bluuebunny/crossref_metadata_2025 huggingface dataset:
Problems in the application of biological control against Trialeurodes vaporariorum in unheated plastic glasshouses in Crete1
Authors: MICHELAKIS S. E.
Published: April 2008

Since 1978, Trialeurodes vaporariorum has caused increasing problems in plastic houses in Crete, and chemical control is complicated by resistance. Effectiveness of biological control by the parasite Encarsia formosa has been tested in five untreated commercial houses in 1981–1983. Whitefly populations peaked in October, then persisted at a low level, to rise again as temperatures rose in spring. Autumn releases of E. formosa gave poor results, but spring releases were more promising, a parasitization rate of up to 75% being reached. Cultural measures and chemical treatments are liable to reduce effectiveness.
Chestnut blight in Yugoslavia1
Authors: HALAMBEK M.
Published: April 2008

The present state of chestnut blight caused by the fungus Cryphonectria parasitica in Yugoslavia is presented. Canker disease is present all over the country wherever chestnut stands occur. Field observations have shown the presence of abnormal disease symptoms at some localities. Isolates of C. parasitica from these sites varied widely in cultural characteristics and pathogenic properties, some showing the characteristics of hypovirulent strains.
Maladies d'origine tellurique en pépinière forestière: problème du diagnostic et lutte intégrèe1
Authors: PERRIN R.
Published: April 2008

Les maladies transmises par le sol représentent la cause principale de dégâts sur graines, plantules et plants repiqués dans les pépinières forestières. Les fontes en pré ou de postémergence constituent la première forme très connue de dégâts pendant les premières semaines qui suivent le semis. A un stade ultérieur, les plantules et les plants repiqués plus âgés peuvent avoir leur croissance ralentie, stoppée ou être tués par la nécrose racinaire, maladie complexe encore assez mal connue. La plupart des espèces de conifères peuvent être atteints à différents degrés: les Pinus, Picea et Larix sont les plus sensibles, alors que les Cupressaceae sont résistants. Pythium spp., Fusarium spp. (particulièrement F. oxysporum) et Rhizoctonia solani, champignons ubiquistes et pléophages, constituent la cause principale de fonte et de pourriture racinaire dans les pépinières européennes. Ces champignons coexistent souvent dans les sols, en particulier dans les pépinières établies depuis longtemps. La cause et la gravité des infections dépendent des conditions de l'environnement; la diagnose et la lutte préventive ne sont pas faciles en pratique. L'efficacité des produits chimiques a tendance à varier beaucoup d'une pépinière et d'une saison à l'autre. La fumigation et le traitement du sol à la vapeur sont les moyens de lutte les plus efficaces, mais ils sont coûteux et d'utilisation difficile au champ. La lutte intégree, combinant le potentiel naturel des sols résistants, des bactéries améliorant la croissance et atténuant les maladies, la capacité protectrice des mycorhizes, et de faibles doses de fongicide, se révèle un moyen très prometteur pour la lutte contre ces maladies.
Disease and pest problems on Pinus sylvestris nurseries in Finland1
Authors: LILJA S.
Published: April 2008

Pinus sylvestris constitutes 75% of the 250 million forest seedlings produced annually in Finland. The main disease problems are: (1) damping‐off by fungi such as Fusarium and Alternaria already infecting the ripening seeds in the cone; (2) Botrytis cinerea in densely sown beds; (3) Lophodermium seditiosum occasionally causing needle cast, controlled with dithiocarbamates; (4) Gremmeniella abietina, controllable with chlorothalonil alone or in mixtures; (5) Phacidium infestans, which is a serious pathogen in central and northern Finland, controlled with quintozene or in trials with chlorothalonil or thiophanate‐methyl. Nutrient imbalances cause seedling growth disturbances and insects like Lygus rugulipennis damage growing points.
Resurgence of Cryptodiaporthe populea in Italy1
Authors: ANSELMI N.
Published: April 2008

Serious resurgence of Cryptodiapor the populea (anamorph Dothichiza populea), with appearance of perithecia, has been reported on poplar in Italy, particularly upon newly commercialized clones. Disease symptoms, incidence of attack and resulting damage have been examined through all phases of poplar cultivation, on various clones and under different environmental conditions. Consideration was also given to predisposing factors such as the water status of the plant, the adaptability to the environment of the clones and its other genetic characteristics. Levels of resistance to D. populea of 131 of the most important European clones are reported for North Italy. Most Populus deltoides and P. trichocarpa clones and their hybrids appeared resistant, while most P. nigra clones were susceptible and P. euramericana clones were partly susceptible and partly resistant. Immediate control strategies, and current genetic improvement programmes in Italy, are discussed.
Les pathotypes de rouille sur peuplier1
Authors: PINON J.
Published: April 2008

Depuis 1982 il est établi qu'il existe en Europe au moins deux races ou pathotypes (E1 et E2) de Melampsora larici‐populina, agent de la rouille des peupliers des sections Aigeiros et Tacamahaca. Seules semblent concernées actuellement quelques stations de Belgique, des Pays‐Bas et de l'est de la France. Ces deux races se distinguent entre elles en terme de virulence, et plus discrètement en terme d'agressivité. Il en résulte que des clones, tels que Isières, Ogy, Rap, Spijk et Unal, jusqu'alors résistants à la race E1, sont notablement infectés par la race E2. On ne sait si E2 constitue un nouveau pathotype ou si sa mise en évidence est le reflet de la diffusion des clones précités. Il devient nécessaire de préciser la répartition des deux races selon les régions et les génotypes de l'hôte, en se basant sur les clones connus pour leur réaction différentielle. D'autre part, les programmes de sélection pour la tolérance doivent être réorientés.
Observations on seedling‐infecting smuts of barley from Turkey and UK
Authors: DAMGACI E. , HEWETT P. D.
Published: April 2008

The identification of smut fungi in smutted barley ears from Turkey and the UK was confirmed. Inoculation of seed showed that certain cultivars from both countries could be attacked by Ustilago hordei from either country and by U. avenae from Turkey. The implications are discussed.
The joint action of fungicides in mixtures: comparison of two methods for synergy calculation
Authors: LEVY Y. , BENDERLY M. , COHEN Y. , GISI U. , BASSAND D.
Published: April 2008

Two methods for evaluating the joint action of fungicides in mixtures were analysed. In order to obtain a relatively rapid answer on the type of interaction between fungicides in a mixture (additivity, synergism or antagonism), one can apply the Abbott formula to data on fungus survival. Tests with this method will not be accurate at high effective dose values. A more accurate determination of the joint action of fungicides can be made by the Wadley method, applied to data on effective doses. This involves more experimental work than the Abbott method. Optimization of mixing ratios of fungicides required a set of experimental data on effective doses with several mixing ratios.
Methods for detection of the blackleg, ring rot and gangrene pathogens in potato nuclear stock mother tubers and plantlets1
Authors: LOGAN C. , O'NEILL R. , McGRANE P. , LITTLE G.
Published: April 2008

Methods are described for the detection of latent infection by Erwinia carotovora ssp. atroseptica (blackleg and soft rot), Corynebacterium sepedonicum (ring rot) and Phoma exigua vat. foveata (gangrene) which are regarded as the most important tuber‐borne pathogens of potato. The methods comprise selective media for E. carotovora ssp. atroseptica and P. exigua var. foveata, indirect fluorescence antibody staining for E. carotovora ssp. atroseptica and C. sepedonicum, and the eggplant test for C. sepedonicum and P. exigua var. foveata. These are used in Northern Ireland to detect pathogen contamination in nuclear stock mother tubers prior to micropropagation. Marked reductions in disease levels of blackleg have been observed in present pre‐basic stocks raised by micropropagation compared with those previously propagated from stem cuttings. It was found that Pseudomonas stutzeri, a saprophytic contaminant bacterium, can pass through the micropropagation process in a latent form.
A rapid method to identify and quantify soft rot erwinias on seed potato tubers1
Authors: PÉROMBELON M. C. M. , LUMB V. M. , HYMAN L. J.
Published: April 2008

Potato tubers are usually contaminated by more than one species or pathovar of soft rot erwinia and, because blackleg incidence is related to the contamination level of seed tubers, the disease potential of seed stocks may be assessed by determining seed‐tuber contamination level. A method is described for identifying and quantifying directly from tubers the three soft rot erwinias commonly associated with potatoes. Replicate lots of 10–15 tubers are peeled by dry abrasion in a commercial potato peeler and the peel weight determined by weighing the tubers before and after peeling. Sap is expressed from the peel, an antioxidant (0.075% dithiothreitol) added, and the sap is dilution‐plated on a diagnostic selective medium (crystal violet pectate [CVP]). After incubating for 24 h at 20°C, the plates are velvet‐replicated onto fresh plates of CVP with or without 35 μg ml‐1 erythromycin and incubated for 48 h at 27°C and 24 h at 33.5 or 37°C. Soft‐rot erwinias typically form deep cup‐like cavities on CVP and they can be identified and enumerated according to the pattern of cavity formation. Cavities are formed by Erwinia carotovora pv. atroseptica only at 27°C, by E. carotovora pv. carotovora at 27 and 33.5°C but not at 37°C, whereas E. chrysanthemi forms cavities at all temperatures but fails to grow in the presence of erythromycin. Contamination levels can be expressed as the number of different erwinias per tuber or per g peel.
Trends in France for the use of the ELISA method in routine seed‐potato testing and problems of cross reactions between potato viruses A and Y1
Authors: DELTOUR A. , GUILLOU M. , KERLAN C.
Published: April 2008

Like other seed‐potato‐producing countries, France has now been using ELISA for many years and this method is now totally integrated into the French laboratory test system. It is applied on an occasional or systematic basis at all stages of genealogical selection, and provides complete satisfaction owing especially to its flexibility. An occasional difficulty has been cross reaction between potato viruses A and Y, and the causes and remedies of this are examined. An ELISA serum production unit was set up in early 1985 to provide for French needs and to allow for the possibility of extension of the method to other pathogens than viruses.
Detection of plum pox virus by isolation of double‐stranded ribonucleic acid (dsRNA)
Authors: MAISS E. , BREYEL E. , CASPER R. , LESEMANN D. E.
Published: April 2008

Double‐stranded RNA (dsRNA) associated with plum pox virus (PPV) in Nicotiana clevelandii and Prunus domestica has been isolated. While dsRNA was detected in N. clevelandii in considerable amounts by electrophoresis, only small amounts were found in P. domestica. This may be due to viscous substances in the leaves of this woody host. Different PPV strains (NAT ‐ not aphid‐transmissible; AT ‐ aphid‐transmissible) showed specific patterns in electrophoresis gels. When PPV was assayed in N. clevelandii by dsRNA detection or by standard ELISA or ISEM, all three methods were found to be efficient, with none being superior. ELISA, as a simple and fast routine method, is still the method of choice. DsRNA detection will be suitable for plant disease agents undetectable by ELISA and ISEM.
Problems of detecting phytopathogenic bacteria by ELISA1
Authors: LÓPEZ M. M. , CAMBRA M. , ARAMBURU J. M. , BOLINCHES J.
Published: April 2008

Xanthomonas ampelina can be detected with the same sensitivity by ELISA double‐antibody sandwich (ELISA‐DAS) or indirect ELISA (ELISA‐I) but the latter is preferred for its greater simplicity. The two methods also gave similar sensitivity results for soft‐rot erwinias, but their application is complicated by the large number of erwinia serotypes. ELISA‐I was unable to distinguish strains of Agrobacterium tumefaciens from A. radiobacter. The cross reactions with other bacteria of antisera against X. fragariae were tested by ELISA‐I. The problems of applying these methods are discussed.
Comparison of immunofluorescence staining and indirect isolation for the detection of Corynebacterium flaccumfaciens in bean seeds1
Authors: CALZOLARI A. , TOMESANI M. , MAZZUCCHI U.
Published: April 2008

Corynebacterium flaccumfaciens, causing bacterial wilt in bean, is a quarantine organism for Europe. This paper compares two methods for detecting C. flaccumfaciens in seed lots on the market. Experimentally contaminated bean seeds were homogenized and a standard extraction and concentration procedure was used. The final pellets were used for immunofluorescence staining and indirect isolation (through bean seedlings). The immunofluorescence staining sensitivity threshold was 1.23 × 107, corresponding to 1.82 × 104 fluorescent cells per ml of final concentrate. The risk of false negative reactions to immunofluorescence staining caused by serologically unrelated C. flaccumfaciens strains was also examined. The indirect isolation sensitivity threshold was 1.23 × 106 producing 43% symptomatic plants and 53% positive reisolation. There was no serious interference between C. flaccumfaciens and Pseudomonas syringae pv. phaseolicola in mixed inoculations and both pathogens were successfully reisolated. The comparative results are discussed in relation to the applicability of the methods to commercial lots of bean seeds.
Monitoring fireblight for official phytosanitary legislation in Belgium1
Authors: VAN VAERENBERGH J. , CREPEL C. , VEREECKE M.
Published: April 2008

Fireblight has been present in Belgium since 1972. An official monitoring project to prevent the spread of the pathogen started in 1978, combining regulations and large‐scale surveys. The most important regulations concern: (a) the concentration of nurseries in officially designated protected zones; (b) prohibition of the growing of highly susceptible Cotoneaster spp.; (c) the supervision of hawthorn hedges; (d) the eradication of diseased host plants. In the surveys, diseased or suspect plant material is diagnosed and Erwinia amylovora populations are monitored on leaves, flowers and buds, sampled from apparently healthy plants during field inspection. The laboratory methods are mainly serological and consist of: (a) direct isolation and testing of suspect colonies by agglutination; (b) screening of samples using indirect immunofluorescence; (c) selective enrichment on immature pear slices. A review of 8 years' work is presented and discussed, illustrated with results of experiments.
The taxonomic position of Xanthomonas ampelina1
Authors: WILLEMS A. , GILLIS M. , KERSTERS K. , VAN DEN BROECKE L. , DE LEY J.
Published: April 2008

The internal taxonomic structure and the suprageneric relations of the causal agent of bacterial blight and canker of grapevine, the misnamed Xanthomonas ampelina, were examined. By studying more than 30 strains of different geographical origin by polyacrylamide gel electrophoresis and DNA: DNA hybridization, we established the homogeneity of X. ampelina. [14C]‐labelled ribosomal RNA (rRNA) was prepared from the type strain of X. ampelina (NCPPB 2217) and hybridized with DNA from different representative strains from the Pseudomonas acidovorans rRNA complex in rRNA superfamily III. X. ampelina was found to be a separate branch in rRNA superfamily III, related at a suprageneric level to P. acidovorans, Alcaligenes paradoxus and the other organisms of the P. acidovorans rRNA complex.
Note sur les épidémies causées en Italie par deux bactéries phytopathogènes dans les cultures de tomates sous abri1
Authors: TAMIETTI G. , CUGUDDA L.
Published: April 2008

Depuis quelques années Pseudomonas corrugata et P. syringae pv. tomato, agents phytopathogènes responsables de deux maladies bactériennes, causent de graves problèmes dans les cultures de tomates sous abri en Italie du Nord. Les symptômes, l'épidémiologie ainsi que plusieurs moyens de lutte contre ces maladies sont décrits.
Biology of Pseudomonas cichorii in chrysanthemum1
Authors: JANSE J. D.
Published: April 2008

Since 1982, outbreaks of stem blight caused by Pseudomonas cichorii are sometimes found in greenhouse‐grown chrysanthemums in The Netherlands. In this study, 13 Dutch chrysanthemum isolates and, for comparison, six from other origins were biochemically, serologically and pathologically characterized. All isolates were biochemically homogeneous in most of some 40 tests. Different serotypes were observed, which were not host or virulence‐correlated. After inoculation into cut and potted chrysanthemum, endive and chicory, P. cichorii isolates were found to be non‐host‐specific. Isolates showed differences in virulence after inoculation into potted chrysanthemum. For five isolates, disease development at high humidity (85–95% RH, 18°C) was more than 100% greater than at low humidity (55–70% RH, 18°C). Using a selective medium and immunosorbent dilution plating (ISDP), P. cichorii could be isolated from symptomless leaves and soil from nurseries where the disease was observed and from soil of a disease‐free nursery. ISDP did not significantly increase the recovery of the pathogen. It was concluded that: (a) P. cichorii is an opportunistic pathogen; (b) epidemic infections of stem blight are due to a combination of high humidity, higher temperatures, high plant density and use of very susceptible cultivars; (c) control measures should concentrate on preventing this combination.
Rhizobacteria with broad‐spectrum antifungal activity*
Authors: LAMBERT B. , LEYNS F. , JOOS H. , TENNING P. , VAN RIJSBERGEN R. , VAN OUTRYVE F. , ZHAO Y. , SWINGS J. , VAN MONTAGU M.
Published: April 2008

Antifungal rhizobacteria were obtained from maize, barley and chicory using direct or indirect isolation procedures. Effective isolates were tested for broad‐spectrum activity against a set of phytopathogenic fungi. Isolates with broad‐spectrum activity were identified as Pseudomonas fluorescens, P. cepacia, Serratia liquefaciens, S. plymuthica and Bacillus sp. Broad‐spectrum compounds produced by P. cepacia and Erwinia herbicola were characterized as pyrrolnitrin and herbicolin‐like compounds respectively.
The occurrence of Phialophora‐like fungi related to Gaeumannomyces graminis under various grass species and some characteristics of these fungi1
Authors: MARTYNIUK S.
Published: April 2008

Phialophora graminicola and Phialophora sp. (lobed hyphopodia) are weakly or not pathogenic to the cereal and grass roots which they colonize and are also known to restrict the infection of these plants by Gaeumannomyces graminis. The occurrence of these fungi under 15 field‐grown grass species has been studied using wheat as the test plant. P. graminicola occurred under all grass species tested but at different population levels. The lowest populations were found under Bromus erectus and B. inermis, and relatively low populations under Agrostis alba, Festuca ovina and Phalaris arundinacea. Festuca pratensis, F. rubra, F. arundinacea, Dactylis glomerata and Arrhenatherum elatius harboured the highest populations of P. graminicola. Phialophora sp. (lobed hyphopodia) was found at low population levels under 7 of the 15 grasses examined. The strains of P. graminicola isolated in these studies differed markedly in growth rate on wheat roots and in restriction of G. graminis on wheat grown in perlite (preliminary results).
Field testing putative biological controls of take‐all: rationale and results1
Authors: HORNBY D.
Published: April 2008

In seeking biological control of the wheat take‐all fungus (Gaeumannomyces graminis var. tritici) by introduced organisms, the demonstration of satisfactory field performance is proving a formidable hurdle. A novel experimental design incorporating small plots, 37 x 31 cm, has been used in UK at Rothamsted and Woburn since 1983 to test different kinds of control for take‐all and to explore some of the problems of providing adequate field tests of putative biocontrol agents. Three years of bacterial treatments, using different plots each year, provided no evidence of effective control of the disease. Of the few significant treatment effects, most occurred in spring and were temporary: at Woburn they were mostly decreases in take‐all and at Rothamsted mostly decreases in growth of the wheat plant without concomitant changes in take‐all.
Concepts and methods in biological control of diseases in apple orchards1
Authors: BOSSHARD E. , SCHÜEPP H. , SIEGFRIED W.
Published: April 2008

The project ‘Promotion of Biological Methods in Apple Growing’ which started in Switzerland in 1985 concentrates on the control of Venturia inaequalis (scab) and Podosphaera leucotricha (powdery mildew). The project considers the selection of suitable cultivars resistant or only slightly susceptible to fungal diseases and the assessment of tolerable economic loss. It also includes curative treatments with sterol‐synthesis‐inhibiting fungicides, according to scab infection periods, as well as applications of plant extracts (proposed by the Institute of Biological Husbandry) and suspensions of antagonists or their culture filtrates as plant‐protecting agents. Screening experiments on apple seedlings showed that root extracts of Rumex obtusifolium significantly reduced powdery mildew infections under greenhouse conditions. In field experiments treatments with R. obtusifolium extracts at intervals of 7–10 days were less effective. Saponin‐containing extracts of different plants gave satisfying control of scab on seedlings in the growth chamber but were not very effective in the field. Applications of spore suspensions and culture filtrates of the phyllosphere fungi Chaetomium spp. reduced scab and mildew infections on apple seedlings to some extent. It was found that in the last 2 years even primary infections of P. leucotricha were severely parasitized by Ampelomyces quisqualis. Preliminary studies showed that the lack of efficacy of this biocontrol system is due to the delayed spread of the hyperparasite.
New trends in orchard spraying1
Authors: CROSS J. V.
Published: April 2008

Since the early part of the century, a steady move in England towards lower volume spraying of orchards has coincided with the progressive introduction of improved spraying techniques. In recent years many growers have adopted very low volume (VLV) spraying (50 litre ha‐1) using spinning‐disc nozzles with greatly reduced dose rates, often only 25% of the product label recommendation. On well managed farms, this method of spraying has been successful for several years and considerable savings have been made in pesticide use and labour for spraying. On other farms there have been pest and disease control problems but few growers have reverted to spraying at conventional volume or pesticide rates. Trials evidence from the UK and the Netherlands shows the VLV reduced dose‐rate spraying technique to be generally less effective than conventional spraying but usually sufficiently effective for commercial purposes. In the Netherlands a compromise method of low volume spraying (150–200 litre ha‐1) is being adopted on the recommendation of research and advisory services. This method of spraying is gaining popularity in England. Unfortunately, the method of application stipulated on product labels is usually restricted to a minimum water volume and a pesticide dose per ha. It might be desirable for experimental work for registration purposes to be done to explore optimum application methods for individual pesticides. This information on labels, in a simple form, might lead to the more efficient use of pesticides as well as reflecting the range of application methods in use in the industry.
Stratégies de la bactérisation par les rhizobactéries1
Authors: DIGAT B.
Published: April 2008

De nombreux travaux montrent que certaines souches de rhizobactéries appartenant au groupe Pseudomonas fluorescens‐putida ont un effet positif sur la croissance des plantes et sur leur protection vis‐à‐vis des agents pathogènies du sol. Si tous les modes ďaction de ces bactéries telluriques sont encore loin ďêtre compris, on observe cependant une corrélation constante entre ľintensité de la production de pigments fluorescents (sidérophores), la capacitéà produire un antagonisme in vitro et la stimulation de la croissance des plantes. Le principe de la bactérisation est ďintroduire une population bénéfique dans un milieu et de ľy maintenir ou de lui faire atteindre un niveau suffisant afin ďobtenir finalement les effets voulus. Il a done été nécessaire de suivre la dynamique des populations introduites dans plusieurs types de milieux de plus en plus complexes: cultures in vitro, substrats artificiels et substrats naturels. Ceci a permis ďobtenir de précieux renseignements sur ľévolution des populations en conditions contrôlées de température et ďHR. Les résultats obtenus montrent que: (1) la bactérisation est ďautant plus efficace qélle est réalisée précocement dans un milieu biologiquement simple. Aussi ľenrobage microbiologique des sentences et des boutures ainsi que le bactérisation de plantules in vitro peuvent donner de bons résultats. Corrélative‐ment, le maintien des populations dans un biotope est ďautant plus difficile à réussir que celui‐ci est biologiquement complexe; (2) le biotope doit offrir à la population introduite la possibilité de se maintenir, ďy trouver des éléments assimilables et de éy multiplier activement. Ceci est malheureusement pas le cas pour certains substrats artificiels et naturels dans lesquels le maintien de la population est encore problématique et nécessite des ‘rappels’ de bactérisation; (3) les caractères intrinséques de la souche sélectionnée en vue de la bactérisation sont déterminants; (4) il est nécessaire de maintenir une quantité minimale de cellules bactériennes au niveau du systéme racinaire pour obtenir un effet sur ľamélioration de la croissance de la plante. Le seuil minimal de biostimulation se situe fréquemment aux environs de 104 bacteries par cm de racine (betterave sucrière, laitue, pelargonium, chrysanthème). Mais le seuil de biosaturation varie davantage selon ľespèce végétale considérée et le stade physiologique.
Growth of Coniothyrium minitans, Gliocladium roseum, Trichoderma harzianum and T. viride from alginate pellets and interaction with water availability1
Authors: MAGAN N. , WHIPPS J. M.
Published: April 2008

Conidia, chlamydospores and mycelia of Coniothyrium minitans, Gliocladium roseum, Trichoderma harzianum and T. viride were obtained from liquid or solid culture and formulated within alginate pellets. Quantitative assessment of these pellets over a 12‐week period showed a decrease in the number of colony‐forming units (cfu) from about 107 to 103‐104 g‐1 air‐dried pellets. Qualitatively, growth was assessed by direct plating the alginate pellets on rich (potato dextrose agar, PDA) and poor (water agar, WA) substrates. Rate of growth (mm day‐1) from individual pellets was decreased by water potential in the range ‐0.25 to‐2.8 MPa, with growth significantly less on WA than PDA for all species except G. roseum. All species grew from 95 to 100% of direct‐plated pellets on PDA over the water‐potential range tested. However, on WA, interaction between water stress (‐2.8 MPa) and lack of nutrients resulted in a reduction, with less than 30% of pellets of some formulations showing growth. In contrast to the quantitative results, there was little change in the growth rate of test species from pellets over a 12‐week period, particularly on PDA. Growth from pellets could not be conclusively demonstrated in unsterile soil. The shelf‐life and viability of alginate pellets in soil is assessed.
Biological control by Trichoderma harzianum of damping‐off of lettuce caused by Rhizoctonia solani1
Authors: WILSON M. , CRAWFORD E. K. , CAMPBELL R.
Published: April 2008

Ten isolates of Trichoderma harzianum were tested for their ability to control lettuce seedling damping‐off caused by introduced Rhizoctonia solani. T. harzianum isolates TRC 9 and 28 both reduced damping‐off. Dual culture experiments were used to select isolates for the study of antibiotic production and mycoparasitism. T. harzianum isolate TRC 12 produced volatile and non‐volatile antibiotics, whilst TRC 33 produced only non‐volatile antibiotics. T. harzianum isolates 018‐2/Y and TRC 9,15 and 28 mycoparasitized R. solani by coiling around and lysing the host hyphae. It appeared that mycoparasitism was more important than antibiosis in the biological control of damping‐off.
Dispersal of Liriomyza trifolii
Authors: MINKENBERG O. P. J. M.
Published: April 2008

The agromyzid fly Liriomyza trifolii, which has generally been considered as a secondary pest, could turn into a major international pest. Up to the seventies this leafminer occurred only in Caribbean countries, and southern and eastern USA. It then became resistant to several insecticides in Florida. Extensive transport of plant material between production areas has resulted in the establishment of this insect in many countries, despite chemical treatment before and after transport and quarantine procedures. The human‐mediated dispersal of L. trifolii is described, phytosanitary and quarantine measures are reviewed and finally plant protection policy is discussed.
An investigation of the parameters of anticoagulant treatment efficiency1
Authors: GREAVES J. H. , RICHARDS C. G. J. , BUCKLE A. P.
Published: April 2008

The traditional technique of applying anticoagulant rodenticides, as shaped by long experience in the use of low‐toxicity, first‐generation anticoagulants such as warfarin, aims to maximize treatment efficiency by maximizing the rate of bait consumption by the target rodents. This is done, somewhat laboriously, by laying surplus amounts of bait initially, and maintaining this surplus throughout the treatment by repeatedly replenishing the bait placements. The suggestion that the high toxicity of the second‐generation anticoagulants should enable a more efficient baiting system to be designed is examined experimentally in this field study of the control of Rattus norvegicus on British farms. Bait toxicity, infestation size and the incidence of complete takes of bait were found to be independent and highly significant determinants of treatment duration whilst, in comparison, the size and density of bait points and the frequency with which the bait was replenished were found to be relatively unimportant. However, bait size and, more especially, replenishment frequency had detectable secondary effects, apparently through partial relationships with the incidence of complete takes and infestation size. The results indicate, in relation to the control of commensal infestations of R. norvegicus on British farms, that the use of high‐toxicity bait formulations and frequent replenishment schedules increase the speed of control, whilst the number and size of bait placements are relatively unimportant; they also suggest that reductions in the frequency of bait replenishment made in order to save labour could be compensated for by increasing the toxicity of the bait and taking other steps to reduce the incidence of complete takes of bait. The results are discussed in relation to the concept of ‘pulsed baiting'.
Rodent tissue residue and secondary hazard studies with bromadiolone1
Authors: POCHÉ R. M.
Published: April 2008

A series of toxicological, residue, secondary hazard, and environmental fate studies were completed with bromadiolone. The compound was eliminated rapidly after ingestion by Rattus norvegicus and Mus domesticus. In R. norvegicus, 75% of the bromadiolone was eliminated within 4 days. Dead rodents collected from field trials using bromadiolone had residue levels of 1.92 in R. rattus, 1.17 in M. domesticus, and 0.49 ppm in Spermophilus beecheyi. The LD50 for bromadiolone in beagle dogs was calculated at 8.1 mg kg‐1 (10.7 for males and 6.3 mg kg‐1 in females). The approximate LD50 in Canis latrans was 10 mg kg‐1. Dietary LC50 determination compound in Putorius putorius furo was 9.8 ppm. Secondary hazard studies showed the rodenticide to have little potential to snakes and birds of prey if used properly. Field tests with grain and pelleted baits over 21 days demonstrated that the active ingredient degraded by 78 and 45%, respectively.
Fireblight in Poland
Authors: SOBICZEWSKI P. , SUSKI Z. W.
Published: April 2008

Fireblight (Erwinia amylovom) was first detected in Poland in 1966 and then occurred irregularly, in isolated foci mainly along the northern coast of the country, until 1975. During this period, radical measures were taken for localization and elimination of the disease. Since 1976, the disease has become established in numerous areas across northern Poland, and since 1985 has spread towards the centre of the country. Pear, apple and wild hawthorn are affected. In recent years, damage in affected areas has been only at a moderate level. A Ministerial Decree makes fireblight control compulsory. Inspections are carried out throughout the country and any outbreaks must be notified. Complete elimination of infected and adjacent host plants is recommended in areas of low incidence. In heavily affected areas, it is recommended to prune away all infected parts. Severe restrictions apply to nurseries. General preventive measures are also recommended.
Description des cycles pluriannuels d'Arvicola terrestris scherman en Suisse occidentale par la méthode de l'analyse des séries temporelles1
Authors: SAUCY F.
Published: April 2008

Pour tenter de prévenir les pullulations d'Arvicola terrestris scherman, certaines communes de Suisse offrent une prime de piégeage pour tout micromammifère capturé sur leur territoire. L'analyse des carnets de comptes permet ensuite de reconstituer les cycles d'abondance d'A. t. scherman. Les données récoltées en Suisse occidentale auprés de 11 communes du Jura et des Préalpes ont permis de reconstituer 37 cycles complets entre 1935 et 1984. La durée de ces cycles est plus longue que chez la plupart des autres espéces de rongeurs, soil 6 ans en moyenne, avec des extrêmes compris entre 4 et 8 ans. Ce matériel a étéétudie par les techniques de l'analyse des séries temporelles. Les résultats prouvent qu'une périodicité, statistiquement démontrée, existe dans ces données et que les fluctuations d'abondance d'A. terrestris ne se déroulent pas selon un rythme aléatoire. L'indice de cyclicité de Lewontin est généralement supérieur à 0,50 et le périodogramme présente un maximum compris entre 5 et 7,5 ans, suivant les cas. Mis à part dans deux localités des Préalpes adjacentes, les pullulations ne sont pas synchrones entre stations éloignées au plus de quelques dizaines de km les unes des autres. Une analyse de corrélation a mis en évidence des décalages entre les séries compris entre 1 et 7 ans. Ces résultats suggèrent que des causes de nature intrinséque sont à l'origine des cycles d'abondance chez A. terrestris. L'impact de la prédation par Mustela erminea en période de déclin et de faible densité explique probablement la durée inhabituelle du cycle.
Assessment of partial resistance of potato to, and pathotype and virulence differences in, potato cyst nematodes
Authors: MUGNIÉRY D. , PHILLIPS M. S. , RUMPENHORST H. J. , STONE A. R. , TREUR A. , TRUDGILL D. L.
Published: April 2008

Results are reported for several international collaborative experiments which examined methods of assessing degrees of partial resistance in potato and virulence in potato cyst nematode (PCN, Globodera pallida). It was demonstrated that absolute rates of multiplication can be extremely variable on both susceptible and partially resistant clones, even when the same population and test procedures are employed. It was therefore concluded that, on clones with quantitatively inherited resistance (i.e. partially resistant), absolute rates of multiplication cannot be used to separate pathotypes. Expression of these rates as percentages of those on the susceptible controls reduced the absolute differences between tests, but the values obtained were still too variable for statutory use. However, whatever the environment or nematode population used, it was observed that the resistance of the test clones and virulence of the nematode populations were generally ranked in a similar order. The main exceptions to this were: (1) a Petri‐dish test where cv. Vantage was less resistant than in canisters or pots and (2) a pot test where cv. Darwina tended to be more interactive with environmental factors than the other test clones. It was also observed that with some populations of PCN in pots the susceptible cv. Bintje was a less good host than cv. Désirée. On the basis of these results it is suggested that certain partially resistant clones should be used as internal references in statutory, recommended list and breeders' assessment tests against which the resistance of the test clones are compared. For international comparability it is necessary that the different centres conducting such tests use the same reference clones and nematode populations, and similar test methods.
Bacterial leaf streak of Gramineae in Iran
Authors: ALIZADEH A. , RAHIMIAN H.
Published: April 2008

Bacterial leaf streaks of wheat and barley in Kerman province (Iran) were found to be distinct in etiology. The barley strains were limited in host range and could only infect barley. The wheat strains were pathogenic to barley, wheat, rye, triticale, Bromus spp., Agropyron spp., Elymus junceus, Lolium multiflorum, and Phalaris tuberosa, but not Dactylis glomerata, Cynodon dactylon, Phleum pratense, and oat. Based on host reactions and electrophoretic patterns of cell proteins, the barley and wheat strains were identified as Xanthomonas campestris pv. hordei and pv. cerealis, respectively.
Investigation of methods for testing the susceptibility of forage grasses to Xanthomonas campestris pv. graminis1
Authors: PAUL V. H. , BIRKENSTAEDT E.
Published: April 2008

The economic importance of Xanthomonas campestris pv. graminis on grasses has made it necessary to look for control measures. The most important is breeding for resistance. Different methods of selection were investigated and compared. Further, production of the inoculum, virulence, host specificity, disease assessment and yield losses of Arrhenatherum elatius were examined.
Sensibilité de cultivars de raygrass ďltalie à Xanthomonas campestris pv. Graminis1
Authors: GONDRAN J. , BETIN M.
Published: April 2008

14 cultivars de raygrass ďltalie ont été inoculés artificiellement au champ par Xanthomonas campestris pv. graminis. La corrélation entre les notes de flétrissement et les pertes de rendement causees par le parasite est satisfaisante: 0,7371 (P<0,01). Le cultivar le plus résistant était Turilo car sa perte de rendement était nulle. Mais les symptômes de flétrissement causés par X.c. graminisétaient décelables sur ce cultivar (10% des feuilles flétries). Tiara était le cultivar le plus sensible: il a subi 47% de pertes et plus de la moitié des feuilles étaient flétries. Des inoculations en serre ont été répétées trois fois sur 11 de ces cultivars. Leurs classements suivant leur sensibilité a ľinfection étaient voisins mais non parfaitement constants: les significations des corrélations 2 à 2 varient (0,5 < P < 0,001). Déautre part, ces inoculations en serre étaient faiblement corrélées avec celles du champ (P=0,05 ou P < 0,10). En conséquence nous pensons que les conditions ďexpression des symptômes en conditions contrôlées doivent être améliorées pour permettre de trier des plantes résistantes au champ.
Susceptibility of cultivars of Italian ryegrass to Xanthomonas campestris pv. Graminis1
Authors: PAUL V. H. , FREUDENSTEIN K. H.
Published: April 2008

Italian ryegrass is one of the grasses that have been adversely affected by Xanthomonas campestris pv. graminis. It is well known that significant differences in susceptibility to the disease exist within the cultivars of this species. In order to describe this characteristic in the official variety list, the Bundessortenamt and the University of Paderborn have worked together in testing for resistance to X.c. graminis. Greenhouse and field experiments were conducted using artificial infection. The results of these tests correlated significantly so that a sufficient description of the cultivars seemed possible. According to the range of parasitic attack, the cultivars could be grouped into five different susceptibility classes. Those cultivars which were only slightly susceptible have been especially selected for bacterial wilt resistance. With regard to ploidy, it could be seen that tetraploid cultivars were on average less susceptible than diploids. The results of this varietal testing made it clear that improvement can certainly be achieved by further breeding activity.
Viruses and virus‐like pathogens transmitted by zoosporic fungi1
Authors: BRUNT A. A.
Published: April 2008

The viruses and virus‐like pathogens transmitted by zoosporic fungi are reviewed. The nine furoviruses (and possible members of the group), with labile rod‐shaped particles, have nearly all been shown to be transmitted by plasmodiophoromycete vectors. As they have been reviewed extensively elsewhere, they are covered only briefly; important examples are beet necrotic yellow vein furovirus and potato mop‐top furovirus. Five viruses with filamentous particles, tentatively recognized as poty viruses, are transmitted by Polymyxa graminis. Within this group, wheat yellow mosaic virus should be considered to include wheat spindle streak mosaic virus, while the M and NM forms of barley yellow mosaic virus, the best known members of the group, should probably be regarded as distinct viruses. Chytrids (especially Olpidium brassicae) transmit a variety of viruses in different groups (e.g. tobacco necrosis necrovirus, lettuce big‐vein virus, melon necrotic spot carmovirus, red clover necrotic mosaic dianthovirus). Finally, several diseases caused by uncharacterized pathogens appear to be transmitted by O. brassicae: freesia leaf necrosis, lettuce ring necrosis, pepper yellow vein, watercress chlorotic leaf spot.
Inoculum potential and host range of Polymyxa betae and beet necrotic yellow vein furovirus1
Authors: GOFFART J. P. , HORTA V. , MARAITE H.
Published: April 2008

The inoculum potential of Polymyxa betae and BNYVV was studied from 52 random samples of Belgian soils and 10 samples from other European countries, by culture of bait plants in tubes under controlled conditions on serial dilutions of the soils in sterile sand. P. betae was detected in all samples within the range of 0.01 to 27.1 infection units per g of soil. BNYVV was detected by ELISA on root extracts of bait plants grown on three Belgian soil samples. All the tested samples from rhizomania‐infested areas in France, FRG, the Netherlands, Switzerland and Austria, were found to be infested by BNYVV by this technique. For BNYVV survey, the plant bait technique appears more reliable than the analysis of rootlets collected in the field and observation of external symptoms in case of low BNYVV infestations or non‐expression because of unfavourable environmental conditions. P. betae isolates from various origins heavily infected Beta spp. but only moderately spinach. Chenopodium album was slightly infected by 2 of the 7 isolates, C. murale by 4 of them.
Electrophoretic study of three related Phytophthora species1
Authors: CACCIOLA S. O. , DI SAN LIO G. MAGNANO , GRECO G. , PANE A.
Published: April 2008

Morphological and cultural characters currently used for the classification of species of Phytophthora are inadequate to distinguish P. cryptogea, P. drechsleri and P. erythroseptica. In this study isolates of the above‐mentioned species, including type and/or authentic cultures of P. cryptogea and P. drechsleri were compared. Morphological and cultural characters, together with electrophoretic patterns of both total mycelial proteins and isozymes (arylesterase and malate dehydrogenase), allowed the distinction of P. erythroseptica from the others. Authentic cultures of P. cryptogea and P. drechsleri showed distinctly different electrophoretic patterns of arylesterase and malate dehydrogenase isozymes and of total mycelial proteins. Some Italian isolates previously identified as P. cryptogea or P. drechsleri showed features of both species, therefore it was impossible to discriminate the two species solely on the basis of the electrophoretic patterns of mycelial proteins.
A system developed by the UK Plant Health Service to report on pest and disease interceptions, communicate diagnoses and summarize data1
Authors: SAVAGE D. E.
Published: April 2008

The Plant Health Inspectorate in the UK carry out a large number of inspections for plant pests and diseases each year and send thousands of samples to the Ministry's Central Laboratory at Harpenden for diagnosis or confirmation. Until 1987 all reports and sample information was sent by post to the laboratory and respective management staff. The resulting information was sent by post to the Laboratory and respective management staff. The resulting information was summarized manually. Using MAFF network and computer facility and programming skills acquired by Plant Health staff, the Inspectorate have, over the last 3 years, developed a suite of systems to help with various aspects of their work. One of these systems provides for standardized reporting of pest and disease interceptions. Each report acquires a unique computer‐generated reference number which can be used for identifying samples sent to the Laboratory. All inspectors have access to terminals, linked to the minicomputer, and the system has recently been enhanced to facilitate the input of Laboratory diagnosis information. This system together with use of an electronic mail facility has not only speeded up reporting procedure and reduced communication costs, but has allowed for the rapid summary of important data.
Potato production and protection in Poland in the 1990s1
Authors: PIETKIEWICZ J. B.
Published: April 2008

Potato is an important crop for Polish agriculture, now grown on an area of 1.8 million ha, with an annual production of about 35 million t. The crop is used for fodder (pork production), human consumption and as a raw material for various branches of industry. High quantity and quality are essential for proper utilization. The main limiting factors in Polish potato production are: water (shortage or excess), seed potato quality, cultivation practices, and damage by pests, diseases and weeds. Improving the economics of potato production depends on decreasing the acreage and increasing the extent of proper protection. The major constraint is late blight (Phytophthora infestans) which causes yield losses estimated at 22.8%. Blight control is indispensable. The level of resistance among Polish cultivars, both in haulm and tuber, is not satisfactory, so more intensive resistance breeding is needed. Chemical control has increased in popularity, but improper use of phenylamides has created new problems. Further progress will depend on cost‐effective methods of control and reliable use of fungicides.
Commercial tissue culture in Europe1
Authors: KERR‐LIDDELL S. R.
Published: April 2008

Micropropagation has developed from a research procedure to a major commercial operation, and the operational and financial problems in this development are reviewed. A brief profile is presented of the industry in western Europe, and of the present nature of the trade in microplants. European laboratories are increasingly concentrating on expensive and specialized plants. The regulatory position for micropropagated plants should be specially adapted for the purpose.