT J. , GRIFFITHS E. , WRATTEN S. D.
Published: February 2008

Field caged populations of Metopolophium dirhodum were established on winter wheat (cv. Norman) during the late spring and summer of 1983. An early (G. S. 30–41), middle (G. S. 41–65) and late treatment (G. S. 65–77) were compared. Yield losses were 5, 8 and 27% respectively, although aphid indices were similar in the three treatments.

For other field cage populations, all established at G. S. 38 and allowed to develop freely, a significant negative relationship existed between aphid index and yield.
Modelling mortality risks for treated insects relative to controls
Authors: ROWELL J. G. , MARKHAM P. G.
Published: February 2008

A model is described for facilitating studies of insect mortality. The main feature of the model is that it includes a readily interpretable parameter which measures the mortality risk in each treatment group relative to a control group. Procedures for fitting the model are illustrated by reference to an experiment where leafhoppers were injected with spiroplasma strains; one such strain was shown to be pathogenic. Good fits have been found for data from other experiments.
Injury to and death of cabbage (Brassica oleracea) seedlings caused by vapours of di butyl phthalate emitted from certain plastics
Authors: HARDWICK R.C. , COLE R.A. , FYFIELD T.P.
Published: February 2008

Many items made of flexible plastic contain the plasticiser di butyl phthalate (DBP). When the plastic is in an enclosed volume, such as a glasshouse, vapours of DBP can reach toxic concentrations and kill cabbage (Brassica oleracea) seedlings. The phenomenon, which varies in severity between varieties, accounts for recent crop losses in certain glasshouses in which the flexible plastic used to cushion the glass, i.e. the glazing strip, was plasticised with DBP. Concentrations of DBP up to 2010 pg litre‐1 were recorded in such a glasshouse. The problem was cured by replacing the glazing strip with a strip plasticised with di iso‐decyl phthalate (DIDP). A residual DBP concentration of 120 pg litre‐1 was traced to DBP contaminants in the DIDP strip.

Other plastic items used in glasshouses such as hosepipes and flexible pots have also been examined, and the results of chemical analyses and bioassays are reported.
Pollination activity by blowflies and honeybees on onions in breeders' cages
Authors: CURRAH LESLEY , OCKENDON D. J.
Published: February 2008

Honeybees (Apis mellifera) and three species of blowflies (Calliphora vomitoria, Lucilia caesar and L. sericata) were observed on mass‐pollinated populations of onions (Allium cepa) in 4·4 × 3·6 m × 2‐2·5 m cages in June‐August 1977. Pollination activity at temperatures from 14° to 28°C was compared on the basis of mean time per flower touched on each umbel visit.

Honeybees did not forage below 16°C. Above 16°C their mean time per flower was short (1·4 s) and varied little with temperature. For blowflies, it decreased markedly from 12·1 s at 14–15·5°C to 2·7 s at 26°C and above, largely because at low temperatures flies spent long periods quiescent or grooming rather than actively feeding.

When flowering was not completely synchronous between cultivars, honeybees were more selective than blowflies, but where flowering was synchronous, both types of pollinator visited the two cultivars at random.

For the size of cage used, neither type of insect had a distinct advantage as a pollinator of onions, despite their different behaviour patterns.
The susceptibility of Heliothis armigera larvae to three nuclear polyhedrosis viruses
Authors: WILLIAMS CERIS F. , PAYNE C. C.
Published: February 2008

Quantitative bioassay techniques were used to measure the susceptibility of Heliothis armigera to three nuclear polyhedrosis viruses (NPVs): H. armigera singly‐enveloped NPV (HaSNPV), H. zea SNPV (HzSNPV) and H. armigera multiply‐enveloped NPV (HaMNPV). Viruses were identified by EcoRI restriction endonuclease analysis. Electrophoretic profiles of DNA fragments revealed that the HaSNPV isolate was a previously undescribed genotypic variant. Bioassays with neonate and 6‐day‐old larvae measured small but significant differences in virulence between the three viruses. HzSNPV was the most virulent for neonate larvae with a median lethal dose (LD50) of five polyhedra. HaMNPV was least virulent for 6‐day‐old larvae, with a LD50 of 1400 polyhedra compared with 640–670 polyhedra for HaSNPV and HzSNPV. In addition, the median lethal time (LT50) for infection with HaMNPV in neonate larvae was approximately 1·7 days longer than for the other viruses. Although they varied in virulence, each of the three viruses was sufficiently virulent to have considerable potential as a microbial control agent of H. armigera.
A model for estimating infection levels of anthracnose disease of mango
Authors: FITZELL R. D. , PEAK C. M. , DARNELL R. E.
Published: February 2008

Anthracnose disease of mango caused by Colletotrichum gloeosporioides var. minor, spreads by water‐borne conidia from vegetative parts of the tree to attack inflorescences and prevent fruit set. An analysis of data from laboratory studies demonstrated that infection by conidia during wet periods was related both to the temperature and to the duration of the wet period. A model was used to estimate infection levels of anthracnose disease in two mango orchards over three seasons.

The number of infection periods recorded and the estimated percentage of conidia forming appressoria in these periods matched disease development during flush growth and flowering. In 1980, only two infection periods were detected during flowering in one of these orchards and blossom blight did not prevent fruit set. In 1981 and 1982 however, higher estimated levels of infection were recorded more frequently during the same time and severe blossom blight developed. A second orchard, situated in an area less favourable to disease, was also monitored during 1982. Nine infection periods were recorded during flowering in this orchard compared to 14 in the first. A moderate level of blossom blight developed in this orchard.
The influence of foliar diseases and their control by selective fungicides on a range of groundnut (Arachis hypogaea L.) genotypes
Authors: SUBRAHMANYAM P. , WILLIAMS J. H. , McDONALD D. , GIBBONS R. W.
Published: February 2008

Twenty groundnut genotypes were grown with various spray treatments which controlled either, only rust, or only leaf spot diseases, or all of these diseases or none of them. The genotypes varied in their resistance to these diseases, some having resistance to only one disease and some having resistance or susceptibility to all the diseases. Chemical control of the diseases resulted in variations in leaf area protection and in yield which were specific to each genotype. For some genotypes the diseases had little influence on yield and foliage, while for others yield and remaining green leaf were varied greatly by the control of diseases. For many of the genotypes the yield achieved was well related to variations in the green leaf remaining at maturity as a result of the spray treatments. Genotypes with good levels of genetic resistance did not have high yield potentials while those with the best yields when diseases were controlled were the most susceptible to these diseases.
Development of a hand tool to test the degree of retting of flax straw
Authors: SEABY D. A. , MERCER P. C.
Published: February 2008

To determine the optimum conditions for inducing retting of flax, by the application of glyphosate herbicide, it is necessary to have an easily portable tool which will give a rapid, accurate assessment of the stage that retting has reached. Such a tool, which can be used to test individual stems, is described and the estimates of retting obtained compared with those from other methods.
The selection of pupation sites by the stalk‐eyed fly Diopsis thoracica (Diptera: Diopsidae) and pupal parasitism in some rice cultivars
Authors: ALGHALI ALIYAGEEN M.
Published: February 2008

Six rice cultivars (lines (TKM6, OS6, ADNY 11, IR28, Rexero and IR579‐48‐1) were used to determine the pupation sites of Diopsis thoracica and their effects on pupal parasitism. There was a general preference for pupation on the first three outer leaf sheaths. Preference was also observed for healthy tillers compared with damaged ones, except in OS6 where there was no significant difference between pupation on healthy and damaged tillers. Pupae on the first two outer leaf sheaths were heavily parasitised by the eulophid Tetrastichus (Neotrichoporoides) sp. (Hymenoptera). The level of parasitism ranged from 17·6% in OS6 to 58·8% in Rexero, with an overall mean of 38·9% for the entire experimental plot. The number of parasites per pupa ranged from 0·5 in OS6 to 3·0 in Rexero, with an overall mean of 1·37. There was a strong relationship between (a) parasitism (%) (r = 0·68); (b) number of parasites per pupa per variety (r = 0·90) and pupal length. The relationship between parasitism (%) and parasite density was very strong (r = 0·89), but a marginal improvement in relationship was obtained when parasitism (%) was correlated with log parasite density (r = 0·94), thus possibly suggesting weak interaction between the parasites.
Crop and weed emergence patterns in relation to time of cultivation and rainfall
Authors: ROBERTS H. A.
Published: February 2008

In experiments over 3 years, separate field plots were cultivated once only at 2‐wk intervals. Cultivation resulted in a flush of weed seedlings, representing usually less than 6% of the apparently viable seeds in the top 10 cm of soil and with a species composition which varied with the time of year. Subsequent flushes coincided in timing and extent with those on soil which had been undisturbed and were related to significant rainfall events. In each year there were periods when lack of soil moisture restricted emergence. At these times, seeds were released from dormancy by cultivation but germination of some or all of them was delayed. There was a general correspondence in the emergence patterns of weeds and of carrot and onion sown after each cultivation. On occasions when the seedbed was drying out, establishment of the comparatively rapidly‐germinating radish and cabbage was greater than that of carrot, onion or weeds. Effective initiation of germination of both crops and weeds was traceable to rainfall events. Emergence was reduced or delayed on more than half of the 45 cultivation occasions during the three growing seasons, and the results emphasise the importance of soil moisture in determining the extent and timing of seedling emergence.
The response of pigeon pea (Cajanus cajan) to the application of fertilisers
Authors: TAYO T. O. , TOGUN A. O.
Published: February 2008

The effects of fertilisers on the performance of three cultivars of pigeon pea, Cita‐1, Cita‐2 and Cita‐4, were measured in a pot experiment and a field trial from February to August 1982. The fertilisers were either applied as complete NPK (15‐15‐15) to the soil at a rate of 50 kg/ha in single or split doses within 4 wk of sowing, or as solutions containing 100 mg/litre each of N, P and K sprayed on to the plants 4 wk after sowing or at anthesis.

The growth of pigeon pea was only enhanced significantly by fertiliser application in the field experiment but yields and their components were changed by fertilisers in both experiments. The magnitudes of the effects on growth and yield were similar with both methods of application.
Identifying soybean lines differing in gas exchange sensitivity to humidity
Authors: BUNCE JAMES A.
Published: February 2008

The ratios of root length and root weight to leaf area differed within and between cultivars of soybean. Plants with low ratios of root length or weight to leaf area had leaf conductances and net photosynthetic rates more reduced by a given increase in the leaf to air water vapour pressure difference around a single leaf than plants with high ratios. Plant and root system conductances to water were estimated as transpiration rate per unit leaf area divided by the difference between substrate and leaf water potentials, and by the rate of water flow through pressurised root systems. These conductances were greater in plants with large, as compared with small, root systems per unit leaf area. Cultivar rankings in sensitivity of gas exchange to humidity were consistent in controlled environment chambers and in field tests.
An appraisal of ear, leaf and stem 14CO2 assimilation, 14C‐assimilate distribution and growth in a reproductive seed crop of amenity Lolium perenne
Authors: CLEMENCE T. G. A. , HEBBLETHWAITE P. D.
Published: February 2008

In seed crops of Lolium perenne, yield may be reduced by competition for a limited assimilate supply from sinks other than the ear. This study was undertaken to evaluate the priorities for allocation of assimilate within the crop from all photosynthetic sites on the main reproductive tiller after anthesis.

Ear, stem and leaves were fed with 14CO2 on two occasions; the assimilatory efficiency of these sources and the magnitude and pattern of 14C‐assimilate export from each was determined. The growth of each part of the main tiller and subtending tillers was also measured.

Stem elongation apparently dominated the current assimilate resource and the ear did not become a net importer of assimilate until this process had ceased. Assimilate allocation to the tillers was high throughout.

The nature of any competition between these sinks is discussed. When crop growth was contrasted with that in a previous year, environmental factors were implicated as determinants of priority for assimilate allocation to each sink. Sources of carbon for seed filling are also discussed as is the relevance of these findings to seed crop management.
Biological effectiveness of electrostatically charged rotary atomisers.
Authors: ARNOLD A. J. , CAYLEY G. R. , DUNNE Y. , ETHERIDGE P. , GRIFFITHS D. C. , JENKYN J. F. , PHILLIPS F. T. , PYE B. J. , SCOTT G. C. , WOODCOCK C. M.
Published: February 2008

Electrostatically charged rotary atomisers deposited greater amounts of pesticides on wheat plants than did a conventional hydraulic sprayer and improved the effectiveness of pirimicarb against aphids, benomyl against eyespot, and dimethoate against wheat bulb fly. Although deposits of triadimefon on barley plants were increased (and soil residues decreased) by the use of the electrostatic sprayer, mildew control was about equivalent to that obtained with the hydraulic sprayer. Similar amounts of herbicide were deposited, and similar biological effects obtained, when electrostatic or hydraulic sprayers were used to control Amsinckia intermedia in winter barley.
Biological effectiveness of electrostatically charged rotary atomisers.
Authors: ARNOLD A. J. , CAYLEY G. R. , DUNNE Y. , ETHERIDGE P. , GREENWAY A. R. , GRIFFITHS D. C. , PHILLIPS F. T. , PYE B. J. , RAWLINSON C. J. , SCOTT G. C.
Published: February 2008

In 1982 seven trials on non‐cereal crops examined the effectiveness of electrostatically charged rotary atomisers with different crop‐pest combinations. Compared with conventional hydraulic sprays electrostatically applied sprays deposited much more chemical on potatoes, field beans, oilseed rape and peas, and gave better control of the pea and bean weevil (Sitona lineatus) on field beans, the pea moth (Cydia nigricana) and of fungal diseases of oilseed rape. However on swedes, sugar beet and Brussels sprouts deposits of pesticide were increased only on some parts of the plant. The control of mildew (Erysiphe cruciferarum) on swede and Erysiphe betae on sugar beet) and of caterpillars (Pieris spp.) living within the central whorl of leaves on Brussels sprouts was not as great as when a high‐volume hydraulic sprayer was used.
A comparison of different chemicals for osmotic treatment of vegetable seed
Authors: BROCKLEHURST P. A. , DEARMAN JANE
Published: February 2008

Samples of carrot, celery, leek and onion seed were treated before sowing by imbibition in osmotic solutions of polyethylene glycol 6000 (PEG), glycerol and potassium dihydrogen orthophosphate (KH2PO4). The solutions were sufficiently concentrated to prevent germination during treatment, and within each species, the amount of water taken up by the seeds during treatment did not vary greatly between solutions. All treatments increased the rates of seed germination and seedling emergence compared to untreated controls, but glycerol‐treated seeds germinated and emerged significantly more slowly than did PEG‐ and KH2PO4‐treated seeds. The effects of PEG and glycerol treatments on percentage germination and seedling emergence were small, but KH2PO4 treatment tended to reduce percentage germination and emergence, most markedly in leek and one cultivar of celery. It is concluded that PEG treatment gives the most consistently beneficial effects for the range of species tested.
Development of a combined cold storage and methyl bromide fumigation treatment to control the American serpentine leaf miner Liriomyza trifolii (Diptera:Agromyzidae) in imported chrysanthemum cuttings
Authors: MORTIMER E. A. , POWELL D. F.
Published: February 2008

Individual chrysanthemum cuttings and leaves infested with eggs and larvae of the alien leaf miner Liriomyza trifolii, and batches of pupae, were treated in the laboratory to find an effective quarantine treatment to control the pest in imported cuttings. The laboratory tests were based on a statutory quarantine treatment of 2 days' cold storage at 1–2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m3, which is used to control Spodoptera littoralis on imported chrysanthemum cuttings. Treatments of 2 days' storage at 1–2°C followed by methyl bromide fumigation at 15°C with a range of CTPs were used to obtain accurate dose‐response lines and estimate the LD99 and LD99 9 for each stage of L. trifolii. The largest estimates of the LD99 for eggs, larvae and pupae up to 3 days old were 40·04, 34·49 and 42·64g h/m3 respectively. These results indicate that the Spodoptera treatment should give high levels of kill of most stages of L. trifolii. However, the LD99 values for pupae more than 3 days old were greater than those for eggs, larvae and young pupae. Therefore if this treatment were adopted as a quarantine measure against L. trifolii, good prophylactic treatments and rigorous pre‐packing inspections in exporting countries would need to be maintained, to minimise any risk of importing pupae. It would also be necessary to ensure that the temperature of the imported cuttings was raised uniformly to 15°C after cold storage and prior to fumigation. The practicality of the technique as a commercial treatment will depend on whether it is possible to achieve this without causing unacceptable phytotoxicity.
Saprophytic survival of Gaeumannomyces graminis and Phialophora spp. at various temperature‐moisture regimes
Authors: WONG P. T. W.
Published: February 2008

The saprophytic survival of the pathogen, Gaeumannomyces graminis var. tritici and two isolates each of three avirulent fungi, G. graminis var. graminis, Phialophora graminicola and a lobed‐hyphopodiate Phialophora sp. was studied in two soil types under controlled temperature and moisture conditions in the laboratory. In general, the fungi survived longest in the cool, dry soil (15°C, < ‐10 MPa) followed by the warm dry soil (30°C, < ‐10 MPa). All the fungi were virtually eliminated from the warm, moist soil (30°C, ‐0.3 MPa) after 3 months. Survival was intermediate under cool, moist conditions (15°C, ‐0.3 MPa). Under cool, moist conditions, G. graminis var. graminis survived better than the other three fungi in the first 3 months in both soil types and continued to do so for a further 3 months in one soil. Both isolates of the lobed‐hyphopodiate Phialophora sp. survived poorly in the two soil types being almost eliminated after 3 months. There were considerable differences between the survival of the two isolates each of G. graminis var. graminis and P. graminicola, especially under cool, moist conditions. Of the six avirulent isolates studied, one isolate of G. graminis var. graminis (DAR24167) survived best under the three temperature‐moisture regimes which showed differences. It also survived better than the take‐all fungus under moist, cool conditions and at a comparable rate under dry conditions. Therefore, this variation in survival should be considered when selecting antagonists for the biological control of take‐all.
The influence of growth stage and foliage or soil application on the activity of AC 222,293 against Alopecurus myosuroides and Arena fatua
Authors: PILLMOOR J. B. , CASELEY J. C.
Published: February 2008

AC 222,293 was active against both Alopecurus myosuroides and Avena fatua following foliage or root entry. The most effective site of application was the foliage for A. fatua and the soil for A. myosuroides. In glasshouse and controlled environment studies, growth inhibition was transient with extensive subsequent regrowth occurring following applications at below recommended field doses. Performance declined when application was delayed until A. fatua had more than five and A. myosuroides more than six leaves. This lower activity could be only partly explained by lower spray retention and uptake of the herbicide, since there were no differences in either translocation from the treated laminae or metabolism to the biologically active free acid. Other factors that may have contributed to the reduced performance are discussed.
Characteristics of resistance to the grain aphid Sitobion avenue in winter wheat
Authors: LOWE H. J. B.
Published: February 2008

Five stocks of winter wheat were resistant to S. avenae in glasshouse screening tests, where resistance was more evident in older than younger plants but different types of resistance were not separated.

Antibiosis was measured from the growth and reproduction of caged individual aphids and antixenosis from the settling of adult aphids on detached leaf portions. Cvs Bounty, Rapier and Virtue were resistant due to antibiosis, whilst cv. Kador and line A4501‐4E showed antixenosis. These and other differences indicated that these five wheat stocks probably include at least four distinct sources of resistance to S. avenae. The existence of different types of resistance could account for variability in the results of screening tests.
Taxonomy, evolution and domestication of Vicia in relation to aphid resistance
Authors: HOLT J. , BIRCH N.
Published: February 2008

Thirty Vicia species and 28 V. faba cultivars were evaluated for Aphis fabae resistance by measuring rates of aphid population increase (rm) on the host plants. A subset of these species (22) and cultivars (five) were evaluated for resistance to Acyrthosiphon pisum and Megoura viciae. For the same subset of 22 Vicia species and all three aphid species, positive correlations were observed between the concentration and numbers of leaf and stem non‐protein amino acids and the level of aphid resistance. Correlations were also observed between trichome density, on some organs of the host, and both nymphal survival and development time. Aphid resistance, together with these possible physical and chemical resistance mechanisms, showed a pattern which was described in relation to the taxonomy of the genus Vicia and the degree of domestication of the host. The least advanced Vicia species were most resistant whilst the more specialised species and those most closely related to V. faba and V. faba itself were most susceptible. Within each taxonomic group (subgenus or section), the most domesticated species were least resistant. The merits of utilising the resistance found in some V. faba cultivars and in other wild Vicia species were considered.