bluuebunny/crossref_metadata_2025 huggingface dataset:
Resistance to raspberry cane midge (Resseliella theobaldi) and its association with wound periderm in Rubus crataegifolius and its red raspberry derivatives
Authors: McNICOL R. J. , WILLIAMSON B. , JENNINGS D. L. , WOODFORD J. A. T.
Published: February 2008

Rubus parviflorus, R. odoratus and F2 plants from the cross R. crataegifolius x R. idaeus were resistant to the raspberry cane midge (Resseliella theobaldi) when exposed to the pest in an insectary or in the field.

Histological studies of R. crataegifolius and one of its hybrids with R. idaeus showed that resistance was associated with a wound periderm of suberised and lignified cells. These cells were formed from the primary cortex and phelloid cells of the polyderm as a rapid response to the occurrence of natural splits and wounds which are the oviposition sites of R. theobaldi. In the hybrid, new tissues from this wound periderm prevented the peeling of the mature primary cortex, thereby precluding serious midge attack, and resulted in a reticulate appearance on the cane surface, a distinctive cane feature useful for identifying resistant segregates.
Callus growth and the effect of wound dressings
Authors: MERCER P. C.
Published: February 2008

Growth of callus tissue on tree wounds tended to be greater if wounds were flush, large and treated with a wound dressing, particularly one containing thiophanate methyl, if the trees were young and vigorous or had had an application of fertiliser. Growth of callus also varied with species, but in beech, at least, did not appear to be affected by season of wounding.
Host range and virulence of five baculoviruses from lepidopterous hosts
Authors: ALLAWAY GRAHAM P. , PAYNE CHRISTOPHER C.
Published: February 2008

The host range and virulence of five insect baculoviruses (two multiply‐enveloped nuclear polyhedrosis viruses (MNPVs) from Agrotis segetum and Mamestra brassicae; one singly‐enveloped NPV from Plusia gamma and two granulosis viruses (GVs) from A. segetum and Pieris brassicae) were studied for seven lepidopterous pests of temperate agriculture (A. segetum, Agrotis exclamationis, Lacanobia oleracea, M. brassicae, Noctua pronuba, P. gamma and Pieris rapae). None of the viruses killed all species but M. brassicae MNPV failed to infect only P. rapae. The other viruses were restricted to the homologous host, or members of its genus or subfamily. In all examples except A. segetum GV, the median lethal dose for the most susceptible host, was less than 22 virus inclusion bodies and median lethal times for all infections ranged from 5·5 to 16·6 days. The low susceptibility of A. segetum and other noctuids to GV infections is discussed in relation to the structure of inclusion bodies and the nature of the infectious unit in baculoviruses.
Assessment of the frost sensitivity of Trifolium species by chlorophyll fluorescence analysis
Authors: BARNES J.D. , WILSON J.M.
Published: February 2008

The potential of the chlorophyll fluorescence technique in screening for frost sensitivity in a range of Trifolium species from different geographical origins was assessed by measuring the decrease in variable chlorophyll fluorescence (Fvar) of leaves after freezing at ‐ 5°C for 60 min. The method was rapid and the results obtained agreed well with a visual assessment of freezing injury carried out after leaves were returned to optimal growth conditions for 72 h. Trifolium alexandrinum (Berseem clover) cv. Tabor originating from Israel was shown to be the most frost sensitive species studied and Trifolium subterraneum (subterranean clover) cv. Mt. Barker, from temperate regions of Australia, the most frost resistant. On extended periods of freezing, frost damage increased and this was associated with a further reduction in variable chlorophyll fluorescence and in quenching capacity of the thylakoid membranes. These results thus indicate that substantial thylakoid membrane dysfunction is induced at freezing temperatures. Furthermore, it was found that frost hardening of the frost sensitive species T. alexandrinum for 21 days at 5°C reduced the extent of damage sustained by the thylakoid membranes as shown by higher fluorescence quenching capacity, smaller reduction in variable fluorescence (Fvar) and higher initial fluorescence (Fo) when leaves of hardened plants were frozen at ‐5°C and ‐7°C.
Nitrogen fertilisation and light effects on growth and photosynthesis of lodgepole pine seedlings
Authors: EKWEBELAM S.A. , REID C.P.P.
Published: February 2008

Seedlings of Pinus contorta were grown for 16 wk without ectomycorrhizas in the greenhouse at three levels of irradiance (100, 210 and 470 μEm‐2s‐1) and three levels of ammonium nitrate (3, 62 and 248 mg litre‐1 of N). Measurements at 5, 10 and 16 wk of age indicated that plants receiving the highest levels of irradiance and nitrogen had significantly larger biomass, a higher total foliar N and P content and net photosynthesis per unit leaf area than those at lower levels of each factor. Although the root/shoot ratio also increased from low to high irradiance at each harvest, nitrogen application resulted in an increased ratio from 3 to 62 mg litre‐1 N, but decreased ratio at 248 mg litre‐1 N.
Phenolic acids associated with the resistance of lettuce cultivars to the lettuce root aphid
Authors: COLE ROSEMARY A.
Published: February 2008

Phenolic acids, particularly caffeoylquinic acids, in lettuce root extracts were analysed by high pressure liquid chromatography (hplc), gas liquid chromatography (glc) and ultra‐violet (uv) absorbance to seek a relationship with the resistance of certain lettuce cultivars to lettuce root aphid, Pemphigus bursarius. Although consistent results were obtained by each method, glc estimates of isochlorogenic acid tended to be low and uv estimates high. Hplc results were intermediate and since it was the easiest technique to perform routinely it was preferred.

Isochlorogenic acid was the only caffeoylquinic acid detected in quantity and there were greater concentrations in resistant than in susceptible cultivars. Phenylalanine‐ammonia lyase (PAL), the first enzyme in the phenyl propanoid pathway, is more active in resistant cultivars. Although these cultivars also had a greater tendency to browning when damaged, it was not due to greater polyphenol oxidase activity but probably to the presence of more isochlorogenic acid substrate.

The results were consistent with an association between isochlorogenic acid concentration, PAL activity and resistance to P. bursarius.
Variation in seedling susceptibility to Bremia lactucae (lettuce downy mildew) in the absence of effective major resistance genes
Authors: NORWOOD JUDITH M. , CRUTE I. R. , PHELPS KATHLEEN
Published: February 2008

In the absence of effective major genes the importance of interactions between cultivar genotype, isolate genotype and environment was investigated in experiments using seedlings of eight lettuce cultivars inoculated with three isolates of Bremia lactucae and grown under a number of different environmental conditions. The outcome of the cultivar‐isolate association was measured using four criteria and the data were examined by analysis of variance and correlation. The relative susceptibility of cultivars was generally independent of environment and there was no evidence that isolates were adapted to particular cultivars. Although significant cultivar X isolate interactions were found in individual experiments they were not consistent between experiments, even where these were conducted under apparently identical conditions. Variation resulted from either cultivar X environment or isolate X environment interaction with the environment always the dominant variable.
The relationship between populations of stem‐boring Dipterous larvae in leys and damage to subsequent winter wheat crops
Authors: FRENCH N. , NICHOLS D. B. R.
Published: February 2008

During September of each year from 1978‐82, dipterous stem‐boring larval populations were assessed in 28–35 grass fields in northern England before they were ploughed and sown with winter wheat. Larvae were mainly Oscinella spp. and their populations ranged from <60–3100/m2 (mean 300/m2). Subsequent damage to winter wheat assessed during December of each year from 1978‐81 was positively related to the larval population in the grass. Regressions of plant damage on larval numbers indicated that 500, 1000 and 2000 larvae/m2 resulted in respectively 10, 19 and 36% damaged wheat plants. Mean populations were greatest (558/m2) in 2‐yr‐old leys containing Lolium multijlorum. Three‐yr‐old leys had a mean of 319/m2 and leys of 4 yr and older had 168 larvae/m2.

Soil type and management of leys had little consistent effect on larval populations. Populations tended, however, to be larger on silty or silty‐clay loams than sandy loams and where leys were grazed in late summer after earlier silage cuts compared with those continuously grazed.
Seasonal occurrence of the potato gangrene pathogen, Phoma exigua var. foveata, in the open air
Authors: CARNEGIE S. F.
Published: February 2008

Using a Casella High Volume Bacterial Sampler air samples were collected down wind of potato fields in central Scotland when it was raining and when it was dry between December 1978 and October 1982. Airborne propagules of Phoma exigua var. foveata were recovered from the open air during rainfall in most months of the year but the frequency of recovery was greatest in September, October and November. The numbers of colonies of P. exigua var. foveata detected during rainfall were much greater in September and October than during the rest of the year. Low numbers of colonies of P. exigua var. foveata were recovered in the absence of rainfall and their occurrence appeared to be associated with strong winds and dry soil conditions. These latter airborne propagules were detected during all the months except November to February when few samples were made. Sampling simultaneously up wind and down wind of potato fields in September and October demonstrated that the potato crop was the main source of airborne propagules caught down wind but small numbers of P. exigua var. foveata were recovered up wind in four out of the seven experiments.
Studies on the occurrence of tomato bushy stunt virus in English rivers
Authors: TOMLINSON J. A. , FAITHFULL ELIZABETH M.
Published: February 2008

Tomato bushy stunt virus (TBSV) of unknown source was isolated from water of the River Thames, near Oxford. The isolate designated TBSV‐T was mechanically transmissible to several tomato (Lycopersicon esculentum) cvs and to other species including Petunia hybrida, pepper (Capsicum annuum). eggplant (Solanum melongena), Nicotiana clevelandii, Chenopodium amaranticolor and C. quinoa in which it caused systemic symptoms. It caused no infection of globe artichoke (Cynara scolymus) or Pelargonium domesticum.

The virus was not adsorbed to soil and could be isolated from leachate of soil in which systemically‐infected tomato or C. quinoa plants were grown. Tomato plants became infected when grown in soil watered with virus suspensions.

TBSV‐T was infective after 10 min at 80°C but not at 90°C and when diluted to 10‐5 but not to 10‐6. Purified virus preparations contained C. 30 nm isometric particles. In gel‐diffusion serological tests, TBSV‐T reacted with homologous anti‐serum and with antiserum to petunia asteroid mosaic virus but not to pelargonium leaf curl virus.

Seed‐borne infection (50–65%) of TBSV was demonstrated in plants grown from seed of symptomlessly‐infected tomato fruit. TBSV was isolated from symptomlessly‐infected tomato fruit imported from Morocco during October‐April 1981. One of the isolates (TBSV‐M) was indistinguishable from TBSV‐T in host range, symptomatology and serological reactions. TBSV was also found in tomato plants growing extraneously in primary settlement beds at sewage works; such plants having been derived from undigested seeds in sewage. Because of its ‘alimentary‐resistance’ in man, it is possible that one ecological route whereby TBSV enters rivers is by man's consumption of TBSV‐infected tomatoes and eventual sewage dispersal into rivers.
Serological relatedness of strains of maize dwarf mosaic and sugarcane mosaic viruses as determined by microprecipitin and enzyme‐linked immunosorbent assays
Authors: JARJEES M. M. , UYEMOTO J. K.
Published: February 2008

Antisera to maize dwarf mosaic virus strain A, B, and Kansas 1 (MDMV‐A, ‐B, ‐KS1) and sugarcane mosaic virus strains A, B, D, and H (SCMV‐A, ‐B, ‐D, ‐H) were prepared and their reactions with these and other SCMV strains (SCMV‐I, ‐J, ‐M) compared by microprecipitin tests and enzyme‐linked immunosorbent assay (ELISA). In microprecipitin tests, antibody titres in heterologous tests were unchanged or up to five two‐fold dilution steps lower than those in corresponding homologous reactions. Microprecipitin tests and ELISA distinguished the same four serogroups among the 10 viruses tested. Strains MDMV‐A and SCMV‐J comprised one serogroup; MDMV‐KS1, a second; MDMV‐B and SCMV‐A, ‐B and ‐D, a third; and SCMV‐H, ‐I and ‐M, a fourth.
The relationship between neutral lipid reserves and infectivity for hatched and dormant juveniles of Globodera spp.
Authors: STOREY R. M. J.
Published: February 2008

A quantitative histochemical technique based on scanning microdensitometry has been used to investigate neutral lipid utilisation by hatched and dormant juveniles of Globodera rostochiensis and Globodera pallida.

During storage in water at 20°C, hatched juveniles of the two species showed no statistical difference in their rate of lipid utilisation. A semi‐logarithmic curve fitted to the pooled data suggests that 50% relative utilisation occurred after 36 ± 4 days of storage. Measurement of the neutral lipid reserves for unhatched juveniles of G. pallida dormant in field soils in Northern England for a maximum of 14 yr showed a reduced rate of metabolism with a 50% loss of neutral lipid reserves after 7·5 ± 1·1 yr.

The use of neutral lipid reserves by the hatched, starved juveniles was correlated with their survival and with a loss of both locomotor activity and an ability to infect tomato seedlings. Furthermore, results suggest that a loss of mobility by juveniles from field populations of G. pallida immediately after hatching was more closely related to their neutral lipid reserves than the duration of their dormancy. Infection of plants was also reduced for one population. This suggests that measurement of the neutral lipid reserves of a population may be of value for modifying the economic threshold to take account of changes in infectivity during prolonged rotations.
Effect of time of staking on the development of anthracnose disease and yield of water yam (Dioscorea alata)
Authors: NWANKITI A. O.
Published: February 2008

Unstaked and late staked yam vines were much more affected with anthracnose disease than those staked during the first 63 days of growth in a susceptible cultivar but not in a resistant one. However, yields of both cultivars were much less on unstaked or late staked yams, probably because unstaked vines suffered from leaf shading and high soil temperatures.
Influence of Vitis source on in vitro shoot apex culture
Authors: FANIZZA G. , TANZARELLA O. A. , CARROZZO G. , GRECO B.
Published: February 2008

In vitro tip culture of grapevine was successful when the tips were removed from glasshouse or shadehouse plants but most of those removed from field grown plants and treated in a similar manner died within 2 days.
Properties of broad bean yellow band virus, a possible new tobravirus
Authors: RUSSO M. , GALLITELLI D. , VOVLAS C. , SAVINO V.
Published: February 2008

A virus was transmitted from broad bean plants in Apulia (Southern Italy) with leaves showing yellow rings, line patterns or yellow vein banding and malformations and necrosis of pods. Symptoms in some, but not all, test plants were similar to those induced by tobraviruses. Purified virus preparations contained two classes of rod‐shaped particles containing c. 5% nucleic acid with sedimentation coefficients of 186S and 276S. After centrifugation to equilibrium in CsCl gradients, two components were resolved, with buoyant densities of 1·298 and 1·316 g/cm3. Unfractionated virus preparations contained two species of single‐stranded RNA with mol. wts of c. 1·06 × 106 and 2·48 × 106 and one species of coat protein with mol. wt of c. 21 300. The modal lengths of the two classes of particles, both in plant sap and in purified preparations, were 77 nm (S particles) and 202 nm (L particles). L particles accumulated in infected cells in paracrystalline aggregates, whereas S particles were randomly distributed in the cytoplasm of cells. The virus was serologically unrelated to two isolates of tobacco rattle virus and two isolates of pea early‐browning virus. The virus, named broad bean yellow band, is considered a distinct tobravirus.
Anther culture in Brussels sprouts (Brassica oleracea var. gemmifera)
Authors: OCKENDON D. J.
Published: February 2008

In Brussels sprouts, yields of up to 357 embryos per 100 anthers cultured were obtained using a thermal shock treatment of 16 h at 35°C at the start of the culture period. Treatments of 48 h at 35°C and 14 days at 30°C gave no embryos. The F1 hybrid cv. Gower consistently gave higher embryo yields than the F1 hybrid cv. Nym, the differences being 3 to 10‐fold. Differences in embryo yield of 3‐fold or less were usually not statistically significant because of great variation within a treatment. This variation was less with donor plants raised in a growth room than with those raised in a glasshouse, where temperature and light intensity could not be so accurately controlled.

From 842 embryos cultured, 270 plants were regenerated, mostly via hypocotyl explants, which developed from the anther‐derived embryos. Most of the regenerants were haploid or diploid, with a few of higher ploidy.
The effects of grading and ‘priming’ seeds of crisp lettuce cv. Saladin, on germination at high temperature, seed ‘vigour’ and crop uniformity
Authors: WURR D. C. E. , FELLOWS JANE R.
Published: February 2008

Three seedlots of crisp lettuce cv. Saladin were ‘primed’ in 1% tri‐potassium orthophosphate (K3PO4) or in water for 6 to 12 h and then dried at room temperature. Two of the seedlots were separated into fractions of different mean weight before ‘priming’. The effects of ‘priming’ and grading on crop uniformity, germination at 35°C and root length in a slant test were evaluated.

In general, ‘priming’ increased root length in a slant test but there were no consistent beneficial effects of ‘priming’ on seedling size, head weight or uniformity of head weight. Larger seed produced longer roots in a slant test than small seed and gave larger seedlings but seed size had no effect on head weight or cv. of head weight. ‘Priming’ had no effect on germination at 20°C but significantly increased germination at 35°C. ‘Priming’ in K3PO4 was more effective than in water. It is suggested that the response of seeds to ‘priming’ varies with seedlot and individual seed weight.
Detection of aphid remains in predatory insects and spiders by ELISA
Authors: CROOK NORMAN E. , SUNDERLAND KEITH D.
Published: February 2008

An ELISA was developed which would detect and quantify ingested aphids in predators found in and around cereal crops. The detection limit of the assay was less than one hundredth of an homogenised adult aphid. Tests with 13 species of aphid showed that those which had been used as the principal immunogens reacted most strongly in the assay. Nearly a hundred species of invertebrates, both predators and alternative prey, have been tested in the assay and no evidence of significant cross‐reaction was found with any of these species or with a number of samples of plant material on which aphids may be found. Aphid material could still be detected in predators which had been stored for up to 7 days in 4% formalin or 70% ethanol.
Effect of maize stunting mollicutes on survival and fecundity of Dalbulus leafhopper vectors
Authors: MADDEN L. V. , NAULT L. R. , HEADY S. E. , STYER W. E.
Published: February 2008

The effect of corn stunt spiroplasma (CSS) on survival and fecundity of three Dalbulus leafhopper species was determined. CSS significantly reduced the survival, as measured by the time to 50% (t50) and 25% (t25) survival, and by the scale parameter (b) of the Weibull model, for D. elimatus and D. gelbus. Fecundity of these two species, as measured by the net and gross reproductive rates, was also reduced by CSS. CSS did not significantly affect the corn leafhopper, D. maidis. In a separate experiment, maize bushy stunt mycoplasma (MBSM) reduced the survival and fecundity of D. maidis at temperatures from 20 to 29 °C. The effect of MBSM on D. maidis survival was less severe than CSS on D. elimatus and D. gelbus; t25, but not t50, was reduced by MBSM. Survival times and the cohort generation time generally declined with increasing temperature. Fecundity, however, generally increased with increasing temperature.
Evaluation of selective media for the isolation ofFusarium solanivar.coeruleumandFusarium sulphureumfrom soil and potato tuber tissue
Authors: JEFFRIES C. J. , BOYD A. E. W. , PATERSON L. J.
Published: February 2008

A new selective medium containing pentachloronitrobenzene and 2‐aminobutane (the PAB medium) was developed for soil‐dilution plate enumeration of fungal propagules ofFusarium solanivar.coeruleumandF. sulphureumfrom field soil. Growth of ‘weed‐fungi’ was less on the PAB medium than on the previously developedF. solanivar.coeruleumisolation medium (the PM70 medium) and significantly more propagules ofF. solanivar.coeruleumwere detected.

Propagule counts (x) ofF. solanivar.coeruleumandF. sulphureumfrom the PAB medium, after log10(x/10 + 1) transformation, were linearly related to the angular transformation of measurements of soil infectivity from the tuber bait method using the susceptible cv. Catriona. Slopes from disease‐inoculum regressions forF. solanivar.coeruleumandF. sulphureumin November and May were similar and this suggests that the mode of pathogenic action ofF. solanivar.coeruleumandF. sulphureumwas similar. Recently harvested tubers, inoculated in November, however, were more resistant to infection by both pathogens than stored tubers inoculated in May. Storage of air dry soil at 4°C for 6 months reduced the population ofF. sulphureumbut not the population ofF. solanivar.coeruleum.

Whereas the PAB medium is recommended primarily for use in the isolation ofF. solanivar.coeruleumandF. sulphureumfrom field soil, the PM70 medium appears to be more suitable for recovery of these pathogens and others, includingPhoma exiguavar.foveatafrom diseased tuber tissue.
Detection of strains of African cassava mosaic virus by nucleic acid hybridisation and some effects of temperature on their multiplication
Authors: ROBINSON D. J. , HARRISON B. D. , SEQUEIRA J. C. , DUNCAN G. H.
Published: February 2008

DNA probes, made by cloning double‐stranded forms of each of the genome parts (DNA‐1 and DNA‐2) of the Kenyan type isolate of African cassava mosaic virus (ACMV‐T), reacted strongly with extracts from Nicotiana benthamiana plants infected with ACMV‐T, or with Angolan or Nigerian isolates that are closely serologically related to the type isolate. However, only the DNA‐1 probes reacted with extracts of TV. benthamiana infected with a Kenyan coast isolate (ACMV‐C), which is serologically less closely related to ACMV‐T. DNA‐1 and DNA‐2 probes also reacted with extracts of mosaic‐affected Angolan cassava plants, including some which have not yielded ACMV particles detectable by immunosorbent electron microscopy and from which virus isolates have not been transmitted to TV. benthamiana. These anomalous plants, unlike other naturally infected cassava plants, showed mosaic symptoms on all their leaves which, however, contained only traces of virus particle antigen detectable by enzyme‐linked immunosorbent assay. They contain isolates of ACMV that are probably defective for particle production.

ACMV‐T particles accumulated optimally in N. benthamiana at 20–25°C. At 30°C fewer particles, which apparently had a slightly greater specific infectivity, were produced. At 15°C, considerable quantities of virus particle antigen, virus DNA and virus particles were produced but the particles were poorly infective, and the few that could be purified contained an abnormally large proportion of polydisperse linear DNA molecules, and fewer circular molecules than usual. Angolan isolates, whether particle‐producing or not, likewise replicated better in cassava plants at 23 °C than at 30 °C. In contrast, ACMV‐C attained only very low concentrations in N. benthamiana, but these were greater at 30 °C than at 23°C.
Peanut stripe virus ‐ a new seed‐borne potyvirus from China infecting groundnut (Arachis hypogaea)1
Authors: DEMSKI J. W. , REDDY D. V. R. , SOWELL G. , BAYS D.
Published: February 2008

A new virus, peanut stripe (PStV), isolated from groundnut (Arachis hypogaea) in the USA, induced characteristic striping, discontinuous vein banding along the lateral veins, and oakleaf mosaic in groundnut. The virus was also isolated from germplasm lines introduced from the People's Republic of China. PStV was transmitted by inoculation of sap to nine species of the Chenopodiaceae, Leguminosae, and Solanaceae; Chenopodium amaranticolor was a good local lesion host. PStV was also transmitted by Aphis craccivora in a non‐persistent manner and through seed of groundnut up to 37%. The virus remained infective in buffered plant extracts after diluting to 10‐3, storage for 3 days at 20°C, and heating for 10 min at 60°C but not 65°C. Purified virus preparations contained flexuous filamentous particles c. 752 nm long, which contained a major polypeptide of 33 500 daltons and one nucleic acid species of 3·1 × 106 daltons. In ELISA, PStV was serologically related to blackeye cowpea mosaic, soybean mosaic, clover yellow vein, and pepper veinal mottle viruses but not to peanut mottle, potato Y, tobacco etch, and peanut green mosaic viruses. On the basis of these properties PStV is identified as a new potyvirus in groundnut.
Observations on the invasion and development of the pea cyst‐nematode Heterodera goettingiana in winter field beans (Vicia faba)
Authors: BEANE J. , PERRY R. N.
Published: February 2008

A plot experiment to investigate the invasion, development and number of generations of Heterodera goettingiana on winter‐sown field beans showed that, although second‐stage juveniles invaded in October, white females did not appear until mid‐May and only one generation occurred. The results are discussed in the context of temperature requirements for the development of this nematode.
Observations on the introduction of Verticillium chlamydosporium and other parasitic fungi into soil for control of the cereal cyst‐nematode Heterodera avenue
Authors: KERRY B. R. , SIMON A. , ROVIRA A. D.
Published: February 2008

Isolates of Verticillium chlamydosporium and a sterile fungus added to soil on ground oat grain reduced the numbers of Heterodera avenae on wheat by between 26 and 80%. Nematode populations in uninoculated soil increased from 15 eggs/g soil before planting to 218 eggs/g after harvest. V. chlamydosporium was isolated from oat grain that had been air‐dried and milled before introduction into soil. Applications of the fungi on attapulgite clay or as suspensions of mycelium and spores in water had no effect on nematode multiplication. The effect of the fungi on numbers of H. avenae eggs was similar in autoclaved and non‐sterilised soil.

V. chlamydosporium added on attapulgite clay to a calcareous sand and a calcareous silty loam could be re‐isolated after at least 6 months. Some isolates colonised the roots of wheat without causing lesions or affecting the dry weights of shoots or roots. These results indicate that V. chlamydosporium may be useful for the biological control of cyst nematode pests.
Expression of genes for resistance to potato virus Y in potato plants and protoplasts
Authors: BARKER H. , HARRISON B. D.
Published: February 2008

Plants of several potato clones with major gene resistance to potato virus Y (PVY) developed necrotic local lesions and systemic necrosis after manual inoculation with common (PVYo) or veinal necrosis (PVYN) strains of the virus. The clones reacted similarly, although their resistance genes are thought to be derived from four different wild species of Solarium. Mesophyll protoplasts from each clone became infected when inoculated with RNA of PVYo by the polyethylene glycol method. The proportion of protoplasts infected, assessed by staining with fluorescent antibody to virus particles, was similar to that of protoplasts of susceptible potato cultivars.

In contrast, plants of potato cultivars Corine and Pirola, which possess gene Ry from S. stoloniferum, developed few or no symptoms when manually inoculated or grafted with PVYo. Moreover, only very few protoplasts of these cultivars produced virus particle antigen after inoculation with PVYo RNA. The extreme resistance to PVY of cvs Corine and Pirola was therefore expressed by inoculated protoplasts whereas the resistance of the necrotic‐reacting potato clones was not.
Further studies on the slant test as a measure of the vigour of crisp lettuce seedlot
Authors: WURR D. C. E. , FELLOWS JANE R.
Published: February 2008

Measurements of seed vigour, emergence and maturity characters were made on six seedlots of crisp lettuce cvs Pennlake and Saladin, vigour being determined by the measurement of root length in a slant test.

There were significant differences between the root length and transplant weight of different seedlots of each cultivar. Root length was significantly rank‐correlated with transplant dry weight in both cultivars (cv. Pennlake rs= 0·94, N = 6; cv. Saladin rs= 0·83, N = 6) but not with head weight at maturity. Percentage germination was significantly correlated with seed weight and root length. It is suggested that the slant test can be reliably used to indicate early plant vigour.
The effect of temperature and wind on the flight activity of cereal aphids
Authors: WALTERS K. F. A. , DIXON A. F. G.
Published: February 2008

The lower temperature threshold for take‐off inSitobion avenaeobtained from an analysis of daily 12·2 m suction trap catches was 16°C. In the laboratory, the take‐off threshold forS. avenaewas 17·5°C in increasing temperatures, but 19°C when aphids were kept at constant temperatures for a short period of time. The equivalent thresholds were both 20·5°C forMetopolophium dirhodum.Over a period of 16 h noS. avenaetook‐off from plants at 10°C, 70% at 15°C and all within 16 h at 20°C. It was concluded that suction trap catches can be used to compare the temperature thresholds for take‐off of both different species and morphs of a species of aphid. Emigrants ofRhopalosiphum padi, but not ofM. dirhodum, took‐off at a higher temperature than the alate exules.

High winds were found to delay but not inhibit take‐off both in the field, and in the laboratory, using both artificial and plant substrates. All aphids eventually flew, even from favourable hosts.

It was concluded that adverse weather conditions will delay but not prevent cereal aphid migration in early summer.
Sporulation of Septoria nodorurn (and S. tritici) on spring wheat cvs Kolibri and Maris Butler in relation to growth stage, plant part and time of season
Authors: JEGER M. J. , JONES D. GARETH , GRIFFITHS ELLIS
Published: February 2008

Sporulation of Septoria nodorum was assessed on inoculated spring wheat cvs Kolibri and Maris Butler. The time from inoculation to first production of spores (latent period) was similar over a range of constant temperatures (12–18°C) but was shorter for Kolibri at 6°C and at 24°C. Spore production was greatest during the period of stem extension and, for equal amounts of disease, was twice as great on Kolibri as on Maris Butler. Spore production on leaves was much more intense with Septoria tritici than S. nodorum for equal amounts of disease, and was less intense on heads than on leaves for both pathogens. Inoculation of plants resulted in significant losses in yield. Mans Butler consistently out‐performed Kolibri on each component of yield. Kolibri was particular affected: 1000‐grain weights were reduced at each growth stage tested especially by S. nodorum, grain numbers and yield/head were reduced particularly following inoculation at heading. Spore production of S. nodorum during the period of stem extension increased to a peak in early July and then declined but no reliable relationship with monitored weather accounted for this seasonal trend.
Fungicidal control of Macrophomina phaseolina altered in pathogenicity by substrate nutrients
Authors: HOODA INDRA , GROVER R. K.
Published: February 2008

The presence of different carbon and nitrogen sources and bivalent metal compounds in the substrate medium influenced the mycelial growth of Macrophomina phaseolina and in vitro susceptibility to fungicides. The inoculum from such substrate media showed differences in pathogenicity on mung bean (Vigna radiata). Sucrose and asparagine significantly increased the mycelial growth as well as pathogenicity of the fungus. Absence of bivalent metal ions, viz., Fe++, Zn++ and Mg++ in the medium produced inoculum which caused maximum seedling mortality and foliage blight.

Carbendazim and thiophanate‐M as seed treatments were significantly less effective when the inoculum was from a medium containing glucose than when the inoculum was from a medium containing sucrose. Captafol and thiram gave significantly better disease control on mung bean when the inoculum used for soil inoculations was from media containing asparagine and ammonium nitrate compared to the inoculum grown on a medium containing sodium nitrate. Carbendazim, thiophanate‐M, PMA, captafol and thiram gave good disease control when the inoculum used was raised on a medium devoid of bivalent metal ions. Carbendazim and thiophanate‐M were the best fungicides as foliar treatments and controlled the disease irrespective of carbon, nitrogen and bivalent metal ion status of the substrate medium used for the production of inoculum.
The relationship between numbers of Heterodera schachtii and sugar beet yields on a mineral soil, 1978‐81
Authors: COOKE D. A.
Published: February 2008

In a 4‐yr field experiment on a mineral soil infested with beet cyst nematode (Heterodera schachtii) the relationship between root yield of sugar beet (y) and initial population of H. schachtii (Pi) fitted the equation:

y=y min +(y max ‐ y min) ZPi‐T

y min = 7·7 t/ha, y max = 39·4 t/ha, 2 = 0·99938 and T= 0 eggs/100 g soil. From this information and that obtained during a recent survey of 2766 beet fields, the total national root yield loss caused by H. schachtii was estimated as approximately 10 000 t/annum on mineral soils and (assuming a similar yield loss relationship on all soil types) 30 000 t/annum on organic soils.

No consistent differences in efficiency of extracting cysts were found between the Fenwick Can and the flotation column. A bioassay technique was as effective as cyst extraction techniques in identifying infested soils.
The tolerance of difenzoquat and diclofop‐methyl by winter wheat varieties at different growth stages
Authors: TOTTMAN D. R. , LUPTON F. G. H. , OLIVER R. H.
Published: February 2008

Winter wheat varieties were treated with the wild‐oat herbicides difenzoquat and diclofop‐methyl at several growth stages in a series of four field experiments.

High rates of difenzoquat damaged the winter wheat varieties Bouquet, Sportsman, Hobbit and Maris Huntsman but not Hustler. Treatment of the sensitive varieties during tillering stimulated excessive tiller production, resulting in more ears with fewer and smaller grains than on the unsprayed controls; later applications reduced the number of grains and severely depressed yield.

In contrast, the early applications of diclofop‐methyl, during tillering, were more damaging than the later ones. Bouquet was more tolerant of diclofop‐methyl than were the other varieties tested.
The role of silica in protecting Italian ryegrass (Lolium multiflorum) from attack by dipterous stem‐boring larvae (Oscinellafiit and other related species)
Authors: MOORE D.
Published: February 2008

The importance of the silica content of the plant as a protection against dipterous stem‐borers was studied. Levels of silica in the stubble were inversely related to the degree of infestation by stem‐borers in 13 varieties of established swards of Italian ryegrass and also in newly‐sown swards of four varieties. There were significant reductions in larval colonisation of Italian ryegrass (cv. RvP) grown on soil watered with sodium silicate solution. A small range of silica content in the stubble was related to large differences in the level of attack by stem‐borers.
Latex content and biomass increase in mycorrhizal guayule (Partheniurn argentatum) under field conditions*
Authors: BLOSS H. E. , PFEIFFER C. M.
Published: February 2008

Guayule seedlings were inoculated with two Glomus species in pasteurised soil and grown in the glasshouse without added fertiliser for 8 wk prior to transplanting to the field. The survival rate of transplanted guayule seedlings was increased by inoculation with vesicular arbuscular mycorrhizal fungi compared with uninoculated controls. Inoculated guayule had greater concentrations of Ca, Fe, Mg and Mn at six months of age, and greater concentrations of Ca, Mg, and Zn at 12 months of age than did uninoculated plants. The latex content of both roots and shoots of guayule was greater in inoculated than in uninoculated guayule plants at 12 and 18 months of age. The resin content remained unchanged between treatments irrespective of sampling date.
The effect of fungicide application on seed yield in perennial ryegrass cv. S.24
Authors: HAMPTON J. G. , HEBBLETHWAITE P. D.
Published: February 2008

Eyespot stem lesions, mildew and leaf spots caused by Drechslera spp. and a Spermospora sp. were identified in perennial ryegrass seed production trials in 1981 and 1982, but their incidence was low, and only rarely was more than 10% of any particular leaf area lesioned at any time during the growing season. Fungicide application (triadimefon plus carbendazim plus captafol) at monthly intervals from tillering (February) until harvest (July) increased seed yield by 15% in 1981 and 43% in 1982, mainly through an increase in the number of seeds per spikelet. Seed yield increases were related to an increased leaf area duration, brought about by delays in senescence of photosynthetic tissue, rather than pathogenic effects. Reasons for this yield response to fungicide application in the virtual absence of pathogens are discussed.
The occurrence and importance of okra mosaic virus in Nigerian weeds
Authors: ATIRI G. I.
Published: February 2008

The Nigerian National Horticultural Research Institute experimental and commercial farm has a long history of okra mosaic virus (OMV) disease. In an attempt to determine possible sources of inoculum, weeds growing within or around the vicinity of the farm were investigated. Several weeds showed virus or virus‐like disease symptoms and mechanical inoculation of crude sap from three malvaceous weeds (Abutilon hirtum, Sida acuta, and Malvastrum coromandelianum) and one solanaceous weed (Physalis angulata) induced symptoms of OMV on okra test seedlings; serological tests confirmed the presence of OMV. Beetle vectors caught both from weeds and from okra were infective when confined on healthy okra seedlings for 48 h. Increase in the abundance of beetle vectors was accompanied by an increase in the incidence of OMV disease. The implications of these findings in the epidemiology and control of OMV are discussed.
Effects of temperature on the flowering and seed production of Stylosanthes guianensis cultivars
Authors: ISON R. L. , HUMPHREYS L. R.
Published: February 2008

Seedlings of Stylosanthes guianensis var. guianensis were grown for 75 days in 16 h photoperiods and transferred to controlled environment cabinets for a further 112 cycles set at 12 h days and 18, 21, 24 or 27 OC constant temperatures. Floral initiation (FI) occurred in cv. Cook after 21 short‐day cycles of 12 h and was independent of temperature. Warm temperatures delayed FI in cv. Schofield and hastened it in cv. Endeavour. Rate of node appearance was positively and the duration of the phase FI to flower appearance negatively related to temperature. Spike production and floret number per spike were maximal for Cook and Endeavour at 24°C; seed setting was independent of temperature above 18°C in Cook. Growth, flowering, and seed production of Endeavour required warm temperatures, but Cook was more versatile in its adaptation to varying temperature regimens.
The potential of a sucrose ester coating material for improving the storage and shelf‐life qualities of Cox's Orange Pippin apples
Authors: SMITH S. M. , STOW J. R.
Published: February 2008

A sucrose‐ester coating material was tested for its potential as a storage technique and as an extender of the shelf life of apple (cv. Cox's Orange Pippin).

Apples treated with 1·25% sucrose ester formulation were stored in air at 3·5°C for up to 5 months. Sucrose ester treatment did not reduce detrimental changes in terms of fruit firmness, yellowing and weight loss but did increase core flush incidence.

When applied after storage, the sucrose ester reduced yellowing and loss of firmness and markedly increased internal carbon dioxide levels during a 21 day simulated marketing period. Effects were enhanced with increasing sucrose ester concentrations between 1% and 4%. Sucrose ester did not markedly reduce weight loss in the fruit, did not cause accumulation of alcohol or induce any internal physiological disorders during the simulated marketing period.

Treatment of fruit with an external atmosphere containing 8% carbon dioxide, a level similar to that found in fruit treated with 3% sucrose ester, did not have the same effects as 3% sucrose ester on firmness or ground colour changes, suggesting that the effects of the sucrose ester are not solely the result of the raised carbon dioxide level.
Effect of heat on zoospore motility and multiplication of Olpidium radicale and O. brassicae
Authors: TEAKLE D. S. , THOMAS B. J.
Published: February 2008

Whereas zoospores of six cultures of O. brassicae were immobile after treating in glycine solution at 35–40°C for 10 min, those of a cucurbit culture of O. radicale were immobile only after heating at 45°C. Further, O. radicale multiplied in cucumber at 20°, 30° and 35°C, whereas O. brassicae multiplied at 20°, but not 30° or 35°C. Such differences in reaction to temperature might sometimes be useful in separating mixtures of the two species in common hosts such as cucumber.
Artificial infection of grasses with endophytes
Authors: LATCH G. C. M. , CHRISTENSEN M. J.
Published: February 2008

The endophytic fungi Acremonium loliae and a Gliocladium‐like sp. were isolated from Lolium perenne; A. coenophialum and a Phialophora‐like sp. from Festuca arundinacea; and Epichloe typhina from F. rubra. All five fungi infected endophyte‐free seedlings of the host grasses and F. arundinacea after artificial inoculation. All fungi except A. coenophialum were able to infect L. perenne. The inoculation technique involved placing endophyte mycelium into the coleoptile tissue of sterile seedlings growing on water agar in Petri dishes. Infection of mature plants with endophytes was not achieved. The presence of some endophytes in grasses can be beneficial to plant growth and persistence but deleterious to the health of animals which graze them. The desirability of infecting cultivars of grasses with endophytes is discussed.
Studies of the antagonistic activities of bacteria endemic to cereal seeds.
Authors: ADETUYI F. C. , CARTWRIGHT D. W. , AW D.
Published: February 2008

The seeds of two cultivars of rice and wheat were examined for the presence of bacteria antagonistic to the growth of fungal plant pathogens. A yellow‐pigmented bacterium was found to predominate on rice seed cv. Sasashigure, and in pure culture strongly inhibited mycelial growth of a wide range of pathogens. A similarly inhibitory, cream‐coloured bacterium was predominant on wheat seeds cv. Longbow.

This paper describes the isolation and range of antagonism of these organisms, and details their identification as a member of the Erwinia herbicola group and Pseudomonas syringae respectively.
Host range, purification and some properties of rubus Chinese seed‐borne virus
Authors: BARBARA D. J. , ASHBY S. C. , MCNAMARA D. G.
Published: February 2008

A previously undescribed virus, for which the name rubus Chinese seed‐borne virus (RCSV) is proposed, was isolated from a single, symptomless plant of an unidentified Rubus species grown from seed collected in the wild in the People's Republic of China, Experimentally RCSV infected 23 out of 39 spp. in six out of eight families. The virus was seed‐transmitted in Chenopodium quinoa (100%) and Nicotiana bigelowii (27%). RCSV was not transmitted by the nematodes Xiphinema diversicaudatum or X. index.

The particles of RCSV were isometric, c. 30 nm in diameter with some penetrated by negative stains. In thin sections particles were found in double walled tubular structures with an outer membrane enclosing one or more tubules. In crude extracts some particles were found within single‐walled tubules. Two virus‐associated bands were seen in sucrose density gradients of purified preparations. The upper band was not infective and consisted of penetrated particles apparently devoid of nucleic acid. The lower, infective band was resolved into two components, of density 1.452 and 1.461 g/ml, in caesium chloride isopycnic gradients. There were two polypeptides (mol. wts c. 47 000 and 25 200 daltons) and two nucleic acid species (one of mol. wt c. 1.4 × 106 daltons; the second was poorly defined by the methods used but was of higher molecular weight).

RCSV was distantly related serologically (6–7 SDI) to the type isolate of strawberry latent ringspot virus (SLRV) and also reacted with antisera to serologicaly distinct grape and olive isolates of SLRV. It did not react with antisera to 10 other isometric viruses.