bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parasitism of grain legumes by Alectra species (Scrophulariaceae)
Authors: RICHES C. R. , HAMILTON K. A. , PARKER C. 
Published: February 2008

SummaryIn glasshouse pot experiments in the United Kingdom, the host preference of nine seed samples of Alectra vogelii from Eastern, Western and Southern Africa and of two samples of A. picta from Cameroon and Ethiopia, to cultivars of cowpea, groundnut, bambara and mung bean, was assessed. A susceptible cowpea cultivar, Blackeye, and four cultivars of groundnut were attacked by all samples of both parasitic species regardless of whether the host of origin was cowpea, groundnut or bambara.Five “strains” of A. vogelii were distinguished using two criteria: their ability to parasitise bambara and/or mung bean and their ability to parasitise cowpea B301 and bambara TVU 870. The latter proved in an associated experiment to be resistant to collections of the parasite from some locations. Strain 1, including populations from Mali, Nigeria and Cameroon, attacked all groundnuts, cowpea cultivar Blackeye, but not cowpea line B301, mung bean or bambara. Strain 2, from Botswana, differed in attacking B301 and mung bean. Three other strains were identified which attacked susceptible lines of all four legume species. Strain 3 from Kenya failed to attack either cowpea B301 or bambara TVU 870, strain 4 from Malawi attacked cowpea B301, but not bambara TVU 870, while strain 5 from Northern Transvaal, South Africa, attacked bambara TVU 870, but not cowpea B301. Cowpea B359 was resistant to A. vogelii samples from all locations and also to A. picta, which has a similar host preference to strain 1 populations of A. vogelii from West Africa. Two out of 13 groundnut lines tested showed low susceptibility to A. vogelii from Cameroon suggesting there is scope for selecting resistance in this crop also.
Improving slug baits: the effects of some phagostimulants and molluscicides on ingestion by the slug, Deroceras reticulatum (Miiller) (Pulmonata: Limacidae)
Authors: HENDERSON I. F. , MARTIN A. P. , PERRY J. N. 
Published: February 2008

SummaryThe effects of seven potential phagostimulants and of four molluscicidal compounds on feeding were examined by confining slugs with agar gels containing the chemicals in varying concentrations. Sugars generally increased the amount of gel ingested; sucrose more than glucose, lactose and fructose. Feeding increased with increasing sucrose concentration to a maximum and then fell progressively: the optimum concentration lay between 2.5% and 5%. The sweeteners saccharin and aspartame at concentrations up to 2.5% did not increase feeding. Addition of the molluscicides metaldehyde, methiocarb and ferric acetylacetonate to gels containing 2.5% sucrose progressively reduced feeding at concentrations of 0.001% and above. Metaldehyde reduced ingestion more than methiocarb and ferric acetylacetonate was intermediate. The molluscicidal herbicide Ioxynil deterred feeding completely at concentrations of 0.001%. The implications for slug bait development are discussed.
Sensitive detection of mycoplasmalike organisms in field‐collected and in vitro propagated plants of Brassica, Hydrangea and Chrysanthemum by polymerase chain reaction
Authors: BERTACCINI ASSUNTA , DAVIS ROBERT E. , HAMMOND ROSEMARIE W. , VIBIO MONICA , BELLARDI MARIA GRAZIA , LEE ING MING 
Published: February 2008

SummaryA polymerase chain reaction (PCR) protocol, previously designed for amplification of a DNA fragment from aster yellows mycoplasmalike organism (MLO), was employed to investigate the detection of MLO DNA in field‐collected and in vitro micropropagated plants. PCR with template DNA extracted from symptomatic, naturally‐infected samples of Brassica, Chrysanthemum and Hydrangea, each yielded a DNA band corresponding to 1.0 Kbp. However, no DNA product was observed when either infected Ranunculus (with phyllody disease) or Gladiolus with (symptoms of ‘germs fins’) was used as source of template nucleic acid for PCR; further experiments indicated absence of target DNA in the case of Ranunculus and the presence of substances in Gladiolus which inhibited the PCR. The MLO‐specific DNA was detected by PCR using less than 95 pg of total nucleic acid (equivalent to total nucleic acid from 1.9, ug tissue) in the case of field‐collected Hydrangea and less than 11.4 pg of nucleic acid (equivalent to total nucleic acid from 19 ng of tissue) in the case of field‐collected Brassica. The findings illustrate highly sensitive detection of MLOs in both field‐grown and in vitro micropropagated infected plants.
Use of a model and toxicity data to predict the risks to some wild plant species from drift of four herbicides
Authors: BREEZE VICTOR , THOMAS GAVIN , BUTLER RUTH 
Published: February 2008

SummaryThe dose responses of 14 wild plant species (two grasses, two legumes, one annual and nine perennial dicotyledons), not usually recognised as weeds, to four herbicides (asulam, glyphosate, MCPA and mecoprop) were measured in glasshouse experiments. Glyphosate was the most toxic; seven of the species tested had EDu, values (measured as shoot dry weight) of < 1.0 μg/plant, compared with only one species for MCPA and mecoprop. Asulam was the least toxic.Results were used to indicate the risk to each species from drift damage. A model of spray drift, based on that developed by Thompson & Ley (1982) for evaporating droplets, was rescaled to allow for field application rates and used to predict the distances travelled by given doses of herbicide. This gave acceptable agreement with reports for drift damage in the field, and predicted that only glyphosate sprayed at the highest recommended concentration might be unsafe to some of the species examined. The two herbicides sometimes used as volatile formulations (MCPA and mecoprop) did not cause damage at the small doses likely to result from exposure to vapour in the field.
Partial antibiosis to Rhopalosiphum padi in wheat and some phytochemical correlations
Authors: KAZEMI M. H. , van EMDEN H. F. 
Published: February 2008

SummaryThe fecundity of the aphid Rhopalosiphum padi during the first ten days of reproduction was measured on five wheats at three growth stages. The wheats were of UK and Iranian origin, but also involved both spring and winter wheats as well as hexaploid and tetraploid types. Aphids which had already been reared on the respective variety for at least one generation were transferred to the experimental plants. The tetraploid Emmer showed some resistance in comparison with the hexaploid UK varieties at later growth stages, whereas the Iranian variety Moghan 2 appeared relatively resistant only at the tillering stage. The other Iranian variety, Ommid, was resistant at all growth stages, and appears to be the most resistant hexaploid wheat variety to R. padi so far identified.Correlations of aphid fecundity with plant chemistry were attempted with total phenolic compounds, hydroxamic acids and amino acids. All three of these chemical groups have previously been reported as correlated with plant resistance to cereal aphids. Even just for the results at the tillering stage, no correlation could be found for phenolics or hydroxamic acids, but a multiple regression based on the levels of alanine, histidine and threonine accounted for over 95% of the variation in aphid fecundity at all 15 data points (5 wheats × 3 growth stages). No cause or effect relationship is necessarily implied.
Vector specificity of barley yellow dwarf virus serotypes and variants in southwestern Idaho
Authors: HALBERT SUSAN E. , CONNELLY B. JUNE , LISTER RICHARD M. , KLEIN ROBERT E. , BISHOP GUY W. 
Published: February 2008

SummaryPlants with symptoms of barley yellow dwarf virus (BYDV) obtained in infection feeding assays of aphids collected in the field in Idaho between 1986 and 1988 were tested for virus transmissibility by possible aphid vectors. Isolates obtained during 1987–1988 were also tested with a range of polyclonal antisera which distinguished PAV, MAV, SGV, RPV and RMV serotypes. In 1989 some Idaho (ID) BYDV isolates, maintained as standards for comparison, were serotyped and tested for aphid transmissibility, using 11 species of aphids.There was not always the expected correspondence between serotype and vector specificity for ID isolates. For isolates obtained from field‐collected Rhopalosiphum padi, vector transmissibility and serotype corresponded with previous reports; however, 44% of isolates which were serotyped as RMV were also transmissible by species other than Rhopalosiphum maidis. Similarly, the transmissibility of the ID laboratory standards did not always conform to the reported vector specificity of serotypes. The laboratory ID‐MAV culture was transmitted by Metopolophium dirhodum and Myzus persicae as well as by Sitobion avenae. The laboratory ID‐SGV culture was transmitted by R. padi and 5. avenae as well as by Schizaphis graminum. The ID‐RPV culture was transmitted by S. graminum and Rhopalosiphum insertum as well as R. padi. Both of two laboratory ID‐RMV cultures were transmissible by R. insertum and R. padi transmitted one of them. The results indicate that, for isolates collected in Idaho, vector specificity cannot be assumed from their serotypes.
Ultrastructural changes associated with June Yellows in strawberry and with leaf yellowing symptoms of viral and genetic origin in Fragaria, Rubus and Ribes
Authors: WATKINS C. A. , ROBERTS I. M. , JONES A. T. 
Published: February 2008

SummaryLight and electron microscopy was used to study the ultrastructural effects of June Yellows (JY) in leaves of strawberry. Four cultivars of strawberry, affected to different extents by JY, were compared with healthy (JY‐free) cv. Cambridge Favourite and with strawberry infected with strawberry crinkle rhabdovirus, Fragaria vesca infected with strawberry mottle virus (SMotV), raspberry and black currant showing virus‐induced yellowing and with strawberry and raspberry showing chaemeric yellow sectors in the leaves. Except for isometric virus‐like particles detected in SMotV‐infected F. vesca, no virus‐like particles or structures of other pathogenic agents were found in any of the tissues examined. Leaf cells of JY‐affected strawberry showed severe disruption of chloroplasts and plasmalemma, whorls of membranous vesicles and decreased vacuole size. The extent and severity of these abnormalities increased with increased severity of JY symptoms but, even in leaves with mild JY symptoms, chloroplast abnormalities were obvious. In the most severely affected leaves, the cells lacked discrete vacuoles and extensive hypertrophy was seen in other organelles such as nuclei and mitochondria. Few, if any, ultrastructural abnormalities were observed in virus‐infected strawberry or F. vesca, or in chaemeric leaves of strawberry and raspberry. By contrast, in raspberry and black currant with yellowed leaves caused by virus infection, the cells showed enlarged chloroplasts, decreased vacuole size and vesicle formation. However, chloroplast enlargement and disruption in this material seemed due to increased size of starch grains which were largely absent from swollen chloroplasts of JY‐affected strawberry. The ultrastructural abnormalities observed in JY‐affected strawberry are, therefore, not inconsistent with the possibility that a pathogenic agent may be involved in the condition.
Stem canker (Rhizoctoniu solani) on three early and three maincrop potato cultivars: effects of seed tuber size on growth and yield
Authors: HIDE G. A. , READ P. J. , HALL SHARON M. 
Published: February 2008

SummaryLarge seed tubers (mean 134 g) and small seed tubers (50 g) of three early and three maincrop potato cultivars, spaced respectively 48 and 30 cm apart within rows, were inoculated with Rhizoctonia solani at planting in 1985 and 1986. All seed of early cultivars was sprouted and maincrop seed was either sprouted or not sprouted.In all cultivars, plant emergence was slower from small than large seed and with both was delayed by inoculation. From 11 wk after planting numbers of stems and tubers and weights of foliage and tubers/m2 were usually similar from small and large seed when not inoculated, but inoculating delayed plant growth and decreased tuber numbers and yield more from small than large seed.Inoculating decreased mean yields from large and small seed of early cultivars at 11 wk by respectively 24% and 31% (Arran Comet), 12% and 18% (Estima) and by 10% and 28% (Wilja) and losses were greatest with saleable sized tubers (3–4 cm). When grown to maturity inoculating decreased yields by 7% (Arran Comet), 5% (Estima) and 14% (Wilja).With maincrop cultivars, yields in October from large and small seed were decreased by respectively 4% and 10% (DCsirke), 9% and 12% (Maris Piper) and by 14% and 22% (Pentland Squire). In all cultivars yields of tubers < 44 mm and 44–70 mm were decreased and, with Pentland Squire, tubers > 82 mm were increased.The incidence of stem canker and of black scurf on progeny tubers was not affected by seed size but in all cultivars the percentage of greened tubers was slightly increased by inoculation.
Almond brown line and decline: a new disease probably caused by a mycoplasma‐like organism
Authors: UYEMOTO J. K. , CONNELL J. H. , HASEY J. K. , LUHN C. F. 
Published: February 2008

SummaryYoung almond (Prunus dulcis, cvs Carmel, Peerless and Price) orchards established on the plum rootstock Marianna 2624 (P. cerasifera×P. munsoniana) contained trees that exhibited poor terminal shoot growth and wilted, chlorotic leaves. The scion/rootstock graft union showed an external splitting of the bark and an internal line of necrotic bark tissues that extended into the woody cylinder of the union, which was deeply pitted. Affected trees declined. The disease was named almond brown line and decline (ABLD). Incidence of ABLD ranged up to 55% per cultivar in some orchards. Numerous attempts to graft‐transmit orchard collections of ABLD to healthy almond/Marianna 2624 indicators failed. Also, ABLD does not appear to be soil‐borne. However, ABLD was serendipitiously determined to be bud‐perpetuated when infected scion buds from an apparently healthy appearing Peerless almond/peach tree located in a foundation orchard were grafted onto healthy rooted cuttings of Marianna 2624 to produce yearling trees. Also, graft‐inoculations on the almond scion portion of healthy trees, but not the plum rootstock portion, with the peach yellow leafroll mycoplasma‐like organism (PYLR‐MLO) caused symptoms resembling ABLD. Laboratory and glasshouse assays of several symptomatic trees did not detect tomato ringspot virus and two ilarviruses. These results suggest that an MLO, possibly PYLR‐MLO, may be the causal agent of ABLD and that Marianna 2624 is probably resistant to the PYLR‐MLO.
Sri Lankan passion fruit mottle virus, a potyvirus infecting golden passion fruit in Sri Lanka
Authors: DASSANAYAKE E. M. , HICKS R. G. T. 
Published: February 2008

SummaryA sap‐transmissible virus, provisionally named Sri Lankan passion fruit mottle virus (SLPFMV), was isolated from Passiflora edulis f. flavicarpa and shown to induce leaf mottling and distortion in that host. The virus infected 23 species in five plant families with systemic infection being common in the Passifloraceae. Chenopodium amaranticolor was a good local lesion host and Passiflora foetida was a useful systemic host for purification. In P. foetida extracts, SLPFMV lost infectivity after 10 min between 70–75°C, 6–7 days at 20–23°C and at dilutions of 10‐‐5 ‐W‐6. The virus had flexuous, filamentous particles with a normal length of c. 841 nm. Two polypeptides of mol. wt c. 33 200 and 28 700 were detected in purified virus preparations, and a major species of double‐stranded RNA (mol. wt 7.0 × 106), was detected in infected plants. Pinwheels, tubular and laminated inclusions were found in ultrathin sections of infected P. edulis f. plavicurpa and cylindrical inclusions were observed in epidermal strips.SLPFMV was transmitted by the aphids Myzus persicae, Aphis spiraecola, A. gossypü and A. cruccivora after brief acquisition feeds. SLPFMV reacted with antisera to several potyviruses including passion fruit woodiness virus, passion fruit ringspot virus, potato virus Y and watermelon mosaic virus 2 and thus, apparently, is a member of the potyvirus group.
Transmission of Pythium aphanidermatum to greenhouse cucumber by the fungus gnat Bradysia impatiens (Diptera: Sciaridae)
Authors: JARVIS W. R. , SHIPP J. L. , GARDINER R. B. 
Published: February 2008

SummaryThe fungus gnat (Bradysia impatiens) was examined for its ability to transmit Pythium aphanidermatum to cucumber plants. Larvae that had ingested oospores and mycelium, and then fed on the roots of young cucumber plants growing in rockwool readily introduced the fungus to them. Trans‐stadial transmission of oospores from the larval to the adult stage of B. impatiens was demonstrated, although decreasing to a very low level (1.67%) in adults. However, external transmission of P. aphanidermatum on the surface of adults could not be shown. These results suggest that the larval stages of fungus gnats play a role in the dissemination of the fungus between cucumber plants but that adults probably play only a minor role.
Susceptibility to purple blotch (Alternaria porri) in garlic (Allium sativum)
Authors: BISHT I. S. , AGRAWAL R. C. 
Published: February 2008

SummaryExperiments were conducted to study the progress of purple blotch disease of garlic caused by Alternuria porri in the field, to determine the relationship between garlic leaf age and susceptibility to Alternaria porri, and also to assess loss in bulb characters due to purple blotch of garlic. Per cent disease severity and number of purple blotch lesions on four garlic genotypes of known susceptibility, Sel‐10 (highly susceptible), G‐41 (highly susceptible), IC‐49382 (moderately susceptible) and IC‐49373 (moderate to less susceptible) were monitored from bulb formation to bulb maturity at weekly intervals. Lesions appeared early on highly susceptible cultivars, Sel‐10 and G‐41. Rapid progress of disease development was noticed during the last 3 wk before bulb maturity. Peak severity at the maturity of the crop was significantly higher on highly susceptible genotypes. No definite correlation could be established between number of lesions and disease severity. A logistic curve was fitted to predict the disease progress on different weeks before bulb maturity. Levels of leaf tissue found damaged by A. porri at weekly intervals from bulb initiation to bulb maturity were significantly lower on younger leaves than on older leaves. Leaves that emerged 7 wk before bulb maturity required more than a 5 wk period to reach 50% leaf damage, whereas leaves emerging 2, 3 and 4 wk before bulb maturity exceeded 50% leaf damage within a 2–3 wk period. Individual garlic leaves became more susceptible to purple blotch as they aged and emerging leaves were more susceptible the closer they emerged to bulb maturity. Per cent loss in bulb weight and bulb volume was found to be significantly higher on highly susceptible genotypes. No significant reduction in number of cloves/bulb was observed. We propose 4 wk before bulb maturity as the action threshold for initiation of fungicidal application to prevent damaging levels of disease.
Study of multiplication of cucumber mosaic virus in susceptible and resistant Capsicum annuuum lines
Authors: NONO‐WOMDIM R. , GEBRE‐SELASSIE K. , PALLOIX A. , POCHARD E. , MARCHOUX G. 
Published: February 2008

SummaryA previous survey on pepper lines (Capsicum annuum L.) indicated that a susceptible cultivar, Yolo Wonder, reacted to cucumber mosaic virus (CMV) by producing a systemic yellow mosaic. By contrast, CMV caused no symptoms on lines Perennial and Vania. The virus is recoverable from the uninoculated leaves of Perennial, while in Vania CMV is restricted to the inoculated leaves. To interpret these phenomena, a comparative study on CMV multiplication rates, yield, specific infectivity and relative proportion of RNAs was made in the inoculated leaves of the three pepper varieties. The rate of CMV multiplication, as estimated by the double antibody sandwich form of enzyme‐linked immu‐nosorbent assay, was lower in Perennial than in Vania or Yolo Wonder. The yield of virus purified from Perennial was very low when compared with Vania or Yolo Wonder. The specific infectivity of the virus extracted from Perennial was less than that from Vania or Yolo Wonder. These results suggest that Perennial is resistant to CMV multiplication, while restriction of the virus in inoculated leaves of Vania is not due to the inhibition of the virus replication. However, polyacrylamide gel electrophoresis revealed that the RNA profiles of CMV purified from the three pepper lines were similar.
Interaction between two synthetic pyrethroids and the spread of two non‐persistent viruses in cowpea
Authors: ROBERTS JULIA M. F. , HODGSON C. J. , JACKAI L. E. N. , THOTTAPPILLY G. , SINGH S. R. 
Published: February 2008

SummaryThe effectiveness of the synthetic pyrethroids deltamethrin and lambda‐cyhal‐othrin in preventing (i) aphid colonisation of four cowpea cultivars with different levels of aphid resistance and (ii) the introduction and subsequent spread of cowpea aphid‐borne mosaic virus and cucumber mosaic virus was investigated under tropical field conditions.Sprays of these pyrethroids eight days apart prevent aphid colonisation and within crop spread of virus by the colonising Aphis craccivora. However, neither deltamethrin nor lambda‐cyhalothrin prevented the initial introduction of virus into the cowpea crop and, when incoming alate incidence was high, virus incidence was higher in the sprayed than in the unsprayed plots. In addition, the degree of aphid resistance of each cultivar affected secondary virus spread within the crop, with greatest spread in the most resistant cultivar.
Classification of cowpea cultivars for field resistance to the legume pod borer, Muruca testulalis in Nigeria using cluster analysis
Authors: OGHIAKHE S. , ODULAJA A. 
Published: February 2008

SummaryCluster analysis was used to classify cowpea cultivars developed for resistance to M. testulalis in Nigeria based on data collected on four damage parameters. The cultivars were grouped into classes for each of two locations under two protection regimes. Differences were observed in the groupings for the two locations while one cultivar, MR×6–84F was found to have wide adaptability in the presence or absence of M. testulalis infestation. This is particularly useful for the selection of breeding materials in cultivar improvement for specific or general ecological zones.
Exploitation of the resistance to carrot fly in the wild carrot species Daucus capillifolius
Authors: ELLIS P. R. , HARDMAN J. A. , CROWTHER T. C. , SAW PAMELA L. 
Published: February 2008

SummaryUnder field conditions a wild Daucus species from Libya, D. capillifolius, supported less than one tenth as many carrot flies (Psila rosae) as the susceptible carrot cultivar Danvers Half Long 126. Breeding lines developed from crosses between D. capillifolius and three different carrot types were grown in a series of field experiments at Wellesbourne between 1980 and 1989. Each year selections were made for agronomic quality and/or for increased resistance to carrot fly. The programme produced lines which for size, shape and colour represented most of the commercially‐important carrot types. Some of these lines were also significantly more resistant to carrot fly than selections from the partially‐resistant cv. Sytan. However, the best lines were not as resistant as the wild parent. The highest quality resistant lines were sold to seed companies for variety production.