bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of infection by the endophytic fungus Acremonium lolii on growth and nitrogen uptake by perennial ryegrass (Lolium perenne) in flowing solution culture
Authors: LEWIS G C , BAKKEN A K , MACDUFF J H , RAISTRICK N. 
Published: February 2008

Summary.Clonal tillers of a genotype of perennial ryegrass (Lolium perenne), either with or without the endophytic fungus Acremonium lolii, were grown under natural light in flowing nutrient solutions with mineral N maintained automatically at concentrations of 3 or 30μm NH4NO3 for 28 days. Uptake of N was monitored daily and dry matter production was assessed by sequential harvesting. The presence of endophyte had no significant effect on shoot or root biomass production at either N level, but shoot: root ratios were significantly increased by endophyte infection at both N levels at some harvests. All plants absorbed NH4+ preferentially to NO3‐ and the ratio was not affected by endophyte infection. Also, infection did not affect total N content of plants, which was significantly more in plants at the higher N level than at the lower level. It is concluded that endophyte infection had only minor effects on growth and N economy of the plant, under the conditions imposed in this experiment.
Analysis of the occurrence and distribution of tobacco rattle virus in field soil and disease in a subsequent tulip crop
Authors: PLOEG ANTOON T , ZOON FRANS C , BREE JOOP DE , ASJES CEES J 
Published: February 2008

Summary.The occurrence and distribution of tobacco rattle virus (TRV) in field plots was determined by soil bait‐testing and disease incidence in tulips subsequently grown on these plots was studied. The virus occurred in patches, calculated as 1.5 m × 3.6 m. The presence of virus was not correlated with numbers of potential vector trichodorid nematodes. Of three trichodorid nematode species present, only Paratrichodorus teres transmitted TRV which, as with virus isolates obtained in bait‐tests and from infected tulips, reacted in serological tests with an antiserum prepared against a Dutch isolate of pea‐early browning virus (PEBV). Virus prevalence in a subsequent tulip crop was 0.8% and in a sample of tulip plants, virus was recovered only from plants showing virus symptoms. Plots from which TRV was recovered in bait‐tests yielded significantly more virus diseased tulips than plots which tested negative for virus. Growing bait‐plants in field‐plots, as compared with greenhouse tests using soil collected as a series of sub‐samples, resulted in an underestimate of the occurrence of TRV.
Resistance of tomato infected with cucumber mosaic virus satellite RNA to potato spindle tuber viroid
Authors: YANG XICAI , KANG LIANGYI , TIEN PO 
Published: February 2008

Summary.Tomato (Lycopersicon esculentum cvs Rutgers and Lichun) plants were firstly pre‐inoculated either with a cucumber mosaic virus (CMV) isolate containing satellite RNA (CMV‐S52) or with a CMV isolate without satellite RNA, and then challenged 14 days later with a severe strain of potato spindle tuber viroid (PSTVd). Also, tomato plants transformed with CMV satellite cDNA and non‐transgenic control plants were directly inoculated with PSTVd. Protection effects were assessed by the observation of symptoms and by assay of PSTVd accumulation in tomato plants using return polyacrylamide gel electrophoresis and silver staining. The results indicated that the satellite‐transgenic plants and plants pre‐inoculated with CMV‐S52 showed much milder symptoms of PSTVd infection than the respective control plants. The concentration of PSTVd RNA in the satellite‐transgenic plants and CMV‐S52 pre‐inoculated plants was reduced to about 0.02–0.03 of the controls. PSTVd infection did not increase the amount of satellite ds‐RNA in plants. It is concluded that the plant resistance to PSTVd is induced by the presence of satellite RNA rather than the CMV infection. It is suggested that as there is considerable sequence similarity between satellite RNA and PSTVd, base pairings may be a cause of reduction of both symptoms and the accumulation of PSTVd.
The experimental transmission of hop latent viroid and its elimination by low temperature treatment and meristem culture
Authors: ADAMS A N. , BARBARA D J. , MORTON A. , DARBY P. 
Published: February 2008

SummaryTwo aspects of hop latent viroid (HLVd) relevant to control were examined: the production of viroid‐free plants from infected material and transmission of HLVd in the field. Plants free from HLVd were obtained by a combination of storing infected source plants at low temperature (2–4oC in the dark) for several months followed by meristem culture using small explants. A total of 77 plants of six cultivars and male pollinator clones were grown from meristems and 28 of these were free from HLVd. Tests showed that the cutting of stems (mimicking the use of tools) was more effective than abrasion (mimicking natural plant to plant contact) for the mechanical transmission of HLVd between hop plants. When field‐grown test plants were inoculated, infection occurred more commonly in May before plants had grown large enough for significant contact between neighbouring plants than later in the season. The aphid Phorodon humuli could not be shown to transmit HLVd.These results indicate that all hop varieties and pollinator clones can be made available to the industry free from HLVd and that the chances of infection can be reduced by avoiding early‐season cultural operations that cut into hop shoots.
The effect of temperature and inoculation access period on the transmission of barley yellow dwarf virus byRhopalosiphum padi (L.) and Sitobion avenae (F.)
Authors: LOWLES A J. , TATCHELL G M. , HARRINGTON R. , CLARK S J. 
Published: February 2008

SummaryWinged individuals of Rhopalosiphum padi and Sitobion avenae transmitted the PAV‐like and MAV‐like isolates of barley yellow dwarf virus respectively. Success of transmission after inoculation access periods of 2, 6, 12, 24, 48 and 72 h were examined and survival, reproduction and movement of the aphid vectors were recorded at these times. The experiment was done at four different temperatures: 6oC, 12oC, 18oC and 23oC. For both isolates the inoculation efficacy did not increase after a 24 h inoculation access period and there was no difference in inoculation efficiency at the three highest temperatures, that at 6oC being significantly lower than at 12oC to 23oC. The results suggest that autumn temperature is a critical factor for BYDV epidemiology in Britain with a small increase in autumn temperature leading to greatly increased infection rates.
Use of polymerase chain reaction (PCR) to study transmission of banana bunchy top virus by the banana aphid (Pentalonia nigronervosa)
Authors: HU J S. , WANG M. , SETHER D. , XIE W. , LEONHARDT K W. 
Published: February 2008

SummaryBanana bunchy top virus (BBTV) is a ssDNA virus transmitted by the banana aphid, (Pentalonia nigronervosa). A polymerase chain reaction (PCR) assay was used to study BBTV transmission efficiency, to determine the minimum acquisition‐access period, the minimum inoculation‐access period, the retention time, and to examine the possibility of transovarial transmission in this vector. BBTV was acquired by banana aphids within 4 h and was transmitted within 15 min feeding. On average, more than 65% of single viruliferous adult aphids transmitted BBTV. The aphids retained BBTV for their adulthood of 15–20 days. None of the 131 offspring from adult aphids reared on infected bananas were BBTV positive. Aphid transmission experiments were conducted to determine if taro and gingers are hosts of BBTV. None of the 87 taro and ginger plants exposed to aphid inoculation were infected by BBTV. The BBTV‐free status of these plants was verified by PCR assay for 6 months post‐inoculation. In addition, none of the taro and ginger samples collected from fields adjacent to BBTV‐infected banana plants tested positive for BBTV.
Ovule abortion in white clover (Trifolium repens L.)
Authors: MARSHALL A H. , JAMES I R. , POTTER J F. 
Published: February 2008

SummaryPlants of white clover (Trifolium repens L.) cv. Olwen were grown in an open glasshouse maintained at a mean temperature of 20oC and ovule growth and seed production measured. Differences in the rate of growth of ovules within ovaries were observed as early as 2 days after pollination. Ovules reached a maximum size after 8 days with the smallest only half the size of the largest. After 8 days, the smallest ovules became flaccid and shrivelled. Ovule position within the ovary had little effect on the frequency of seed set and although there was an apparently higher probability that central ovules produced a seed than those nearer the peduncle or style this was not statistically significant. Inflorescence position and floret position on the inflorescence had a significant effect on the number of seeds per floret and seed weight; the first formed inflorescences and the first florets to be pollinated on each inflorescence had more seeds per floret and heavier seeds and fewer florets with no seed than later pollinated florets. There were also differences between florets within the same whorl. The role of a number of factors which may influence floret site utilisation are discussed.
Varietal mixtures: a viable strategy for sustainable productivity in subsistence agriculture
Authors: SMITHSON J B. , LENNÉ J M. 
Published: February 2008

SummaryRemarkable parallels link the development of varietal mixtures across subsistence farming systems. Mixtures are grown and persist because they prolong harvest and income flow and provide diversity of diet. From our review of research on agronomic and disease aspects of mixtures in modern agriculture, it is also clear that improved stability and decreased disease severity are common features of mixtures relative to their components in monoculture. Such advantages are of value to both modern and subsistence agriculture. However, in the majority of cases, the yield advantage of mixtures is small. Overall, we conclude that varietal mixtures are presently a viable strategy for sustainable productivity in subsistence agriculture, have potential for improvement without sacrifice of diversity, are an important resource for future global food production and may have an expanding role in modern agriculture in situations where qualitative uniformity is not the guiding priority.
Influence of Liriomyza species (Diptera: Agromyzidae) and their host plants, on oviposition by Opius dissitus females (Hymenoptera: Braconidae)
Authors: OLIVERA CAROLINA ROUX , BORDAT DOMINIQUE 
Published: February 2008

SummaryTwo factors, among others, influence the oviposition of Opius dissitus Muesebeck. The first was the host species, the second the plant upon which the pest host larvae develop. O. dissitus females prefer Liriomyza trifolii (Burgess) larvae over those of L. huidobrensis (Blanchard). O. dissitus females were more attracted to the larvae of L. trifolii or L. huidobrensis when these were present on courgette rather than tomato or lettuce.
Development of selective aphicide treatments for integrated control of summer aphids in winter wheat
Authors: OAKLEY J N. , WALTERS K F A. , ELLIS S A. , GREEN D B. , WATLING M. , YOUNG J E B. 
Published: February 2008

SummaryField experiments on the use of recommended and reduced application rates of aphicides for control of summer aphid infestations on winter wheat have been done at five sites each year from 1990 to 1992. The experiment compared sprays of pirimicarb at recommended rate (140g a.i. ha‐1) and reduced rate (25 g a.i. ha‐1) and of alphacypermethrin at recommended rate (15 g a.i. ha‐1) and one third recommended rate (5 g a.i. ha‐1), each applied either at flag leaf emergence or at flowering. Aphid infestations were allowed to develop naturally and were measured at critical growth stages. In 1990, overwintered aphid infestations, together with established populations of parasitoids, were detected at four of the five sites when the first assessment was made in April. Parasitoids provided sufficient aphid control to prevent yield loss at two sites, without pesticide applications. At three sites both aphicides gave similar levels of control and yield response at both recommended and reduced application rates. In 1991 and 1992 no overwintered aphids were detected in the crops and aphid infestations developed much later. Aphicide applications gave significant yield responses at four sites in 1992. Recommended rates gave better control of aphids than reduced rates. There was no significant difference in the yield response obtained with different rates of aphicide.
Fungicidal activity of Ranunculus asiaticus and other weeds against Fusarium oxysporum f.sp. lycopersici
Authors: QASEM J R. 
Published: February 2008

SummaryThe effects of aqueous extracts of some common weed species against Fusarium oxysporum Schlecht f.sp. lycopersici (the causal agent of tomato wilt disease) were investigated under laboratory conditions. Anagallis foemina L., Cerastium dicotomum L., Falcaria vulgaris L., Ranunculus asiaticus L., Scorpiurus mur‐icatus L. and Solanum nigrum L. extracts were the most toxic to the fungus. Further studies on buttercup (Ranunculus asiaticus L.) showed that fresh shoot extract of this species prevented growth of F. oxysporum when incorporated into agar medium. Extracts of different parts of the plant inhibited fungus growth and sporulation, but the fungitoxicity decreased with incubation period with only slight changes in the toxicity of fresh shoot extract. The shoot and fresh parts extracts were more toxic than root and dried tissue extracts. Addition of 0.5 ml fresh shoot or 1 ml fresh root extract to the growing medium significantly reduced fungal colony growth, and the effect was extract concentration dependent. Fresh shoot extract of R. asiaticus added to a liquid medium significantly reduced mycelial dry weight compared with the control, and incorporation of 0.1 g dried shoot or 0.2 g dried roots in the media strongly inhibited fungus growth. Results of a pot experiment showed no harmful effects of R. asiaticus extracts on tomato growth.
Variation in pathogenicity of isolates of Cercospora spp. attacking Heliotropium spp.
Authors: BRUN L. , SHEPPARD A W. , LOPES V. 
Published: February 2008

SummaryThe pathogenicity of a set of 13 Cercospora samples collected in France, Turkey and Australia from four Heliotropium species has been evaluated with a detached leaf technique. All of five Euro‐Asian Heliotropium species tested were susceptible to all Cercospora species isolates. However, variation in the degree of partial resistance to different isolates was observed and showed some similarity for isolates from the same region of origin. Further studies are required to clarify the taxonomy of Cercospora blight strains, but the consequences of the noted differences in pathogenicity are discussed in relation to the biological control ofH. europaeum L. in Australia.
Cavity spot of carrots: II. Cell‐wall‐degrading enzymes secreted by Pythium and pathogen‐related proteins produced by the root cells
Authors: ZAMSKI E. , PERETZ I. 
Published: February 2008

SummaryThis study investigates the biochemical relationships between carrot roots and Pythium violae, the pathogen responsible for cavity spot (CS) disease. P. violae isolates obtained from CS lesions, cultured in Petri dishes on agar were used for inoculation of uninfected mature carrots. The fungus secreted a wide spectrum of enzymes that degraded the cellulose and pectic substances of the carrot cell walls. Cellulase and polygalacuronase (pg) showed the highest activity during the first day post‐inoculation, subsequently declining. Pectin lyase (PnL), pectate lyase (PeL) and pectin methylesterase (PME) gradually increased to their highest levels of activity 14 to 30 days post‐inoculation. This pattern of activity enables the penetration of the fungus through the walls of the host cells and the establishment of the hyphae. Several plant pathogen‐related substances such as peroxidase, chitinase, glucanase and polyphenol oxidase were produced in the infected tissue. Peroxidase activity rose in the inoculated roots from day 1 post‐inoculation. Chitinase, glucanase and polyphenol oxidase activities first appeared 3–4 days post‐inoculation. At this time, two bands corresponding to chitinase at about 26 and 33 KDa and one band corresponding to glucanase at about 24 KDa could be resolved by SDS‐PAGE.
Variation in pathogenicity among isolates of Elsinoe phaseoli from Phaseolus species
Authors: PHILLIPS A J L 
Published: February 2008

SummaryExpanding primary leaves of 11 cultivars of Phaseolus vulgaris, and one each of Phaseolus coccineus, Phaseolus lunatus and Vigna unguiculata were inoculated with 23 isolates of Elsinoe phaseoli from Phaseolus spp. and one from Vigna unguiculata. On the basis of the macroscopic and microscopic appearance of the lesions, symptoms were placed into five classes. Spore yields from the lesions in each class were used to classify the types of lesions as representing resistance or susceptibility to each isolate. There was a differential response of cultivars to isolates. According to the reaction of five cultivars of P. vulgaris to infection, isolates were placed in four pathogenicity groups.In addition to the differential reaction of cultivars, there was some evidence of host specificity among the isolates. Thus, P. lunatus was susceptible to most of the P. vulgaris isolates but resistant to the ones from P. coccineus. Vigna unguiculata was susceptible only to the V. unguiculata isolate and was resistant to all the isolates from Phaseolus spp. The isolate from V. unguiculata failed to infect any of the bean cultivars or the other Phaseolus spp. The need to select suitable isolates for challenging cultivars in a breeding programme is stressed.
Host range, vector relations and serological relationships of cotton leaf curl virus from southern India
Authors: NATESHAN H M , MUNIYAPPA V. , SWANSON M M , HARRISON B D 
Published: February 2008

SummaryIn 1989 to 1991, leaf curl disease was observed in cotton (Gossypium bar‐badense cv. Local) grown in kitchen gardens in five districts in Karnataka State, India, and in 1994 it was recorded in G. hirsutum cv. Sharada in two districts. Symptoms consist of leaf curling, vein thickening, leaf enations, and stunting and distortion of plants. The disease is caused by cotton leaf curl virus (CLCuV‐K), which was transmitted by the whitefly Bemisia tabaci to 24 plant species in six families. Hosts include bean (Phaseolus vulgaris), pepper, tobacco, tomato and several weeds, almost all of which developed leaf curl, with or without vein thickening. CLCuV‐K was transmitted from cotton to cotton by adult B. tabaci after an acquisition access period of 1 h, could be inoculated in 5 min, had a minimum latent period of 8 h and was retained by viruliferous insects for up to 9 days. Female B. tabaci transmitted more frequently than males. CLCuV‐K is a whitefly‐transmitted geminivirus. It reacted with two out of 17 monoclonal antibodies (MAbs) raised to African cassava mosaic virus and five out of 10 MAbs raised to Indian cassava mosaic virus. CLCuV‐K isolates from different locations in Karnataka had similar epitope profiles. As judged by these profiles, CLCuV‐K is closely related to Indian tomato leaf curl virus from Karnataka, is distinguishable from several other whitefly‐transmitted geminiviruses found in India and is still more distantly related to those, including cotton leaf crumple virus from the USA, found in other continents.CLCuV‐K infected all cultivars tested of G. barbadense and one of six cultivars of G. hirsutum but none of G. arboreum or G. herbaceum.
Serological studies on the accumulation and localisation of three tomato leaf curl geminiviruses in resistant and susceptible Lycopersicon species and tomato cultivars
Authors: FARGETTE D. , LESLIE M. , HARRISON B D 
Published: February 2008

SummaryAccessions of wild Lycopersicon spp. and selected Fl hybrid tomato cultivars were compared for their resistance to three whitefly‐transmissible geminiviruses: Indian tomato leaf curl virus (ITmLCV) and tomato yellow leaf curl viruses from Sardinia (TYLCV‐Sar) and Senegal (TYLCV‐Sen). The resistance of different plant lines was expressed in different ways but in most instances a given line reacted similarly to graft inoculation with the three viruses. L. pimpinellifolium LA1478 produced as much virus antigen, assessed by triple antibody sandwich‐ELISA, as the susceptible cv. Moneymaker but developed only very mild symptoms and is therefore tolerant of infection. In L. hirsutum LA1777 and L. peruvianum CMV‐INRA, very mild or no symptoms developed but antigen concentrations were substantially less than in Moneymaker. L. chilense LA1969 remained symptomless and its antigen concentration was < 1% of that in Moneymaker. Symptoms were mild or barely evident in the Fl hybrid cultivars. Cultivars Tyking and Fiona had antigen concentrations about 5–10% of those of Moneymaker, whereas TY20, Top 21 and Tyger had intermediate antigen concentrations. In a few instances, the extent to which virus accumulation was restricted depended on the challenge virus. Accumulation of TYLCV‐Sen in TY20, Top 21 and Tyger was less affected than that of the other two viruses, and accumulation of TYLCV‐Sar in accessions LA1777 and CMV‐INRA was less affected than that of TYLCV‐Sen or ITmLCV.Tissue‐printing tests showed that ITmLCV and TYLCV‐Sen antigens were confined to phloem tissue. In Tyking, the number of virus antigen‐containing phloem traces and the antigen content of individual traces were less than in Moneymaker but the partitioning of antigen between internal and external phloem was unaffected.
Effects of sub‐lethal cold stress on the Western Flower Thrips, Frankliniella occidentalis
Authors: McDONALD J R , BALE J S , WALTERS K F A 
Published: February 2008

SummaryIn order to establish in a new geographical area, introduced insects must be able to survive any period of adverse conditions such as a temperate winter and be capable of subsequent development to adulthood and/or reproduction. However, this aspect of insect overwintering and cold tolerance has been poorly studied. At high latitudes, Frankliniella occidentalis is typically associated with artificially heated glasshouses, but has some ability to tolerate low temperatures and may survive winter field conditions for short periods, or for longer periods of time during mild winters. The effects of overwintering on the viability of survivors are, however, unknown. In this study, acute and chronic cold exposure regimes were imposed on first instar larvae and adult female Western Flower Thrips, after which the longevity, development and reproductive capacity of the survivors were monitored and compared to those of non‐stressed individuals. Survival of cold exposure did not affect subsequent survivorship of immature or adult insects, though cold treated larvae took approximately two days longer to reach adulthood than untreated individuals (at 20°C, 18L:6D). Chill treatment of adult females significantly reduced their rate of reproduction (from 1.45 to 0.93 larvae day‐1), reproductive lifespan (from 13.3 to 9.2 days) and as a result, total reproductive output (from 20.4 to 10.8 larvae), compared to control females. Acute exposure resulted in non‐significant decreases of the same parameters. The relevance of the above effects to overwintering of F. occidentalis is discussed.