bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of re‐use of polyethylene glycol priming osmotica upon the development of microbial populations and germination of leeks and carrots
Authors: PETCH G. M. , MAUDE R. B. , BUJALSKI W. , NIENOW A. W.
Published: February 2008

Three batches of leek seeds were osmotically primed successively in the same polyethylene glycol solution in a bubble column at a seed concentration of 100 g/litre for seven days at 15°C. Three batches of carrot seeds were similarly primed in a separate solution for six days at 15°C. The concentration of microorganisms in the solutions increased rapidly during priming of the first seed batch for both seed types, but increases during priming of the second and third batches were small. The seeds were the main source of the microorganisms; priming reduced the numbers of colonies of filamentous fungi and increased those of bacteria and yeasts. The priming treatments improved the percentage germination of the three seed batches of primed carrots and reduced the mean time to germination in both species and the mean time to emergence in compost.

Percentage emergence was not affected by priming except in the third batch of primed carrot seed. The presence of large numbers of microorganisms in the priming solutions did not greatly affect seed performance when the same osmoticum was used three times with leeks and twice with carrots. Priming did not affect the number of abnormal seedlings.
Role of alternative pathway respiration in tomato roots attacked by Meloidogyne incognita
Authors: MOLINARI SERGIO
Published: February 2008

The effect of nematode infestation on the alternative pathway respiration of mitochondria isolated from resistant and susceptible tomato roots greatly depended on the oxidisable substrate tested. The percentage of alternative respiration in NADH, malate and succinate oxidation was markedly different between the resistant (Rossol) and the susceptible (Roma VF) cultivars before infestation. Only the percentage of malate alternative oxidation in mitochondria from the resistant roots was influenced by nematode invasion. Conversely, attacked roots showed consistent variations in the content of mitochondria per unit fresh weight and in the phosphorylation efficiency (ADP/O) of the organelles. Expression of the alternative pathway (ρ' value) was found to be unchanged in intact roots and isolated mitochondria six days after nematode inoculation.
A key for the stages of development of potato (Solatium tuberosum)
Authors: JEFFERIES R. A. , LAWSON H. M.
Published: February 2008

A key is presented to describe stages of development and growth of the potato (Solanum tuberosum L.). The code is divided into seven principal stages: seed germination and emergence, tuber dormancy, tuber sprouting, emergence and shoot expansion, flowering, tuber development, and senescence. Each of these is subdivided into secondary stages. Flowering and tuber development stages can be concurrent with the other stages to enable the separate description of the development of these organs. The practical uses of the key are discussed.
Modelling damage on maize by the European Corn Borer, Ostrinia nubilalis
Authors: LABATTE J. M. , GOT B.
Published: February 2008

The European Corn Borer (ECB), Ostrinia nubilalis Hbn. (Lepidoptera: Pyralidae), is a major pest of maize in many countries. Yield losses caused by larvae of this insect depend mainly on the extent of cavity damage, the timing of tunnelling, and their within‐plant distribution. To describe these factors, a mechanistic model of cavity appearance is proposed here. It takes into account the main biological processes which determine damage. These are the development, mortality and within‐plant distribution of the ECB larvae. The model has been estimated and tested on field data collected at INRA‐Versailles in France. Model fittings showed that (i) creation and lengthwise extension rates of cavities per larva depend on location and instar of the larvae, and that (ii) only instars 4 and 5 make cavities. This model described, with a high precision level, the appearance and lengthwise extension of cavities over time and their within‐plant distribution for two maize varieties, several infestation dates and levels, and various climatic sequences.
Influence of the green spruce aphid on defoliation and radial stem growth of Sitka spruce
Authors: DAY K. R. , McCLEAN S. I.
Published: February 2008

Premature abscission of older Sitka spruce foliage on trees within forests in Northern Ireland was compared with green spruce aphid population levels 2 to 3 months earlier. Each aphid has a lower relative impact on needle loss at higher aphid population density; nevertheless, more aphids on a tree results in greater rates of needle loss. Evidence from horizontal stem increment sequences suggested that aphid feeding inhibited incremental growth, and that this inhibition might be delayed for up to two field seasons. However, the effect of aphids on stem growth in most years and on most trees seems relatively small compared with the potential of other tree‐or year‐specific processes.
Effect of annual and/or biennial burning of seed alfalfa stubble on populations of alfalfa weevil and pea aphid
Authors: SCHABER B. D. , ENTZ T.
Published: February 2008

The effects of five burning treatments of alfalfa (Medicago sativa L.) stubble combined with two insecticide treatments on populations of alfalfa weevil, Hypera postica (Gyllenhal), and the pea aphid, Acyrthosiphon pisum (Harris) were evaluated over an eight year period. The effects of the burn treatments were dependent on insect species, time of burn and year. Immature alfalfa weevil population levels were significantly reduced by the burn‐every‐autumn treatment in 3 of the 8 years, in 2 out of 8 years by the burn‐e very‐spring treatment, and by the alternate‐year‐burn treatment in 1 out of 4 years. Burning had little or no effect on pea aphid populations.
The economics of reduced‐rate insecticide applications to control aphids in winter wheat
Authors: MANN B. P. , WRATTEN S. D. , POEHLING M. , BORGEMEISTER C.
Published: February 2008

Applications of pirimicarb and fenvalerate at full‐rate and at a range of reduced dosages were applied on fields of winter wheat between 1983 and 1988 in West Germany. The relative effects of these treatments on the control of cereal aphids varied according to the growth stage at which spraying took place and the size of the aphid populations. The economic profitability of these treatments depended on the extent of post‐treatment recovery of the aphid populations, the cost of control and the crop value.

Under certain circumstances the high efficiencies of commonly‐used insecticides at full dose‐rate are not necessary to gain effective aphid control economically; a better return can be made by reducing the quantity of active ingredient per hectare.
The susceptibility of tubers of potato cultivars to black dot (Colletotrichum coccodes (Walk.) Hughes)
Authors: READ P. J.
Published: February 2008

In experiments with commercial seed of different cultivars at Rothamsted and Woburn, Bedfordshire in 1985 – 88 the severity of black dot on daughter tubers at harvest differed between cultivars. The disease was most severe on Desiree tubers. Amounts of disease were similar at both sites in 1986 – 88 but in 1985 it was more severe at Woburn than at Rothamsted.

Disease‐free seed of 12 (1987) or 15 (1988) cultivars were planted in experiments at Rothamsted (inoculated with Colletotrichum coccodes or not) and at Mepal, Cambridgeshire (not inoculated) and black dot assessed at harvest in October 1987 and in September and October 1988. There were significant differences in the amount of disease on different cultivars and the order of severity was similar at the two sites, on the two harvest dates in 1988 and in both years. Desiree, Maris Piper, Maris Peer and Record were amongst those cultivars severely affected whereas Cara, Pentland Crown and Romano were least affected.

Skin discoloration caused by black dot was more noticeable on white‐skinned than red‐skinned cultivars and was severe on the Dutch cultivars Estima, Marfona, Santé and Wilja.
Improvement of persistence and yield of Italian ryegrass (Lolium multiflorum) through pesticide use
Authors: CLEMENTS R. O. , BENTLEY B. R. , MURRAY P. J. , HENDERSON I. F.
Published: February 2008

The present two field experiments, involving plots of Italian ryegrass sown in 1976, 1980 and 1984 confirmed results of earlier work in which the yield and persistence of Italian ryegrass was greatly increased by the application of pesticide. A range of pesticide treatments were used. The responses to application of permethrin applied three times per year average 8% for the three years of the first experiment and 5% for the five years of the second experiment. Such responses appeared cost‐effective, but the overall environmental impact of such applications is not known.
Association of soybean root mycoflora with root modulation, root necrosis and plant fresh weight
Authors: FORBES G. A. , DAVET P.
Published: February 2008

Fungi were isolated from soybean plants in ten fields in south‐west France. Correspondence analysis (COA) was used to find associations among taxa (species, genera, groups) and sampling units (i.e. one field at one sampling date). The first axis of the COA demonstrated a dominant sampling date effect; the second indicated an association among certain sampling units and specific taxa. Regression analysis of COA coordinate values indicated that fields with high relative isolation frequencies of Fusarium spp., F. oxysporum and ‘other species’ (mostly Chaetomium spp. and sterile fungi) were characterised by greater plant fresh weight and nodule number and lower ratings for root necrosis. Cylindrocarpon spp., Cephalosporium spp. and F. solanihad high relative isolation frequencies in fields with lower plant weight, lower nodule number and higher root necrosis ratings. The relative importance of fungal taxa was also related to soil type.
Infective behaviour and aphid‐transmissibility of Italian isolates of potato virus Y in tobacco and peppers
Authors: MARTE M. , BELLEZZA G. , POLVERARI A.
Published: February 2008

When mechanically inoculated to susceptible tobacco (Nicotiana tabacum L.) cultivars, nine isolates of PVY from Umbria (Central Italy) and two from Southern Latium gave rise to rapid systemic infection which developed within 6–8 days after inoculation. Systemic spread of the same isolates was slower, or much slower, in infected pepper (Capsicum annuum L.) cultivars, 8–14 days for Southern Latium isolates and 20 ‐ 35 days for Umbrian ones. Aphid (Myzus persicae)‐moculation of pepper and tobacco plants with two of the Umbrian and one of the Southern Latium isolates confirmed the results from sap‐transmission and showed that fewer inoculated pepper plants become infected, especially with Umbrian isolates. In agreement with the data on systemic spread, aphid‐acquisition trials indicated that tobacco plants became efficient PVY sources for vectors 6–8 days after inoculation with either group of isolates. Peppers became efficient acquisition hosts 8–15 days after inoculation with Southern Latium isolates but not until 22–45 days after inoculation with Umbrian ones. Southern Latium isolates induced more severe symptoms in pepper cultivars than Umbrian isolates did. One of the Southern Latium isolates was able to systemically infect the resistant pepper cv. Yolo Y, which was never infected by the Umbrian isolates. The Umbrian isolates tested seem to be better adapted to tobacco than peppers, while Southern Latium ones are well adapted to both.
A time‐course study of early establishment stages of parasitic angiospermStriga asiaticaon susceptible sorghum roots
Authors: RAMAIAH K. V. , CHIDLEY V. L. , HOUSE L. R.
Published: February 2008

A time‐course study of the early establishment stages ofStriga asiaticawas carried out on a susceptible sorghum hybrid, CSH 1, using polyethylene bags and whole‐root clearing and staining techniques. PreconditionedStrigaseeds were applied to different aged segments of primary root but the results did not differ for these different aged segments. Most of theStrigaseeds (63%) germinated within 24 h of inoculation on the host roots. The attachment ofStrigaradicles to host root was rapid and it occurred between 36 and 48 h after inoculation. Only 9% of the germinatedStrigaseeds attached to the host root but 65% of these attachments successfully penetrated through the epidermis and entered the host cortex within 72 h. Penetration through the cortical cells was difficult; only 17% of attachments were able to reach the endodermis. Penetration took from 12 to 43 h after the first appearance of haustorial cells in the cortex; a total of 84 to 120 h after inoculation on the host root. Penetration through the endodermis and establishment on the host stele was relatively easier, as most of the haustoria reaching the endodermis were able to establish on the host stele. But this is a slow process taking a minimum of 24 h, and a maximum of 60 h after first contact of haustorial cells with the endodermis. The minimum time taken from inoculation of ungerminatedStrigaseed on the host root to establishment is about 108 h. The results are discussed in relation to published reports on other parasitic species such asAgalinis purpurea.
Influence of growth form of Arena fatua L. on the growth and yield of Triticum aestivum L.
Authors: ROONEY JOY M.
Published: February 2008

In a field experiment, all components of winter wheat grain yield, except grain number per ear, were reduced by wild‐oat competition, and more so by a prostrate form of wild‐oat than by an upright form. The prostrate form, ‘Churston’, shaded the crop at anthesis. Although there were no significant differences in photosynthetic activity in the flag leaves of wheat at saturating light intensities during the later stages of grain filling, it is likely that differences in growth form, height, weight and area of these two forms of wild‐oat, competing principally for light, accounted for their different effects on wheat grain yield.
The assessment of two barley starch mutants as potential parents in a malting quality breeding programme
Authors: SWANSTON J. S.
Published: February 2008

Grain and malt quality parameters were assessed in the barley starch mutants Waxy Hector, characterised by high levels of amylopectin, and Chalky Glenn, which has lines of cleavage across the large starch granules. Results were compared with those of their parental cultivars and suggested differences in the contribution of endosperm cell walls to milling energy. Although hot water extracts were not improved, other components, especially those associated with the fractured starch mutant, could be used in breeding programmes to improve aspects of quality, if they could be disassociated from deleterious effects of the starch mutation, e.g. poor grain filling.
The use of DNA markers to estimate the extent and nature of genetic variability in Solatium tuberosum cultivars
Authors: POWELL W. , PHILLIPS M. S. , McNICOL J. W. , WAUGH R.
Published: February 2008

High levels of DNA polymorphism were detected in 27 Solanum tuberosum cultivars examined. Combinations of at least two c‐DNA clones have been identified which in conjunction with EcoRI allow important UK potato cultivars to be characterised by their molecular profiles. The widely grown North American cultivar Russett Burbank was also successfully fingerprinted. Estimates of genetic diversity based on restriction fragment length polymorphism (RFLP) data indicate the important role that wild potato species and exotic germplasm have played in the development of the cultivars studied. A graphical method for simultaneously highlighting similarities and differences between genotypes for individual hybridising fragments is presented. This approach is particularly useful in identifying and recording fragments which are unique to certain genotypes.

Two potato cultivars: Fiona and Morag produce unique RFLP profiles when digested with EcoRI and EcoRV and probed with a flax ribosomal DNA sequence. Both Fiona and Morag possess incomplete or partial (quantitative) type resistance to G. pallida which was transferred from S. vernei. The preferential transmission of the r‐DN A fragments from S. vernei may indicate that this locus is associated with genetic factors controlling resistance to G. pallida.
The combined effects of a newly designed dibber drill, irrigation and seed covering treatments on lettuce and calabrese establishment
Authors: FINCH‐SAVAGE W. E. , RAYMENT M. , BROWN F. R.
Published: February 2008

A comparison was made between seedling establishment following sowing with the Mk2 dibber drill and a conventional coulter drill at three sowing occasions with both lettuce and calabrese. Different seed covering materials used to cover dibber‐drilled seed were also compared.

With lettuce, the rate and uniformity of seedling emergence and the numbers of seedlings emerging were greater following sowing with the dibber drill than with the coulter drill. Seedling establishment was further improved with irrigation especially when seeds were sown with a small quantity of the hydrophillic polymer, Alcosorb, which avoided associated problems of increased soil impedance. Alcosorb was a more effective seed cover than a peat and vermiculite mix and better suited for mechanical metering. Results indicate that the dibber drill can be considered as a realistic and cheaper alternative to transplanting for establishing later‐season lettuce crops. With calabrese, however, percentage seedling emergence on all dibber‐drilled plots was lower than that on plots sown with the coulter drill. This result may have been due to seed‐coat damage caused as seeds are plunged into the soil during sowing with the dibber drill.
Transmission of plant viruses by fungi
Authors: ADAMS M. J.
Published: February 2008

The evidence for the mechanisms involved in virus transmission by fungi is reviewed in relation to the non‐persistent and persistent categories usually recognised.

Non‐persistent transmission by Olpidium spp. has been little studied in the last 20 years, but appears to depend on adsorption of virus to the outside of the fungal zoospores. This seems to be under the genetic control of both the virus (via its coat protein) and the vector. Such viruses are not transmitted in the fungal resting spores. The route by which the virus is transferred from the vector to the host may involve uptake into the zoospore but this deserves further study.

Persistent transmission by Olpidium, Polymyxa and Spongospora spp. is less well characterised. Some of the evidence used for its support is inconclusive. The viruses are probably always carried inside zoospores, and they also persist in the fungal resting spores. Transmission depends on the genome of the vector and the virus, but not exclusively on the virus coat protein.
Variation in virulence to dry beans, soybeans and maize among isolates of Rhizoctonia solani from beans
Authors: PHILLIPS A. J. L.
Published: February 2008

The relative susceptibility of dry beans (Phaseolus vulgaris), soybeans and maize to anastomosis group 4 isolates of Rhizoctonia solani was determined in greenhouse experiments. Large variations in virulence were found among 30 field isolates. This variation was not due to differential reductions in isolate virulence during axenic culture. There was considerable variation among isolates from within the same field but variability within isolates was small. Twelve of 30 isolates of R. solani were highly virulent to dry beans and soybeans, while the others were of low virulence. Soybeans were more susceptible than dry beans to both pre‐emergence mortality and hypocotyl disease. No isolates were highly virulent to maize. The importance of using isolates with a high level of virulence for testing soybean cultivars for resistance to Rhizoctonia disease is stressed.
Effects of Caenorhabditis elegans (Nematoda: Rhabditidae) on the spread of the bacterium Pseudomonas tolaasii in mushrooms (Agaricus bisporus)
Authors: GREWAL P. S.
Published: February 2008

The effects of mass‐produced saprobic rhabditid nematodes, Caenorhabditis elegans on the spread of the bacterial blotch pathogen, Pseudomonas tolaasii, were studied in mushroom growth chambers. C. elegans significantly reduced the intensity of blotch on sporophores. Repeated isolations of the bacterial flora from the gut of C. elegans recovered from mushroom sporophores during cropping, revealed the presence of Pseudomonas fluorescens biovar reactans. All the isolates of P. fluorescens biovar reactans isolated from nematodes were antagonists of P. tolaasii.

C. elegans produced much larger populations in monoxenic cultures with P. fluorescens biovar reactans than with P. tolaasii. It is suggested that as C. elegans selects P. fluorescens biovar reactans rather than P. tolaasii as a food substrate it probably spreads the antagonist in the mushroom crop and may contribute to the control of bacterial blotch.
Occurrence of an isolate of maize stripe virus on sorghum in India*
Authors: PETERSCHMITT M. , RATNA A. S. , SACKS W. R. , REDDY D. V. R. , MUGHOGHO L. K.
Published: February 2008

A disease characterised by chlorotic stripes and bands, named sorghum stripe disease (SStD), was observed on sorghum in India with an incidence of less than 0.5% to nearly 10%. The affected plants were dwarfed and had poor or no panicle formation. This disease could be transmitted by the delphacid planthopper Peregrinus maidis to sorghum but not to Brachiaria eruciformis; Cenchrus ciliaris; Chloris barbata; Dichantium annulatum; Dichantium aristatum; Digitaria ciliaris: Dinebra retroflexa; Echinocloa colona; Eleusine coracana; Pennisetum glaucum; Pennisetum violaceum; Setaria pallida Fusca; Triticum aestivum and Zea mays. Sorghum stripe disease was shown to be caused by a tenuivirus serologically related to maize stripe virus (MStV). Virus particles were filamentous, less than 10 nm in width. The purified virus preparation contained only one polypeptide of 34 500 D. Eight species of nucleic acids, four ssRNA of 1.21, 0.87, 0.73, 0.47 ± 106D and four dsRNA of 2.43, 1.69, 1.40, 0.71 ± 106D, were extracted from purified virus preparations. When the four dsRNA were denatured, they migrated along with the four ssRNA species indicating that dsRNA contained duplex RNA of same molecular weight as the four ssRN A. In enzyme‐linked immunosorbent assay and in electro‐blot immunoassay it was evident that MStV‐Sorg was serologically more closely related to the MStV isolates from Florida, Reunion and Venezuela than to a RStV isolate from Japan. The virus was named MStV‐Sorg to distinguish it from MStV which readily infects maize. This is the first report of occurrence of a tenuivirus in the Indian subcontinent.
Detection of coconut cadang‐cadang viroid‐like sequences in oil and coconut palm and other monocotyledons in the south‐west Pacific
Authors: HANOLD D. , RANDLES J. W.
Published: February 2008

Fractionation, electroblotting and molecular hybridisation of nucleic acids extracted from tissue of African oil palm and coconut palm and some other monocotyledonous species, collected in several areas of the south‐west Pacific region, demonstrated the presence of small nucleic acids with nucleotide sequences and secondary structure similar to coconut cadang‐cadang viroid (CCCVd). The oil palms which contained CCCVd‐related molecules showed orange leaf spots resembling those described for oil palm naturally infected with CCCVd in the Philippines, and also characteristic of a condition known as “genetic orange spotting” (GOS). We provide preliminary evidence that GOS is an infectious disorder caused by a viroid. The coconut palms did not show symptoms typical of cadang‐cadang disease, but sometimes were chlorotic, stunted, or had a reduced yield. The possibility that the isolates represent variants of CCCVd is discussed. The data suggest that viroids with nucleotide sequences similar to CCCVd occur widely in palms and other monocotyledons outside the Philippines.
Effect of parental genotypes, cross direction and temperature on the crossability of bread wheat with triticale and on the viability of f1 embryos
Authors: NKONGOLO K. K. C. , ST‐PIERRE C. ‐A. , COMEAU A.
Published: February 2008

The relevant importance of parental crossability genes, cross direction and ambient temperature in bread wheat/triticale hybridisation were evaluated. Crossability genes were found to be useful but not essential. The use of triticale as the female gave significantly fewer embryos, but these embryos were symmetrically shaped and normal. The use of bread wheat as the female gave a seed set generally above 30% and sometimes as high as 86%, but embryo necrosis resulted in rapid death in vivo or non‐regeneration in vitro. By keeping the plants at 14 °C during pollination and in vivo embryo growth, necrosis was partly eliminated, so that in one case the rate of plant production in crossing bread wheat/triticale became about as good as for the triticale/bread wheat cross direction. Crossing at 14°C could be useful when a bread wheat cytoplasm is desired by the breeder.
Peroxidase from cultured carrot cells: affinity purification and characteristics
Authors: ANANTHANARAYANAN T. V. , SWAMY R. DORE
Published: February 2008

Peroxidase, from cultured carrot cells, has been isolated and purified over Concanavalin‐A‐Sepharose by lectin affinity chromatography. The enzyme protein registers a gradual enhancement in activity concomitant with the growth of callus. Extracellular (ECP) & intracellular (ICP) peroxidases have been demonstrated in suspension cultures of carrot.
Canopy development of a determinate and an indeterminate cultivar of Vicia faba L. under contrasting plant distributions and densities
Authors: STÜTZEL H. , AUFHAMMER W.
Published: February 2008

Field experiments were conducted in 1987 and 1988 to quantify differences in canopy formation between an indeterminate and a determinate genotype of Vicia faba L., grown at two plant densities and three spatial distributions. The number of stems per unit area produced by determinate plants was related to the growth rate before flowering. Leaf production per stem per unit of thermal time was similar in both plant types, but twice as many leaves per stem were produced by the indeterminate cultivar. The indeterminate cultivar produced fewer and smaller leaves in the warmer and drier weather of 1988 than in 1987. The determinate genotype produced similar sizes and numbers of leaves in both years, but fewer tillers developed in 1988 than in 1987. Accordingly, leaf mass per unit ground area was greater in 1987 than in 1988 in both genotypes. Except during early flowering, relationships between leaf mass and leaf area were constant, with higher specific leaf areas in the determinate than the indeterminate genotype. Shoot dry matter partitioning into leaves was identical in both years for indeterminate plants, but differed in determinate ones.

It is concluded that canopy development is regulated through individual leaf weight and leaf number per stem in non‐tillering indeterminate, and by stem numbers per unit area in tillering determinate plants.
Temperature and daylength control of flower initiation in winter oilseed rape (Brassica napus L.)
Authors: TOMMEY ANDREW M. , EVANS ERIC J.
Published: February 2008

The influence of low temperature and daylength on pre‐floral growth and flower initiation in winter oilseed rape cv. Mikado was examined under controlled environment conditions at the University of Newcastle upon Tyne during 1985 and 1986.

The vernalisation requirement of Mikado was most effectively fulfilled by temperatures of 6 °C and 9 °C. Plants maintained at both higher and lower temperatures had an extended pre‐floral growth phase. The transition from vegetative to reproductive growth in plants maintained at 12 °C was delayed by slow accumulation of the cold requirement, whereas flower initiation appeared to be delayed by limited leaf production, dry matter accumulation and/or assimilate availability in plants grown at 3 °C. The mechanism of floral induction remained unresolved but it was clear that flower initiation was not controlled by low temperature per se. Short days partially substituted for the cold requirement at 12 °C but photoperiodic induction of flower initiation was less important than the influence of low temperature.
The control of postharvest decay in table grapes using acetaldehyde vapours
Authors: AVISSAR ILANA , PESIS EDNA
Published: February 2008

Grapes (Vitis vinifera L. cv. ‘Sultanina’) harvested at the end of the 1985–1988 seasons, received postharvest application of acetaldehyde (AA) vapours for 24–40 h. Treatment with AA vapour at 20 °C or 0 °C reduced significantly the decay caused by several fungi: Botrytis cinerea, Rhizopus stolonifer, Aspergillus niger and Alternaria alternata. In grapes treated with 0.5% AA for 24 h, no R. stolonifer was found after 8 days of storage at 20 °C. Treatment with 0.25% AA vapour for 40 h of grapes cv. ‘Perlette’ inoculated with R. stolonifer reduced the decay by 89%.
The short‐term effects on wild goose behaviour of chlorpyrifos application to permanent pasture
Authors: CLEMENTS R.O. , MURRAY P. J. , TYAS C. J.
Published: February 2008

Chlorpyrifos (Spannit 48% e.c.; PBI) was applied at the recommended rate of 0.72 kg a.i./ha to two pastures on which either Brent Geese (Branta bernicla) or Canada Geese (Branta canadensis) were grazing. Observations of the number of geese and their behaviour were made on two or three occasions before spraying and four or five occasions after. Observations enabled an activity index and a count of pecks/minute to be calculated. No changes in the numbers or behaviour of the geese that could be attributed to chlorpyrifos application were found. Thorough searches were made for cadavers of the experimental fields, their environs and the roosts the day after other observations were made. Only one cadaver was found which had died as a result of swallowing angling equipment. Samples for chlorpyrifos residue analysis in the herbage and goose faeces showed no chlorpyrifos to be present prior to spraying the fields and that the chemical was present after spraying in both the herbage and faeces but fell to negligible levels within a few days. At least in the short‐term, chlorpyrifos application to pasture appeared to have no perceptible or statistically significant effect on goose behaviour or well‐being.
The effects of three film‐forming polymers, with and without a polyamine biosynthesis inhibitor, on powdery mildew infection of barley seedlings
Authors: WALTERS D. R.
Published: February 2008

Powdery mildew infection of barley seedlings was significantly reduced using either pre‐inoculation or post‐inoculation sprays of the film‐forming polymers Nu‐Film P, Emerald or Vapor Gard. The greatest reduction in mildew infection was obtained with a pre‐inoculation spray of the polymer Vapor Gard. Although the addition of 1 mmα‐difluoromethylornithine (DFMO) to a 2% solution of Emerald or Vapor Gard resulted in better control of powdery mildew infection than that obtained using the polymer or DFMO alone, the reductions in infection were not significant. Reduction in mildew infection was greatest when the Vapor Gard + DFMO mixture was applied 1 day prior to inoculation with the fungus. Although substantial reduction in mildew infection was achieved using as little as 0.1 mm DFMO with 2% Vapor Gard, or reducing the polymer concentration to 1% in combination with 1 mm DFMO, best control was achieved using 2% Vapor Gard plus 1 mm DFMO.
The effect of stem nematode on establishment and early yields of white clover
Authors: COOK R. , EVANS D. R. , WILLIAMS T. A. , MIZEN K. A.
Published: February 2008

The effects of stem nematode (Ditylenchus dipsaci) infestation on the establishment of white clover sown in mixed swards with perennial ryegrass, were investigated in two field trials. Clover cultivars known to have different degrees of resistance were sown on land in which stem nematode was controlled either by aldicarb (Experiment 1) or crop rotation (Experiment 2). The establishment of white clover was greatly improved and subsequent clover yields were inversely related to stem nematode infestation. At the first harvest after sowing, clover yields were 3.6 and 3.3 times greater from aldicarb and rotation treatment plots than from check plots; over the first nine months, total clover yields were increased by 3.5 and 8.9 times by aldicarb and rotation treatments. In both trials, plots of resistant cultivars had less stem nematode infestation and yielded better than the very susceptible cultivar, S184. Stem nematode infestations eventually developed on all plots, after the establishment phase.

This is the first report showing that resistant cultivars improve establishment of clover in mixed swards on stem nematode infested soils. In both experiments, plots became dominated by clover and even cv. S184 eventually produced good clover swards.

Aldicarb and rotation treatments also controlled clover cyst and root lesion nematodes, and numbers of these were inversely related to first harvest yields. Other soil borne pests and diseases, although not prominent, have not been ruled out as possible confounding factors. There was no correlation between grass yield and aldicarb treatment.
The agronomic performance of anther culture derived plants of barley produced via pollen embryogenesis
Authors: POWELL W. , THOMAS W. T. B. , THOMPSON D. M.
Published: February 2008

Anther culture was used to generate microspore‐derived doubled haploid (DH) plants from four spring barley crosses. The culture medium used contained maltose as the sole carbohydrate source and the mode of plantlet regeneration was mainly via pollen embryogenesis. Both haploid and spontaneously doubled regenerants were produced and the doubled haploids were compared to recom‐binant inbred lines generated by several rounds of selfing (single seed descent). Parental, DH and single seed descent (SSD) lines were grown in randomised, replicated field trials and the samples were scored for a range of agronomic traits. The mean performance and phenotypic distribution of the DH and SSD samples were similar and there was little evidence to support the conclusion that anther culture derived lines exhibit a reduction in vigour. Where significant differences were detected between groups these were mainly confined to crosses which were segregating for the denso dwarfing gene. The differential transmission of particular regions of the barley genome may therefore influence and confound the expression of agronomic traits in DH populations. This is the first report of the agronomic performance of anther culture lines produced via pollen embryogenesis and the results are discussed in relation to the exploitation of anther culture technology in barley breeding.
Effect of high temperature treatment on disinfestation and quality characteristics of sorghum
Authors: MORE HARI G. , STENNING BRIAN C. , MAGAN NARESH
Published: February 2008

Sorghum grain (two varieties) was modified to different water contents (12% to 16% wet weight basis) and heated to 60°C, 70°C and 80°C for periods of 4, 8 and 12 min. Germination, seedling vigour, seedling dry matter, free fatty acid (FFA) content, fungal contamination and infestation with the insect pest Rhyzopertha dominica (F.) were all markedly affected by heat treatment. The effectiveness of the heat treatment was also influenced by the size of the sample used. Heat treatment at 60°C and 70°C resulted in germination being unaffected or stimulated while at 80°C and the higher water contents significantly reduced, when compared to untreated controls. The dry matter of seedlings, and seedling vigour was positively correlated with germination and heat treatment. Heat treatment had no effect on FFA. All stages of the insect pest, R. dominica, were destroyed at 70°C and an 8 min exposure time. However, the water content of the sorghum was critical in determining the efficacy against this pest. The percentage fungal contamination of grain was reduced from 90% to about 25% by heat treatment. However, some grain fungi, particularly Eurotium spp., Aspergillus niger and Penicillium spp. could still be isolated from sorghum grain treated at 80°C for up to 12 minutes.
Bendiocarb and diflubenzuron as substitute insecticides for endosulfan in commercial mushroom growing
Authors: GEELS F. P. , RUTJENS A. J.
Published: February 2008

Diflubenzuron and bendiocarb treatments of compost and casing soil at a rate of 1 g a.i./m2 each, resulted in comparable or even improved compost and casing soil colonisation over endosulfan treatments (at a rate of 1.5 g a.i./m2). Alternating diflubenzuron/bendiocarb treatments were preferable to the reverse treatments, which tended to diminish total yield of mushrooms significantly by 1.4–3.9 kg/m2. This effect was due to the casing soil treatment with diflubenzuron and not due to the compost treatment with bendiocarb after spawning. The effectiveness of these substitutes for endosulfan was tested on five commercial mushroom farms, where a similar or improved control of Megaselia halterata (Diptera: Phoridae) was obtained over control (endosulfan) treatments. If present, Lycoriella auripila (Diptera: Lycoriidae) was very effectively controlled by the substitute insecticides compared with endosulfan. Relatively high numbers of M. halterata were occasionally observed in endosulfan‐treated houses, indicating that a certain level of resistance towards this insecticide may already have developed. This assessment of tolerance in M. halterata emphasised the need for substitute insecticides with different modes of action, in addition to environmental reasons. The chemicals should be alternately applied within individual crops to avoid resistance development.
Detection of Pythium violae and Pythium sulcatum in carrots with cavity spot using competition ELISA
Authors: LYONS N. F. , WHITE J. G.
Published: February 2008

Conventional methods indicated that Pythium violae was most commonly isolated from carrot cavity spot samples from 14 UK sites. For one site the most frequently isolated species was Pythium sulcatum. Results of similar isolation work were compared with the assay of cavity spot lesions using polyclonal antibodies, raised to P. violae or P. sulcatum, in competition ELISA. Where lesions were artificially induced the test confirmed which pathogen was causal. With cavities developed on the field‐grown carrots P. violae again predominated and the ELISA confirmed this. In one sample P. sulcatum was also isolated from a small number of lesions and was not detected in ELISA. The competition ELISA did not indicate presence of either Pythium in a range of non‐cavity spot lesions from which attempts at isolation were negative.
Serological relationships and purification of bud necrosis virus, a tospovirus occurring in peanut (Arachis hypogaea L.) in India*
Authors: REDDY D. V. R. , RATNA A. S. , SUDARSHANA M. R. , POUL F. , KUMAR I. KIRAN.
Published: February 2008

A procedure for the purification of a tospovirus which causes bud necrosis disease (BND) of peanut in India is described. The virus contained three polypeptides of 78 kDa, 54 kDa and 31 kDa. In two ELISA procedures the virus failed to react with antisera to tomato spotted wilt virus (TSWV) obtained from different sources and with an antiserum to impatiens necrotic spot virus (INSV). Additionally, in reciprocal tests TSWV and INSV antigens failed to react with antiserum to the virus infecting peanut in India.

In electro‐blot immunoassay 54 kDa and 31 kDa polypeptides of the virus reacted with the homologous antiserum. None of the heterologous antisera reacted with any of the three viral polypeptides. On the basis of serological differences the virus that causes BND in India is distinct and therefore has been named bud necrosis virus (BNV). This serotype appears to be restricted to Asia.
Morphological variability of potato cyst nematodes (Globodera spp.) in the Canary Islands
Authors: GONZALEZ J. A. , PHILLIPS M. S. , HACKETT C. A.
Published: February 2008

Thirty populations of potato cyst nematode (Globodera spp.) from the Island of Tenerife and two populations from the UK were assessed for several morphometric and non‐morphometric characters thought to discriminate between the species G. rostochiensis and G. pallida. Also 200 cysts from each population were analysed by isoelectric focusing of soluble proteins. Correlation analysis, analysis of variance and principal component analysis were used to investigate relationships between the morphometric characters, how the relationships varied between species and between populations, and which characters were most useful for discriminating between species.

The two species differed significantly for each of the four morphometric characters: stylet length, fenestra length, anus‐fenestra distance and the number of ridges. The stylet length and fenestra length also showed differences between populations of G. rostochiensis while stylet length and number of ridges showed differences between populations of C. pallida. In general, populations of G. pallida showed greater variation than populations of C. rostochiensis.

Principal component analysis of the population means indicated that over 73% of the variation in the characters could be explained by the contrast of stylet and fenestra lengths against the anus‐fenestra distance and number of ridges. A plot of the first two principal components separated the two species. Stepwise discriminant analysis provided a linear combination of these four variables which discriminated between the species. Stylet length was found to be the most useful characteristic for distinguishing the species whilst anus‐fenestra distance was the least useful.
The growth of Bibio johannis (L.) and Dilophus febrilis (L.) (Diptera: Bibionidae) larvae in the field
Authors: BLACKSHAW R. P. , D'ARCY‐BURT S.
Published: February 2008

Bibionid larvae were extracted from soil samples collected from June 1985 to March 1987. Each larva was identified, weighed and measured for maximum head capsule width. Both Bibio johannis and Dilophus febrilis have six larval instars. Bibio johannis grew slowly in late summer and early autumn but rapidly from October to January. Early and late instar larvae of D. febrilis occurred simultaneously and it was concluded that this species was not bivoltine but may exist as two separate cohorts with distinct flight periods.
Genetical variation for resistance to Alternaria solani in an advanced population of potatoes
Authors: BRANDOLINI A.
Published: February 2008

Eighteen clones, selected over three seasons for resistance to Afternaria solani, were evaluated in San Ramon, Peru (warm tropics), to determine their general combining ability for resistance to the diseases, earliness and yield per plant, using a North Carolina design II. Six susceptible and six resistant varieties were included as controls. Narrow sense heritability (h2) and genetic components of the variance were estimated, both for the North Carolina design II population, and for the advanced clones and resistant controls.

Outstanding parents for the transmission of resistance were the clones C85.003, C85.008, C85.009, C85.051 and C85.144. Narrow sense heritability in the North Carolina design II population was 0.44, while in the population of the advanced clones and resistant controls h2 was 0.31. The increased levels of resistance found and the rapid reduction, after selection, of the heritability values from about 0.7–0.8 in the starting population of the CIP breeding programme (Mendoza, Martin & Brandolini, 1987a), linked to a decrease in the additive variation, suggest a good breeding efficiency. The introduction of new resistant genotypes and the use of recurrent selection with progeny testing might further enhance the high levels of resistance to A. solani in this population.
Chemical control of Western Flower Thrips (Frankliniella occidentalis Pergande)
Authors: HELYER NEIL L. , BROBYN PATRICIA J.
Published: February 2008

Fifty‐one pesticides currently registered for use in the UK were tested in the laboratory against Western Flower Thrips (Frankliniella occidentalis) maintained on chrysanthemum leaf discs. In an initial screening trial of the pesticides against larval thrips, 14 caused more than 75% mortality three days after exposure. These were tested further against adults and pupae and retested against larvae. A series of glasshouse trials were conducted using the most efficacious pesticides evaluated earlier. Granular and systemic compounds were included in the glasshouse trials since these could not be evaluated satisfactorily in the laboratory. Malathion proved to be the most potent chemical currently registered for control of thrips on a wide range of horticultural crops.
Studies on the feeding of Sitona lineatus L. (Coleoptera: Curculionidae) on white clover (Trifolium repens L.) seedlings
Authors: MURRAY P. J. , CLEMENTS R. O.
Published: February 2008

Measurements of feeding damage by sitona weevil (Sitona lineatus L.) adults on differing numbers of seedlings of white clover (Trifolium repens L.) at the first and fourth trifoliate leaf stage were made in the glasshouse at 20°C. S. lineatus consumed more of the trifoliate component of the seedling. Sitona adults caused significant yield reduction at all levels of plant population. Total clover consumption increased with increasing size of sitona population, but consumption per adult weevil was reduced.
Purification and properties of closterovirus‐like particles associated with a whitefly‐transmitted disease of sweet potato
Authors: COHEN J. , FRANCK A. , VETTEN H. J. , LESEMANN D. E. , LOEBENSTEIN G.
Published: February 2008

A virus causing sunken veins on ‘Georgia Jet’ sweet potato, and yellow brittle leaves and stunting on Ipomoea setosa, was purified and a specific antiserum was prepared. Flexuous particles with a normal length of 850 nm and a diameter of 12 nm with an open helical structure typical of closteroviruses were observed. The virus particle protein has an apparent mol. wt of c. 34 kD. Double‐stranded RNA isolated from SPSVV‐infected I. setosa and subjected to electrophoresis in agarose consisted of one major band with an estimated Mr of 10.5 kbp and two minor bands with Mr of 9.0 and 5.0 kbp. Fibril‐containing vesicles in phloem cells were observed in ultrathin sections of infected leaf tissues. The virus was transmitted by the whitefly Bemisia tabaci in a semi‐persistent manner and by grafting, but not mechanically. The virus could be transmitted to various Ipomoea species, to Nicotiana clevelandii, N. benthamiana and Amaranthus palmeri. The virus did not react with an antiserum to lettuce infectious yellows virus. Based on particle morphology, serology and symptom expression, the virus appears unique and different from all other reported whitefly‐transmitted closteroviruses. We propose it be named “sweet potato sunken vein virus” (SPSVV).
Evaluation of biological indexing and dsRNA analysis in grapevine virus elimination
Authors: HABILI N. , KRAKE L. R. , BARLASS M. , REZAIAN M. A.
Published: February 2008

Fragmented shoot apex culture (FSAC) was used to eliminate some diseases caused by viruses and virus‐like agents from 24 varieties of imported grapevines. Each cultivar was examined by biological indexing before and after FSAC. Graft indexing revealed that leaf roll, stem pitting and yellow speckle diseases were common before FSAC. A correlation was observed between the incidence of leafroll disease and the presence of specific dsRNA species which were removed after FSAC. One of these species, an RNA of about one kilobase pair was associated with low yielding Sultana clones. Both biological indexing and dsRNA assay indicated no recurrence of the leafroll disease in material regenerated by FSAC even after 10 years in the field. It is concluded that dsRNA assay may be used as a faster and less expensive method than biological indexing in assessing the success of leafroll elimination by FSAC. The test also provides some information on the genome size of the viruses associated with leafroll disease. Graft indexing indicated that yellow speckle disease was resistant to elimination by FSAC, while stem pitting was removed from some of the vines and the grapevine fleck disease was eliminated from most sources.