bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of brief exposures to low temperature on the development, longevity and fecundity of the grain aphid Sitobion auenae (Hemiptera: Aphididae)
Authors: PARISH W. E. G. , BALE J. S.
Published: February 2008

First instar nymphs and adults of the grain aphid Sirobion auenae that had been reared at 10°C and 20°C over a number of generations, were cooled to ‐5°C and ‐10°C for 1 h and 6 h and returned to 20°C to assess the effects of brief exposures to low temperatures (cold‐pulses) on their survival. rate of development, longevity and fecundity. A strong acclimation response was observed in first instar nymphs, with significantly less mortality in groups reared to 10°C compared to 20°C. Mean development time from first instar to adult was not significantly affected by low temperature exposure at the first nymphal stage. Longevity in all groups cooled as first instars was reduced by the sub‐zero cold‐pulses, and was also dependent on temperature and exposure time. Acclimated aphids survived longer than non‐acclimated individuals. Reproductive rate, in terms of the number of nymphs born per aphid per day, was unaffected by cold stress applied at the first instar stage. Total fecundity was however reduced, being a function of the number and longevity of the survivors.

Adult aphids were less cold hardy than nymphs; mortality was higher at ‐10°C than ‐5°C increasing with duration of exposure from 1 h to 6 h. Mean fecundity was reduced significantly in aphids cooled at the adult stage, the number of aphids born per day decreasing as the exposure period of the cold‐pulse increased, suggesting that low temperature had affected embryogenesis. All the nymphs born to adults surviving exposure to ‐5°C for 6 h died within 48 h of birth, indicating that low temperature has a pre‐natal effect on mortality.
An eclipse of pea seed‐borne mosaic virus in vegetative tissue of pea following repeated transmission through the seed
Authors: LIGAT J. S. , RANDLES J. W.
Published: February 2008

Four isolates of pea seed‐borne mosaic virus (PSbMV) representing pathotypes P1 (isolates US and Q) and P4 (isolates S4 and S6), and groups III (US and Q) and V (S4 and S6) have been used in a study of the survival and partitioning of PSbMV under conditions of continuous seed transmission in the commercial pea cultivar Dundale.

Assays suitable for detecting virus in small tissue samples were developed, and included dot‐immunobinding assay with antisera to both PSbMV and cytoplasmic inclusion body (CIB) protein, and dot hybridisation assay (DHA) with cDNA transcribed from virus RNA. Under the conditions of our experiments, seed transmission occurred at rates exceeding 90% for all virus isolates.

Virus was detectable by serology and symptoms in inoculated plants, and in all vegetative tissue of second generation plants raised from seed of the inoculated plants. However, in the third, fourth and fifth sequential generations raised from seed, all plants were symptomless. Neither virus nor CIB were detectable in leaf, stem or roots by serology, but both were readily detectable in some floral parts, and in immature and mature seed. Mature seed contained virus and CIB antigen in the testa, cotyledon and embryo. Inoculum prepared from whole seeds was infectious. The testa was shown not to be involved in transmission between generations, thus implicating the embryo alone in vertical transmission. Virus antigen could not be detected in the emerging cotyledons of germinating seed and all true leaves by serology, but the leaves contained PSbMV RNA detectable by DHA.

These results show that PSbMV infection can be transferred through the vegetative phase at a subliminal level, and reaches relatively high concentrations in floral parts and seeds. Thus PSbMV may be maintained at a high level of infection in seed in the absence of any apparent symptoms in the plant, and without a requirement for horizontal transmission between plants by vectors. Such a mechanism may explain the high levels of infection commonly reported in pea breeding lines.
The enhanced infectivity of Metarhizium flavoviride in oil formulations to desert locusts at low humidities
Authors: BATEMAN R. P. , CAREY M. , MOORE D. , PRIOR C.
Published: February 2008

Formulation in non‐evaporative diluents such as oils is required to exploit the advantages of controlled droplet application methods for biopesticides based on conidial suspensions of entomopathogenic fungi. In laboratory assays on desert locusts (Schistocerca gregaria), formulations of Metarhizium flauoviride conidia in cotton seed oil showed superior performance to water‐based suspensions and this was especially pronounced at low humidities (35% r.h.). The LD50s for oil and water suspensions at 5 days were 8900 and > 106 conidia/insect respectively. The dose‐mortality regression line for oil was more than four times steeper and median lethal times were typically 76% of those for aqueous suspensions. Formulation in oil improves the efficacy of this fungus and may extend the application of species with lipophilic conidia into less humid agricultural environments.
Crop monitoring to assess the risk of slug damage to winter wheat in the United Kingdom
Authors: GLEN D. M. , SPAULL A. M. , MOWAT D. J. , GREEN D. B. , JACKSON A. W.
Published: February 2008

The percentage of winter wheat seeds killed by slugs was measured, together with various risk factors, at 93 sites throughout the UK from 1987 to 1990. Estimates of slug populations at each site were obtained from traps baited with methiocarb pellets. The peak number of slugs trapped during the period from July until just before cultivation accounted for 26% of the variability in seed damage, more than any other single risk factor. A combined function of the number of slugs trapped at drilling and the percentage of fine soil aggregates in the seed‐bed accounted for 21% of the variability in seed damage. Both (i) the peak number of slugs trapped before drilling, and (ii) the combined function of number of slugs trapped at drilling and the percentage of fine soil aggregates in the seed‐bed, have potential for identifying fields with a negligible risk of slug damage to wheat seeds. However, further research is needed to improve the accuracy of forecasting slug damage. In particular, other forms of trap should be tested for their potential use in providing more accurate estimates of slug numbers and biomass at drilling, and techniques of assessing seed‐bed conditions should be improved. The percentage of seedlings grazed by slugs was correlated with the numbers of slugs trapped before drilling, at drilling and after crop emergence.
Elimination of cymbidium mosaic virus and odontoglossum ringspot virus from orchids by meristem culture and thin section culture with chemotherapy
Authors: LIM S. T. , WONG S. M. , GOH C. J.
Published: February 2008

Most commercially cultivated orchid plants are generally infected with cymbidium mosaic virus (CyMV) and odontoglossum ringspot virus (ORSV). Two methods were used in order to generate virus‐free plants: meristem culture and thin section culture with chemotherapy. Meristems (0.10 mm to 1.00 mm) were excised from infected axillary shoots of an infected monopodial orchid hybrid (Mokara Char Kuan ‘Pink’) and cultured in modified Vacin and Went medium. Only larger meristem explants survived and the regenerated plantlets remained virus‐infected. In contrast, high percentages of virus‐free plantlets were obtained from thin section cultures of infected plantlets and protocorm‐like bodies with ribavirin treatment. Interestingly, regenerants from thin section cultures without ribavirin treatment were also found to be free from CyMV and ORSV. All plantlets were tested by enzyme‐linked immunosorbent assay (ELISA) and/or polymerase chain reaction (PCR).
Temperature accumulation and physiological ageing of seed potato tubers
Authors: JENKINS P. D. , GILLISON T. C. , AL‐SAIDI A. S.
Published: February 2008

Tubers of cv. Maris Bard were allowed to accumulate different numbers of day‐degrees early, late or continuously throughout the seed storage period. Sprout growth, time of emergence, development of early canopy cover and early tuber yield were increased more by late temperature accumulation than by increasing the number of day‐degrees experienced from 250 up to a maximum of 700°C days. The relative physiological age of seed, as indicated by the subsequent rate of early crop growth, was poorly related to the number of day‐degrees accumulated. The implications for the quantification of seed physiological age are discussed.
Crop growth, water‐use efficiency and carbon isotope discrimination in groundnut (Arachis hypogaea L.) genotypes under end‐of season drought conditions*
Authors: RAO R. C. NAGESWARA , WILLIAMS J. H. , WADIA K. D. R. , HUBICK K. T. , FARQUHAR G. D.
Published: February 2008

Ten groundnut genotypes were grown under adequately irrigated conditions or subjected to drought during the pod filling phase (83–113 days after sowing) in a medium deep Alfisol at the ICRISAT Centre during the 1986–1987 post‐rainy season. Crop growth was measured in both treatments, but transpiration (7) and water‐use efficiency (W) were quantified only in the drought treatment. Leaf samples from both treatments were assayed for discrimination against 13CO2 fixed in leaves (Δ) to examine the relationships between Δ, crop growth, and W under field conditions.

The shoot dry matter accumulated during the period of drought (Y) ranged from 72–150 g m‐2 and was closely related to transpiration. This indicates scope for selection of traits and practices to increase T. Water‐use efficiencies ranged from 1.38–2.50 g kg‐1 and were inversely related to Δ in eight out of the 10 genotypes. For the other two genotypes, there was evidence that T was underestimated by field measurements. Water‐use efficiency and transpiration were not correlated suggesting that these two traits might be combined through breeding. Variation between genotypes was greatest for the partitioning of total dry matter to pods (73%), followed by water‐use efficiency (31%) and transpiration (29%). Crop growth rates were negatively related to Δ under irrigated conditions but not under drought.
Relationships between turnip root fly (Delia floralis) larval development and the sugar content of swede (Brassica napus ssp. rapifera) roots
Authors: HOPKINS R. J. , GRIFFITHS D. W. , BIRCH A. N. E. , McKINLAY R. G. , HALL J. E.
Published: February 2008

Eight genotypes of swede (Brassica napus L. ssp. rapifera [Metz.] Sinsk.) at the 8–10 true leaf stage were inoculated with five, 10 or 20 eggs of the turnip root fly Delia floralis (Fall). The roots were sampled, with control roots, after 6 weeks of larval development. D. floralis root damage, as measured by reduction in root weight, was found to be linked to inoculation level. Neither D. floralis egg numbers nor swede genotype had a significant effect on the percentage of larvae developing to pupation. Mean pupal weight varied by a factor of ×1.4 and consistently decreased with increasing egg inoculation level. Changes in the root concentrations of glucose, sucrose and fructose were measured. All swede genotypes showed a similar response in their sugar concentrations after root damage. Glucose and fructose concentrations were reduced whilst sucrose concentration remained unaffected. The concentrations of glucose and fructose were highly correlated. Pupal weight, used as a measure of larval development, was significantly correlated with the concentrations of individual and total sugars in the roots. The implications of sugar responses to damage in brassicas, and the correlation between sugar concentrations in the roots and D. floralis pupal weights are discussed.
Effects of DIMBOA levels in wheat on the susceptibility of the grain aphid (Sitobion avenue) to deltamethrin
Authors: NICOL D. , WRATTEN S. D. , EATON N. , COPAJA S. V.
Published: February 2008

The effects of DIMBOA in cultivars of wheat on aphid antibiosis and tolerance to the insecticide deltamethrin were investigated for the aphid Sitobion auenae. Over 48 hours the mean relative growth rate differed significantly between nymphs of S. auenae reared on wheat cultivars containing different levels of DIMBOA. Nymphs on the resistant cv. Altar showed a significantly greater susceptibility to deltamethrin, with nearly a three‐fold increase in the relative toxicity of deltamethrin, compared with the susceptible cv. Dollarbird. The LC50, adjusted for weight, was reduced by 91% for nymphs reared on the high DIMBOA cultivar. The potential for the enhancement of predation under a reduced pesticide régime is discussed in relation to this research.
Effect of surfactants and fungicides on clubroot (Plasmodiophora brassicae) of brassicas
Authors: HUMPHERSON‐JONES F. M.
Published: February 2008

Two formulations of the surfactant sodium dioctyl sulphosuccinate (Aerosol OT, Monawet MO70), one of alkyl phenyl ethylene oxide (Agral) and three fungicides (PP192, dichlorophen and a thiabendazole/iodophor complex ‐Byatran) were tested in field trials for control of clubroot (Plasmodiophora brassicae) on cabbage in 1988 and 1989. A standard mercurous chloride treatment (pre‐sowing compost incorporation) was included in all experiments. Plants were raised in 64 cm3 blocks (1988) or 15 cm3 free‐fill cells (1989). Mercurous chloride reduced disease severity and increased yield in both years. Byatran was ineffective. The surfactants and dichlorophen, applied as pre‐planting soaks to the plant‐raising compost, restricted disease development and increased yield in 1988 but not in 1989. A similar treatment with PP192 restricted disease severity and enhanced yield in both years. Pouring the surfactants and dichlorophen into the planting hole was more effective than using them to soak the compost. In 1989 pour treatments with Agral and a combined soak/pour treatment with dichlorophen reduced disease severity and increased yields by 250% and 97% respectively; compost treatment with PP192 gave a 150% increase.
The effect of varying rates of glyphosate and an organosilicone surfactant on the control of gorse
Authors: BALNEAVES J. M. , GASKIN R. E. , ZABKIEWICZ J. A.
Published: February 2008

The herbicidal effect of glyphosate applied to gorse (Ulex europaeus L.) was improved by the addition of increasing amounts (0.5–20 g/litre) of Silwet L‐77, an organosilicone surfactant. Increasing the rate of herbicide also enhanced control. There was a highly significant interaction between surfactant rate and herbicide dosage; as the amount of Silwet L‐77 was increased the rate of glyphosate could be reduced without loss of herbicide efficacy. However, without any added organosilicone surfactant, glyphosate did not provide more than 73% control of gorse at any rate up to 6.5 kg a.i./ha. With the addition of Silwet L‐77, complete mortality of all plants could be achieved with 2.2 kg glyphosate/ ha.
The genetic control of seven isozymic loci in Vicia faba L. Identification of lines and estimates of outcrossing rates between plants pollinated by bumble bees
Authors: CARRÉ S. , TASEI J. N. , GUEN J. Le , MESQUIDA J. , MORIN G.
Published: February 2008

A simplified and non‐destructive method using starch gel electrophoresis has been developed on seeds to identify inbred lines of Vicia faba and assess outcrossing rates and gene dispersal in pollination experiments. Six enzyme systems (Alcohol dehydrogenase, Aspartate aminotransferase, Glucose‐6‐phosphate isomerase, Isocitrate dehydrogenase, Phosphogluconate dehydrogenase and Shikimate dehydrogenase) were analysed from parental lines, crosses performed between lines bearing dissimilar isozyme patterns in pollination cages with Bombus and F2 progenies obtained from manual selfing of F1 hybrids. The allozymes at each of the seven studied loci segregated in the expected Mendelian fashion and behaved in a co‐dominant manner except for the Adh‐2 locus where the only variant was a null allele. No evidence of genetic linkage was observed between at least 13 of the 15 pairs of the studied loci. Percentage of cross fertilisation by Bombus between seven pairs of inbred lines ranged between 1.7% and 28.3%. Pollen transfer between a donor line and a recipient line by two species of Bombus did not lead to differences in outcrossing rates (both about 8%). The new PGD marker with two loci at three alleles each is particularly discriminating and valuable in pollination studies and breeding of V. faba.
Effect of the stem blight pathogen, Phomopsis emicis, and the weevil, Perapion antiquum, on the weed Emex australis
Authors: SHIVAS R. G. , SCOTT J. K.
Published: February 2008

The stem blight pathogen, Phomopsis emicis, and the weevil, Perapion antiquum, are two potential biological control agents for the annual weed, Emex australis. Neither pathogen nor weevil affected the development of rosette (5‐wk‐old) E. australis, but both significantly reduced stem length and number of new fruits in mature plants (10‐wk‐old) in growth room experiments. Stems grew two‐thirds less than controls in plants attacked by weevils, had no net increase when both weevils and fungus were present, and collapsed in the presence of the fungus alone. Attack by weevils elicited a host response that slowed the development of the disease. Phomopsis emicis and Perapion antiquum reduced the ability of E. australis to produce new fruits by 77% and 68%, respectively. Pathogen and weevil together reduced the number of new fruits by 83%. Perapion antiquum did not carry or provide infection sites for P. emicis. The lack of damage by pathogen and weevil to rosettes could compromise their effectiveness as biological control agents.
Diapause termination in the spotted stem borer, Chilo partellus (Lepidoptera: Pyralidae) in the laboratory
Authors: KFIR RAMI
Published: February 2008

The effect of temperature, photoperiod, artificial diet and water on the termination of diapause by larvae of the stem borer, Chilo partellus (Lepidoptera: Pyralidae), was studied in the laboratory. Termination of diapause as indicated by pupation was affected mainly by a combination of high temperature and a long day photoperiod. Total darkness did not prevent termination of diapause and pupation occurred also in larvae which were never exposed to water. Long days accelerated pupation, but, under 16 h daylength, termination of diapause was faster than under constant illumination. Provision of artificial diet had no effect or slowed down pupation but water decreased the time to pupation. Under 28°C, 16 h daylength and availability of water, C. partellus diapausing larvae terminated diapause and pupated in about 9 days.
Evaluation of selected cowpea varieties for resistance to Aphis craccivora Koch (Homoptera: Aphididae) at the seedling and podding phase
Authors: OFUYA THOMAS I
Published: February 2008

Twelve varieties of cowpea (Vigna unguiculata) were tested at the seedling and podding growth phases for resistance to infestation and damage to Aphis craccivora Koch. Nine of these cowpeas have previously been known to exhibit seedling resistance and the other three, susceptibility to the insect. A. craccivora could not colonise pods of TVu 9930. Pods of Tvu 36 also manifested a high level of resistance to the aphid. The three seedling susceptible varieties proved quite susceptible to A. craccivora at the podding phase. The other varieties were more resistant to the aphid in the seedling phase than in the podding phase.
The elimination of clover diseases by shoot tip culture
Authors: DALE P J , CHEYNE V A
Published: February 2008

Shoot tip culture was used to eliminate white clover mosaic virus (WCMV) and red clover necrotic mosaic virus (RCNMV) from red clover, and clover phyllody disease (CP) and clover red leaf disease (CRL) from white clover. Shoot tips up to 2.4 mm (in some cases 3 mm) could regenerate plants free from the pathogens, but the efficiency of elimination, at least for WCMV and CRL, tended to decrease with increasing shoot tip size. The efficiency of plant regeneration from shoot tips generally improved with increasing tip size.
Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes
Authors: ŠPAK J , KUBELKOVÁ DARINA , HNILIČKA E
Published: February 2008

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities.

The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus‐infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL‐507 0.2%, SL‐509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.
The occurrence of barley yellow dwarf viruses in CIMMYT bread wheat nurseries and associated cereal crops during 1988–1990
Authors: WEBBY G N , LISTER R M , BURNETT P A
Published: February 2008

Enzyme‐linked immunosorbent assay (ELISA)‐based surveys of the occurrence of five barley yellow dwarf virus (BYDV) serotypes (MAV, PAV and SGV in “Group 1”; RPV and RMV in “Group 2”) in CIMMYT bread wheat nurseries and other small grain crops in various locations world‐wide were undertaken in 1988, 1989 and 1990. The objective was to investigate the relative occurrence of BYDV serotypes in areas relevant to CIMMYT cereal breeding programs. Overall, MAV and PAV serotypes predominated in the samples collected, though their relative frequencies depended on the location. SGV serotypes were uncommon in most locations. Group 2 serotypes occurred widely, but RMV serotypes were more common than RPV serotypes.
In vitro activity of glucosinolate‐derived isothiocyanates against postharvest fruit pathogens*
Authors: MARI M , IORI R , LEONI O , MARCHI A
Published: February 2008

The authors assayed the ability of some reaction products, essentially isothiocyanates, derived from the myrosinase‐catalysed hydrolysis (neutral pH) of six natural glucosinolates to inhibit germination and mycelial growth of Botrytis cinerea, Rhizopus stolonifer, Monilinia laxa, Mucor piriformis and Penicillium expansum, the leading postharvest fungal pathogens of fruit and vegetable crops. All of the tested products showed antifungal activity, although they proved less effective against mycelial growth than in germination control. The isothiocyanates produced by enzymatic hydrolysis of glucoraphenin, sinalbin and sinigrin were particularly effective because they completely inhibited conidic germination of all five pathogens considered. The sinigrin‐derived isothiocyanate exhibited a wide pathogen‐control spectrum, either inhibiting conidia germination altogether or delaying by 3–6 days the onset of mycelial growth compared to the control.
A description and code of development of borage (Borago officinalis)
Authors: SIMPSON M J A
Published: February 2008

A description and code of development is proposed which divides the life cycle of borage (Borago officinalis L.) into eight stages, namely germination and emergence, leaf production, stem extension, flower bud development, flowering, seed maturity and abscission, leaf senescence, and stem senescence. The most important difference between the borage system and one devised for oilseed rape lies in the description of flowering and seed development, reflecting the cymose structure of the borage inflorescence which contrasts with the raceme of oilseed rape. The borage description and code should facilitate assessment of harvest stage and other critical stages that determine the timing of husbandry techniques.
Interactions of fungicide and insecticide combinations against Rhizoctonia damping‐off and root rot in canola*
Authors: KATARIA H R , VERMA P R
Published: February 2008

In growth chamber pot experiments with soilless mix infested with an isolate of Rhizoctonia solani AG2‐1, two seed‐dressing insecticides (cloethocarb and gamma‐HCH) and two granular insecticides (carbofuran and terbufos) were tested alone and in combination with five seed‐dressing fungicides (carboxin, cyproconazole, furmecyclox, iprodione and tolclofos‐methyl) against pre‐emerg‐ence damping‐off and post‐emergence seedling root rot in canola cv. Westar (Brassica napus). Each fungicide provided almost complete control of damping‐off, but, against post‐emergence root rot, furmecyclox, iprodione and tolclofos‐methyl gave far better control than carboxin and cyproconazole. Cloethocarb and carbofuran increased the incidence of damping‐off and, when used in combination with fungicides, lowered the disease control against damping‐off and root rot. Gamma‐HCH and terbufos decreased the incidence of pre‐emergence damping‐off, and terbufos also reduced post‐emergence root rot. Combined treatments with gamma‐HCH and terbufos gave better control against damping‐off than either gamma‐HCH or terbufos alone. Disease control by fungicides against both damping‐off and root rot was enhanced by the use of either gamma‐HCH or terbufos together with fungicide treatments. Fungicide combinations with gamma‐HCH and terbufos were at best additive in their activity for overall disease control. Maximum disease control with insecticide‐fungicide combinations was achieved when terbufos granules were applied at the time the pots were sown with fungicide + gamma‐HCH‐treated seed. Adding terbufos granules to the treated seed 1–4 wk before seeding, resulted in a considerable loss of efficacy of each of the five fungicide + gamma‐HCH seed treatments.
Surveys of diseases of spring barley in England and Wales, 1976–1980
Authors: POLLEY R W , KING J E , JENKINS J E E
Published: February 2008

Samples from 200–300 randomly selected spring barley crops were taken annually at growth stage 73–77 (milky ripe) from 1976 to 1980. The number of samples from each region was proportional to the area of barley grown in each region. The percentage of the area of the top two leaves affected by diseases was recorded. Mildew (Erysiphe graminis) was the most widespread and severe disease recorded. Brown rust (Puccinia hordei) and rhynchosporium (Rhyn‐chosporium secalis) occurred frequently but at relatively low levels. Yellow rust {Puccinia striiformis) and septoria (Septoria nodorum) were seen on less than 50% of the samples in most years, and halo spot (Selenophoma donacis) and net blotch (Pyrenophora teres) were rarely recorded. There was an association between the severity of rhynchosporium and the number of rain days in May and June. The highest levels of brown rust occurred in the south and east and rhynchosporium was more common in Wales and the south‐west than in the east, but there were no differences in the regional distribution of other diseases. Cultivar resistance, sowing date, previous cropping and fungicide usage were all found to be associated with altered disease levels. The proportion of crops treated with a foliar fungicidal spray rose from 26% in 1976 to 47% in 1980. The use of tridemorph declined but that of triadimefon increased reaching 29% of crops treated by 1980. The use of ethirimol as a seed treatment declined from 16% of crops grown from treated seed in 1976 to 7% in 1980. Estimated yield losses between 1976 and 1980 varied between 4% and 9% due to mildew, between 0.3% and 0.8% due to brown rust and between 0.2% and 0.5% due to rhynchosporium.
Surveys of diseases of winter barley in England and Wales, 1981–1991
Authors: POLLEY R W , THOMAS M R , SLOUGH J E , BRADSHAW N J
Published: February 2008

Samples from 200–400 randomly selected winter barley crops were taken annually at growth stage 71–73 from 1981 to 1991, with the exception of 1984 and 1985. The number of samples from each region was proportional to the area of barley growth in each region. The percentage of the area of the top two leaves affected by diseases and the severity of stem base diseases were recorded. Mildew(Erysiphe graminis)was the most widespread of the foliar diseases and in three years (1982, 1986 and 1991) was also the most severe. Rhynchosporium(Rhynchosporium secalis),net blotch(Pyrenophora teres)and brown rust(Puc‐cinia hordei)were also prevalent in some years. Of the stem base diseases, fusarium was often the most widespread. Eyespot(Pseudocercosporella her‐potrichoides)severity varied widely from year to year ranging from 1.2% of stems affected by moderate or severe symptoms in 1982 to 24.1% in 1988. There were regional differences in the severity of mildew, rhynchosporium, brown rust, halo spot(Selenophoma donacis)and eyespot. Cultivar resistance affected disease severity and previous cropping affected eyespot and less frequently mildew, rhynchosporium and net blotch. Eyespot, and to a lesser extent, sharp eyespot, were less severe in late‐ than in early‐sown crops. The percentage of crops treated with a fungicidal spray increased from 72% in 1981 to 95% in 1991. The use of benzimidazole fungicides for the control of eyespot declined in response to the development of resistance, and more recently the use of prochlo‐raz also declined. Broad spectrum DMI fungicides were widely used, and the use of morpholines to improve mildew control increased significantly. The proportion of crops grown from seed treated with a non‐mercurial fungicidal seed dressing reached a peak of 47% in 1986 but subsequently declined to 22% in 1990 and 1991.
Comparison of population density of plant parasitic and free‐living nematodes in earthworm casts and adjacent soils of fallow and cultivated land in South Eastern Nigeria
Authors: RUSSOM Z , ODIHIRIN R A , MATUTE M M
Published: February 2008

Numbers of nematode species, juveniles, females and males in earthworm casts and in adjacent soils were studied in fallow (FL) and in cultivated lands (CL). In the FL each cast had an average of 5.6 different species of nematodes, while a soil sample of equal weight to the cast and within a 10 cm radius of the cast averaged 2.5 species. The difference between these means was highly significant. In the CL there were 4.7 species/cast and 2.9 species/soil sample. The difference between these two means was also highly significant.

A total of 16 plant parasitic species, five omnivorous, two predacious and eight free‐living nematode species were observed in the casts and in the adjacent soils of both FL and CL. The results partially contradicted the widely held view that earthworm casts are beneficial because the casts harboured numerous plant parasitic nematodes.
Characterisation of a 34 kD protein from potato cyst nematodes, using monoclonal antibodies with potential for species diagnosis
Authors: ROBINSON M P , BUTCHER G , CURTIS R H , VIES K G DA , EVANS K
Published: February 2008

Two monoclonal antibodies, which differentially recognise the two species of potato cyst nematodes (PCN), Globodera pallida and G. rostochiensis, are described. They have been shown to have potential for quantification of these two species, recognising proteins of the same molecular weight (34 kD) in both species. Further investigation showed these proteins to have isoelectric points at pH values of 5.7 in G. pallida and 5.9 in G. rostochiensis, in common with the proteins used by Fleming & Marks (1983) to differentiate the species of PCN. They are likely to be structurally very similar, with the same physiological function (and therefore similar concentrations) in the two species. In cross‐reactivity tests with a wide range of soil nematode species, the antibodies reacted strongly only with species of the genus Globodera, and thereby confirmed their potential as the basis of a quantitative immunoassay likely to be useful in management of PCN populations.
Soil sampling to detect potato cyst‐nematodes {Globodera spp.)
Authors: TURNER SUSAN J
Published: February 2008

Sampling agricultural land prior to planting potatoes usually forms the basis of estimating levels of potato cyst‐nematode (PCN) populations for certification, advisory and research programmes. A series of investigations studied the design and efficiency of sampling equipment and the intensity and pattern of soil collection for PCN detection. A single 360 g sample in fields up to 2 ha is recommended as the minimum practical and economic sampling intensity for PCN detection for certification purposes. Additional rates are recommended for ‘high risk’ situations such as high grade seed and resampling with a view to descheduling land.
The effect of parent plant nutrition on seed size, viability and vigour and on germination of wheat and triticale at different temperatures
Authors: NAYLOR ROBERT E L
Published: February 2008

Seed was obtained from two adjacent trials of wheat (cv. Avalon) and triticale (cv. Lasko) harvested in 1990. The treatments consisted of factorial combinations of five levels of spring nitrogen (50, 100, 150, 200 and 250 kg N ha‐1) with fungicide treatments designed to control foliar diseases. Seed was graded by size into different fractions.

Application of foliar fungicides to the parent plant increased the proportion of large seed in wheat but not in triticale. Fungicide application had no effect on seed vigour (quantified as the value of K; after controlled deterioration), final germination, median germination time (t50) or rate of germination.

Parent plant nutrition altered the proportions of seed in different size categories in triticale and wheat. In laboratory germination tests, final germination of wheat increased with seed size. Large (> 3.0 mm diameter) wheat seed from plots receiving 50 kg N ha“1 had a lower final germination than large seed from plots which had received greater amounts of nitrogen, but t50 and K; were similar for all nitrogen levels. In triticale, the higher the seed weight, the higher the final germination, the faster the rate and the higher the Ki. Final germination, t50 and K;, were all positively correlated with the amount of nitrogen received by the parent plants.

Parent plant nutrition had no effect on the response to temperature of final germination, t50, or rate of germination for large or small seeds of both wheat and triticale.
Chloroplast DNA variability in old and recently introduced potato cultivars
Authors: POWELL W , BAIRD E , DUNCAN N , WAUGH R
Published: February 2008

Chloroplast DNA (cpDNA) variability has been examined in a range of tetraploid European potato cultivars. The potato genotypes studied included primitive cultivars such as Lumpers (1806), Yam (1836), Myatts Ashleaf (1847) and more recently bred cultivars such as Brodick (1990). Three cpDNA pheno‐types were detected and these probably represent original introductions from South America into Europe. The most common cp phenotype was the T type cpDNA (Hosaka & Hanneman, 1988) characteristic of cultivars descended from cv. Rough Purple Chili. The presence of the T type cpDNA in the cultivar Yam indicates that this genotype which is of Andigena origin shares a common cytoplasm with other 5. tuberosum ssp. tuberosum clones which have a Chilean type cytoplasm. The implications of these results are discussed in relation to the origin of the T type cpDNA. Methods for increasing the cytoplasmic diversity of the cultivated potato gene pool are proposed.
Glycoalkaloid increase in Solarium tuberosum on exposure to light
Authors: DALE M F B , GRIFFITHS D W , BAIN H , TODD D
Published: February 2008

Tubers of six commercially available potato cultivars were placed in bright light (140 jUmol“1 m”2), approximately equivalent to dull daylight, for a continuous period of up to seven days. The tubers were sampled at intervals, scored for degree of greening, freeze‐dried and subsequently assessed for glycoalkaloid and chlorophyll content. There were significant differences between the cultivars in their rates of greening and increase in glycoalkaloid content. There was an apparent relationship between the two characters. Increases in the individual glycoalkaloids a–chaconine and a‐solanine were also assessed. The results are discussed in terms of the implications for the potato industry.
Cultural manipulations affecting callus formation from seedling explants of the pearl lupin (Lupinus mutabilis Sweet)
Authors: PHOPLONKER MUSHTAQ A , CALIGARI P D S
Published: February 2008

The influences of several cultural factors were investigated in relation to callus formation from seedling explants of L. mutabilis Sweet. The interaction of low culture temperature (18°C), light differences, rapid callus transfer, and media additions led to the successful abolition of media browning which usually accompanied callus senescence. The supplement of activated charcoal slowed down the growth rate of the callus produced, and made it appear friable. Low levels of picloram and dicamba were found to produce large quantities of friable callus especially when combined with kinetin. The availability of nitrogen, as well as type of explant, markedly influenced callus induction and growth, whilst the addition of glutamine enhanced callus formation.
Relationships between fruit mineral content and the “albinism” disorder in strawberry
Authors: LIETEN F , MARCELLE R D
Published: February 2008

Albinism is a physiological disorder of strawberry characterised by the production of colourless fruit. This paper demonstrates that the mineral composition of albino fruit is characteristic of them being riper and more senescent than normal fruit. Ratios of K:Ca and N:Ca were greater in albino than in normal fruit. Relationships between fruit mineral content and albinism are discussed.
Antibiosis component of resistance in sorghum to sorghum midge, Contarinia sorghicola
Authors: SHARMA H. C. , VIDYASAGAR P. , SUBRAMANIAN V.
Published: February 2008

Sorghum midge, Contarinia sorghicola Coq. (Diptera: Cecidomyiidae) is an important pest of grain sorghum, and host‐plant resistance is one of the most effective means of controlling this pest. We studied the antibiosis mechanism of resistance in sorghum to C. sorghicola in a diverse array of midge‐resistant and midge‐susceptible genotypes. Data were recorded on adult emergence, postembryonic developmental period, number of mature eggs in the ovary, fecundity, larval survival from artificially implanted eggs; and the tannins, soluble sugars, and protein content of 10‐day old and mature grains during the 1982‐91 rainy and post‐rainy seasons.

Adult emergence was significantly lower in the midge‐resistant genotypes compared with the susceptible controls. Initiation of adult emergence was delayed by 4–8 days on DJ 6514, IS 8571, IS 9807, IS 10712, IS 19474, IS 19512, ICSV 830 and ICSV 197. Postembryonic developmental period was prolonged on DJ 6514, IS 15107, IS 3461, IS 7005, IS 19474, ICSV 831 and ICSV 197. However, the delay in adult emergence or the extended developmental period was not observed during the post‐rainy season in some genotypes. These differences in the expression of antibiosis to midge in resistant genotypes over seasons may be attributed to the effect of environmental conditions on the insect development and chemical composition of sorghum grain. Amounts of tannins and proteins were generally greater in the midge‐resistant lines compared with the susceptible ones (except tannins in DJ 6514) while the soluble sugars were low in the midge‐resistant lines (except TAM 2566). These differences in chemical composition of the grain between genotypes and variations over seasons have been discussed in relation to the expression of antibiosis mechanism of resistance to the sorghum midge. Antibiosis to sorghum midge was also evident in terms of smaller size of larvae, lower number of eggs in the ovary, reduced fecundity, and larval survival. Midge‐resistant lines have diverse effects on the biology of this insect. Antibiosis along with other components of resistance can be used to develop cultivars with stable resistance to C. sorghicola.
Changes in wheat bulb fly (Delia coarctata) populations in East Anglia in relation to crop rotations, climatic data and damage forecasting
Authors: YOUNG J. E. B. , COCHRANE J.
Published: February 2008

Records of wheat bulb fly egg (Delia coarctata) population densities in fields sampled throughout East Anglia in the autumns of 1953–1990 are presented. In descending order of risk, fallow, potato, pea (mainly vining), sugar beet and oilseed rape are the main crops preceding wheat or barley which attract oviposition. A declining trend of egg populations observed over the study period may be associated with climatic changes as well as with the elimination of fallow in the rotation and the dramatic increase in the use of insecticides against the pest. Negative correlations (P < 0.05) in mean annual egg numbers were found with departures from average of July temperature and January air or soil temperature; positive correlations (P<0.05) with departure from average of August raindays. Stepwise regression analysis was used to identify the most important relationships of meteorological variables with mean annual egg numbers, or the proportion of fields sampled with egg numbers in excess of the action threshold of 2.5 million eggs/ha. Up to 59% of the variation in the annual proportion of fields above threshold was accounted for in a regression equation using departures from average of July temperature, August raindays and the percentage of average of October (preceding year) rainfall. Estimated mean annual egg populations and the proportion of fields above threshold showed a good fit with the observed values. The findings are discussed and compared with previous work. The forecasting model may be readily incorporated as a regional risk‐prediction component of a knowledge‐based system for the management of wheat bulb fly control. Regional forecasts of wheat bulb fly oviposition from this work should be tested and modified as necessary according to experience or changing climatic or agricultural factors.
Relationships between nematodes, weevils, banana and plantain cultivars and damage
Authors: SPEIJER PAUL R. , BUDENBERG WILLIAM J. , SIKORA RICHARD A.
Published: February 2008

Infestation of banana and plantain suckers by nematodes (Pratylenchus good‐eyi, Radopholus similis and Helicotylenchus multicinctus) and weevils (Cosmopolites sordidus) increased with time from establishment in a field of eight different cultivars. There was a strong association between nematode and weevil infestation; suckers infested with nematodes were more than four times more likely to be infected by weevil than suckers without nematodes. Weevil damage, measured by percentage coefficient of infestation (PCI) at harvest of the bunch, was higher on a plantain (cv. Gonja) and on an east African highland cooking banana (cv. Lusumba) than on the sweet and multi‐purpose cultivars. There was a correlation between numbers of male weevils caught in a plot and the mean PCI measured in the plot, but no correlation with female numbers.
Modification of growth, yield and lodging response of lentil to phosphorus by paclobutrazol
Authors: GILL D. S. , SINGH O. S.
Published: February 2008

A foliar application of paclobutrazol (1 litre a.i. ha“1) was applied before flowering of lentils grown with different levels of phosphorus (0, 20, 40, 60, 80 and 100 kg P205 ha”1). Increasing amounts of P up to 80 kg ha“1 increased plant height, crop dry matter and grain yields but also increased crop lodging. Paclobutrazol decreased plant height and lodging and increased grain yield. Maximum yields were obtained with a combination of 80 kg P ha”1 and paclobutrazol.
Rapid methods to assess the chlorophyll and carotenoid content of leaves and fruits using a microplate reader
Authors: MARTINEZ J. , DAMIDAUX R.
Published: February 2008

Rapid, small‐scale, accurate and inexpensive procedures have been developed to assess pigment content of leaves and tomato fruits for plant breeding programs. New formulas allowing the use of a microplate reader instead of a spectrophotometer have been computed. The theoretical background is presented for users to calibrate their own apparatus.
Evaluation of a genetically selected strain of Steinernema feltiae against the mushroom sciarid Lycoriella mali
Authors: GREWAL P. S. , TOMALAK M. , KEIL C. B. O. , GAUGLER RANDY
Published: February 2008

The control potential of a strain (ScP) of Steinernema feltiae genetically selected against the mushroom sciarid Lycoriella solani, was evaluated for the management of L. mali. Trials were conducted at two commercial mushroom farms with high and low levels of fly infestation. The efficacy of the ScP strain was compared with the SN strain of S. feltiae and the chitin synthesis inhibitor, diflubenzuron. At low densities of L. mali, the two strains did not differ in efficacy and caused 85–94% reduction in fly populations. At high fly densities with a mixed infestation of the phorid fly, Megaselia halterata, the ScP stain caused 56–83% reduction in L. mali populations whereas the SN strain caused 51–73% reduction. Two doses of the improved strain (0.5 times 106 and 1.0 times 106 infective juveniles per m2 cropping area) did not differ in efficacy from diflubenzuron which caused 80% reduction in L. mali populations. The lower dose (0.5 times 106) of the SN strain was less effective than diflubenzuron. The ScP strain had a major advantage over the SN strain in persistence in casing material. Nematodes had no significant effect on mushroom yields.
Effect of fluchloralin on protein synthesis, free amino acids and hydroxyproline content in groundnut (Arachis hypogaea L.)
Authors: DURGESHA M.
Published: February 2008

Cultivar TMV‐2 of groundnut plant {Arachis hypogaea L.) was grown in a nutrient solution containing fluchloralin at the rate of either 2 mg litre‐1 or 4 mg litre“1. Protein synthesis and hydroxyproline content in the cell walls of roots, stem and leaves were determined. Free amino acids content and total ammonia in leaves and roots were also analysed. Presence of fluchloralin did not adversely affect protein synthesis. No significant effect of herbicide was observed on hydroxyproline content of a purified cell wall fraction of groundnut roots, stem and leaves. The total amount of ammonia increased in roots and leaves of plants which received the higher concentration of fluchloralin. With the exception of aspartic acid, asparagine, glutamic acid and glutamine, free amino acids content decreased considerably with herbicide treatment. Alanine and glycine were strongly reduced. It is suggested that transamination reactions could be affected and the process of senescence may be enhanced.
Effect of annual and biennial burning of seed alfalfa (Lucerne) stubble on populations of lygus (Lygus spp.), and alfalfa plant bug (Adelphocoris lineolatus (Goeze)) and their predators1
Authors: SCHABER B D , ENTZ T
Published: February 2008

The effects of six burning treatments combined with two insecticide treatments of alfalfa (Medicago sativa L.) stubble on alfalfa plant bug, Adelphocoris lineolatus (Goeze) and Lygus spp. populations were evaluated over an 8‐yr period (1982–1989). The burn treatments were: burning every spring and autumn, burning in alternate springs, burning at 50–100 mm and 150–200 mm of spring growth, and an unburned control. Alfalfa plant bug, which overwinters in the egg stage in alfalfa stems, were reduced by the spring burns. First generation populations of Lygus spp., were enhanced by the burn treatments before spring growth appeared, but were reduced when alfalfa was burned over 50 mm of spring growth. Counts of the minute pirate bug, Onus tristicolor White, were enhanced in 1983 by all burn treatments, and in 1985 by some of the burn treatments. Of all the predators, only spiders were significantly reduced and only in 1986 by the burned every autumn and spring treatments.