bluuebunny/crossref_metadata_2025 huggingface dataset:
Diagnosis and detection of Phytophthora fragariae in raspberry and strawberry 1
Authors: COOKE D. E. L. , DUNCAN J. M. , UNKLES S.
Published: April 2008

Specific detection and identification of Phytophthora fragariae and its varieties are important for the management of this quarantine pest. PCR primers for the amplification of the ITS1 and ITS2 regions of rDNA in Phytophthora spp. have given very promising results.
Detection of banana leaf spot pathogens by PCR 1
Authors: JOHANSON A.
Published: April 2008

Two sigatoka leaf‐spot diseases affect banana and plantain: yellow sigatoka and black sigatoka. These are caused by two closely related and morphologically similar species of fungi: yellow sigatoka by Mycosphaerella musicola, and black sigatoka by M. fijiensis. Correct identification of these pathogens is hampered by the ambiguity of symptoms on different cultivars, and the difficulty in successfully isolating the pathogens in pure culture. Subsequent identification relies on sporulation which may also be difficult to induce. A diagnostic test based on the polymerase chain reaction (PCR) was therefore developed for these pathogens. The internally transcribed spacer (ITS1) region of ribosomal DNA (rDNA) of several isolates of M. fijiensis, M. musicola, and M. musae was sequenced, and a 21‐base oligonucleotide primer constructed for each species from a variable region identified in the sequences. These primers were used with primers in the conserved regions of the rDNA to produce a species‐specific product for each of the three species using PCR. The primers also amplified a fungal product from single ascospores placed in the PCR reaction, and from DNA from banana leaf tissue showing disease symptoms. No PCR products were produced when DNA from other species commonly found on banana was amplified. The fungi have been detected in herbarium samples up to 3 years old. The technique is very sensitive, and is able to detect DNA in a 1:20000 dilution of DNA extracted from 50 mg of freeze‐dried fungal mycelium.
Identification of Fusarium oxysporum f.sp. cyclaminis by DNA fingerprinting and PCR 1
Authors: WOUDT L. P.
Published: April 2008

A set of 55 isolates of the wilt pathogen Fusarium oxysporum f.sp. cyclaminis was separated into three groups by DNA fingerprinting. A common genomic DNA fragment was identified in all isolates. This fragment was cloned and found to consist of subfragments which are also present in non‐pathogenic isolates of F. oxysporum obtained from cyclamen plant material, but not similarly linked. PCR primers derived from these subfragments proved to be effective tools for identification and detection of F.o. cyclaminis.
Development of in vitro identification techniques for special pathogenic forms of Fusarium oxysporum1
Authors: RUTHERFORD M. A. , BRIDGE P. D. , PATERSON R. R. M. , BRAYFORD D. , THOMAS V.
Published: April 2008

Fungal wilt diseases of plants caused by Fusarium spp. are of major economic importance in a wide range of tropical crops, including banana, cotton, tomato, oil palm, date palm and melon. Unfortunately disease control is hampered by both difficult diagnosis and pathogen variability. Our project is elucidating rapid laboratory techniques, suitable for use in developing countries, which will differentiate saprobic and parasitic forms of the fungus and identify particular special forms. Fusarium isolates pathogenic to cotton, banana and tomato and a range of saprobic forms have been screened by physiological testing and thin layer chromatography for detection of secondary metabolites and isozyme electrophoresis. Molecular systematic analyses of chromosomal and mitochondrial DNA have also been investigated. Results show that an integrated approach, involving application of more than one of the techniques developed, is most useful for the differentiation of strains belonging to specific pathogenic groups, such as special forms or races. The techniques being developed will benefit disease diagnosis, research into mechanisms of plant resistance and development of resistant cultivars, epidemiological studies and soil‐based control measures, resulting in overall reductions in yield loss in countries where fusarium wilt diseases are problematic.
Profiling techniques for the identification and classification of plant pathogenic bacteria 1
Authors: STEAD D. E.
Published: April 2008

Profiling techniques are becoming widely used in the classification and identification of plant pathogenic bacteria. They are loosely defined as those techniques which produce a profile or fingerprint of a cellular component or its activity. They generally give much taxonomically useful information. They are relatively easily adapted for computerized comparisons of strains either for classification or for identification. The major genetic method is based on genomic fingerprinting or restriction fragment length polymorphism. Several phenetic chemotaxonomic methods are available, including protein profiling, fatty‐acid profiling and pyrolysis mass spectrometry. Nutritional profiling techniques are based on kits in which 20‐100 individual nutrients are included. All have their advantages and disadvantages and no single method should be used solely for classification or identification. Together with a few other well selected key tests, they have good potential as rapid, reproducible, low‐cost methods with high specificity. Several of these are now being commercially developed.
Fatty acid analysis for the identification of Erwinia carotovora subsp. atroseptica and E. carotovora subsp. carotovora1
Authors: PERSSON P. , SLETTEN A.
Published: April 2008

The pectolytic bacteria Erwinia carotovora subsp. atroseptica and E. carotovora subsp. carotovora were analysed by fatty acid profiling, using a gas chromatograph and a commercial software package for data processing. A fatty acid library was built from the analysis of 261 strains of the two bacteria from different sources and countries. Independently of source or geographical origin, 98% of the E.c. atroseptica strains and 97% of the E.c. carotovora strains were correctly identified. Analysis in two separate laboratories of identical strains gave highly reproducible results. Fatty acid profiling is a rapid, reliable and reproducible method for the identification and differentiation of these bacteria.
Evaluation of PCR methods for the diagnosis of bacterial ring rot infections in potato 1
Authors: KARJALAINEN R. , KANGASNIEMI A. , HÄMÄLÄINEN J. , TEGEL J.
Published: April 2008

A 434‐bp fragment of Clavibacter michiganensis subsp. sepedonicus DNA was sequenced and four different primers were designed for PCR amplification. PCR products of 200 bp and 300 bp were consistently amplified with genomic DNA of the bacterium. Preliminary specificity experiments indicated that these primers only amplified DNA from the ring‐rot bacterium. Composite 400‐tuber samples were collected from a lot of 20 000 kg of potatoes or individual tuber samples with suspected ring‐rot symptoms. The samples were divided into two parts and parallel tests with immunofluorescence and PCR were done. Potato‐tissue samples for PCR detection were extracted once with 1:1 phenol‐chloroform. The optimal dilution of the sample for PCR‐based detection was 1:10. Altogether 200 samples were analysed by both immunofluorescence and PCR methods. In most cases, the same positive and the same negative samples were revealed. In some cases, PCR revealed the samples with a lower degree of contamination more easily. Positive and negative samples were very easily detected by the PCR‐based assay. Large‐scale specificity experiments will be needed to clarify whether our primers only detected the ring‐rot bacteria and not closely related saprophytic bacteria.
Serological methods to quantify potato seed contamination by Erwinia carotovora subsp. atroseptica1
Authors: PÉROMBELON M. C. M. , HYMAN L. J.
Published: April 2008

The main causal agent of potato blackleg in cool temperate regions is Erwinia carotovora subsp. atroseptica. Blackleg is a seed‐borne disease and its development is closely related to the level of seed contamination by the bacterium under any given weather conditions. It is therefore important to plant seed with a low inoculum level. This is better achieved by determining the number of E.c. atroseptica in tuber peel extracts in the laboratory than by visual examination of the parental crop for blackleg in the field. Several microbiological and serological quantification methods have been developed. They should satisfy four main criteria: (a) specificity, (b) detection of live cells, (c) adequate sensitivity (< 103 cells ml‐1 tuber peel extract, the threshold level for blackleg development), and (d) speed and general user friendliness for large‐scale use. Probes specific to E.c. atroseptica are now available in the form of monoclonal antibodies and polyclonal antisera are specific when used in some methods only. Three methods which satisfy most of these criteria will be discussed: (a) immunomagnetic separation prior to viable count on a selective medium; (b) DAS‐ELISA modified by preliminary enrichment of E.c. atroseptica directly in the microtitre plate; (c) immunofluorescence colony‐staining.
Characterization of a pseudomonad‐like bacterium pathogenic for Anthurium species 1
Authors: SADDLER G. S. , O'GRADY E. B. , SPENCE J. A.
Published: April 2008

Bacterial isolates were obtained from diseased anthuriums at a number of locations in Trinidad. The biochemical and physiological characteristics of these strains were identical to those of a recently described group of pseudomonad‐like bacteria pathogenic on Anthurium species. These isolates were studied further using chemotaxonomic and molecular techniques to elucidate the true identity of the pathogen. Fatty‐acid profiles showed marked similarities to certain pseudomonads now placed within the genus Acidovorax. In general, major amounts of 16:1 and 16:0 were detected. Significantly, only a single hydroxy fatty acid, 10:0 3‐OH, was found in all strains. The latter characteristic is common for most members of the genera Acidovorax and Comamonas. Isolates could not be unequivocally assigned to any known taxa within these genera. Isolates were also studied by randomly amplified polymorphic DNA analysis (RAPD). Results from this simple method have confirmed the uniqueness of this group whilst establishing its similarity to the genus Acidovorax.
Specific detection of mycoplasma‐like organisms in European fruit trees by PCR 1
Authors: JARAUSCH W. , SAILLARD C. , DOSBA F. , BOVÉ J.‐M.
Published: April 2008

DNA amplification by PCR was employed to detect MLOs affecting Malus (apple) and Prunus (peach, apricot, plum) in Europe. Three primer pairs were chosen in a previously established sequence of a chromosomal fragment of apple proliferation MLO. Template DNA was extracted from experimentally inoculated trees and from symptomatic, naturally infected trees. Primer pair AP 5/4 specifically detected the DNA of apple proliferation MLO in infected trees resulting in a 483‐bp PCR product. Using primer pair AP 3/4, an MLO‐specific PCR product of 162 bp was obtained with total DNA extracted from MLO‐diseased Malus and Prunus. The PCR signal originating from Prunus MLOs was consistently weak, indicating a lower degree of homology to the primer. Therefore, nested PCR using external primer pair AP 5/6 in combination with internal primer pair AP 3/4 was applied to increase the sensitivity of detection of Prunus MLOs. Differentiation from apple proliferation MLOs was achieved using primer pair AP 5/4. No amplification with either primer pair could be obtained with DNA extracted from healthy plants.
PCR‐based detection and characterization of Pseudomonas solanacearum for use in less developed countries 1
Authors: SEAL S.
Published: April 2008

Pseudomonas solanacearum‐specific DNA sequences were identified by 16S rRNA sequencing and genomic subtraction experiments. Oligonucleotide primers for these regions were constructed allowing single cell detection by PCR amplification. These specific PCR tests are being adapted for use in less sophisticated laboratories in Asia and Africa.
The electron microscope as a diagnostic tool in plant virology 1
Authors: VAN BALEN E. , BOUWEN I.
Published: April 2008

In plant virology, the electron microscope is often used to determine whether or not a plant is infected by viruses. The morphological data obtained may help to identify the virus. With the help of serological techniques, e.g. decoration, serological relationships between viruses can also be found. All this can be done with specimens prepared by simple suspension techniques. By making ultrathin sections of infected material, the cytopathology can be revealed and, with the aid of immunogold labelling on ultrathin sections, virus proteins can specifically be detected in the cytoplasm of plant cells. Using the above‐mentioned techniques, we have, for example, found a potyvirus in kalanchoë, which showed a close serological relationship with zucchini yellow mosaic potyvirus (ZYMV). Although the viruses were identical in morphology and serologically closely related, the ultrastructure of diseased plant cells showed large morphological differences. However, good labelling of the virus‐like structures with ZYMV antiserum coupled to gold particles was obtained for both viruses.
Optimizing immunosorbent electron microscopy for detection of pelargonium flower‐break carmovirus in pelargonium 1
Authors: BLYSTAD D.‐R. , NAESS V. , HAUGSLIEN S.
Published: April 2008

With the aim of optimizing the detection of pelargonium flower‐break carmovirus in Pelargonium×hortorum by immunosorbent electron microscopy (ISEM), several factors were investigated. The best results were obtained when we used NPPI‐polyclonal antiserum diluted 1:1000 for coating and prepared the pelargonium samples in 0.05 M acetate buffer, pH 6.0, with the additives polyvinyl pyrrolidone (2%) and activated charcoal (10%). More particles were trapped if the homogenized samples were incubated for 24 h before ISEM.
Approach to a general tospovirus assay using antibodies to purified tomato spotted wilt tospovirus G proteins 1
Authors: ADAM G. , ROGGERO P. , MALAVASI F. , MILNE R. G. , PAPA G.
Published: April 2008

The generally assumed presence of common epitopes on the glycoproteins (G proteins) of different tospovirus species should make possible an ELISA with broad reactivity. We have isolated the native G proteins of a type isolate of tomato spotted wilt tospovirus (TSWV) from purified complete virus particles and used them to raise monoclonal and polyclonal antibodies. Purification of the G proteins was achieved by isoelectric focussing in a Rotofor apparatus after solubilization of the lipid envelope with non‐ionic detergent and removal of the nucleoprotein complexes by ultracentrifugation. After isoelectric focussing, three fractions predominantly contained proteins that reacted with antisera against complete virus and with a monoclonal antibody against the G1 protein. These fractions were used to immunize rabbits and mice. The polyclonal antibodies obtained reacted well in DAS‐ELISA with all TSWV and impatiens necrotic spot tospovirus (INSV) isolates tested and also reacted with groundnut bud necrosis tospovirus (GBNV). Several positively reacting hybridoma mother clones were obtained. One of these was cloned and the resulting monoclonal antibody was tested for the detection of all available tospovirus isolates using TAS‐ELISA. Except for GBNV, all isolates were detected with equal efficiency, supporting the view that most tospoviruses share common epitopes in their G proteins. Seventy additional clones await intensive screening and it is hoped that at least one of these may possess even broader reactivity.
Improved PCR procedures for multiple identification of some artichoke and grapevine viruses 1
Authors: MINAFRA A. , GRIECO F. , GALLITELLI D. , MARTELLI G. P.
Published: April 2008

Reverse transcription polymerase chain reaction (RT‐PCR) amplification was adapted for detection of either single or mixed viral infections in grapevine and artichoke. DNA primers specific for grapevine A closterovirus (GVA), grapevine B trichovirus (GVB), or grapevine leafroll‐associated closterovirus III (GLRaV‐III) were used for RT‐PCR amplification of specific genomic segments from GVA, GVB and GLRaV‐III‐infected grapevine tissues. The reactions produced discrete fragments of 0.43, 0.45 and 0.34 kb which were representative of GVA, GVB and GLRaV‐III, respectively. Immunocapture RT‐PCR (IC‐RT‐PCR) or multiplex RT‐PCR (M‐RT‐PCR) were utilized for the detection of these viruses in extracts of infected grapevine leaves, dormant cuttings and/or viruliferous mealybugs. IC‐RT‐PCR was more efficient than RT‐PCR for the detection of GVA in viruliferous mealybugs, whereas M‐RT‐PCR was easier and faster than IC‐RT‐PCR for the detection of GLRaV‐III and GVB in infected grapevine tissues. Six specific primers were used for RT‐PCR amplification of specific genomic segments of artichoke mottled crinkle tombusvirus (AMCV), artichoke Italian latent nepovirus (AILV) and artichoke latent potyvirus (ALV) in artichoke plant sap. This set of primers was also successfully used for the simultaneous detection of the three viruses in cases of mixed infections, because each primer pair retained its specificity and reverse transcription‐amplification reactions ran independently, yielding products of the expected virus‐specific size. The limits of simultaneous detection were about 400 fg for AMCV and ALV and 4 pg for AILV, whereas the limits of detection in separate reactions were about 100fg for all three viruses.
Biomolecular and serological methods to identify strains of cucumber mosaic cucumovirus on tomato 1
Authors: ILARDI V. , MAZZEI M. , LORETI S. , TOMASSOLI L. , BARBA M.
Published: April 2008

Biomolecular and serological methods were used to classify 52 Italian isolates of cucumber mosaic cucumovirus (CMV) into S and WT subgroups. Two synthetic oligonucleotides, specific for the coat‐protein genes of the S and WT subgroups, were designed. These probes, used in Northern blot assays, were able to identify viral RNAs present in total nucleic‐acid extracts from fruits and leaves of infected field tomatoes. CMV‐specific primers, flanking the coat‐protein gene, were used to amplify, by RT‐PCR assay, a fragment of approximately 870 bp from either dsRNA replicative intermediates or purified genomic ssRNA. The restriction pattern analysis of the PCR product distinguished between the two subgroups. Monoclonal antibodies specific for CMV isolates belonging to the S and WT subgroups were produced. Five of these were able to detect and distinguish the strains in indirect ELISA using crude extracts from field samples. The three strategies gave concordant results and were useful in detecting and typing CMV subgroups on tomato.
Diagnostic methods for the detection of faba bean necrotic yellows virus, a circular ssDNA virus 1
Authors: KATUL L. , VETTEN H. J. , LESEMANN D.‐E. , MAISS E. , MAKKOUK K. M.
Published: April 2008

Faba bean necrotic yellows virus (FBNYV), a circular ssDNA virus, infects a wide range of legume crops in West Asia and North Africa. Based on symptom development, host range and aphid transmission mode, FBNYV could not be differentiated from bean leaf roll luteovirus (BLRV). An antiserum prepared against purified FBNYV permitted specific detection of the virus and was used for its serological comparison with other ssDNA viruses and for the differentiation from BLRV by immunoelectron microscopy, ELISA, tissue blot immunoassay and Western blot analysis. Moreover, FBNYV DNA was 32P‐labelled and used in dot‐blot hybridization experiments for virus detection in plant samples and further differentiation from BLRV.
The identity of the African pine woolly aphid: a multidisciplinary approach 1
Authors: BLACKMAN R. L. , WATSON G. W. , READY P. D.
Published: April 2008

A pine woolly aphid of the genus Pineus was inadvertently introduced to Zimbabwe in 1962, and now damages plantations of exotic pines in eight countries of eastern and southern Africa. Identification of the species and its area of origin were needed to facilitate collection of potential control agents. Samples of Pineus were collected from Africa, Europe, USA, Australia and New Zealand. These were subjected to cytological, multivariate morphometric and DNA (RFLP) analyses. The African Pineus showed close correspondence with some of the Australian samples, confirming suspicions that Australia was the source of the introduction. However, there are no native pines in Australia. On morphological and cytological grounds, the African pine woolly aphid also shows affinity with samples from California and Hawaii, and seems likely to be conspecific with P. boerneri, originally described from Pinus radiata in California. Pine woolly aphid populations in Australia and New Zealand were found to include both P. boerneri and a species of European origin, P. pini.
A comparison of immunoassays for the quantification of root‐knot nematodes extracted from soil 1
Authors: DAVIES K. G. , CARTER B.
Published: April 2008

Monoclonal antibodies are useful in the identification of root‐knot nematode females, and immunoassays using polyclonal antibodies have been developed to quantify root‐knot nematodes in root systems. The development of immunoassays for quantification of nematodes present in soil is, however, proving more difficult to accomplish. This study compares several different types of immunoassay using an ELISA‐based system. Antigens can be released from second‐stage juveniles of root‐knot nematodes using Ballotini glass beads, agitated by means of a vortex shaker in a buffer containing urea. Polyclonal antibodies were highly sensitive, but they cross‐reacted with other unrelated nematode genera such as Panagrellus spp. Although monoclonal antibodies were genus‐specific, they were not sufficiently sensitive to quantify small numbers of nematodes. Antigen‐coated plate assays were more sensitive than trapping assays and, similarly, indirect assays were more sensitive than direct assays. Milling a suspension of nematodes extracted from soil with Ballotini glass beads in buffer containing urea showed that it was possible to quantify juveniles at the equivalent of less than one juvenile per g of soil using polyclonal antibodies.
Monoclonal antibodies for the identification of slugs and their eggs 1
Authors: SYMONDSON W. O. C. , MENDIS V. W. , LIDDELL J. E.
Published: April 2008

Molluscs are major pests of agriculture and horticulture, and have caused significant damage worldwide as a result of inadvertent introductions of exotic species. Monoclonal antibodies raised against slugs and slug eggs demonstrated a range of useful specificities for diagnostic and other purposes. Specificity was at a number of levels. General‐purpose antibodies were raised that can detect molluscs and their eggs. A genus‐specific antibody was selected that can identify arionid slugs, and a second that appears to react specifically with the eggs of Deroceras spp. Three species‐specific monoclonal antibodies reacted with Deroceras reticulatum but not with the closely related D. caruanae, while a fourth reacted with the eggs of Arion ater but not with those of A. hortensis.
Appropriate diagnostic systems for less developed countries 1
Authors: BLACK R. , SWEETMORE A.
Published: April 2008

Strategies for effective diagnostic systems appropriate to plant pathology in less developed countries are presented. The development of diagnostic facilities (adapting current methods and developing new systems) must allow for the prevailing conditions, especially lack of trained personnel and finance, poor communications and unreliable utilities. Appropriate systems for each category of pathogen are discussed in this context. New molecular and serological technologies have great potential, but mainly where there is a clearly denned need, for example with routine work on specific pathogens. The first priority is a general diagnostic capacity to deal with new or unknown cases. New information technology will be an essential resource in making identifications and in consequent decision‐making. To gain the maximum benefit from improved technology, diagnosticians should also be trained to take appropriate decisions during identification work. Because resources are generally scarce, identification should proceed only as far as is necessary in each case, providing a timely diagnostic report fitting the needs of the users. A computer program has been developed to assist training in decision‐making and resource use in diagnosis.
International programme on the serological detection of bacterial, fungal and viral pathogens of protein pea seeds 1
Authors: LYONS N. F. , TAYLOR J. D. , ROBERTS S. J. , MAURY Y. , DUBY C. , MASMOUDI K. , FARIS‐MOKAIESH S. , CORBIÈRE R. , MENDES‐PEREIRA E. , SPIRE D. , SAMSON R. , MALANDRIN L. , GRONDEAU C. , FRANKEN A. A. J. M. , FRAAIJE B. A.
Published: April 2008

Arable (protein) peas are widely grown in northern Europe, specifically for use in animal feed. The main production areas (1 million ha) are France, UK and Denmark; The Netherlands is a major seed producer. There are a number of important seed‐borne pathogens, including bacterial blight (Pseudomonas syringae pv. pisi), leaf and pod spot (Mycosphaerella pinodes) and pea seed‐borne mosaic potyvirus (PSbMV), that cause crop losses. There is a need for improved rapid methods for the detection of these pathogens both to monitor the production of high‐quality seed and for quarantine purposes. Using knowledge of the specificity of antibodies raised to these organisms, techniques were developed for simultaneous detection of the pathogens from the same seed sample. Methods were developed that permitted the detection of 101–102 bacterial cfu ml‐1 in seed‐soak fluid, soluble antigen from seed with and without obvious fungal infection and the presence of PSbMV within the embryo of homogenized seed.
Validation of thresholds for serological tests that detect Clavibacter michiganensis subsp. sepedonicus in potato tuber tissue
Authors: DE BOER S. H. , BOUCHER A. , DE HAAN T. L.
Published: April 2008

To evaluate positive/negative thresholds for serological tests, composite samples consisting of 200 potato‐tuber cores were extracted and tested for the presence of Clavibacter michiganensis subsp. sepedonicus by ELISA and immunofluorescence using specific monoclonal antibodies. Transformed ELISA absorbance values for ring rot‐infected tuber tissue diluted in 10‐fold increments in known negative composite sample extracts were fitted to a‘broken stick’nonlinear regression model. Of the 103 dilution series that were tested, 91% fitted the model with R2 > 0.98. The model consisted of a response and non‐response domain. The absorbance values in the non‐response domain, which served as estimates of background readings, ranged from 0.006 to 0.049. The values did not differ significantly among brands of ELISA plates used for between laboratories, and thus provided a reference point for setting a positive/negative threshold for the ELISA test. In the immunofluorescence test, 94% of composite samples from 1003 commercial seed lots had <1 immunofluorescing unit (IFU) per microscope field; only 1% of samples had >2 IFU per field. A positive/ negative threshold at 5IFU per field was considered to be appropriate for avoiding false positive readings.
Detection and eradication of chrysanthemum stunt viroid in Spain
Authors: DURAN‐VILA N. , ROMERO‐DURBAN J. , HERNANDEZ M.
Published: April 2008

Chrysanthemum stunt disease has been detected in Spain. An imprint‐hybridization method using digoxigenin‐labelled probes has been evaluated for quick detection of chrysanthemum stunt viroid (CSVd). The sensitivity of the method has been evaluated with several cultivars grown under different environmental conditions. The method has been successfully used in the eradication of CSVd.
Evidence for a non‐infectious phyllody disease of strawberry
Authors: MARCONE C. , RAGOZZINO A. , BABINI A. R. , SEEMÜLLER E.
Published: April 2008

A phyllody disease of strawberry suspected to be of phytoplasmal etiology has been observed in the Campania region of southern Italy. The most characteristic symptom was a pronounced foliaceous growth arising from the achenes. Symptomatic fruits developed poorly and were unmarketable. However, the foliage of affected plants appeared normal. Symptom expression was most pronounced from September through December of the planting year, whereas symptomatic fruits were rare in the second crop. The disease, which has also been observed in northern Italy, appears to be restricted to plants grown from cold‐stored runners (frigo plants). To elucidate the etiology of the disease, symptomatic plants were examined for phytoplasmal infection, employing fluorescence microscopy as well as direct and nested PCR assays. However, all plants tested negatively. Also, attempts to transmit the disease to periwinkle or healthy strawberry plants were unsuccesful. Thus, the disease is likely to be of physiological etiology.
Establishment potential and damage probability of Meloidogyne chitwoodi in Germany 1
Authors: BRAASCH H. , WITTCHEN U. , UNGER J. G.
Published: April 2008

Meloidogyne chitwoodi is a major potato pest in the western USA. Its presence in Europe, in The Netherlands, has been known since 1985. There is a risk that the nematode may spread from locally contaminated areas to other regions of Europe. We tried to assess possible establishment in Germany, and associated damage to potatoes, on the basis of biological facts and ecoclimatic data. Determination of the establishment potential was mainly based on the availability of host plants and the influence of temperature in connection with the biological characteristics of M. chitwoodi. Analysis of these parameters revealed that the nematode could become established in many places in Germany, especially in the potato‐growing regions. On the basis of temperature accumulation, two or three generations of the nematode may be possible in Germany; but completion of a third generation or possible hatching of a fourth would be restricted to a few places and to climatically favourable years. The multiplication rate and damage probability of M. chitwoodi seems to depend mainly on weather conditions in spring and temperature accumulation during the vegetation period. Damage probability decreases from west to east in the northern lowland of Germany, where the main potato‐growing regions are located. The coastal regions are less at risk.
Establishment potential of Diabrotica virgifera in Germany 1
Authors: BAUFELD P. , ENZIAN S. , MOTTE G.
Published: April 2008

If introduced into Germany, Diabrotica virgifera would find maize in all regions of the country. Climatic conditions in winter would favour establishment. Though conditions in the growing season would be suboptimal, they would still be sufficient for development and completion of a full generation. D. virgifera has good potential for adaptation to different conditions and a high reproductive rate facilitating establishment in a new area. The type of maize grown would have no substantial effect on establishment of the pest. Crop rotation is important as a method for suppressing populations of the pests and restricting losses, but would not prevent establishment. Further containing factors (such as antagonists) are not available. So it can be concluded that D. virgifera is able to establish in Germany and could become an important maize pest.
Conceptual GIS derivation and spatial modelling of abiotic covariates influencing maize‐Striga dynamics 1
Authors: SCHMIDT K.
Published: April 2008

The spatial scale of a model for description of the maize‐Striga system has been extended. The model uses abiotic covariates transformed according to the different physiological responses of maize and Striga. The driving covariates may be derived from geographically distributed data sets. A digitized area in Mauretania, used as an example, combines the relevant attributes, while local references result in different submodels for the environmental variables. This additional information allows different simulations, reflecting the underlying structure of the area, but these are characterized by a degree of uncertainty. A second process for the description of the post‐maturity behaviour of Striga seed is added (derived from a Negative Binomial Distribution), and the GIS formation is used as a platform for simulating regional dispersal. The generated pattern, over time and space, was plausible, reflecting certain views on spatial heterogeneity. The system offers scope for development of spatially related control strategies. The implementation of a point model at regionalized scale shows advantages and limitations: the system is strongly dependent on the quality and accuracy of the underlying point model; requirements for simplicity, precision and computer capacity have to be reconciled.
Model cases for evaluating the impact of pest introduction and phytosanitary measures 1
Authors: KEHLENBECK H.
Published: April 2008

The establishment of common markets (EU, NAFTA) and the SPS Agreement (GATT/WTO) lead to an increasing necessity for importing countries to justify the phytosanitary measures they take, concerning both challenges from exporting countries and their own economies. A common method for the economic evaluation of phytosanitary measures is the application of cost/benefit analysis. However, this procedure depends on the availability of appropriate methods for estimating costs and benefits of quarantine measures. While costs are clear and measurable, benefits can only be estimated by an intensive analysis of the possible economic impact of pest introduction and the probable effects of phytosanitary measures. The economic impact of a pest can be described in terms of potential losses, and also of market effects the pest may cause if it spreads in the endangered area. In order to take time effects into consideration, appropriate models for pest spread in accordance with pest biology are needed. Total losses occurring over an appropriate period can then be calculated as well as annual losses. The evaluation of phytosanitary measures can be simplified by separating the effects of phytosanitary measures, assumed to be effective, into the following cases: (1) avoidance of pest introduction, (2) delay in pest introduction, (3) avoidance of pest spread, (4) delay in pest spread, (5) containment of pest spread, and (6) a combination of delay and containment of pest spread. In these cases, the possible economic benefit from phytosanitary measures can be calculated as annual Net Present Values, thus making it possible to compare annual benefits with annual costs and to decide from the cost/benefit ratio about the usefulness of the strategy concerned.
Evaluation and utilization of FIRESCREENS, a computer program for the control of fireblight 1
Authors: LECOMTE P. , JACQUART‐ROMON C. , PAULIN J. P.
Published: April 2008

FIRESCREENS is a computer program devised for the control (through sanitation and/or spray treatment) of fireblight caused by Erwinia amylovora on apple and pear. It has been evaluated at the orchard level in France since 1990. Experiments were performed in spring in three different climatic areas, where the disease is endemic: Loire Valley, Aquitaine and Normandie, in pear or in cider‐apple orchards. Plots were divided into three parts, in one of which trees were sprayed according to the recommendations of FIRESCREENS, in another according to a standard procedure (3–5 calendar‐based sprays during flowering), and in the third no treatment was applied. Assessment of the improvement in quality of control due to the use of FIRESCREENS was obtained by a comparison of the number of sprays applied in each block, and by monitoring of disease incidence. The overall result of these experiments was that the use of FIRESCREENS tended to reduce the number of sprays applied for control during flowering without affecting the level of protection obtained.
Appearance of Puccinia recondita f.sp. tritici on winter wheat: a simulation model 1
Authors: ROSSI V. , RACCA P. , PANCALDI D. , ALBERTI I.
Published: April 2008

A simulation model was developed for the appearance of leaf rust (Puccinia recondita f.sp. tritici) on winter wheat. The model was based on the uredospore cycle. Relationships between weather, host and infection processes (such as uredospore germination, germ‐tube penetration, length of latent period, uredia eruption) were transformed into model parameters by curve fitting, corrections and empirical assumptions. The model was validated by a backward method: model outputs were compared with actual data collected at eight sites in northern Italy over 4 years. The model gave a good simulation of the establishment of primary infections of leaf rust: an agreement between disease appearance in the field and model outputs was found in 93% of the 28 cases in which rust appeared. Air temperature and leaf wetness were the limiting factors for infection establishment. A prevalent (96% of cases) association between rain and infection showed that uredospores causing infections were washed onto the ground by rainfall.
Current methods of desert locust forecasting at FAO 1
Authors: CRESSMAN K.
Published: April 2008

Desert locusts (Schistocerca gregaria) have been feared by farmers in Africa, the Near East and South‐West Asia since antiquity. Given favourable environmental conditions, locusts can rapidly breed and form highly mobile swarms which may threaten agriculture in about 60 countries covering more than 20% of the total land surface of the earth. During this century, there have been eight major plagues, the last being in 1986/1989. Periods of recession broken by the occasional relatively minor outbreak of locusts occur in between plagues. For example, there has been an outbreak of locusts in Africa since 1992 which has not reached the proportions of a true plague. FAO operates a Desert Locust Information Service to provide early warning to affected countries of potential locust invasions and advice to the international donor community. Within this service, the locust situation and environmental conditions in affected countries are monitored on a daily basis using reports from national locust survey teams, remote‐sensing imagery and meteorological data. Short and medium‐term forecasts are prepared indicating potential locust migrations and areas of breeding. These forecasts form the basis of action plans in affected countries. This paper presents a brief introduction to desert locust biology, behaviour and population dynamics and a general overview of desert locust forecasting at FAO.
Organization and operation of forecasting and warning systems against pests in Turkey 1
Authors: ZEKI C.
Published: April 2008

The first studies of pest forecasting and warning in Turkey started in 1972, against Cydia pomonella, a key pest of apple orchards. Projects have been applied since 1981. The Turkish forecasting system has been in operation for some 14 years and continuous progress has been made during this period. Monitoring was carried out in 119 stations in 41 provinces of the country in 1995 and warnings were applied in about 7 million apple trees. Visual control, sex‐pheromone trapping and the sum of effective temperature have been used in determination of critical biological stages of this pest. The target of the C. pomonella control programme is to destroy the larvae before they enter the fruits. It is forecast that the first larvae of the first generation will appear when the sum of the effective temperatures from 01‐01 reaches 250 day‐degrees. A total of 5‐6 treatments used to be applied against this pest but the number has been reduced to 3 by use of the forecasting and warning system. The other main pest against which a forecasting and warning system is being applied is Lobesia botrana, a key pest in vineyards. Monitoring was carried out in 52 stations in 17 provinces of the country in 1995 and warnings were applied in 109 490 ha of vineyards. The forecasting and warning systems in apple orchards and vineyards are being run by the General Directorate of Protection and Control of the Ministry of Agriculture and Rural Affairs. Plant Protection Research Institutes act as the coordinators.
Development of the PRO_PLANT decision‐support system for plant protection in cereals, sugarbeet and rape 1
Authors: FRAHM J. , VOLK T. , JOHNEN A.
Published: April 2008

The decision‐support system PRO_PLANT was developed in Nordrhein‐Westfalen (DE) to help farmers to reduce the input of plant protection products to a minimum while giving them economic returns as good or even better than high‐input routine sprays. PRO_PLANT now covers cereal diseases, growth regulators in cereals, sugarbeet diseases, rape pests and weeds in maize. Meteorological data from the Deutscher Wetterdienst is one of the most important elements used in the system. PRO_PLANT is now used all over Germany by official and private advisers, as well as by farmers as a stand‐alone version. Experience over recent years shows that farmers can reduce fungicide inputs by almost 30%, by applying fewer treatments or reducing doses.
Integrating environmental impact in decision support‐a way for farmers to choose the least harmful plant protection product 1
Authors: GYLDENKÆRNE S. , SECHER B. J. M.
Published: April 2008

Unwanted side‐effects of plant protection products and related problems have become a major issue in the public discussion in Denmark. It is expected that side‐effects can be reduced if knowledge about the risks for non‐target organisms and the environment are made available to farmers, thus enabling them to choose products which in a particular situation will minimize the overall risk. It is important that the farmers can identify their own situation when such a risk assessment is used at the farm level. The Danish decision‐support system PC‐Plant Protection will be improved with a module which provides farmers with environmentally relevant information about plant protection products. The module will present users with estimated relative risk quotients for bees, aphid‐predating insects, earthworms, birds, mammals and aquatic organisms, risk of ground‐water contamination and operator exposure, together with general information. The risk quotients are calculated by dividing the toxicity by an estimated PIEC value (Predicted Initial Environmental Concentration). PIEC is calculated from the application rate recommended by PC‐Plant Protection, the growth stage of the crop, expected yield and an estimated leaf‐area index. The farmer can select the risk quotients he considers relevant when planning plant protection applications during the winter and in each individual spraying situation.
Integration of cultivar selection in a decision‐support system for plant protection 1
Authors: MURALI N. S. , SECHER B. J. M.
Published: April 2008

The Danish decision‐support system for plant protection, PC‐Plant Protection, has been in commercial use since 1993 and has proved reliable in reducing use of plant protection products without affecting net returns. One of the factors in the fungicide dosage estimate is cultivar susceptibility to diseases. However, the disease susceptibility data is not made visible to the user. In order to make the data available to the user together with other important cultivar characteristics, a relational database has been designed and incorporated into the decision‐support system. The user can view cultivar characteristics both during the selection of a cultivar at farm planning and during the use of the decision‐support system to control diseases in the season. Both qualitative and quantitative data can be stored and the data can be grouped and prioritized for display. The database is intended to be used as a foundation in the development of a decision‐support system for the selection of a cultivar on any given farm.
LantNet – cooperation between agricultural organizations in Sweden about information technology 1
Authors: GRÖNTOFT M.
Published: April 2008

LantNet is a cooperative venture between different agricultural organizations in Sweden. It covers both national authorities and private companies. The aim is to enhance the number of products in different electronic media. LantNet concentrated initially on products based on documents, pictures and video, already produced by the participants. The backbone of the LantNet cooperation is tagging of documents by their authors at the word‐processing stage. A tagged document can be electronically published without much additional manual work. If various types of texts, pictures or video are published electronically, there will be an increasing interest among companies, advisers and farmers to use Internet, CDs, etc. If more material is available in electronic form, it will also be easier to make more advanced products based on this material.
Occurrence of Erwinia amylovora on pear in Albania
Authors: PACE H. , MAZZUCCHI U.
Published: April 2008

Pear trees were observed in the province of Durres (AL) with typical symptoms of fireblight on the shoots, fruit and branches. Bacteriological analysis of samples of diseased material confirmed the presence of Erwinia amylovora. The isolates were identified on the basis of phenotypical and pathogenic characteristics. The total protein electrophoretic profiles of the Albanian isolates were indistinguishable from those of the strain found in the Po valley (IT).
Web blight, a new disease of Sechium edule
Authors: RAJNAUTH G. L. , St HILL A. A.
Published: April 2008

Symptoms of a new disease of christophine (Sechium edule) were observed in Trinidad in 1991. The disease caused extensive leaf blight and webbing together of leaves, both of which were associated with the presence of numerous microsclerotia on dried leaves and petioles. This disease, called web blight, was shown to be caused by Thanatephorus cucumeris (anamorph Rhizoctonia solani). This is the first report of this disease on christophine.
Legislation for plant protection in Germany and in the European Union1
Authors: LUNDEHN J.‐R.
Published: April 2008

The first regulations on plant protection in Germany date from the last century and the first basic rules from 1937. New legislation was published in 1968. The key basis for modern plant protection is the Plant Protection Act of 1986. The legal basis, organization and scope of legislation i n the tield of plant protection in Germany are dcscrihed. The specific role of the rederal German states (Linder) is pointed out. The competent authority for granting authorization o f plant protection products in Germany is the Federal Biological Research Centre for Agriculture and Forestry in Braunschweig. The maximum period of authorization is 10 years. The legal basis for placing plant protection products on the market within the Member States of the European Union is summarized. together with the main elements of the regulations regarding authorization of plant protection products. There is a need for international cooperation to overcome foreseeable problem and workload regarding risk reduction in plant protection.
Standardization of plant protection equipment in the EU: aspects of pollution control1
Authors: ALT N.
Published: April 2008

Within the European standardization process for agricultural machines, the standards dealing with pollution control aspects are the second important field of activity after the standards for safety. Even though there are for the time being no EU directives dealing with pollution control in the way that the Machine Directive (89/392) deals with the safety of agricultural machinery, the relevant standards under preparation will surely become important in a short time. The early start of European standardization in this field has led to harmonization of different national requirements, on the one hand, and makes it possible, on the other hand. that further European legislation can be reduced to essential guidelines. The basic work already done within the International Organization for Standardization (ISO) is allowing the European Committee for Standardization (CEN) to make rapid progress in the European context.