bluuebunny/crossref_metadata_2025 huggingface dataset:
Collection, processing and transfer of weather data in the Agrometeorological Measuring Net of Rheinland‐Pfalz: a prior condition for using weather‐based forecasting systems*
Authors: Zollfrank U.
Published: April 2008

The fundamental and most important condition for running forecasting systems successfully is the input of correct meteorological data. Rheinland‐Pfalz owns more then 30 agrometeorological measuring stations, which automatically collect data 24 h a day. This article describes how the data is managed (collection by modem, plausibility tests, filling blanks in the weather files), how the data flow from the Agrometeorological Measuring Net Rheinland‐Pfalz (AMN RP) to the adviser in the plant protection office is organized, how administration of data, sensors and service routines works and, finally, the conclusions and improvements that are made based on the results. This leads to meteorological data of high quality, which are necessary for weather‐based forecasting systems to guarantee a high standard of certainty when using the results of simulation in agricultural practice.
Structure and development of decision‐support systems and their use by the State Plant Protection Services in Germany*
Authors: Kleinhenz B. , Rossberg D.
Published: April 2008

To ensure continuing work on decision‐support systems (DSSs) and the elaboration of new systems according to the needs of the Plant Protection Services of the federal states of Germany, these services have installed ZEPP (Central Institution for Decision Support Systems and Programmes in Crop Protection). At the national level, ZEPP guarantees a permanent supply of meteorological data, organizes and co‐ordinates trials, incorporates scientific progress into the existing DSSs and, in close co‐operation with universities and federal research stations, develops new systems for important pests. The PASO desktop system includes a data bank that administers all relevant meteorological files and field data. It allows for automated simulation runs and forecasts, serving as input for timely warnings by different media. Depending on the individual decision‐support modules, results are presented as tables and/or graphs.
Computer‐aided design of improved warning systems – a case study for Botrytis control in flower bulbs*
Authors: de Kraker J. , van den Ende J. E. , Rossing W. A. H. , Bastiaansen C. , van der Werf W.
Published: April 2008

Development and improvement of warning systems are often done empirically, relying on extensive field testing. As this approach is both costly and time‐consuming, there is a need for a more rational and efficient alternative. In a study to explore the options for improvement of a Botrytis warning system in flower bulbs, we applied a computer‐based approach to systems design. The approach consisted of the construction and evaluation of modified versions of the warning system using epidemiological knowledge, data sets of recorded and forecast weather and a simulation model of epidemic development and fungicide spray impact. Performance of modified versions was evaluated with regard to fungicide input, efficacy of disease control and sensitivity to the prediction error in weather forecasts. This approach can be more efficient than a purely empirical one, as it enables the designer to limit the number of alternative versions to be field‐tested on the basis of explicit performance criteria. It also has the advantage that it provides insight into the potentials for improvement of the warning system.
Tortricid pests in orchards and viticulture, from basic data sampling to Internet warning service*
Authors: Polesny F. , Rupf O. , Kührer E.
Published: April 2008

Cydia pomonella, Cydia funebrana, Eupoecilia ambiguella and Lobesia botrana are key pests in orchards and viticulture. The specific situation in Austria makes it impossible to use pheromone traps for decision making without additional information. Models based on temperature sums give information on the expected beginning of moth emergence and egg‐laying activity, but not on the intensity of reproduction over a period of time. An additional method for advisory services on tortricid pests, the‘branch cage technique’, has been developed and introduced in Austria. The technique is described in detail. At the beginning of the season, overwintered larvae or pupae are exposed in a so‐called branch cage in the field. As they emerge, adults are transferred from the branch cage into an egg‐laying box with an exchangeable polyethylene foil inside, offered to the females for egg laying. This technique monitors reproductive activity over a period of time and can be used even for following generations of adults during the season. The results of branch cage stations with (updated) information on moth emergence, egg laying and hatching of caterpillars are published within the Internet plant protection service of the BFL.
Intranet in Baden‐Württemberg (Germany) – using the technology of the Internet for internal information interchange within a State Plant Protection Service*
Authors: Dölz A.
Published: April 2008

This article describes the new possibilities of an intranet for internal interchange of information within the plant protection service of a German federal state. In Baden‐Württemberg, the precondition is a closed internal network with central information servers and workstations at the local offices of agriculture. The intranet with information servers is based on the technology of the Internet and is a modern and user‐friendly tool for supplying advisers highly efficiently and economically with current comments, relevant notices, files, weather data and evalutions of computer aids for decision‐making. In the last 2 years, significant progress has been made in the automation of procedures for data request, transmission and evaluation of weather data for the warning service. In the plant protection service of Baden‐Württemberg, the most important data‐processing routines and evaluations of computer aids for decision‐making are running automatically as batch files. In order to save time in the preparation of regional warnings, the relevant information is available to the advisers via intranet at the beginning of their work. Compared with traditional procedures, the intranet with information servers is advantageous to the information supplier (Central Institute of Plant Protection) as well as to the user (advisers at the local offices of agriculture).
Development of an interactive decision‐support system on a Web site for control of Mycosphaerella graminicola in winter wheat*
Authors: Moreau J.‐M. , Maraite H.
Published: April 2008

A decision‐support system (DSS) has been developed in Belgium to help farmers and advisers to manage Mycosphaerella graminicola in winter wheat during stem elongation. The system calculates in real time the interactions between winter wheat and M. graminicola development to simulate disease progression in the canopy in order to guide field observations on the different leaf layers and determine the risks for the crop. It has been structured to run with individual field input and local hourly meteorological data. An interactive Internet version of the system has been developed to facilitate the delivery of information. It allows users to base their decisions on advice tailored to conditions in their own fields, as well as to recent and validated hourly local meteorological data that is regularly updated on the server computer.
Incidence des maladies des cucurbitacées en France (melon, concombre, courgette, cornichon)*
Authors: Monnet Y.
Published: April 2008

Les principaux problèmes pathologiques des cucurbitacées en France sont essentiellement le fait de champignons telluriques rencontrés pendant la phase juvénile (Pythium spp., Rhizoctonia solani), puis pendant la phase de croissance végétative (Pythium. aphanidermatum, Fusarium oxysporum f. sp. melonis ou Phomopsis sclerotioides), des champignons à développement aérien (Sphaerotheca fuliginea et Pseudoperonospora cubensis) et de virus parmi lesquels les plus fréquents sont le cucumber mosaic cucumovirus et le zucchini yellow mosaic potyvirus. Dans le cas des champignons du sol, les efforts sont apportés sur la qualité des substrats, la rusticité des porte‐greffe, la recherche d'efficacité d'agents antagonistes. Dans celui des champignons aériens, le choix des cultivars, et celui des fongicides compatibles avec le développement de la production intégrée, ont pris ces dernières années une importance grandissante. Dans certains cas, une meilleure connaissance des phénomènes épidémiologiques permet de mieux cerner les risques encourus sous abri ou en plein air (bactériose du melon, mise au point de modèles). Les mesures prophylactiques, la protection physique contre les vecteurs potentiels et le choix des cultivars tolérants ou résistants sont des solutions partielles aux attaques de virus.
Optimization of chemical control of Pseudoperonospora cubensis on cucumber in Ukraine
Authors: Chaban V.S. , Okhrimchuk V.N. , Sergienko V.G.
Published: April 2008

Downy mildew (Pseudoperonospora cubensis) is one of the most harmful diseases of cucumber in Ukraine. At high disease severity, the growing season is considerably shortened and yield is reduced. The most effective method of control is the development of resistant cultivars but, in the absence of absolutely resistant forms, control with fungicides remains very important. The effectiveness of such treatment depends on the dates of application, the number of sprays and the efficacy of the fungicides used. An improved scheme is presented, based on three components: use of cultivars with increased resistance; application of highly effective systemic + contact fungicides; and reliable short‐term forecasting of disease appearance. The predictors for downy mildew forecasting are: sum of effective temperatures, weather index, duration of leaf wetness, concentration of sporangia in air and latent period of disease development. These conditions determine‘critical days’for disease development. The first fungicide spray on less susceptible cultivars is recommended on the first critical day, and the next on the day of appearance of first disease symptoms. This scheme allows the fungicide load to be approximately halved, while ensuring higher yield.
Screening for resistance to Didymella bryoniae in rootstocks of melon
Authors: Nisini P. Trionfetti , Buzi A. , Granati E. , Chilosi G. , Crinò P. , Magro P.
Published: April 2008

Glasshouse evaluations of rootstocks of melon for resistance to Didymella bryoniae were conducted on different cucurbits previously selected as resistant or partially resistant to race 1,2 of Fusarium oxysporum f. sp. melonis. Cucumis anguria, C. ficifolius, C. figarei, C. metuliferus, C. zeyheri and Benincasa hispida showed a very high degree of resistance to D. bryoniae both on leaves and stems. Among the commercial rootstocks, Cucurbita hybrids ELSI, ES 99‐13, RS 841, displayed a similar level of resistance. Stem inoculation of three cucurbit species grafted with susceptible melon cv. Proteo determined the occurrence of limited symptoms, but the lesions remained confined in the rootstock not affecting the grafted plant. Cultivation of susceptible melon cultivars grafted on resistant rootstocks may represent an efficient method for controlling Didymella crown rot and Fusarium wilt.
Hosts of Verticillium dahliae in Kriti (Greece)*
Authors: Ligoxigakis E. K.
Published: April 2008

Naturally wilted cultivated and weed species were collected from several fields in Kriti (GR) over the years 1992/1997, and tested by isolation for the presence of Verticillium dahliae. The fungus was most frequently recovered from cultivated Solanaceae and Cucurbitaceae. Infection of many known Verticillium hosts was confirmed, and the fungus was found for the first time in Kriti in pistachio and grapevine and in several common weeds.
Screening tomato and cucurbit rootstocks for resistance to Verticillium dahliae*
Authors: Paplomatas E. J. , Elena K. , Tsagkarakou A.
Published: April 2008

Seedlings of tomato (19) and cucurbits (33), previously selected as rootstocks for commercial cultivars, were evaluated for their resistance to verticillium wilt under glasshouse conditions. Disease scoring was based on foliar symptoms, but in plants with no visual or ambiguous symptoms the presence of the pathogen was confirmed by isolations or PCR using specific DNA primers. Five of the cucurbit rootstocks showed resistance to infection, 11 were moderately infected, 11 were susceptible, while the remaining six were very susceptible. In general, Cucurbita pepo (courgette, pumpkin) and Lagenaria siceraria tolerated infection, Cucumis melo rootstocks were susceptible and Citrullus vulgaris was the most susceptible. When inoculated with race 1 of the pathogen, one of the tomato rootstocks was very resistant, three moderately resistant, nine tolerant, ten susceptible and one very susceptible. Pathogenicity tests with race 2 showed that none of the rootstocks exhibited high tolerance, but that there was some variation in susceptibility. Research is under way to evaluate the reaction of commercial cultivars to verticillium wilt when grafted onto resistant rootstocks.
Behaviour of Solanum spp. on inoculation with different isolates of Fusarium oxysporum f. sp. melongenae*
Authors: Stravato V. M. , Cappelli C.
Published: April 2008

Twelve wild Solanum accessions were tested in a glasshouse at the seedling stage for resistance to Fusarium oxysporum f. sp. melongenae, the causal agent of fusarium wilt of aubergine. Four isolates of the fungus (three Turkish and one Italian) were used. Solanum incanum and S. linneanum were highly susceptible, whereas S. sisymbrifolium, S. torvum and S. aethiopicum Gilo group (one accession) were resistant. In Solanum aethiopicum Aculeatum (two accessions), S. aethiopicum Gilo, S. viarum and S. macrocarpon there were both resistant and susceptible individuals. The sources of resistance found in these wild Solanum spp. could be conveniently used to breed aubergine cultivars resistant to fusarium wilt.
Phytophthora species causing crown and root rot of tomato in southern Italy*
Authors: Pane A. , Agosteo G. E. , Cacciola S. O.
Published: April 2008

Phytophthora capsici, Phytophthora cryptogea and Phytophthora nicotianae were isolated from tomato plants with symptoms of crown and root rot in plastic‐house crops in Sicilia and Calabria (southern Italy). The species were identified primarily on the basis of morphological and cultural characteristics. The identification was confirmed using molecular methods, polyacrylamide gel electrophoresis (PAGE) of mycelial proteins and polymorphism of DNA sequences amplified by polymerase chain reaction using random primers (RAPD‐PCR). P. capsici caused significant losses in tomato crops that had succeeded capsicum crops. P. cryptogea was found to be the most frequent species causing basal stem rot of tomato, a disease of increasing importance in commercial tomato crops in plastic houses in Sicilia. P. nicotianae was common in plastic houses where poor drainage resulted in standing water.
Resistance of Phytophthora capsici to metalaxyl in plastic‐house capsicum crops in southern Italy*
Authors: Agosteo G. E. , Raudino F. , Cacciola S. O.
Published: April 2008

In Calabria (southern Italy), control of crown and root rot of capsicum caused by Phytophthora capsici has relied primarily on soil drenches of metalaxyl. However, severe outbreaks occur every year in glasshouse crops, in which the practice of using plastic mulch and furrow irrigation favours the disease. Single‐hypha isolates of P. capsici collected in Calabria in 1992/1998 were tested in vitro for their level of sensitivity to metalaxyl. Isolates of other species of Phytophthora were used as reference. Fungicide sensitivity was determined by plating mycelial plugs onto potato dextrose agar amended with metalaxyl, at final concentrations ranging from 0.1 to 1000μg mL−1 a.s. Inhibition of radial growth (%) was determined when colonies on unamended medium had covered approximately two‐thirds of the plate. The ED50 values for inhibition of mycelial growth of P. capsici isolates ranged from 1.41 to44.6μg mL−1 a.s. More than 80% of the P. capsici isolates from commercial plastic‐house crops in Calabria showed a moderate level of resistance as they were inhibited less than 60% at 5 μg mL−1 but more than 60% at 100μg mL−1
Epidemiology and control of Botrytis cinerea in tomato crops grown under cover in Greece
Authors: Pappas A. C.
Published: April 2008

Out‐of‐season tomatoes grown in unheated glasshouses in Greece annually suffer considerable losses from grey mould induced by Botrytis cinerea. Characteristic soft rots of young fruit by the calyx end, flower abortions and stem lesions or cankers are the most commonly occurring symptoms of the disease. Severe ghost spots on fruit only appear when fungicides inhibiting spore germination are not applied. Conidia produced on plant debris of the previous year's crop serve as primary inoculum. Disease starts in late autumn, increases rapidly during the winter period and ceases abruptly at the end of April. Infections caused by isolates resistant to dicarboximides or to both dicarboximides and benzimidazoles are uncommon at the beginning of each new crop cycle. These increase substantially as the season progresses and decline after cessation of fungicide sprays. By contrast, infections caused by benzimidazole‐resistant strains are stable throughout the growing season. Efficient disease control implies use of proper glasshouse covering material, adequate indoor air circulation, partial night heating, strict indoor and outdoor hygiene and regular fungicide sprays. When disease pressure is low, application only of conventional compounds like dichlofluanid and chlorothalonil is recommended. Under conditions favourable to Botrytis infections, mixtures of conventional compounds with reduced strength specific botryticides should preferably be applied. Such regimes efficiently minimize losses from fungicide resistance development and ghost spot.
Intensity of infection of tomato by Phytophthora infestans in central Ukraine in relation to varietal resistance
Authors: Chaban V. S. , Kyrylyuk T. P.
Published: April 2008

Phytophthora infestans is widespread in the central part of Ukraine, infecting tomatoes everywhere but not to the same extent in different years. The disease can completely destroy the crop in epiphytotic years. We have studied commercial cultivars and hybrids of tomato with different degrees of resistance to P. infestans. The degree of disease development and the date of its appearance were found to depend on the resistance group of the genotype investigated. In weakly resistant tomato cultivars and hybrids, first disease symptoms were noticed 3–4 days earlier than in more resistant ones. The degree of disease development reached 40–80% on weakly resistant genotypes at the end of the growing season, but only 5–40% on resistant ones (depending on the suitability of conditions for development of P. infestans). The development of P. infestans on fruits also depended on the degree of resistance. Differences between moderately and weakly resistant tomatoes in the degree of disease development and the date of its appearance were not significant. The data was corroborated in the laboratory conditions in the way of artificial inoculation.
Occurrence of melon necrotic spot carmovirus in Italy
Authors: Tomassoli L. , Barba M.
Published: April 2008

Since 1995, a severe necrosis disease has been observed in winter melon (Cucumis melo var. inodorus) grown in the open in Sardegna region. At the stage of fruit ripening, infected plants show decline and premature death, a syndrome known as‘collapse’. Fungal pathogens have never been detected. In 1998, melon necrotic spot carmovirus (MNSV) was isolated from diseased plants showing necrotic symptoms on leaves and branches. The virus was identified by biological and serological assays. MNSV may represent a limiting factor to winter melon production in Sardegna where the‘inodorus’group is widely cultivated and appreciated for local consumption. This is the first occurrence of MNSV in Italy.
Tospoviruses infecting vegetable crops in Israel
Authors: Gera A. , Kritzman A. , Cohen J. , Raccah B. , Antignus Y.
Published: April 2008

Symptoms of vein clearing, stem necrosis, curling, necrotic spots and rings on the leaves associated with infection by tomato spotted wilt tospovirus (TSWV) were documented among vegetable crops growing in commercial glasshouses and open fields in Israel. Plants exhibiting symptoms were collected, from 1994‐01 to 1998‐12. Among cultivated vegetable crops analysed for TSWV by ELISA, the following plants were found to be infected: tomato, capsicum, aubergine, lettuce, cabbage and cucumber. These incidences of the virus were all correlated with the occurrence in high population of Frankliniella occidentalis. Transmission of the virus from infected Datura stramonium to Petunia leaf discs, by F. occidentalis, was up to 26%. TSWV antigens were readily detected by ELISA in seeds harvested from naturally infected vegetable crops. However, we failed to show virus transmission to the progeny plants. Iris yellow spot tospovirus (IYSV) was detected in onion. High incidence of the disease was associated with large populations of Thrips tabaci.
Identification of the principal viruses infecting tomato crops in Tunisia
Authors: Moussa A. Ben , Makni M. , Marrakchi M.
Published: April 2008

Serological tests have been used to detect viruses associated with tomato in 257 samples collected in different regions in Tunisia, Cap‐Bon, Sahel and South during successive seasons. The viruses detected were cucumber mosaic cucumovirus (CMV) and tomato aspermy cucumovirus (TAV), potato Y potyvirus (PVY), tobacco etch potyvirus (TEV) and pepper veinal mottle potyvirus (PVMV), tomato mosaic tobamovirus (ToMV) and tobacco mosaic tobamovirus (TMV), tobacco rattle tobravirus (TRV), alfalfa mosaic alfamovirus (AMV), tomato spotted wilt tospovirus (TSWV), tomato ringspot nepovirus (TomRSV) and potato X potexvirus (PVX). Some were detected in all three regions surveyed, at variable frequencies: TMV, CMV, TEV, PVY, ToMV, AMV, TAV, TSWV and TRV. Others were only detected in two regions (PVMV in Cap‐Bon and Sahel and PVX in Sahel and in the south) or one region (TomRSV in Cap‐Bon). Movement of individual viruses from one region to another may be due to movement of specific vectors, as in the case of the thrips‐transmitted TSWV moving from the south to the north. Some of these viruses were found for the first time in Tunisia.
Biodiversity of viruses infecting tomato in Italy: methods for diagnosis and diversification*
Authors: Sialer M. M. Finetti , Parrella G. , Papanice M. , Vovlas C. , Gallitelli D.
Published: April 2008

An account is given of strain‐specific diagnostic methods currently adopted in Italy to detect alfalfa mosaic alfamovirus (AMV), cucumber mosaic cucumovirus (CMV) and tomato spotted wilt tospovirus (TSWV). These viruses are highly detrimental to tomato crops as the introduction of new virus strains has deeply changed the population structure of resident viruses. RT‐PCR coupled with restriction analysis of amplicons proved suitable for differentiating CMV and AMV strains whereas single‐stranded conformational polymorphism (SSCP) was used for the identification of TSWV isolates. Application of strain‐specific diagnostic methods to phytosanitary inspection of plant propagules is suggested as a powerful tool for timely identification of new virus strains
Cucumber mosaic cucumovirus incidence in open‐field tomato in the Olympia area and trap captures of alate aphids*
Authors: Kyriakopoulou P. E. , Perdikis D. CH. , Sclavounos A. P. , Girgis S. M. , Lykouressis D. P. , Tsitsipis J. A. , Christakis P. A.
Published: April 2008

Cucumber mosaic cucumovirus (CMV) has been the most serious pathogen of tomato in Greece for the last 15 years, causing tomato shrinkage, tomato necrosis and tomato fruit necrosis. In an epidemiological study in Eleia county, one of the main centres of production of processing tomato in Greece and one most affected by CMV, it was confirmed that the virus had an extremely high frequency. Disease frequency and severity was found to have a patchy spatial and temporal distribution at county, zone and locality level, during the years and within 1998, the main year of experimentation (and a disastrous year for CMV). Great variation was found in the trends of infection frequencies during the growing season of 1998 in the 15 experimental fields but all were finally 100% or almost 100% infected. The trends of infection frequency in these 15 fields paralleled total captures of alate aphids by a Rothamsted‐type trap, whereas in one of these fields, with a Moericke‐type trap, these parallel captures were composed almost exclusively of Aphis spiraecola.
Breeding tomatoes for resistance to tomato yellow leaf curl begomovirus
Authors: Lapidot M. , Goldray O. , Ben‐Joseph R. , Cohen S. , Friedmann M. , Shlomo A. , Nahon S. , Chen L. , Pilowsky M.
Published: April 2008

Tomato yellow leaf curl begomovirus (TYLCV) can be devastating to tomato crops in tropical and subtropical regions. The development of resistant cultivars is the best option for the control of TYLCV. The TYLCV‐resistance level of a new breeding line, TY172, alongside that of commercial cultivars known to be resistant to the virus, was evaluated in a field test by comparing the yield performance of inoculated plants with that of uninoculated plants of the same line or cultivar. There were substantial differences among the different entries tested in the extent of yield loss relative to the corresponding uninoculated control plants. This comparison between inoculated and uninoculated plants of the same entry provides a quantitative assay for resistance level. All resistant commercial cultivars tested developed different levels of disease symptoms. Only line TY172 showed no symptoms of the disease. A low level of viral DNA was detected in infected TY172, showing that it is a symptomless carrier of TYLCV. When TY172 was crossed with susceptible lines, the hybrids exhibited milder symptoms than the susceptible parent, yet higher than that of TY172, suggesting a partial dominance for TY172 resistance. Upon inoculation of F2 populations, the amount of symptomless individuals appeared in a ratio approximating 7:64. This suggests that at least three genes appear to account for the resistance.
Studies on the reaction of cucumber cultivars to Pseudomonas syringae pv. lachrymans in Western Anatolia*
Authors: Türküsay H. , Saygili H.
Published: April 2008

The main objective of this research was to determine the severity of disease caused by Pseudomonas syringae pv. lachrymans on cucumbers grown in the İzmir, Bursa, Balikesir and Manisa provinces of the Western Anatolia Region (Turkey). The resistance, tolerance or susceptibility of commonly used cultivars to the pathogens was also studied. Mean values of disease severity were calculated as 32.7, 17.0, 16.1 and 15.3% for the Manisa, Bursa, Balikesir and İzmir provinces respectively. Cvs Ophix, Fancipak and AG 1204 (of the pickling cultivars) and Reia, Sahara, Vlasstar, Octopus (of the table cultivars) were found to be less susceptible to the pathogen than other cultivars.
Association of stolbur phytoplasmas with diseased tomatoes in Italy*
Authors: Favali M. A. , Musetti R. , Fossati F. , Vighi C.
Published: April 2008

Since 1989, tomato plants showing symptoms of stolbur disease have been sporadically noticed at the ‘Stuard Experimental Farm for Agriculture’in the Province of Parma, Emilia‐Romagna region (north Italy). In this farm, one of the largest in Italy for tomato plantation, more than 36 commercial tomato lines have been comparatively evaluated for suitability for processing into diced or crushed tomato products. Recently, among these lines, some plants of two hybrids (Perfect Peel, TI 991) showed the typical symptoms of ‘stolbur’infection (yellowing and reduction of leaves, sterility or fruit alterations, stunting of the plants). In order to protect these plants, as Perfect Peel is one of the most important commercial hybrids, transmission electron microscopy was used to identify the pathogens responsible for the disease and to study the alterations caused in cells. Phytoplasmas were observed in the phloem cells of leaf and stem tissues of the two tomato hybrids and also in Catharanthus roseus used as test plant. This is the first report of identification, by electron microscopy, of stolbur phytoplasma affecting economically important tomato crops in Emilia‐Romagna region.
Bacterial diseases of tomato in southern Spain: application of a detached tissue assay to evaluate bacterial pathogenicity
Authors: Cazorla F. M. , Pérez‐García A. , Rivera M. E. , Codina J. C. , Torés J. A. , de Vicente A.
Published: April 2008

Tomatoes are one of the most important crops in southern Spain, especially during the cold season. As a preliminary step in the design of an integrated disease management programme for tomato, a study on the occurrence of bacterial diseases in tomato houses of Almería (ES) was carried out during the 1993/1997 growing seasons. Sixty‐four bacterial strains were isolated from tomato plants showing symptoms of bacterial diseases and 41 of them (64%) were characterized as pathogenic. The bacterial tomato pathogens most frequently isolated were Erwinia carotovora subsp. carotovora, Pseudomonas corrugata, Pseudomonas syringae pv. tomato and Xanthomonas vesicatoria. The pathogenicity of the bacterial isolates on tomato was tested by the conventional seedling assay and by an in vitro assay using detached tissues developed in our laboratory. Close correspondence between the two assays was observed. An in vitro detached tissue assay is proposed for determining the pathogenicity of bacterial isolates on tomato.
Opportunities and constraints in the adaptation of technology for the diagnosis of bacterial plant diseases — experience from Tanzania*
Authors: Black R. , Abubakar Z. , Seal S.
Published: April 2008

In order to improve diagnostic services and plant quarantine capabilities in Tanzania, the techniques of semi‐selective media, the BACTID system, metabolic profiling (Biolog), indirect enzyme‐linked immunosorbent assays (ELISA) and polymerase chain reaction (PCR) were assessed for suitability with the existing facilities for the diagnosis and detection of plant‐pathogenic bacteria of vegetables. Field‐collected samples as well as farmers' own and commercial germplasm were used in studies involving Ralstonia solanacearum, Clavibacter michiganensis subsp. michiganensis and Xanthomonas campestris pv. vesicatoria in Solanaceae and X. c. pv. campestris in Brassicaceae. Each of the techniques was used successfully with one or more of the target pathogens; each had advantages depending on the speed, sensitivity and specificity required, as well as the costs of carrying out the diagnosis. However, constraints emerged relating to the use and disposal of materials such as plastic Petri dishes and toxic substances. The more familiar underlying constraints of high cost and poor availability of consumables and erratic water and electricity supply continued to present problems. These problems will be discussed in relation to the development of an integrated and sustainable approach to the provision of routine diagnostic services.
Reproducibility of enzyme‐linked immunosorbent assay and immunofluorescence for detecting Clavibacter michiganensis subsp. sepedonicus in multiple laboratories*
Authors: De Boer S. H. , Hall J.W.
Published: April 2008

Results from enzyme‐linked immunosorbent assays (ELISA) and immunofluorescence (IF) tests for the detection of Clavibacter michiganensis subsp. sepedonicus in potato tissue were analysed to determine the variation that occurs when different analysts perform the test. Data generated in accredited laboratories from sets of proficiency panel samples were used for the analysis. Sensitivity and specificity for both the ELISA and IF tests were very high as very few false positive and false negative results occurred. Analysis of z‐scores for the positive samples in the proficiency panel sets showed, for both serological tests, that about 90% of the results were within the acceptable range around the assigned values for the samples. Rescaled sum of scores for individual analysts who had false positive or negative results in ELISA were generally outside the acceptable range, although most analysts with high or low rescaled sums of z‐scores still identified each sample correctly as being positive or negative for the ring‐rot pathogen. For IF there were no false positive results, and the false negative results were not associated with aberrant rescaled sums of z‐score for the analysts, suggesting that perhaps an error in testing occurred rather than a problem with quantifying cell numbers.
Development of a quantitative PCR‐based detection system for Erwinia carotovora subsp. atroseptica on potato tubers*
Authors: Hyman L.J. , Birch P.R.J. , Dellagi A. , Avrova A.O. , Toth I.K.
Published: April 2008

A polymerase chain reaction‐based method has been developed for quantitative detection of Erwinia carotovora subsp. atroseptica on potato tubers. It uses a competitor template cloned into Escherichia coli added to the test tuber‐peel extract to both detect and quantify E. c. atroseptica.
Use of multiplex real‐time PCR (TaqMan) for the detection of potato viruses*
Authors: Boonham N. , Walsh K. , Mumford R.A. , Barker I.
Published: April 2008

Certain viruses affect the quality of potato tubers for either table use or processing. Visual discrimination of these viruses is problematic because of variable symptoms, but is important if proper controls are to be implemented. Work at the Central Science Laboratory has concentrated on the detection of Potato mop‐top pomovirus (PMTV), Tobacco rattle tobravirus (TRV) (both associated with the disease spraing) and the tuber necrotic strain of Potato Y potyvirus (PVYNTN), the symptoms of which can often be confused with spraing. A nucleic acid‐based approach has been adopted as TRV is often found as naked RNA with no associated coat protein, and accurate discrimination of PVY strains is impossible by serology. The multiplex TaqMan assay developed in this work streamlines the testing, replacing two separate tests currently used (a TRV RT‐PCR and a PMTV enzyme‐linked immunosorbent assay) with a single‐tube assay, which has no post‐PCR manipulations. The assay has been shown to be more sensitive than either of the tests which it replaces, allowing 100‐ and 10000‐fold increases in sensitivity for TRV and PMTV detection respectively. The test reliably detected over 40 different isolates of TRV and PMTV obtained from a wide range of cultivars and locations, including samples where existing tests failed. A PCR‐based method capable of discriminating strains of PVY was also developed.
Development of routine RT‐PCR tests for certification of fruit tree multiplication material*
Authors: Kummert J. , Vendrame M. , Steyer S. , Lepoivre P.
Published: April 2008

Current developments in certification procedures for propagating material require the availability of rapid, sensitive, reliable and user‐friendly detection protocols applicable for routine testing. Our research concerns the possible use of reverse transcriptase‐polymerase chain reaction (RT‐PCR) for the detection of the pathogens listed for virus‐tested pome and stone‐fruit propagating material in Belgium. Although RT‐PCR satisfies the need for rapidity and sensitivity, the usual protocols relying on the use of purified nucleic acid preparations as template and ethidium bromide‐stained agarose gels for detection are not appropriate for routine use. We therefore first optimized the parameters and cycling conditions of the RT‐PCR reactions to allow direct use of crude extracts of either leaf or bark material as a template. Sandwich hybridization between a covalently linked capture probe and a biotinylated detection probe was then used for the detection of the specific amplicons (Lambdatech S.A. kits in development). These assays have the sensitivity and specificity of the RT‐PCR, enhanced by sandwich hybridization with specific probes, and ease of sample preparation and detection of the amplicons. They make it possible to analyse a great number of samples and are thus well adapted for routine quality‐control testing of propagating material.
A ligation‐anchored PCR method for the cloning of the 3’end of a tobamovirus infecting Impatiens New Guinea hybrids*
Authors: Wetzel T. , Moerbel J. , Krczal G.
Published: April 2008

The development of the polymerase chain reaction (PCR) and PCR‐derived methods has greatly improved the sensitivity and specificity of the detection of pathogens. We have developed a ligation‐anchored PCR technique (LA/PCR) to clone the 3’end of the viral genome of a new tobamovirus infecting Impatiens New Guinea hybrids. Purified viral RNA was ligated to an EcoRI‐linearized plasmid using T4 RNA ligase, and the ligation product subjected to a reverse transcription‐PCR (RT/PCR), with a degenerate tobamovirus primer located in the tobamovirus 3’non‐coding region and the universal reverse primer corresponding to plasmidic sequence. The resulting PCR product, which contained some plasmidic sequence and the 3’end of the viral genome, was cloned and sequenced. Sequence comparisons with the corresponding sequences of other tobamoviruses revealed very high homologies with oilseed rape mosaic tobamovirus
Detection and quantification of fungal and bacterial potato pathogens in plants and soil*
Authors: Cullen D. W. , Lees A. K. , Toth I. K. , Bell K. S. , Duncan J. M.
Published: April 2008

We have developed polymerase chain reaction (PCR)‐based diagnostic assays for fungal and bacterial diseases of potato together with rapid methods of DNA extraction and purification from soil and plant samples. Pathogen detection and quantification is a crucial step in the control of crop diseases. PCR primers were designed to unique sequences for specific detection of the potato blemish complex of pathogens: Spongospora subterranea (powdery scab), Streptomyces scabies (common scab), Helminthosporium solani (silver scurf), Rhizoctonia solani AG‐3 (black scurf) and Colletotrichum coccodes (black dot). A multiplex PCR test was designed with a high level of sensitivity to detect H. solani, C. coccodes, and S. scabies simultaneously in one reaction, and individual quantitative PCR assays were also developed to detect these pathogens and S. subterranea in soil and tubers. PCR‐based detection systems for the major storage‐rot pathogens of potato (Fusarium spp., Phoma foveata, Pythium ultimum and Phytophthora erythroseptica) are also under development. The potential of these techniques to detect and monitor these pathogen populations in soil and potato tubers for epidemiological studies is discussed.
Application of nr‐DNA ITS sequence for identification of Fusarium culmorum isolates*
Authors: Mishra P. K. , Fox R. T. V. , Culham A.
Published: April 2008

Variation within the internal transcribed spacers (ITS1 and ITS2) and 5.8S ribosomal DNA region of 60 Fusarium culmorum isolates (section Discolor), representing different hosts and diverse geographical origins was examined by polymerase chain reaction (PCR), coupled with sequencing. Phylogenetic relationships of these F. culmorum isolates were estimated in relation to Fusarium spp. from this and other sections of the form‐genus, using sequences available from Genbank. The amplified ITS region was approximately 570 bp long in 56 isolates and approximately 585 bp in four other isolates. The inferred phylogeny distinguished clearly four isolates supplied as F. culmorum. These isolates differed in both morphology and sequence from the remaining F. culmorum material. Sequence analysis revealed that the remaining 56 isolates were divided into three ITS types, within which the divergence was extremely low. ITS sequence comparison among the Fusarium isolates showed two major clades, one comprising sections Discolor, Sporotrichiella and Gibbosum and the other comprising Elegans, Liseola, Martiella and Roseum. These results demonstrate the use of the ITS region to resolve the identification and taxonomic problems of Fusarium spp. especially at sectional level but demonstrate the need to develop some other molecular markers for identification at the level of species or race.
Development of new PCR primers for identification of Monilinia species*
Authors: Hughes K. J. D. , Fulton C. E. , McReynolds D. , Lane C. R.
Published: April 2008

New polymerase chain reaction (PCR) primers were developed for the identification of the EU quarantine pest Monilinia fructicola. These allowed nine M. fructicola isolates to be distinguished from other fungi, including six isolates of M. laxa and six isolates of M. fructigena (which also cause brown rot of stone and pome fruit). Three M. fructicola isolates from Japan and one from Australia did not react with a primer set previously published for M. fructicola. M. fructicola isolates could be subdivided into three groups based on the size of their nuclear rDNA small subunit. The subunits from the four non‐reactive isolates were either smaller or larger than the reactive group. Further primers were developed which were specific for either M. laxa or M. fructigena. Another new primer identified both M. laxa and M. fructigena, and yet another M. laxa and M. fructicola. When used in combination, these primers specific for two species correctly identified unknown isolates of all three Monilinia species. The new primers designed in this study have been used to identify, rapidly and correctly, pustules taken directly from infected plum fruits, thus demonstrating their diagnostic potential.
European collaboration on eliminating Phytophthora fragariae from strawberry multiplication*
Authors: Duncan J. M. , Cooke D. E. L. , Seemüller E. , Bonants P. , Olsson C.
Published: April 2008

Red core is a serious root rot of strawberry caused by Phytophthora fragariae. Despite having a‘nil tolerance’in propagation schemes and being a quarantine pest, P. fragariae has spread steadily throughout Europe such that only a few Mediterranean countries are now apparently free from it. Field inspections of nurseries are inadequate for detection of red core and a bait test, although sensitive, takes too long to be useful commercially. The European Union, through its Standards, Measurements and Testing Programme has funded the further development of prototype molecular and immunological tests for red core to routine tests that meet ISO 9002 standards. The principal thrust has been the development of a nested polymerase chain reaction (PCR), supported by immunological tests for rapid screening of large numbers of routine samples. Nested PCR has suitable speed, sensitivity and specificity for testing and is now being used routinely in some laboratories. The finished tests will be freely available to all parties after the final stage of the project, a demonstration phase in which the technique will be tested widely in Europe.
Identification of Phytophthora species on the basis of restriction enzyme fragment analysis of the internal transcribed spacer regions of ribosomal RNA*
Authors: Cooke D. E. L. , Duncan J. M. , Williams N. A. , Weerdt M. Hagenaar‐de , Bonants P. J. M.
Published: April 2008

There are approximately 60 described species in the genus Phytophthora. Despite the economic and ecological damage they cause worldwide, the genus is poorly understood. A major difficulty, with implications for scientific communication as well as phytosanitary regulations, is species identification. With a paucity of stable morphological characters, even specialists can have difficulty in identification beyond the genus level. Appropriate molecular methods offer an objective alternative. In this paper, the utility of the internal transcribed spacer (ITS) regions of the subunit which encodes ribosomal RNA will be discussed. At the Scottish Crop Research Institute, an examination of the ITS restriction digest patterns of over 450 Phytophthora isolates representing almost all known taxa has allowed an evaluation of the method. Sophisticated band‐matching software has been used to compare new isolates rapidly with those in the database. Limitations of such methods are also discussed. In some cases (e.g. closely related taxa with identical ITS regions, or where discrimination at the intraspecific level is needed), amplified fragment length polymorphism (AFLP) analysis is necessary. The database of AFLP fingerprints developed in Plant Research International is discussed in this context.
Characterization and detection of Phytophthora fragariae in plant, water and soil by molecular methods*
Authors: Bonants P. J. M. , van Gent‐Pelzer M. P. E. , Weerdt M. Hagenaar‐de
Published: April 2008

Phytophthora fragariae var. fragariae is pathogenic to strawberry only and is an EPPO A2 quarantine pest. Seventy‐five isolates of P. fragariae from all over the world have been characterized by amplified fragment length polymorphism (AFLP) analysis. However, a sensitive, specific and fast method of detection is now needed, and polymerase chain reaction (PCR)‐based methods have now been set up. Based upon sequences of the ITS (internal transcribed spacer) regions of rDNA of several Phytophthora species, PCR primers specific for P. fragariae have been developed together with SCRI (Dundee, GB). These primers were tested on DNA extracted from water, soil and plant material. A nested PCR procedure has been included in the currently used bait test to improve sensitivity and reliability. Also several methods have been studied to detect the amplicon of the PCR reaction: gel electrophoresis, DIAPOPS (detection of immobilized amplified products in a one‐phase system), PCR‐ELIS A, TaqMan and molecular beacon. With the last two methods, using the ABI 7700 detection system, quantification of target DNA is possible.
Detection of Phytophthora nicotianae by PCR*
Authors: Grote D. , Olmos A. , Kofoet A. , Tuset J. J. , Bertolini E. , Cambra M.
Published: April 2008

Phytophthora nicotianae is an important soil‐borne pathogen. The classical determination based on morphological or physiological characters is time and labour‐consuming and is taxonomically unsure. Two specific primers designed from the spacer regions ITS1 and ITS2 were used to detect P. nicotianae by polymerase chain reaction (PCR). A PCR fragment of 737 bp was obtained from all P. nicotianae isolates assayed, but not from other Phytophthora spp. or other genera. Thus, the PCR characterization was species‐specific. Polyclonal antisera against mycelium and zoospores were used for comparison and were only genus‐specific.
PCR‐based diagnostics of Microdochium nivale and Tilletia tritici infecting winter wheat seeds*
Authors: Mulholland V. , McEwan M.
Published: April 2008

UK cereal‐seed producers work under severe time constraints during the autumn harvest period. Management of seed health during seed production is restricted by the lack of prompt information from seed‐health assays. Currently, advisory testing is carried out using a lengthy agar‐plate test for Microdochium nivale (up to 7 days) and a seed‐washing/filtration method for Tilletia tritici (24 h). Although the T. tritici test can be completed within 1 day, the throughput for this test is restrictive. Polymerase chain reaction (PCR) assays for the detection of these two fungal pathogens of wheat have been developed, initially using purified fungal DNA, cultured mycelia and spores. The PCR Mimic technique, a form of competitive PCR, was chosen for the quantification of fungal infection. The development of simple DNA isolation methods for use with the PCR Mimic technique is described.