bluuebunny/crossref_metadata_2025 huggingface dataset:
Onion pollination by blowflies and honeybees in large cages
Authors: CURRAH LESLEY , OCKENDON D. J.
Published: February 2008

Three experiments to investigate the effect of pollination by blowflies (Calliphora and Lucilia spp.) and honeybees (Apis mellifera) on seed yield and crossing level were made using a mixture of plants from two open‐pollinated cultivars of onions (Allium cepa) in breeders' cages.

No consistent differences were found between pollinators. In two experiments, fly pollination gave significantly higher yields than bee pollination but in the third, bee pollination gave slightly more seed. Crossing between cultivars, assessed by progeny testing on one cultivar, varied between 22‐7 and 55‐9%. Differences in crossing level attributable to the pollinators were not consistent and were not or only just statistically significant, but there were significant and substantial differences between the experiments themselves. Where more umbels were produced by the red‐bulbed cultivar than by the yellow, higher crossing levels were found in the yellow cultivar. The highest crossing levels were found in the only experiment where insects were not introduced until peak flowering time, but where seed yield was comparatively low. Crossing levels were lowest where the umbel numbers were approximately equal.

Individual umbels studied showed that while seed set was usually heaviest at and just before the mid‐flowering date, this period could correspond with the lowest levels of crossing during the flowering period, particularly if flowering of the two cultivars was not completely synchronous.

In field plots, approximately 75% of crossed seeds sown survived to give harvestable bulbs, but fewer than 50% of selfed seeds did so. In an experiment in which crossing levels from different pollinators were similar but survival levels differed significantly, it was deduced that bees performed more crossing within a cultivar than flies.
Stem‐boring Diptera in perennial ryegrass in relation to fertiliser. I. Nitrogen level and form
Authors: MOORE D. , CLEMENTS R. O.
Published: February 2008

The effects of applying nitrogen to a perennial ryegrass sward were studied in relation to the size and nature of populations of dipterous stem‐bores. Two levels of both ammonium sulphate and calcium nitrate were applied to the sward. Larvae were more numerous in the plots treated with high levels of nitrogen regardless of the form applied. Also, there were more larvae in the plots treated with ammonium sulphate than in those treated with calcium nitrate. A limited range of stem‐borer species predominated. These were Oscinella vastator, two forms of O. frit and Geomyza tripunctata. Stem‐borer species were distributed differently between plots receiving high and low nitrogen levels; G. tripunctata occurred almost exclusively on plots receiving high nitrogen applications while O. vastator was more frequent in those receiving low levels of nitrogen.
Isolates of raspberry bushy dwarf virus differing in Rubus host range
Authors: BARBARA D.J. , JONES A.T. , HENDERSON S.J. , WILSON S.C. , KNIGHT V.H.
Published: February 2008

Isolates of raspberry bushy dwarf virus (RBDV) occurring in the field at East Mailing Research Station (EMRS), and an isolate from raspberry seed imported from the USSR, were found to differ from the Scottish type isolate (D200) of RBDV in that they infected red raspberry cultivars that are resistant, possibly immune, to isolate D200. Of several red raspberry, blackberry and hybrid berry cultivars and EMRS raspberry selections graft‐inoculated with these recently discovered RBDV isolates only two raspberry cvs (Haida and Rannaya Sladkaya) and one EMRS selection did not become infected.

Differences in the conclusions reached in two previous studies on the inheritance of resistance to RBDV in raspberry can be explained by the use of virus isolates that differed in Rubus host range.
Cherry leaf roll virus in the female gametophyte and seed of birch and its relevance to vertical virus transmission
Authors: COOPER J. I. , MASSALSKI P. R. , EDWARDS MARY‐LOU
Published: February 2008

ELISA detected cherry leaf roll virus (CLRV) in infected birch leaf sap diluted 1/320 in buffer, in extracts of one infected leaf with nine healthy leaves and in leaf sap frozen for 2 wk. Similarly, ELISA detected CLRV in mixtures of one infected bud with four virus‐free buds. Intensive bioassays and ELISA showed that in some trees CLRV was restricted to only a few branches whereas in others it occurred throughout the tree. The prevalence of CLRV in unmanaged birch populations in Britain was less (3%) than in Midlands street trees (17%).

In CLRV‐free birch trees that received pollen from infected ones, ELISA indicated that antigen was introduced into, and multiplied within, the embryos but not the seed coat or the pericarp/wings. In one instance, antigen was detected in a branch of an experimentally pollinated tree but not in those parts of the crown that had been exposed to open pollination. The proportion of seed germinating after crosses in which both parents were CLRV‐free was greater than when either or both parents were infected but the largest difference occurred with infection in the female parent. Few embryos seemed to escape invasion with CLRV when the maternal tissue was naturally infected. Overall, seed transmission ranged between 0 and 38% (mean 17%) when only females in a cross were infected, and between 11 and 75% (mean 30%) when only the males were infected. Assuming no selective advantage that would help infected plants to achieve reproductive age, we found that CLRV would be lost from a birch population within two generations if transmitted only through seed.

Embryos in seeds from CLRV‐infected birch that received CLRV‐free pollen differed from their healthy counterparts in being shrunken and suspended in a loosely fibrillar matrix that contained numerous virus‐like particles in tubular inclusions. In two trees, CLRV‐free pollen tended to fertilise a greater percentage of ovules than did CLRV‐infected pollen. Seedlings derived from infected seed and cuttings from naturally‐infected trees grew less rapidly than their healthy counterparts.

In still air, most birch pollen liberated from a height of 3·5 m fell within 3 m of the drop zone and none was detected 10 m from the source. Field observations on the patterns of virus spread as measured by seedling infection were consistent; about 3% of seedlings from a tree 6·9 m away from the nearest source of inoculum were infected but no infected seedlings were detected in more distant trees, even though each was experimentally infectible with CLRV and pollen from the infected tree germinated on their stigmas.
Production of polysaccharide‐degrading enzymes by saprophytic fungi from glyphosate‐treated flax and their involvement in retting
Authors: BROWN AVERIL E. , SHARMA H.S.S.
Published: February 2008

The fungi present on glyphosate‐treated flax plants were isolated. Cladosporium herbarum, Epicoccum nigrum, Botrytis cinerea and yeasts occurred most frequently immediately after glyphosate treatment but as retting progressed the frequency of occurrence of Fusarium culmorum, Alternaria alternata and a Phoma sp. increased. Many of the fungi isolated from retting flax were also present as epiphytes on healthy flax stems. Glyphosate was shown to be fungitoxic in vitro but it had only a very slight effect on fungi colonising the flax. The application of sucrose and urea to flax 1 wk after glyphosate treatment resulted in more rapid fungal colonisation of the stems, but did not significantly enhance retting.

When grown on sterilised flax stem sections, fungi known to be saprophytic on flax produced polysaccharide‐degrading enzymes. All seven fungi tested produced polygalacturonase, pectin‐lyase and xylanase. The greatest cellulase activity was present in stem tissues inoculated with F. culmorum and the Phoma sp. while no cellulase was detected in tissue inoculated with B. cinerea, a Mucor sp. or a Penicillium sp. Extracts from flax inoculated with the cellulolytic fungi caused the solubilisation of native cellulose. Pectinases, xylanase and cellulase were also detected in naturally‐colonised senescing and dead flax stems. Stems which had been treated with a sucrose solution tended to contain the greatest enzyme activity.
Reasons for poor establishment of direct re‐seeded grassland
Authors: MARSHALL A. H. , NAYLOR ROBERT E. L.
Published: February 2008

These experiments suggest a number of causes for the poor establishment of direct reseeded grass. An adequate supply of moisture to the seed is of prime importance and burial of trash in drill slits may impair this supply by preventing seed/soil contact directly or by preventing closure of the drill slit.

Management techniques which aim to reduce the burden of trash in areas to be sown by direct drilling, usually result in improvements in emergence. This is achieved by improved seed/soil contact, reduced evaporation of water from an open drill slit and lowered probability of phytotoxic leachates being produced. It is possible that benefits might be achieved were it possible to select for sowing seed of proven high vigour, i.e. seed that establishes well in poor conditions.
Effects of the deficiens allele on ear development and yield in barley
Authors: HABGOOD R.M. , CHAMBI J.Y.
Published: February 2008

Lines partially‐isogenic for the deficiens (VtVt and two‐rowed (VV) barley ear types were developed in the genetic background of cv. Kym, for comparisons of ear development and yield components.

The suppression of lateral floret growth by the Vt allele during pre‐anthesis ear development occurred at a relatively late stage and only occasionally was median floret survival enhanced in the deficiens line. The final size of lateral florets in both deficiens and normal ear types appeared to be largely governed by assimilate supply. At anthesis, the lateral florets comprised about 10% of the dry matter of normal ears, whereas in the deficiens ears the median florets were correspondingly heavier. After anthesis, grain growth in the deficiens line was slower than in the normal line, although final grain weight was not affected.

In another experiment the Vt allele occasionally increased the number of grains per ear, but consistently decreased the weight per grain. In drilled plot trials, the mean yield of the deficiens line was 8% lower than the normal. Excision of lateral florets at anthesis showed that photosynthesis in these organs did not contribute to the yield advantage of the normal ear type.

It is suggested that the inferior performance of the deficiens type was attributable to the greater physical constriction of endosperm expansion imposed by the development of thicker, more rigid, palea and lemma tissues.
Effects of straddle‐harvester design on cane blight (Leptosphaeria coniothyrium) of red raspberry
Authors: WILLIAMSON B. , RAMSAY A.M.
Published: February 2008

A new fruit catching device developed for raspberry straddle harvesters to reduce wounding of young canes and their consequent infection by Leptosphaeria coniothyrium was tested. During picking the young canes were contacted only by the foam rubber on a pair of belts which moved backwards along the harvester at the same speed that the machine advanced. The incidence of canes with cane blight lesions in 1981 was 18% following the use of the new device in 1980, and 79% following the use of a conventional commercial harvester equipped with overlapping metal fruit‐catching plates. In comparison with the latter plates, the new device avoided wounding the cane surface directly: when the belt marks on these canes were inoculated with mycelium, however, the disease incidence was 77%. The new device caused wounds in 1980 by ripping leaves from nodes. In comparison with the commercial harvester the new device led to smaller lesions in 1981 and a lower percentage of canes dead above the fruit‐catching zone.

A modified new catching device tested in 1982 made barely detectable pressure marks on the young canes without bruising them. Only 6·6% of these canes developed vascular lesions after inoculation, an incidence similar to that for unwounded control canes (2·5%). The modified new device is advised for regions prone to cane blight where the cropping system has young and fruiting canes growing together.
Sterilisation of the potato moth, Phthorimaea operculella (Lepidoptera: Gelechiidae) by fumigation with thiotepa
Authors: NABI M. N. , HARRISON R. A.
Published: February 2008

The chemosterilant thiotepa was used in fumigation chambers for sterilisation of male and female potato moths. Its effectiveness was registered by recording egg production, egg hatch, longevity of moths, and mating frequency. Also studied was the effect on the persistence of the chemical of temperature, exposure time and concentration.

The tests showed that it was possible to sterilise fully male and female moths with thiotepa without adverse effects on mating and longevity. Generally, males were more susceptible to sterilisation than females. No definite relationship was found between dosage and egg production, longevity and mating frequency of moths. The compound did not lose its sterilising activity when used successively up to five times during the same day or once weekly for a total of 4 wk. The sterilising activity was related to temperature, exposure time, concentration and rates of airflow of the circulatory fumigation chambers.

Some reduction of fertility occurred when F, adults paired with untreated moths.
Soil‐applied fungicides for controlling take‐all in field experiments with winter wheat
Authors: BATEMAN G. L.
Published: February 2008

Soil treatment fungicides were tested against take‐all (Gaeumannomyces graminis var. tritici) in three field experiments with winter wheat. Fungicides were applied as drenches either before sowing in autumn, and incorporated by rotary harrowing, or to the crop in spring. The most effective treatments were autumn applied benomyl (20 kg/ha) and nuarimol (0·55‐4·4 kg/ha). However, the highest nuarimol concentration depressed yield. Benomyl sometimes induced a resurgence of take‐all in the second wheat crop after treatment. Nuarimol had no adverse effects in subsequent crops, and neither fungicide hindered the onset of take‐all decline in a third crop after treatment. The possible value of soil treatment in future control strategies is discussed.
Immunodiagnosis of plant viruses by a virobacterial agglutination test
Authors: CHIRKOV S. N. , OLOVNIKOV A. M. , SURGUCHYOVA N. A. , ATABEKOV J. G.
Published: February 2008

A new virobacterial agglutination (VBA) test for the immunodiagnosis of plant viruses is described. The test is based on the agglutination of Staphylococcus aureus cells by virus particles after treatment of the cells with homologous antiserum. The agglutination occurs within 1–5 min. The sensitivity of the test is 0·1‐0·4 μg virus/ml and is not affected by the shape of the virus particle. The use of affinity purified antibodies for sensitisation of S. aureus cells increases the sensitivity of the reaction 50‐fold and enables the detection of tobacco mosaic and cucumber green mottle mosaic viruses at a concentration of 2 ng/ml. The VBA test allows the estimation of potato viruses X, S, M and Y in the eyes and sprouts of infected tubers and in the leaves of infected plants. The diagnosis of carnation mottle virus in carnation plants and of mushroom viruses in mushroom (Agaricus bisporus) fruit‐bodies and mycelium are also described.
Glucose phosphate isomerase polymorphism in field populations of the potato cyst nematodes, Globodera rostochiensis and G. pallida
Authors: FOX P. C. , ATKINSON H. J.
Published: February 2008

The isozymic variation of glucose phosphate isomerase (GPI) was compared in 20 field populations of potato cyst‐nematode (PCN) and related to variation in reference pathotypes of PCN. Populations pathotyped as G. rostochiensis Ro 1 by conventional differential cultivar tests were found to be different from populations of G. pallida. Variation within populations pathoptyped as G. pallida was seen and three populations were found to be similar to the reference G. pallida Pal pathotype. This seemed to be confirmed for two populations using cysts formed on a cultivar resistant to the Pa 1 pathotype when an isoenzyme pattern characteristic of G. palida Pa2 and Pa3 was found. The feasibility of the use of isozyme identification of PCN pathotypes is discussed in the light of these results.
Diffusive conductance of rice (Oryza sativa) leaves during gradually induced soil water stress
Authors: SAINI B. C. , RATHORE T. R.
Published: February 2008

The diffusive conductance (Cs) of rice (Oryza sativa cvs Jaya and Bala) leaves was measured during a soil drying cycle from flooding to decreasing soil water potential (φs) in a controlled‐environment chamber. Plants were grown continuously under 5 cm submergence up to 69 days after transplanting and thereafter were subjected to gradual soil drying for a period of 17 days in the vegetative growth stage. In both the cultivars, the values of Cs were generally more on adaxial than abaxial leaf surfaces. This response of stomata during the period of soil drying was independent of leaf rolling. Further, the slopes of the curves (Cs, vs φs) also did not differ significantly (P= 0·05). The total Cs, of both cultivars during flooding was almost equal (0·60 cm s‐1) but at the end of the soil drying cycle, the values of total Cs, were 0·11 cm s‐l at ψs of ‐1·3 MPa and 0·08 cm s‐1 at ψs, of ‐0·8 MPa in cvs Jaya and Bala, respectively. For total Cs, slopes differed significantly (P = 0·05). A close relationship between total Cs, and ψs, in both cultivars (Cs, = 0·58‐0·40 ψs, for cv. Jaya and Cs= 0·46‐0·56 ψs, for cv. Bala) indicated that stomata were sensitive to increasing soil water deficit.
Tiller dynamics and assimilate partitioning in Lolium perenne with particular reference to flowering
Authors: COLVILL KAY E. , MARSHALL C.
Published: February 2008

The fate of 100 seedling plants of Lolium perenne L. was studied over a period of 2 years in a field plot. The birth and death of tillers and the production of inflorescences was followed, and the components of seed yield were recorded in detail in the first year. The pattern of distribution of 14CO2 assimilated by the main shoot was examined at monthly intervals and during the first flowering season the distribution of 14C‐assimilate from individual leaves and from the inflorescence was also studied. The capacity of individual tillers to assimilate 14CO2 prior to flowering and the re‐distribution of previously accumulated assimilate during seed growth were also assessed.

Plants died at a more or less constant rate with time and only 54 survived to the end of the 2–yr period. First year mortality was associated with severe grazing or cutting but in the second year the death of ungrazed plants was observed. There was great variability in the production of tillers by surviving plants. In both years the number of live tillers per plant increased from July to the end of April with particularly rapid tillering in March and April establishing the maximum value for each year. There was a similar phase of rapid tillering after flowering in July. The number of live tillers per plant declined by 50% during stem elongation and inflorescence emergence and the majority of dead tillers were young secondary (in the first year) and tertiary (in the second year) tillers with a mean age of 40 days. Such tillers had poor assimilatory capacity prior to the onset of death and were not supplied with assimilate from the main shoot. Most of the plants surviving at the end of the experiment flowered in both years and one quarter of the maximum number of live tillers per plant recorded in April of each year produced inflorescences. The earlier a tiller was produced the greater was its chance of flowering and the greater its production of seed. The greater weight of seed produced was associated with the development of more seed‐bearing florets per spikelet. There was relatively little export of “C‐assimilate from the flowering main shoot, and the lower internodes formed the major sink for post‐anthesis assimilate. The growth of seeds appeared to be relatively independent of the leaves for current assimilate. There was some evidence that assimilate accumulated in lower internodes was remobilised and utilised in the growth of seeds and new tillers.

Overall, the results confirm the view that the grass plant is a dynamic population of short‐lived tillers and indicate that increasing competition for assimilate at flowering exerts a major influence on the production and survival of tillers.
The performance of carrot seeds in relation to their viability
Authors: GRAY D.
Published: February 2008

The germination and emergence characteristics, and early seedling growth, of carrot seeds cv. Chantenay red‐cored from different sources with a range of germination from 54–94%, was compared.

Seeds from protected crops (mean temperature of growth 21°C, r.h. 45–70%) gave higher percentage germination than those from crops grown outdoors (mean temperature 15°C, 70–100% r.h.). Germination was also higher from mature (seed moisture content at harvest 20% or lower) than immature seed (seed moisture content at harvest between 20 and 60%). High percentage germination (>90%) was associated with low mean germination times and low spreads of germination times whilst the reverse was true for low percentage germination. Similar relationships were found for seedling emergence characters in the field although a lower proportion of the viable seeds produced seedlings from slowly than rapidly germinating seed lots. In general, seed lots having a low percentage germination gave greater variability in plant weight than those of higher percentage germination. There was no effect of seed source on radicle or shoot relative growth rates or on post‐emergence seedling growth rates.
Effects of powdery mildew on grain filling in spring barley in contrasting environments
Authors: JENKYN J. F.
Published: February 2008

Circumstantial evidence from field experiments at Rothamsted suggested that effects of powdery mildew on grain filling in spring barley may be determined partly by temperature during the grain‐filling period. An experiment was, therefore, done which compared the effects of fungicides applied to control powdery mildew on grain filling in early‐ and late‐sown spring barley plants kept either out‐of‐doors throughout their growth (‘cool’ environment) or under the same conditions until the start of grain filling and then transferred to a heated glasshouse (‘warm’ environment) until harvested. Fungicides that controlled mildew increased the total grain yield of the late‐sown barley more than that of the early‐sown and much more in the warm environment than in the cool. On average, the effect of the fungicides in the cool environment was to increase grain yield by 17·7%. Small increases in numbers of grains/ear (+ 3·4%) and thousand‐grain weight (TGW) (+ 2·3%) contributed to this increase but it could be attributed principally to an average increase in numbers of ears/plant of 12·4%. Contrastingly, fungicides increased average grain yield in the warm environment by 58·2%. Effects of the fungicides on numbers of ears/plant (+ 27·8%) and on numbers of grains/ear (+ 4·5%) were not significantly different to those in the cool environment, and the much greater responses in the warm than in the cool environment could be attributed mostly to much larger effects on grain size (+ 19·2%)

The greater benefits of the fungicides and, by implication, the greater damage done by powdery mildew in the warm than in the cool environment cannot, unequivocally, be attributed to differences in temperature during grain‐filling because the two environments clearly differed in other ways and especially in light intensity. Nevertheless, the results obtained do illustrate the potential risks involved in using data obtained under one set of circumstances to predict what will happen in another, especially when environments differ as greatly as glasshouses and fields.
Epidemiology of three viruses infecting the rose in the United Kingdom
Authors: THOMAS B. J.
Published: February 2008

Studies on the epidemiology of arabis mosaic (AMV), prunus necrotic ringspot (PNRSV) and strawberry latent ringspot (SLRV) viruses were made in relation to commercial production of standard and bush roses. AMV or SLRV apparently induced either symptomless infection in rose cultivars and Rosa spp., or leaf symptoms ranging from small chlorotic flecks to severe chlorotic mosaic and, occasionally, plant death. Infection of R. canina ‘inermis’ or R. corymbifera by an isolate of SLRV from R. corymbifera also severely depressed flowering and hip formation. In addition, whereas this isolate could be graft‐transmitted to all Rosa spp. tested, isolates from R. rugosa and R. multiflora failed to be graft‐transmitted to R. canina ‘inermis’ or R. corymbifera. No difference was detected in graft‐transmission tests of Rosa spp. with several isolates of AMV or PNRSV.

In plantings of up to 7 yr none of the viruses was transmitted through pollen to healthy roses grown in nematode‐free soil, and only SLRV was readily seed‐transmitted, particularly in R. rugosa. Nevertheless, in soil containing viruliferous nematodes, AMV and/or SLRV were transmitted to c. 80% of healthy plants.

AMV and particularly SLRV were each damaging to field‐grown maiden rose bushes cv. Fragrant Cloud. SLRV delayed the onset of flowering, and reduced the number and size of blooms. Diseased bushes were less vigorous, and half or none of the AMV‐ or SLRV‐ infected bushes respectively, conformed to the British Standards Institution specifications for maiden bush roses.

These results are discussed in relation to the commercial production of field‐grown roses in the UK.
Differential control of potato cyst‐nematodes, Globodera rostochiensis and G. pallida by oxamyl and the yields of resistant and susceptible potatoes in treated and untreated soils
Authors: WHITEHEAD A. G. , TITE D. J. , FRASER JANET E. , NICHOLS A. J. F.
Published: February 2008

In sandy loam infested with Globodera rostochiensis (2–95 eggs g‐1 soil) the yield of Desiree potatoes was decreased by 8·2 t ha‐1 for every increment of 20 eggs g‐1 soil. Oxamyl incorporated in the seedbed at 5 kg ha‐1 before planting prevented significant loss of yield and damage to the tubers and minimised nematode increase. Cara and Maris Piper potatoes, which were resistant and tolerant to G. rostochiensis usually responded less to oxamyl than did susceptible cultivars. In a range of cultivars, yield responses to oxamyl treatment of soil infested with G. rostochiensis often differed from those in soil infested with G. pallida. In field experiments, oxamyl controlled G. pallida less than G. rostochiensis. In pots, such differential control of the two species by oxamyl was not observed.
Effects of aldicarb and benomyl on nematodes, vesicular arbuscular mycorrhizas and the growth and yield of forage maize
Authors: WILLIAMS T. D. , BEANE J.
Published: February 2008

The effects of aldicarb and benomyl on plant‐parasitic nematodes, vesicular arbuscular mycorrhiza and the growth of forage maize were measured in 1980—1982 in two field experiments at Woburn, Bedfordshire and in a pot experiment using loamy sand soil from the field site. The most numerous migratory nematode, Tylenchorhynchus dubius increased three to four‐fold during each season in untreated soil and was effectively controlled by aldicarb. Pratylenchus species were fewer but equally well controlled. The cereal cyst‐nematode (Heterodera avenae), a serious maize pathogen in Northern France, was relatively scarce in untreated roots and was further decreased by aldicarb treatment; post‐harvest H. avenae egg numbers were not affected by treatments; they declined equally because maize is such a poor host. Significant yield benefits (up to 37%) followed aldicarb treatment and were ascribed to nematode control in the absence of attribution to insect or other pests. Benomyl did not increase yields nor did it significantly affect the incidence of mycorrhiza.

The results confirm that considerable losses of forage maize can be caused by nematodes in light soil and that aldicarb is an effective nematicide even at the rate of 1·7 kg a.i./ha.
Laboratory tests for leaf resistance to Botrytis squamosa in onions
Authors: CURRAH LESLEY , MAUDE R. B.
Published: February 2008

Two laboratory methods of testing for resistance to Botrytis squamosa in Allium cepa, A. fistulosum and hybrid material derived from them were developed. In one method, seedlings were sprayed with conidiospores, incubated for 3 days at 15°C (2 days at 100% r.h.) and the numbers of lesions per leaf assessed. This test was destructive. The second method was non‐destructive, the plants being retained for breeding purposes. Leaf segments (25 × 15 mm) or leaf discs (14 mm diameter) were inoculated individually with a drop (0·014 ml) of spore suspension, and maintained at 15°C and 100% r.h. with a 12 h photoperiod. The length of the latent period, denned as the number of days for 50% of the leaf portions to produce lesions bearing visible mycelium, was determined for each onion line in a test. The reciprocal (1/t) of the latent period was used to test for significant differences between lines by analysis of variance.

With both test methods, spores were applied at concentrations that discriminated relative resistance most readily.

In both seedling and leaf segment tests A. fistulosum was more resistant than A. cepa to B. squamosa. The leaf disc test indicated that cultivars of A. fistulosum differed in their resistance. In hybrid material resistance was intermediate or more like that of A. fistulosum.
Soil compaction and the growth of vining peas
Authors: DAWKINS T. C. K. , HEBBLETHWAITE P. D. , MCGOWAN M.
Published: February 2008

The effects of differing soil conditions at two sites on the growth of vining peas are described. The work was carried out over several seasons having contrasting rainfall at the time of crop emergence.

Topsoil compaction induced by tractor wheelings reduced plant population and yield of vining peas by up to 70%. On the compacted plots peas were unable to compensate for the low population which was demonstrated by the inclusion of a non‐compacted treatment thinned to the same population as the compacted plots.

The severity of compaction was greatest when soil conditions were dry at emergence and least severe when wet. It is suggested that compaction resulted in increased ethylene production in the root and shoot tissues and this may be a causal agent of the observed growth modifications.

Recultivation of a compacted seed bed prior to sowing resulted in better establishment and higher yields than with the topsoil compacted but final yields were variable when compared to a ploughed control.

Double digging did not increase yield above a ploughed control. In one year a 25% yield reduction was attributed to this treatment. The reasons for the reduction in yield are complex but it is suggested that the causal agent was modfied soil and plant water relations resulting in altered crop physiology.

Tramlining the crop reduced yield in one year but when the frequency of wheeling damage is considered they would be unlikely to affect productivity.
Biological effectiveness of electrostatically charged rotary atomisers.
Authors: ARNOLD A. J. , CAYLEY G. R. , DUNNE Y. , ETHERIDGE P. , GRIFFITHS D. C. , PHILLIPS F. T. , PYE B. J. , SCOTT G. C. , VOJVODIC P. R.
Published: February 2008

Electrostatic sprayers charged to 30kV and placed 20 cm above the crop increased the chemical deposition of permethrin in field beans and improved control of the pea and bean weevil, Sitona lineatus. Control of the black bean aphid, Aphis fabae, was improved by electrostatic sprayers only when a systemic chemical, demeton‐S‐methyl, was used. In spring barley, sprays applied electrostatically or hydraulically gave similar control of barley mildew, Erisyphe graminis.
A review of the performance of electrostatically charged rotary atomisers on different crops
Authors: CAYLEY G. R. , ETHERIDGE P. , GRIFFITHS D. C. , PHILLIPS F. T. , PYE B. J. , SCOTT G. C.
Published: February 2008

The collaborative trials described by Arnold et al., 1984a, b, c provided an extensive range of data on the performance of electrostatically charged rotary atomizers on a variety of crops, at different growth stages, using systemic and non‐systemic pesticides. The purpose of this paper is to review the subject to date.
Effect of gibberellic acid, kinetin and naphthylacetic acid on the growth of coconut seedlings
Authors: REMISON S. U.
Published: February 2008

The effects of three growth regulators, namely gibberellic acid (GA3), kinetin (6‐furfuryl‐aminopurine) and α‐naphthyl‐acetic acid (NAA), each at five concentrations (0, 25, 50,102 and 103 mg/litre) on the growth of coconut seedlings (Cocos nucifera) were examined. GA3 at 25 mg/litre increased growth in height; higher concentrations had no significant effect. Kinetin at 102 and 103 mg/litre and NAA at all concentrations reduced height growth compared with the control. No treatment caused a significant increase in total dry weight.
The germination of grass seeds after storage at different temperatures in aluminium foil and manilla paper packets
Authors: BEAN E. W. , SENGUL S. , TYLER B. F.
Published: February 2008

The germination of seeds of three species of forage grasses, Lolium perenne, Festuca pratensis and Dactylis glomerata, was studied after storage for 3–5 years under five different storage conditions: in aluminium foil packets at —25°C, 0°C and laboratory temperature (c. 18°C), and in manilla paper packets at 0°C and laboratory temperature. With Lolium perenne and Festuca pratensis high germination values at 3 and 7 days were obtained from seed stored at — 25 °C and 0°C in foil packets (5% moisture), but at laboratory temperatures, seed from foil packets gave lower germination values than those from manilla paper packets. At all three temperatures Dactylis glomerata germination after 7 and 14 days was higher in seed stored in foil than in manilla packages. With all three species stored in manilla packets, germination was higher after laboratory than cold storage.
Systematic differences in the population density of green spruce aphid, Elatobium abietinum in a provenance trial of Sitka spruce, Picea sitchensis
Authors: DAY KEITH
Published: February 2008

Aphid populations were evaluated on foliage samples within an experimental forest area. There were marked differences in aphid density between three areas within the experiment and between individual trees. Significant differences between provenances of Sitka spruce were of particular interest since aphid density appeared to be related to the latitudinal origin of the seed. The more southerly provenances were especially susceptible. The accumulated evidence suggests that no single physiological difference between trees will account for all observed variations in aphid density although the later growth cessation of susceptible provenances deserves further study.
The distribution and abundance of predatory arthropods overwintering on farmland
Authors: SOTHERTON N. W.
Published: February 2008

Soil samples (0·04 m‐2) were taken from December to January in 1981‐82 and 1982‐83 from five crop and two non‐crop habitats on farmland in Hampshire to quantify the distribution and abundance of overwintering polyphagous predatory arthropods. Total numbers of overwintering polyphagous predators were greater in field boundaries, winter‐sown cereals and established grassland than in the other four habitats. Many individual species overwintered in significantly higher densities in field boundaries than in any other habitat; others predominated in woodland, grassland and winter‐sown cereals. The carabids Agonum dorsale and Demetrias atricapillus, probably the most important predators of cereal aphids, overwintered almost entirely in field boundaries.
Immunoenzymatic techniques for the detection of Phoma exigua in infected potato tissues
Authors: AGUELON M. , DUNEZ J.
Published: February 2008

Antisera to Phoma exigua var. foveata and var. exigua were prepared by injecting rabbits and mice with protein solutions from mycelium. Specific antibodies were isolated and immunoenzymatic techniques (double antibody sandwich ELISA and indirect ELISA) were used to test for the fungus in inoculated tubers and sprouts and in stems grown from these tubers. The fungus was detected in these different tissues, with var. foveata being more aggressive, demonstrating the applicability and sensitivity of the techniques. The antibodies produced to the two varieties of the fungus were not specific to their own varieties. They also reacted with Phoma tracheiphila but did not react with several other common potato pathogens. Preliminary results obtained with antibodies from mouse ascite liquid suggest the possibility of producing specific monoclonal antibodies.
Galactogen, a virus‐like particle from slugs
Authors: KASSANIS B. , WOODS R. D. , MACFARLANE I.
Published: February 2008

Virus‐like particles were isolated from three species of slugs. Further investigation showed that the preparations contained very little nucleic acid and not more than 2% protein. Colorimetric and chromatographic analyses showed that they were composed almost entirely of galactogen and glycogen.
Change of virulence of Septoria nodorurn during passage through barley and wheat
Authors: CUNFER BARRY M.
Published: February 2008

The barley biotype of Septoria nodorum was recovered from isolates of the wheat biotype after 2–6 passages through barley. Shifts in the population of the two biotypes during host passage were determined by isolating single spores after passage and observing changes in symptom expression on both hosts. The number of passages required before the barley biotype was recovered varied with the fungus isolate and barley cultivar. Attempts to recover the wheat biotype from isolates of the barley biotype during several passages through wheat were unsuccessful when 105 to 106 conidia m1‐1 were used as inoculum. However, the wheat biotype was recovered from two isolates of the barley biotype during a single passage when a very high concentration of conidia (>1012 ml‐1) were used as inoculum. From the results of this study and a previous report by the author, the biotype of S. nodorum on barley which occurs in the southeastern United States appears to be largely restricted to barley.
Characterisation of an Australian isolate of tomato yellow top virus
Authors: THOMAS J. E.
Published: February 2008

An Australian isolate of tomato yellow top virus (TYTV‐A) was transmitted in the persistent manner by the aphid Myzus persicae. Its host range was mainly restricted to the Solanaceae, though Capsella bursa‐pastoris and Gomphrena globosa were symptomlessly infected.

TYTV‐A was purified from Physalis Joridana, using an enzyme‐assisted method in which the initial tissue homogenate was incubated with cellulase. Yields of purified virus were 100–900 μg/kg tissue and depended on the age of the infected plants. Maximum yields were obtained 4–5 wk after inoculation. The particles of TYTV‐A were c. 24 nm in diameter, had a buoyant density of 1.34 in caesium sulphate and a coat protein mol. wt of c. 25.7 × 103.

TYTV‐A was shown to be closely related serologically to potato leafroll virus (PLRV), TYTV from New Zealand and more distantly related to several other luteoviruses. An antiserum to TYTV‐A was used in enzyme‐linked immunosorbent assay tests to detect TYTV in field‐infected tomato plants and also luteoviruses from potato plants with leafroll symptoms. It is clear that TYTV‐A is a luteovirus closely related to PLRV.
The effect of oxamyl and the growing of susceptible and resistant potato cultivars on the population dynamics of Globodera rostochiensis throughout the soil profile
Authors: STOREY G. W.
Published: February 2008

Comparisons are made between the population dynamics of potato cyst nematode and root growth of Pentland Crown and Maris Piper potato cultivars. Large changes in the number of eggs occurred to a depth of 48 cm, particularly in a peaty loam and in plots treated with oxamyl. Oxamyl delayed the hatch of eggs in the peaty loam but not in the sandy loam, giving the protected plants several weeks without invasion damage during which they became bigger with their roots better established deeper in the soil. Oxamyl killed or impaired the movement of second stage juveniles but appeared to have little systemic activity to hinder juvenile development within roots.
Mass algal culture in outdoor plastic‐covered minipond systems
Authors: WALMSLEY R. D. , SHILLINGLAW S. N.
Published: February 2008

A comparative study was undertaken to evaluate the performance of algal cultures grown in plastic‐covered outdoor minipond systems. It was demonstrated that production in enclosed miniponds was higher than in open ones on account of the stimulatory effects of elevated temperatures which developed in the enclosed systems. Although the plastic covering reduced the amount of light which was available for photosynthesis, this had minimal effects on production due to the light saturation characteristics of the algal cells. The practice of enclosing mass algal cultures with transparent plastic appears to show promise in semi‐arid regions not only as a procedure to reduce evaporation, but also as one for increasing algal yields.
Effects of aphid alarm pheromone derivatives and related compounds on non‐ and semi‐persistent plant virus transmission by Myzus persicae
Authors: GIBSON R. W. , PICKETT J. A. , DAWSON G. W. , RICE A. D. , STRIBLEY M. F.
Published: February 2008

A derivative, prepared from the aphid alarm pheromone (E)‐β‐farnesene and the saturated straight 14‐carbon chain dialkyl ester of acetylene dicarboxylic acid, was the most active compound tested for inhibiting acquisition by the aphid Myzus persicae of the non‐persistently transmitted potato virus Y (PVY). Derivatives lacking, or with shorter, or branched or partially‐unsaturated carbon side‐chains were less active. The one derivative tested also inhibited inoculation of PVY, and acquisition of beet mosaic virus (also non‐persistent) and the semi‐persistent beet yellows virus. However, it had no obvious effect on aphid probing behaviour; related compounds lacking the (E)‐β‐farnesene moiety also inhibited acquisition of PVY.
Biological treatments for the control of decay in tree wounds.: Field tests
Authors: MERCER P. C. , KIRK S. A.
Published: February 2008

In an attempt to control fungi causing decay a range of micro‐organisms, selected after laboratory tests, was inoculated into wounds made in the trunks of beech trees. The most successful micro‐organism was an isolate of Trichoderma viride, which, over a period of 4 years, maintained significantly lower colonisation by decay fungi at both sites ‐ c. 15% of the level found in uninoculated wounds. T. viride could be reisolated from the majority of wounds into which it had been inoculated up to 4 years later. No other antagonist persisted very effectively. Inoculation of T. viride in glycerol improved its establishment but malt extract and sucrose had no such effect. Both the addition of glycerol to wounds and the wrapping of them in black PVC sheet increased natural colonisation by T. viride. The use of PVC but not glycerol reduced numbers of decay fungi but not through the agency of T. viride present by natural infection, as this proved generally ineffective in the control of decay fungi. Another isolate of T. viride persisted considerably better when covered with a wound sealant.
A seed treatment for the control of Pythium damping‐off diseases and Peronospora parasitica on brassicas
Authors: WHITE J. G. , CRUTE I. R. , WYNN E. C.
Published: February 2008

In soil inoculated with Pythium ultimum or Pythium irregulare, seed treatment with either Apron 70 (=1 g metalaxyl and 1 g captan/kg seed) or thiram gave control of pre‐emergence damping‐off of Brussels sprout and cabbage seedlings. On cauliflower, Apron 70 was significantly more effective than thiram. No post‐emergence damping‐off occurred in either of these crops or in oil‐seed rape following seed treatment with Apron 70 whilst post‐emergence losses from untreated seed ranged from 10·2–19·4% and from thiram treated seed from 5·7‐7·4%. Apron 70 gave complete control of Peronospora parasitica on cauliflower inoculated 10 days after sowing; thiram was ineffective. Following seed treatment with Apron 70, metalaxyl was detected in the cotyledons, true leaves and roots of cabbage seedlings up to 4 wk from sowing.
Effects of soil treatments and cultivars on ‘early dying’ disease of potatoes caused by Globodera rostochiensis and Verticilliurn dahliae
Authors: HIDE G. A. , CORBETT D. C. M. , EVANS K.
Published: February 2008

Plots in a field infested with Globodera rostochiensis and Verticillium dahliae were treated in 1971 with methyl bromide, dazomet, aldicarb, benomyl or aldicarb + benomyl and potatoes (cv. Pentland Dell) were grown in four consecutive years. In 1971, all treatments delayed the development of haulm symptoms, decreased soil populations of G. rostochiensis and increased yields. In the second year yields were increased by all treatments except dazomet whereas in the third and fourth years only benomyl or aldicarb + benomyl increased yields. Soil populations of V. dahliae were decreased by methyl bromide in 1971 but not by other treatments or in later years.

In 1976, Pentland Dell and Pentland Crown were grown on an infested field in plots fumigated with methyl bromide. Fumigation slightly delayed shoot emergence but increased plant height, ground cover and the size and persistence of the leaves; development of haulm symptoms was delayed and yield increased. Fumigating with methyl bromide at five times the normal rate was more beneficial to Pentland Dell than to Pentland Crown.

In a comparison of 10 cultivars in 1975, symptoms developed sooner and yields were smaller on a field infested with G. rostochiensis and V. dahliae than on a non‐infested field and on both sites Maris Peer plants died soonest and yielded least. Pentland Crown yielded most on the non‐infested field and Maris Piper on the infested field.
Nematodes associated with dipterous stem‐boring larvae (Chloropidae and Opomyzidae) in ryegrass
Authors: MOORE D. , HUNT D.J.
Published: February 2008

Associations between different species of nematodes and stem‐boring larvae were studied over two years. Howardula oscinellae was rarely found in stem‐boring larvae. Usually mermithids were also uncommon, but in one Italian ryegrass (Lolium multiforum) variety trial over 12.5% of stem‐boring larvae were attacked, with different levels of parasitism in larvae from the different ryegrass varieties. Panagrolaimus rigidus nematodes were also identified from stem‐boring larvae and Oscinella frit larvae were the most common host. Greater infestation levels of P. rigidus were found in larvae from grazed swards than from cut swards. P. rigidus may cause the death of some stem‐boring larvae.
The effect of aphid‐resistance in cowpea on infestation and development of Aphis craccivora and the transmission of cowpea aphid‐borne mosaic virus1
Authors: ATIRI G. I. , EKPO E. J. A. , THOTTAPPILLY G.
Published: February 2008

The virus‐vector‐host relationships of cowpea aphid‐borne mosaic virus (CAMV) and its vector, Aphis craccivora, were studied in cowpea lines differing in resistance to aphid infestation. CAMV was acquired and inoculated by its vector during brief probes, confirming that it is non‐persistently transmitted. On aphid‐resistant cowpea lines, the abundance and the relative sizes of aphids was less than in aphid‐tolerant and aphid‐susceptible lines. However, aphids were observed to make more numerous probes and probes of shorter duration on aphid‐resistant lines than on aphid‐susceptible lines. Resistance to aphid infestation in cowpea did not provide resistance to infection with CAMV.