bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forecasting of peak population density of the rose grain aphid Metopolophium dirhodum on wheat
Authors: HOWARD M. T. , DIXON A. F. G. 
Published: February 2008

SUMMARYSuction trap catches for the period 1969 to 1984 were used to develop a forecasting system for M. dirhodum. This was achieved by using the strong relationships that exist between: a) suction trap catches of Metopolophium dirhodum at Broom's Barn and populations of the aphid in fields near Norwich, and b) winter and spring temperatures and the time when the crop became unsuitable for this aphid.This forecasting system was tested in 1985, 1986, 1987 and 1988 and successfully forecast early in the season that it would not be necessary to apply aphicides in 1987 and 1988. The use of this forecasting system would have correctly indicated that aphicide application against this aphid was unnecessary in 9 out of the 16 seasons from 1969 to 1984.
Double‐stranded RNA analysis of strawberry plants affected by June yellows
Authors: WATKINS C. A. , JONES A. T. , MAYO M. A. , MITCHELL M. J. 
Published: February 2008

SUMMARYUsing an improved method for extraction of dsRNA from strawberry leaf tissue, small quantities of several dsRNA species with mol. wt greater than 1.0 × 106were detected in strawberry plants free from known strawberry viruses but affected by June yellows (JY). No such dsRNA species were detected in plants of Fragaria vesca or seven strawberry cultivars known to be free from JY. Neither JY symptoms nor these dsRNA species were detected in healthy strawberry and F. vesca plants graft‐inoculated with tissue from JY‐affected plants. It is not known whether the JY‐associated dsRNA species are those of a causal agent of JY or are a consequence of the JY condition. Nevertheless, the detection of such dsRNA species in plants affected by JY may offer a possible objective method for detecting the incipient condition in symptomless strawberry plants. However, the concentrations of dsRNA in JY‐affected plants are very low and dsRNA analysis is thought not to be sufficiently reliable for routine testing of plants. The occurrence of anomalous dsRNA species in extracts from some strawberry plants was caused by dsRNA from two‐spotted spider mites (Tetranychus urticae) infesting the plants.
Different variants of the satellite RNA of groundnut rosette virus are responsible for the chlorotic and green forms of groundnut rosette disease*
Authors: MURANT A. F. , KUMAR The late I. K. 
Published: February 2008

SUMMARYGroundnut plants with symptoms of rosette disease contain groundnut rosette virus (GRV), but GRV is transmitted by Aphis craccivora only from plants that also contain groundnut rosette assistor virus (GRAV). Two main forms of rosette disease are recognised, ‘chlorotic rosette’ and ‘green rosette’. GRV cultures invariably possess a satellite RNA and this is the major cause of rosette symptoms: satellite‐free isolates derived from GRV cultures from Nigerian plants with chlorotic or green rosette, or from Malawian plants with chlorotic rosette, induced no symptoms, or only transient mild mottle or interveinal yellowing, in groundnut. When the satellite RNA species from GRV cultures from Nigerian green or Malawian chlorotic rosette were reintroduced into the three satellite‐free isolates in homologous and heterologous combinations, the ability to induce rosette symptoms was restored and the type of rosette induced was that of the cultures from which the satellite RNA was derived. Thus different forms of the satellite are responsible for the different forms of rosette disease. Other forms of the satellite induce only mild chlorosis or mottle symptoms in groundnut. Individual plants may contain more than one form of the satellite, and variations in their relative predominance are suggested to account for the variable symptoms (ranging from overall yellowing to mosaic) seen in some plants graft‐inoculated with chlorotic rosette.
The interaction between lodging and plant population in combining peas
Authors: PULLAN M. R. , HEBBLETHWAITE P. D. 
Published: February 2008

SUMMARYThe effects of preventing lodging in three varieties of combining peas with contrasting standing ability were studied over a range of plant populations and in two growing seasons.Maximal yield losses resulted when lodging occurred prior to the end of the flowering period. The likelihood of this event occurring was increased by high populations and was maximised when such populations were used in conjunction with conditions suitable for vigorous plant growth. In such seasons, optimum plant populations (30 plants m‐2) were seen to be very much below those currently recommended.When conditions were less favourable to plant growth, lodging tended to occur after flowering had ceased. Little yield loss due to population effects were then recorded. Under such conditions, yields were maximised by high plant populations. Under all growing conditions, little yield loss due to interplant competition was noted with increasing plant populations.It was concluded from these results that if combining pea production is to be successfully expanded out of traditional production areas, plant population recommendations should be lowered to compensate for increased plant vigour.
Inhibition of degreening in the peel of bananas ripened at tropical temperatures.
Authors: BLACKBOURN H. D. , JEGER M. J. , JOHN P. , TELFER A. , BARBER J. 
Published: February 2008

SUMMARYFunctional and structural changes in peel tissue have been followed by analysing fluorescence induction curves and the lipid composition during the ripening of bananas (Musa AAA, Subgroup Cavendish) at 20°C and 35°C. Changes in the fluorescence induction curves indicated that electron transport capacity was lost more rapidly at 35°C than at 20°C, thus revealing that the chlorophyll retained by bananas ripened at 35°C soon becomes non‐functional photosynthetically, probably because of serious disturbances in thylakoid organisation during ripening at tropical temperatures. By contrast, in plantains (Musa Group AAB, Plantain Subgroup), where degreening is complete at both 20°C and 35°C, the loss of electron‐transport capacity closely corresponds to the loss of chlorophyll. The lipid composition of unripe banana peel resembled other photosynthetic tissue in possessing a high proportion of mono‐ and digalactosyl diacylglycerols, containing predominantly polyunsaturated fatty acids, particularly linolenic acid. Following ripening for four days at 20°C, when degreening was complete, some 50% of the galactolipids had broken down, and the polyunsaturated fatty acids were recovered in the neutral lipid fraction. By comparison, after ripening at 35°C there was a greater loss of galactolipids, and a lower overall recovery of linolenic acid. The significance of these findings for the stability of the chlorophyll‐protein complexes during the incomplete degreening of bananas at tropical temperatures is discussed.
Inhibition of degreening in the peel of bananas ripened at tropical temperatures.
Authors: BLACKBOURN H. D. , JEGER M. J. , JOHN P. 
Published: February 2008

SUMMARYA linolenate‐dependent chlorophyll oxidase activity resembling the activity considered responsible for chlorophyll bleaching in senescing leaves has been studied in thylakoids isolated from the peel of bananas (Musa AAA, Subgroup Cavendish). While the degreening of bananas is inhibited as the temperature was raised above 24°C, chlorophyll oxidase activity increased linearly as the temperature was raised from 20°C to 40°C. Cyanide inhibits the chlorophyll oxidase activity in vitro, but the increased amounts of cyanide produced by banana peel ripened at high temperatures do not accumulate, despite the fact that β‐cyanoalanine synthase activity, which effectively traps the cyanide, remains relatively unaffected by the increased temperature. The association of chlorophyll oxidase activity with the functional and structural organisation of the light‐harvesting complexes and photosystems is discussed in relation to the inhibition of degreening in the peel of Cavendish bananas ripened at tropical temperatures.
Biological control of Dutch elm disease: Larvicidal activity of Trichoderma harzianum, T. polysporum and Scytalidium lignicola in Scolytus scolytus and S. multistriatus reared in artificial culture
Authors: JASSIM H. K. , FOSTER H. A. , FAIRHURST C. P. 
Published: February 2008

SUMMARYA method is described for the culture of larvae of Scolytus multistriatus and Scolytus scolytus on an artificial medium following exposure to cultures of microorganisms. In control cultures, a natural mortality rate of 21.2% was found for S. multistriatus and 17.6% for S. scolytus. The effects of Trichoderma harzianum, T. polysporum and Scytalidium lignicola on fifth instar larvae of S. scolytus and S. multistriatus reared on the artificial medium were studied. The fungi were larvicidal and larval mortality was increased to more than 80% by inoculation of the larvae with the fungi. Another fungus, Phomopsis oblonga, had little effect on larvae of S. scolytus. The results are discussed in relation to mechanism of pathogenicity of the fungi and their potential use in the control of Dutch elm disease. It is proposed that with modifications, the method is applicable to other bark beetle pests.
Damage to oilseed rape seedlings by the field slug Deroceras reticulatum in relation to glucosinolate concentration
Authors: GLEN D. M. , JONES H. , FIELDSEND J. K. 
Published: February 2008

SUMMARYSeedlings of nine commercial cultivars of oilseed rape were exposed to the field slug Deroceras reticulatum immediately after sowing in compost in trays. There was a small reduction in seedling numbers in the presence of slugs which was not related to glucosinolate concentration in seeds or seedlings. However, the number and leaf‐area of seedlings with damage symptoms were strongly and inversely related to the total concentration of glucosinolates in seeds and one wk‐old seedlings. The presence of barley seedlings as alternative food did not significantly affect this relationship. The glucosinolate concentration of seeds was closely correlated with that of wk‐old seedlings. Analysis of individual glucosinolates in four cultivars spanning the range of concentrations found, showed that the concentration of most components declined as total glucosinolate concentration decreased. However, 2‐phenyl ethyl‐glucosinolate (gluconasturtiin) concentration tended to increase in seeds and 3‐indolyl methyl‐glucosinolate (glucobrassicin) increased in seedlings as total glucosinolate concentration decreased. Damage by slugs was inversely related to the concentration of those glucosinolates which decreased and was positively correlated with the two compounds which increased as total glucosinolate concentration decreased. The results support the hypothesis that glucosinolates in brassicas protect them from polyphagous herbivores, and, in particular, that an important function of glucosinolates in rape seeds is to protect seedlings from slugs. As glucosinolate concentrations of oilseed rape cultivars continue to decline, so the risk of slug damage to seedlings may well increase.
Resistance in groundnut (Arachis hypogaea L.) to Aphis craccivora (Koch).
Authors: PADGHAM D. E. , KIMMINS F. M. , RAO G. V. RANGA 
Published: February 2008

SUMMARYThe behaviour, development and reproductive capacity of Aphis craccivora, vector of a number of groundnut viruses, are compared on a range of susceptible and resistant genotypes. Field trials demonstrated no significant difference between genotypes in the rate of arrival of alates, but population development was slower, and subsequent population decline faster, on the genotype EC 36892 (ICG 5240). Behavioural studies in the screenhouse, likewise showed no inhibition to alighting onto EC 36892 though choice tests demonstrated a significant redistribution of the population in favour of the susceptible genotype TMV 2 (ICG 221) over the following 10 h. In clip cage experiments, development was faster and nymphal numbers were higher on the genotype TMV 2 compared to EC 36892.
Induction of edible sclerotia of Pleurotus tuber‐regium (FR) Sing, in the laboratory
Authors: OKHUOYA J. A. , OKOGBO F. O. 
Published: February 2008

SUMMARYIn the field, sclerotia of Pleurotus tuber‐regium were found in dead trees and fallen logs of Daniella oliveri. Sclerotia of P. tuber‐regium were produced in the laboratory when the fungus was cultured in moist drill dusts of D oliveri and Elaeis guineensis. The resulting sclerotia were viable and had features similar to those found in the natural habitat.
Mycological studies on the equine intestinal tract with particular reference to equine dysautonomia (grass sickness)
Authors: DOXEY D. L. , ROBB JEAN , MILNE E. M. , GILMOUR J. S. 
Published: February 2008

SUMMARYA wide variety of non‐endophytic fungi was isolated from the stomach, colon and rectum of healthy horses, horses suffering from equine dysautonomia and horses suffering from other disorders clinically resembling dysautonomia. Of the isolates with toxin‐producing potential, species of Aspergillus and Penicillium predominated. Absidia spp. occurred in virtually all horses and Rhizopus was very common, but neither is known to produce toxins. The survey did not associate any particular fungal species with equine dysautonomia.
Some effects of hop latent viroid on two cultivars of hop (Humulus lupulus) in the UK
Authors: BARBARA D. J. , MORTON A. , ADAMS A. N. , P.GREEN C. 
Published: February 2008

SUMMARYSome effects of infection by hop latent viroid (HLVd) on two commercial plantings of hop, one each of two high alpha‐acid cultivars, are described. The cultivar Omega was severely affected: yield of cones and individual cone weights from infected plants were both lower than from uninfected plants by c. 35% and the alpha‐acids content (as assessed by HPLC) of the cones c. 30% lower. Wye Northdown was less severely affected: cone weight was 8% less (though this was not statistically significant) and alpha‐acids content lower by c. 15%. In both cultivars beta‐acids were higher in infected plants which, together with differences in other chemical components, suggested that cones on infected plants had matured, or were maturing, earlier than those on uninfected plants.These effects, together with the previous finding that HLVd occurs frequently in some cultivars (Barbara, Morton & Adams, 1990), suggest that HLVd is a potentially important constraint on hop production in the UK and should be eliminated if possible.
Variations in the “cross protection” effect between two strains of citrus exocortis viroid
Authors: DURAN‐VILA N. , SEMANCIK J. S. 
Published: February 2008

SUMMARYIn a survey conducted to evaluate the biological properties of several field sources that induced a severe exocortis reaction on citron (Citrus medica L.), a viroid isolate which induced mild symptoms on Gynura aurantiaca was detected. This isolate was characterised as a strain of the citrus exocortis viroid (CEV) by size and homology, and was designated as CEV‐129. Cross protection assays using CEV‐129 as a “protecting” strain against the severe type strain of CEV demonstrated that a mild strain of CEV could provide apparent ‘protection’ against challenge inoculations with the severe strain. The protection effect, however, displayed a variability which ranged from only a brief delay to almost total impairment of symptom expression. The level of protection was dependent upon the length of the interval between the inoculations with the mild and the severe strains. In all cases the effect was temporary since the symptoms and viroid concentration which ultimately prevailed reflected the predominance of the severe strain in the mixed infection. The interpretation of these results and their relationship with previous reports of ‘cross protection’ reactions are discussed along with the consideration of the efficacy and limitations of this term with viroid infection.
The nature of the resistance in groundnut to rosette disease
Authors: BOCK K. R. , MURANT A. F. , RAJESHWARI R. 
Published: February 2008

SUMMARYGroundnut rosette disease is caused by a complex of three agents, groundnut rosette virus (GRV) and its satellite RNA, and groundnut rosette assistor virus (GRAV); the satellite RNA is mainly responsible for the disease symptoms. Groundnut genotypes possessing resistance to rosette disease were shown to be highly resistant (though not immune) to GRV and therefore to its satellite RNA, but were fully susceptible to GRAV.
The identification and fitness of virulent potato cystnematode populations (Globodera pallida) selected on resistant Solarium vernei hybrids for up to eleven generations
Authors: TURNER SUSAN J. 
Published: February 2008

SUMMARYSelection of Globodera pallida populations on resistant Solanum vernei‐hybrids resulted in distinct virulent strains after eleven generations.Some of these virulent populations were assessed on their environmental fitness under field‐type conditions. All reproduced less well in unsterilised soil, but virulent populations were less affected by environmental variation than their avirulent counterparts. Evaluation of their reproductive ability could not equate virulence to overall enhanced or reduced genotypic fitness compared with their avirulent counterparts.These populations were shown to be genetically distinct from their unselected counterparts using isoelectric focusing and specific enzyme staining. The control and management of virulent G. pallida populations is discussed.
Seed vigour and water relations in wheat
Authors: NAYLOR ROBERT E. L. , GURMU MULUGETA 
Published: February 2008

SUMMARYThe laboratory germination (criterion radicle emergence) of seven seed lots of winter wheat cv. Slejpner was similar. However, they differed in vigour as demonstrated by differences in germination after controlled deterioration carried out at a range of seed moisture contents, at two temperatures and for different times. A vigour assessment for each lot was quantified by calculating a value for the seed lot constant Ki, of the viability equation.Germination in lower water potentials reduced the uptake of water, radicle and coleoptile emergence and radicle and coleoptile extension. There was no difference in the water uptake of seed lots differing in vigour. However, seed lots of lower vigour showed less radicle emergence, less coleoptile emergence and shorter radicles than higher vigour seed lots in low water potentials. Similarly, controlled deterioration resulted in reduced radicle and coleoptile emergence and growth compared to unaged seed, and also to a greater sensitivity to low water potentials.The implications for field establishment are discussed.
Evaluation of defined‐area trapping for estimating the density of the field slug Deroceras reticulatum (Müller)
Authors: FERGUSON C. M. , HANKS C. B. 
Published: February 2008

SUMMARYA novel quantitative method (defined‐area trapping) devised in New Zealand for sampling slugs was tested in pastures in the UK and compared with cold water extraction processes and surface searching. Despite the different soils and conditions compared with New Zealand, the technique gave results for the UK comparable with accepted methods of estimating slug density with savings in time and labour and provided a non‐destructive means of sampling for slugs.
The effects of sowing date and planting method on stem borer damage in dauro millet
Authors: AJAYI OLUPOMI , LABE D. A. 
Published: February 2008

SummaryIn field trials conducted at Samaru, Nigeria in 1983, 1984 and 1985, damage to dauro millet by the millet stem borer, Coniesta ignefusalis Hampson (Lepidoptera: Pyralidae), varied between years and dates of planting. The crop was almost completely destroyed by the stem borer during 1984. Based on 1983 and 1985 data, the period between 10 July and 2 August appears to be best for planting dauro millet at Samaru for least stem borer damage while planting between 11 and 30 July appears to be optimum for grain yields.The direct sown crop suffered more damage than the transplanted crops in all years but only in 1985 was the difference significant. There was no significant difference between slant and upright transplanting in terms of stem borer damage and grain yield. It is concluded, therefore, that the choice of planting method would depend on its convenience to the farmer.
Phytophthora cryptogea root rot of tomato in rock woo] nutrient culture. II. Effect of root zone temperature on infection, sporulation and symptom development
Authors: KENNEDY R. , PEGG G. F. 
Published: February 2008

SummaryThe effect of root‐zone temperature on Phytophthora cryptogea root rot was studied in tomato cv. Counter grown under winter and summer conditions in rockwool culture. A nutrient temperature of 25°C resulted in increased root initiation and growth, higher in winter‐grown than in summer‐grown plants. Rhizosphere zoospore populations were greatly reduced at 25°C and above.Growth of P. cryptogea in vitro was optimal between 20°C and 25°C and completely suppressed at 30°C. Encystment was enhanced by increased temperatures above 20°C. Zoospore release in vitro occurred in cultures maintained at constant temperatures in the absence of the normal chilling stimulus. Optimal release was at 10°C; no zoospores were released at 30°C.Inoculated, winter‐grown tomato plants maintained at 15°C developed acute aerial symptoms and died after 21 days. Comparable plants grown at a root‐zone temperature of 25°C remained symptomless for the 3‐months duration of the experiment. Summer‐grown infected plants at the higher root temperature wilted but did not die. Enhanced temperature was ineffective as a curative treatment in summer‐grown plants with established infection.Aerial symptoms of Phytophthora infection are seen as a function of the net amount of available healthy root. With high root zone temperatures this is determined by new root production and decreased inoculum and infection.
Distinction of strains of bean common mosaic virus and blackeye cowpea mosaic virus using antibodies to N‐ and C‐ or N‐terminal peptide domains of coat proteins
Authors: KHAN JAWAID A. , LOHUIS H. , GOLDBACH R. W. , DIJKSTRA JEANNE 
Published: February 2008

SummaryEarlier attempts to discriminate serologically strains NL1, NL3 and NY15 of bean common mosaic virus (BCMV) and strain W of blackeye cowpea mosaic virus (B1CMV) had been unsuccessful. Antibodies directed towards N‐ and C‐, or N‐terminal peptide regions of the coat proteins of the above strains enabled the distinction between B1CMV‐W, BCMV‐NY15 and BCMV‐NL3 in electroblot immunoassay and in ELISA. The distinction was better with antibodies directed towards N‐termini than with those to N‐ and C‐termini. Strain NL1 of BCMV cross‐reacted with both B1CMV‐W and BCMV‐NY15, but not with BCMV‐NL3. Taxonomic implications of these findings are discussed.