bluuebunny/crossref_metadata_2025 huggingface dataset:
Signification de l'étude qualitative et quantitative des champignons phytopathogènes telluriques
Authors: Louvet J.
Published: April 2008

Sommaire

L'importance de la détermination précise des champignons phytopathogènes actifs dans le sol est rappelée. La nécessité de réaliser des inoculations pour déterminer les formes spéciales et les races de Fusarium oxysporum (Schlecht.) Sn. et H. responsables de trachéomycoses est prise comme exemple. Des recherches sur le mode d'action de ces champignons vis‐à‐vis des plantes et sur leur comportement dans le sol en fonction des facteurs de l'environnement doivent également être développées.

Les études quantitatives sur Ies populations de champignons phytopathogènes existant dans le sol peuvent permettre de mieux déterminer si ces champignons sont présents ou non dans un sol donné (détection), d'étudier la dynamique de leurs populations en fonction des facteurs du milieu (écologie) et d'établir s'il existe des corrélations entre les quantités de germes et la gravité des mabdies. De nombreux facteurs encore insuffisamment connus entrent en jeu, mais ces études ont permis de prendre conscience de l'importance de certains d'entre eux et elles aboutiront à la découverte de nouvelles méthodes de lutte reposant sur des bases biologiques précises.
Soil‐borne Pathogens in Ornamental Bulbs as Related to Quarantine Problems
Authors: Schenk P.K.
Published: April 2008

The introduction of systemic fungicides belonging to the group of benzimidazoles has greatly improved the available methods for the control of several destructive diseases of ornamental bulbs. This is illustrated on the basis of two diseases of tulips that may be soil‐borne, viz. Botrytis tulipae (Lib.) Lind and Fusarium oxysporum Schl.

Benomyl in particular appears to be very active against these and certain other pathogens sometimes carried by planting material. With respect to Fusarium, treated tulip bulbs planted in contaminated soil are protected against infection occurring at high soil temperatures (15°C and higher) shortly after planting. Improved methods of chemical soil disinfection (methylbromide and DD under plastic seal) provide almost complete eradication of nematode populations in sandy soils. Application of these methods will further reduce problems given by stem eelworms (D. dipsaci Kühn and D. destructor Thorne) and free‐living nematodes that transmit soil‐borne viruses (Trichodorus spp.).
The Present Position in the Systematics of Meloidogyne
Authors: Franklin Mary T.
Published: April 2008

The genus Meloidogyne includes 32 species. The main character used for differentiation is the posterior cuticular pattern of the female. This is difficult to define and often variable but in most species it is characteristic. The body length and length and shape of the tails of the larvae, and the head characters of males, can also be used in identification of some species. The morphological and physiological variability in the commonest species is so great as to suggest that they may be species complexes or that evolution may be proceeding at an observable rate. This results in some uncertainty in the systematics.
Rôle économique et importance des Meloidogyne en Europe et dans le bassin Méditerranéen
Authors: Ritter M.
Published: April 2008

Sommaire

Les nématodes appartenant au genre Meloidogyne peuvent être considérés à I'échelle mondiale comme le groupe le plus important de ces parasites. Les « anguillules des racines noueuses », ou « rootknot nematode « des auteurs anglosaxons, ont été longtemps jugées comme étant graves seulement dans les pays tropicaux ou méditerranéens chauds. Les différentes espèces sont souvent difficiles à distinguer on les a confondues jusqu'à une date récente et nombre d'entre elles restent encore à décrire — neuf ont été signalées en Europe.

La fréquence et la gravité des attaques semblent augmenter dans les régions méditerranéennes, surtout sur cultures maraîchères, florales, fruitières et sur coton (M. arenaria [Neal] Chitwood, M. incognita [Kofoid et White] Chitwood, M. javanica [Treub] Chitwood). Ces espèces posent aussi de graves problèmes dans toutes les serres européennes. En Europe occidentale, M. hapla Chitwood attaque de multiples cultures légumières: M. naasi Franklin, découvert et décrit récemment, devient un ennemi grave des céréales. Les pertes dues à ces nématodes représentent plusieurs pour cent du produit brut des cultures intéressées dans les aires géogra‐phiques infestées.
An Interpretation of the Ultrastructural Response of Tomato Roots Susceptible and Resistant to Meloidogyne incognita (Kofoid et White) Chitwood
Authors: Webster J.M. , Paulson R.E.
Published: April 2008

Giant cells, which are nutrient sources for the developing larvae of Meloidogyne incognita (Kofoid et White) Chitwood in susceptible tomato roots, are characterized by proliferation of cytoplasm and organelles, lobing of nuclei and irregularly thickened walls. The hypersensitive response of resistant tomato roots occurs more quickly than does the susceptible response and is characterized initially by intercellular deposits, loss of vacuolar electron‐dense deposits, increased electron‐density of the cytoplasm and an increase in the number of ribosomes. Eventually there is a loss of membrane‐distinctness in the cell. The sequence and type of organelle changes suggest that the oesophageal secretions of the nematode into susceptible cells may de‐repress a gene (s) to induce DNA synthesis. Subsequently auxin activity increases ribosomal RNA synthesis so facilitating protein synthesis and water and solute translocation. In a resistant plant the oesophageal secretions may activate a gene that produces a thermolabile enzyme that rapidly releases substances from the vacuoles or lysosomes and so manifests the hypersensitive response. The effect of this enzyme is overcome by exogenous kinetin thus supporting the role of cytokinins in the host response.
Problems and Programs in the Application of the Sterility Principle for the Control of Ceratitis capitata Wied.
Authors: Chance L.E. La
Published: April 2008

In spite of the good results obtained in the control of Ceratitis under field conditions on the Italian islands of Capri and Procida, in Nicaragua and in the Spanish Murcia area, several problems connected with the sterile male technique still have to be solved. Mass rearing of the insects must be improved. Perhaps, total sterility of the males is not required and the necessary dose of irradiation must be studied in relation to its effect on their competitiveness in the field. In checking the efficacy of field operations the recapture of marked individuals will have to be supplemented or gradually replaced by the time‐consuming assessment of egg‐hatching and fruit‐damage. Studies of the influence of environmental factors on population densities must be intensified.
The Ecology of Soil‐borne Pathogens
Authors: Oort A.J.P.
Published: April 2008

The complexity of the interrelations of the varying environmental factors which may affect the host, the pathogen and consequently the host‐pathogen inter‐ action is stressed. The effect of climatic conditions, soil properties, soil biota and human influences is indicated. Two aspects of the ecology of soil‐borne pathogens, viz. dispersal and survival are discussed.
The Use of Insect Viruses for the Protection of Forests
Authors: Wellenstein G.
Published: April 2008

Among the various possibilities for biological control the use of insect polyhedral, granulosis and polypox viruses in the forest is especially promising. Specific virus diseases are known for more than 15 forest insect pests and some have been tested successfully.

In close collaboration with the « Institute for Biological Control of Insect Pests » in Darmstadt and other European entomologists, the polyhedral viruses of Lymantria dispar L., L. monacha L., Malacosoma neuslria L., Choristoneura murinana Hübn. (Tortricidae) and Neodiprion sertifer Geoffr. have been produced by mass rearing of caterpillars, since 1968, at the Institute of Forest Zoology of the University of Freiburg im Breisgau. The optimal concentrations and application rates and the best timing to produce infections can be found by experiments in the laboratory and in the forest. A disadvantage of viruses is their long incubation period. This can be shortened considerably by the addition of safe chemicals to the virus suspension (for example 0.05%‐0.1% CuSO4).

Resume

L'utilisation des virus entomopathogènes dans la protection des forêts

Parmi les différentes possibilités de lutte biologique, l'emploi en sylviculture des virus à action insecticide des types polyédrique, granulaire ou « polypox » ouvre des perspectives particulièrement intéressantes. Pour plus de 15 insectes nuisibles aux forêts, les viroses spécifiques sont connues et, contre plusieurs de ces ravageurs, elles ont permis d'obtenir d'excellents résultats expérimentaux.

Depuis 1968, l'Institut de zoologie forestière de l'Université de Fribourg en Br., en étroite collaboration avec l'Institut de lutte biologique de Darmstadt, s'est occupé de la production des virus polyédriques de Lymantria dispar L., L. monacba L., Malacosoma neustria L., Choristoneura murinana Hübn. et Neodiprion sertifer Geoffr., au moyen d'élevages massifs de chenilles. Les conditions optimales d'application, ainsi que la meilleure période d'infection, ont pu être établies en laboratoire aussi bien qu'en forêt. Un desavantage des viroses réside dans leur période d'incubation prolongée; l'adjonction aux suspensions virosiques de composés chimiques n'ayant pas d'effets indésirables sur le plan hygiénique permet de réduire cette période dans des proportions considérables.
Cost‐benefit Analysis in Orchards where Integrated Control is Practised
Authors: Steiner H.
Published: April 2008

Plant protection practices applied during 1972 in 25 apple orchards with integrated control and 20 with conventional control in the Stuttgart area are discussed. It has been found that integrated control has succeeded in reducing the total variable costs of plant protection by about 20 %. The resulting expenses for training plant protection officers and fruit growers are explained. One of the main reasons, why farmers applying the conventional method are forced to switch to integrated control is undoubtedly on economic grounds because of increasing costs for controlling either resistant pests or formerly minor pests becoming serious problems.
Incidence économique des nématodes sur la production agricole
Authors: Ritter M.
Published: April 2008

Sommaire

Les pertes de récoltes dues aux nématodes sont importantes et difficiles à réduire, en raison même de la nature des dommages et des relations multiples qui existent entre la plante‐hôte et le ravageur. Ainsi, en dehors des dégâts directs, les nématodes peuvent déclencher ou favoriser le développement d'autres maladies, ou agir en tant que vecteur. d'incidence économique est aussi bien quantitative que qualitative.

Les semences ou le matériel destinéà la reproduction, qui sont contaminés, devraient être systématiquement détruits ou désinfectés. Le coût des traitements, l'amélioration des pratiques culturales en matière de fumure, irrigation ou assole‐ment doivent faire l'objet d'études consciencieuses, de faĉon à assurer une protection économique.

Pour mesurer et chiffrer les pertes, on peut utiliser divers critères: essais de pathogénicité en conditions artificielles, traitements de plein champ plus ou moins sélectifs, établissement de formules de corrélation entre les densités de populations révélées par l'analyse du sol et les diminutions de récoltes observées ou escomptées.

Les préjudices causés par les nématodes aux diverses cultures européennes sont du même ordre que ceux qui ont été constatés aux Etats‐Unis et sétablissent comme suit: 5 % pour les céréales et le maïs, 10 % environ pour la pomme de terre, la betterave et les diverses cultures maraîchères ou ornementales (ce pourcentage est probablement dépassé pour les cultures fruitières). Ces données montrent que l'on sous‐estime en général l'importance économique des divers nématodes phytophages, et justifient les mesures préconisées pour en limiter la propagation.
Yield Responses in Relation to the Chemical Control of Root‐knot Nematodes in Southern Italy
Authors: Lamberti F.
Published: April 2008

Nematicide trials have been conducted in Southern Italy to determine the yield response of tobacco, tomato and egg‐plant. The nematode species involved were mainly Meloidogyne incognita (Kofoid & White) Chitwood and M. arenaria (Neal) Chitwood. Many nematicides have an impact also on other soil pathogens or even on insects, so that the yied increase observed in the field has to be considered as a combined effect. On tobacco, most of the nematicides gave positive results, but it appeared that there might be important differences according to the variety considered. In certain tomato fields, which had not been specially attacked by Meloidogyne, the positive effects seemed to be also due to the insecticidal or fungicidal effect of the chemicals. No statistically significant yield increases were, however, obtained on treated egg‐plant fields.
The Problem of Protecting Crops Against Harmful Birds in Poland
Authors: Pinowski J.
Published: April 2008

From the point of view of Polish agriculture, the rook (Corpus frugilegus L.) causes the most damage. Jackdaws (C. monedula L.) usually forage together with rooks and are equally abundant as a breeding species in the southern and central regions of Poland. Fields under spring oats, barley, wheat, maize, peas and winter wheat are the main feeding grounds of rooks and jackdaws. Unlike the corvine birds, starlings (Sturnus vulgaris L.), in Poland, only cause damage to cherry orchards, although in certain areas they also attack strawberries and currants. The house sparrows (Passer domesticus L.) cause considerable damage to ripening crops of wheat, barley, and sunflowers. Domestic pigeons cause considerable damage to crops of peas, wheat and maize grown within a 50 km radius of a town.
Environmental Quality and the Economics of Agricultural Pest Control)
Authors: Headley J.C.
Published: April 2008

Even though there have been many actions to limit chlorinated hydrocarbons used to control insects, many significant environmental problems connected with agricultural pest control remain. To deal with environmental effects in pest control strategy requires economic evaluation even though there are analytical difficulties. Environmental effects of pest control methods can be given economic meaning through the use of implied values measured in terms of sacrifices of conventional benefits. Where the biological significance of damages from pest control methods is known, the problem is to evaluate the differences in net benefits for alternative strategies. However, for those damages which involve uncertainty some sort of hazard‐benefit analysis is needed with the ultimate decision made by persons responsible to society for value judgements. More co‐operation is needed by economists and pest control experts to provide the best information possible within the limits of their professional expertise including analyzing pest control methods in the time dimension. High quality scientific analysis reduces the uncertainty for political decisions.
Economic Aspects of Pest Control1)
Authors: Davidson A. , Norgaard R.B.
Published: April 2008

The activities of economists associated with the IBP project entitled « The Principles, Strategies, and Tactics of Pest Population Regulation and Control in Major Crop Ecosystems » and their interaction with entomologists in the design and implementation of integrated control strategies are described. Profit maximization criteria and a method of considering farmers behaviour with respect to risk are developed. The term «economic threshold » is further clarified; and a simpler concept, « the damage threshold », is introduced. Regional institutions such as pest management co‐operatives and districts and the factors which affect their introduction and successful operation are considered.
Breeding Plant Varieties Resistant to Pests1)
Authors: Sneep J. , Dieleman F.L.
Published: April 2008

In The Netherlands at present the research on resistance against pests is aimed at red spider mite in cucumber, glasshouse whitefly in tomato, carrot fly, aphids in lettuce. In addition projects are planned with a view to breeding resistance against Myzus persicae Sulz. in paprika, and aphids in barley.

Tolerance can hardly be considered as a type of resistance, since it does not control the parasite population. Non‐preference has some advantages, but does not reduce the size of the insect population and causes pests to migrate to other plants and possibly to the neighbours. Antibiosis is the more desirable type of resistance. To prevent it from being broken, antibiosis ought to be based on polygenes. Another method of prevention is to breed multiline varieties.

When creating new varieties that possess certain valuable qualities in combination with a resistance based on polygenes, the breeder has to test yearly thousands of plants. Rapid methods for mass‐testing for resistance are therefore urgently needed.

Breeders have found high‐yielding varieties, which help to feed the world population. However, the desired resistance against pests must frequently come from low‐yielding varieties. To combine the indispensable high yields with resistance against pests is a time‐consuming work. The process will be shortened as better screening methods become available.
Studies on Insect Damage and Economic Thresholds in the Soviet Union
Authors: Tanskii V.I.
Published: April 2008

Studies on damage caused by insects in the USSR provide a basis for establishing economic threshold levels for pest populations. Consideration is given to the relationship existing between insects and their host‐plants and to the efficacy of insecticide treatments.

Economic thresholds depend to a large extent upon weather conditions and varietal characteristics of a crop. However, when considering different geographical zones it appears that there are no significant differences in economic thresholds. In the USSR, the wide use of economic thresholds yields excellent results and allows for a substantial economy in insecticide use on millions of hectares.
A Review of Changes in the Pattern of Infestation in International Trade1
Authors: Freeman J.A.
Published: April 2008

Changes in the degree and kind of infestation by storage insects and mites in imports into Great Britain since the EPPO Conference in Lisbon, 1967, are reviewed. There has been an overall fall in the percentage of infested cargoes from 33 % in 1967 to 23 % in 1973, and a corresponding fall in the incidence of occurrence of many species. The various changes in different classes of commodities, cereals, oilseeds, cocoa beans, etc., according to country of origin, are discussed in detail. The effects of containerisation and greater use of road transport, the growing problem of insecticide resistance in storage insects and mites and the significance of infestation in imports are discussed in relation to future developments in international trade.
Problems Arising from Insecticide Resistance in Storage Pests1
Authors: Dyte C.E.
Published: April 2008

A survey of the occurrence of insecticide or fumigant resistant strains of stored‐product insects is given. Studies on the geographic distribution of insecticide‐resistant strains show that some resistances are localised and others almost universal. Cross‐resistance has been studied in few strains, but malathion resistance may involve resistance to other organo‐phosphorus compounds in at least 6 species. Although resistance to pyrethroids and juvenile hormone analogues is known, these compounds show promise for future use against storage pests.
Research in Progress at the Pest Infestation Control Laboratory1
Authors: Freeman J.A.
Published: April 2008

The paper describes some of the research currently in progress on insects, mites and fungi injurious to stored products, how problems are identified and how the results are put into practice. The research includes surveys in warehouses, farms, etc.; laboratory studies of biology under controlled conditions; storage of grain under various conditions; studies of the effects of contact insecticides, with special reference to resistance; fumigation, and the investigation of insect behaviour in relation to existing and novel control methods.
The Use of Sex Pheromones in the Control of Spodoptera littoralis Boisd.1)
Authors: Campion D.G.
Published: April 2008

An even network of pheromone traps baited with virgin females of Spodoptera littoralis Boisd. was established in Cyprus. By relating trap catches with meteorology it was shown that no major immigration of S. littoralis to Cyprus from surrounding land‐masses had occurred. Direct control of S. littoralis by the synthetic pheromones recently synthesized or the sterile male technique may therefore be possible in such an area of ecological isolation.
Possibilities of Using Insectistatics and Pheromones in the Control of Stored Product Pests1
Authors: Levinson H.Z.
Published: April 2008

Salient aspects of insect cuticle formation, hormone action, nutritional requirements, feeding stimulants, sex and aggregation pheromones are discussed in the light of their possible contribution to controlling storage pests. Agents decimating pest populations by suppression of growth and reproduction (rather than by rapid mortality) are defined as insectistatics. Their mode of action includes inhibition of chitin and sclerotin formation, hormonal imbalance induced by extrinsic juvenoids or ecdysoids, developmental disturbances due to nutrient or metabolite antagonists, accelerators of metabolism and symbioticides. Disruption of mating may be accomplished by pheromone trapping and disorientation, or prevention of sex attraction due to pheromone isomers.

The relatively limited space and constant conditions in storehouses (moderate levels of humidity, temperature and ultraviolet light) as well as the rapid developmental rate and low population density of storage pests render them suitable for control by insectistatics and pheromones. Some of the latter are currently tested under natural conditions. The limitations of these biotechnical procedures are discussed.
Economic Aspects of Integrated Control1)
Authors: Mathys G.
Published: April 2008

Evaluation of economic returns resulting from plant protection measures are receiving increased attention. Since control measures are likely to affect not only a single production but also future crops and may entail resistance phenomena, as well as other inconveniences, the entire lifetime of a control strategy should be considered in a cost/benefit analysis.

Although all the needed parameters for such an evaluation are not available, simplified computer‐based models, now in use in advanced pest management studies, turned out to beextremely useful.

The possibility of assessing the impact of control measures on single crops is reviewed in the light of recent studies (Headley, 1972, 1973, Davidson and Norgaard, 1973) and data stressing the economic advantages of pest management schemes in European orchards and U.S. cotton areas are studied.

With increased prices for pesticides and application, the benefit derived from integrated control schemes becomes more evident.
Space Treatment of Warehouses Using Dichlorvos1)
Authors: Ashman F. , Webley D.J. , Achillides N.Z.
Published: April 2008

Details are given of the performance of Vapona Pest Strips and of an automatic dichlorvos sprayer developed to prevent infestation of clean or fumigated stored commodities, for infestation control on stored carobs. Air concentrations after spraying a nominal dose of 10 μg/1 of total store space averaged approximately 1.0. μ g/l after 30 minutes and less than 0.3 μ g/l after 3 hours. Residues found on carobs after daily spraying of stores at 10 μ g/1 for 96 days were in the range of 0.2 ‐ 2.0 ppm.

Ephestia cautella Walk, and Lasioderma serricorne (F.) become established in carobs after harvest and are the principle pests causing damage during storage. Effective control of E. cautella was obtained by using Shell Vapona Pest Strips at two strips/100 m3 or by daily spraying of dichlorvos at 10g/1,000 m2 (10μ g/1). No effect was observed against migrating larvae of E. calidella (Guen.) or E. figulilella Greg, nor against Bracon hebetor Say., the hymenopterous parasite attacking all three Ephestia species.

The automatic dichlorvos sprayer is equipped to apply a predetermined dose at time of peak flight activity, 18–20 hours each evening. On stored carobs, no spraying is needed after October because the commodity temperature falls below 200C, too low for active development of the pest species. 23 automatic sprayers are now used in Cyprus to protect the whole carob crop from storage pests.
Distribution of Potato Cyst Eelworm in Scotland1
Authors: Mabbott T.W.
Published: April 2008

Although potato cyst eelworm has been known in Scotland for more than 60 years, infestations are fewer than might have been expected. In 22 years of soil testing, based on nominal 500 g samples and sampling units of up to 6 ha, 80% of the farms examined were found free from detectable infestation and 10%, i.e. half the infested farms, had one infestation only. Most populations were light; one third of all infested samples contained a single viable cyst and 80%, ten cysts or fewer. It is suggested that long rotations have kept eelworm populations in check over much of the country, but in some areas their effectiveness has been reduced by persistent groundkeepers. Surveys indicate that Heterodera pallida Stone is uncommon and so the progressive use of resistant varieties, which are proving popular with seed growers for their commercial qualities, coupled with the long rotations generally practised, may well tip the balance even more favourably towards increased control.
Research being Undertaken by the Tropical Stored Products Centre in the United Kingdom and Overseas1
Authors: Wheatley P.E.
Published: April 2008

Research is undertaken by the Tropical Stored Products Centre both overseas and in the United Kingdom on storage problems facing developing countries. Much of it is of a strictly applied nature although some longer‐term basic studies are also underway. Our research includes biological, chemical and engineering studies and may be concerned with any level of storage, from farm to central storage depot, and with any durable agricultural produce, whether for consumption H the country of production or for export.
Identification of Pathotypes of the Potato Cyst Nematode1
Authors: Kort J.
Published: April 2008

Since the discovery of pathotypes of the potato cyst nematode (Heterodera rostochiensis Wollenweber, 1923), surveys on the distribution of these pathotypes have been carried out in different European countries. Test varieties of potato were selected according to findings resulting in the present situation of varying distinctive host‐plants and of diverging programs for breeding potatoes resistant to the potato cyst nematode.

With respect to rational selection and use of resistant potato varieties, there is a great need for standardization in pathotype identification (nomenclature), maintenance and supply of appropriate genotypes of Solanum species and methods for testing resistance in new potato varieties.

Anticipating a cross‐experiment with pathotypes and test varieties from Great Britain, the Federal Republic of Germany and the Netherlands in 1974, a preliminary test with all recognized or presumed pathotypes from these countries, but with only part of the potential differential host‐plants was carried out by the Plant Protection Service at Wageningen. The results of this experiment are discussed.
Take‐all (Gaeumannomyces graminis [Sacc.] Arx & Olivier) Incidence in Continuous Barley Growing and Effect of Tillage Method1
Authors: Lockhart D.A.S. , Heppel V.A.F. , Holmes J.C.
Published: April 2008

Take‐all (Gaeumannomyces graminis [Sacc.] Arx & Olivier) infection was measured over 7 years (1968–1974) in a long‐term tillage experiment involving deep and shallow ploughing, tined cultivation, no‐tillage and 4 rates of N. Average infection increased from 4% to 15% and 9% to 35% over the 7 years for June and August samplings respectively. The severity of infection was light and did not change over the years. Increasing N rate consistently reduced infection. In the early years, shallow ploughing and tined cultivation gave greater infection than deep ploughing and no‐tillage. In the last 2 years infection levels were the same for all 4 tillage treatments in both June and August, except that in August the no‐tillage system continued to show a much lower incidence of infection. The take‐all appeared to have little effect on yield because the relative yields from the different tillage treatments did not change with the change in relative degree of infection. Lack of take‐all decline was possibly due to the relatively low incidence and severity of infection.
Cereal Cyst Nematode and N Fertilization1
Authors: Juhl M.
Published: April 2008

The effect of increasing amounts of nitrogen on the propagation of the cereal cyst nematode was studied. Nitrogen applications as nitro‐chalk ranged 0–1,500 kg/ha (0–232.5 kg N/ha). Maximum propagation was obtained at about 46.5 kg N/ha. Increasing N doses reduced propagation to about 1/2 ‐ 1/3 of the maximum. Two factors seem to be involved: 1) reduced fertility of females with increasing N application and 2) apparently fewer females developed with N applications greater than 46.5 kg/ha.

Hatching in solution of calcium nitrate decreased with increasing concentration.
Propagation of Pathogen‐free Potato Stocks by Stem Cuttings within a Clonal Selection Program1
Authors: Hardie J.L.
Published: April 2008

Clonal selection with associated clinical tests and based on stem cuttings as the initial propagative material has been successfully adopted as a method of producing nuclear stocks of potato varieties free from certain important viruses, fungi and bacteria. The maintenance of health of such nuclear material during the subsequent period of multiplication to commercial quantities, however, has emphasized that gaps in our knowledge of the epidemiology of the diseases caused by these organisms exist and require investigation, so that clonal selection programs can make a maximum contribution to crop improvement.

La sélection clonale assortie de tests cliniques, basés sur le bouturage par prélèvement sur tiges pour le matériel initial de reproduction, a été adoptée avec succès pour la production de stocks nucléaires de variétés de pommes de terre indemnes de certains virus, champignons et battéries importants. Les difficultés rencontrées dans le maintien d'une qualité sanitaire élevée de ce matériel nucléaire, pendant la phase de multiplication précédant la commercialisation, ont révélé les lacunes qui subsistent dans la connaissance épidémiologique des différents organismes pathogènes en cause.
Erwinia carotovora (Jones) Bergey et al. var. atroseptica (Hellmers et Dowson) Dye. Seed Tuber Infection Versus Symptom Expression in the Field1
Authors: Geesteranus H.P. Maas , Vruggink H.
Published: April 2008

Based on the time that symptoms of blackleg become evident in the field and the various ways of inoculation, it is concluded that the spread of symptom expression is due to the depth at which the bacteria penetrate into the interior of the tubers. Moreover, it is demonstrated that it is not the closed lenticels which prevent penetration, but the absence of a waterfilm in the intercellular spaces of the tuber tissue.
Potato Wart Disease in Newfoundland1
Authors: Proudfoot K.G.
Published: April 2008

Techniques in use for evaluating reaction of potato selections to wart disease are described. Races of potato wart similar to European Races 1, 2 and 8 have been detected in Newfoundland. To enable the results from potato wart investigations carried out in different countries to be compared, standard test procedures and an agreed series of differential varieties must be introduced.
Current Research Studies on Potato Wart Disease in Newfoundland1
Authors: Hampson M.C.
Published: April 2008

Research includes studies on physiology of germination of the causal agent, infectivity parameters, and systemic chemotherapeutants. Germination is studied with plant and fungal extracts, plant exudates and soil leachates. Sporangia are not found to respond readily to exogenously applied chemicals. Maturity appears to be hastened under incubation with plant products. Inoculum density, sporangial age, temperature and irrigation are studied for their influence on infection. Infection appears to be less dependent on external influences, and more dependent on internal timing mechanisms. Tomato varieties tested are found to be susceptible. European races 1, 2 and 8 are used in comparative studies. Germination and infectivity are studied to throw light on possible eradication mechanisms. Chemical control is studied with systemic fungicides. To date, no control is promised. Techniques have been developed to assay germination by secondary fluorescence, and to examine large numbers of soil samples by flotation.
Re‐infection by Erwinia carotovora (Jones) Bergey et al. in Potato Stocks derived from Stem Cuttings1
Authors: Graham D.C.
Published: April 2008

Propagation of potato stocks by the stem cutting method has produced crops almost entirely free from infection with the soft rot coliform bacteria, Erwinia carotovora (Jones) Bergey et al var. atroseptica (Hellmers et Dowson) Dye and E. carotovora var. carotovora Dye. However, low levels of re‐infection have occurred and evidence indicates that a source of the organisms was infected insects. Air‐borne spread of bacterial aerosols generated by raindrop impaction on infected stems might also result in healthy stocks becoming re‐infected.
Systems Modelling as an Approach to Pest Management
Authors: Baker Elizabeth A.
Published: April 2008

Emphasis is placed upon the value of a systems approach as a tool for interrelating the complex interdisciplinary components of the increasingly desirable pest management programs. A brief outline of the parameters incorporated and construction of a mathematical model are given. Selected examples are given of models being implemented at present, and the benefits arising from them, such as in the cotton, alfalfa and apple ecosystems in the United States. Future effectuation, in Europe, of complete pest management schemes for plant diseases and nematodes, insects and mites, birds, rodents and weeds is needed, but will require concerted co‐operation between governments and organizations to initiate programs comparable to those implemented in the United States. Provision should be made for some form of extension/education system, such that the methods and benefits will be realized.
Is the Loss of Cereals in the Field as a Consequence of a Narrow Rotation Always Caused by Pathogens 1)?
Authors: Kupers L. J. P.
Published: April 2008

In a long‐term field experiment on rotational effects with winter wheat as the test crop, continuous cereal growing leads to a depression in yield. The depression in yield of these rotations persists even when the nitrogen fertilization is increased to relatively high levels and the sole occurring pathogen, in this case Cercosporella herpotrichoides Fron, is kept in check by treatment with a fungicide. From the evidence obtained from the field experiment and additional information from an experiment in the glasshouse where the same rotations were involved, it is concluded that the observed depression in yield originates very early in the growing season. As a cause for this effect, the evidence points towards a lack of available nitrogen in late autumn and late winter.
The Golden Nematode (Heterodera rostochiensis Woll.) in Greece: History, Distribution, Economic Importance, Research and Phytosanitary Regulations1
Authors: Koliopanos C.N.
Published: April 2008

Heterodera rostochiensis Woll. was reported for the first time in Greece in 1933, but was probably introduced from Europe before 1914. Its distribution in the country is restricted, mainly to isolated fields; many districts still remain uncontaminated. In 1972, about 7–12% of the area cultivated with potatoes was infested with H. rostochiensis, and the damage caused was estimated to be 1.6‐2.4% of the total annual yield.

Only few experiments have been carried out on biology, Control and other aspects. Domestic and international phytosanitary regulations for combatting this nematode are in force.
Seed Pathology and Plant Quarantine in India
Authors: Raychaudhuri S.P. , Kumar D. , Nath R.
Published: April 2008

The present situation regarding problems and achievements in seed pathology and domestic and international quarantine in India is described. Emphasis is placed upon the need for resolving present inadequacies in this country's quarantine legislation and for international alignment in seed health testing methods, in addition to a general information exchange on plant pathogens.
Cytospora Canker and Dieback of Apricots
Authors: Rozsnyay Zs. D.
Published: April 2008

Cytosporal canker and dieback (Cytospora cincta Sacc.) is a widespread disease in apricot growing areas of Europe, excluding the Mediterranean. The pathogen attacks xylem and phloem. If the necrotic phloem completely girdles the branches or trunk, the section above the girdled region dies. When cambium necrosis does not girdle the branch or trunk, canker development ensues. Apricot trees are susceptible to Cytospora infection between July and the next bud opening.
Simultaneous Infection by Pseudomonas syhngae van Hall and Cytospora cincta Sacc. on Apricots
Authors: Rozsnyay Zs. D. , Klement Z.
Published: April 2008

Simultaneous inoculation with Pseudomonas syringae van Hall and Cytospora cincta Sacc. induced more extensive cankers than those caused by either pathogen alone. Freshly cut wounds remained susceptible to cytosporal infection for a longer period than to bacterial inoculation. Knowledge gained of the annual cycle of cytosporal and bacterial diseases offers possibilities for effective control against both pathogens.
Stone Fruit Tree Apoplexy Caused by Phytophthora Collar Rot
Authors: Kouyeas Hebe
Published: April 2008

Stone fruit tree apoplexy in Greece is often caused by Phytophthora spp. Two types of Phytophthora apoplexy of stone fruit tree can be distinguished, one occurring during the hot summer period and usually caused by P. cactorum (Leb. et Cohn) Schröt. or P. citrophthora (R. et E. Smith) Leonian, and a second occurring in winter or early spring, and caused by P. syringae (Kleb.) Kleb. or sometimes P. megasperma Drechsler. Inoculation tests showed P. syringae to be highly pathogenic to apricot and almond, whereas certain clonal rootstock material showed resistance. Measures of control against Phytophthora attacks are given.
Apricot Root Rot, Armillariella mellea (Vahl.) Karst.
Authors: Guillaumin J.J.
Published: April 2008

This paper deals with honey root rot of apricots, caused by the fungus Armillariella mellea (Vahl.) Karst. =Armillaria mellea (Vahl.) Quelet. Symptoms of the disease are described, both on the root system and on the aerial parts, where the action of the fungus mostly provokes a sudden wilting or apoplexy. The infection process is elaborated and the importance of the subterranean rhizomorph in the infection cycle is emphasized. Conditions favourable and unfavourable to the disease are briefly discussed and it is shown that presence of woody remains in the soil is the most important factor in the spread of the disease.

Some isolation and inoculation methods are described. Discussion of the methods of control places emphasis mainly on preventive measures, such as use of tolerant rootstocks, destruction of potential nutrient sources and soil disinfection by fumigation.
Importance de l‘évaluation biologique des pesticides et des méthodologies mises en ceuvre à cet effet
Authors: Mathys G.
Published: April 2008

Sommaire

L'alignement sur des méthodes normalisées reconnues constitue une simplification considérable du travail pour l'industrie et les instances officielles chargées dévaluer l'efficacité des nouveaux pesticides. Les résultats obtenus en application d'une méthode commune deviennent comparables et les extrapolations ou fractionnements de l'expérimentation sont alors relativement faciles.

La France, en 1952 déjà, puis la République Fédérale d'Allemagne ont été parmi les premiers en Europe à reconnaître toute la valeur de létablissement de méthodes agréées par les services officiels et l'industrie.

De son côté, le Comité Européen de Recherche sur les Mauvaises Herbes (EWRC) s'est penché sur létude des possibilités de parvenir à une entente sur la façon dévaluer l'efficacité des herbicides, alors que I'OEPP a commencé en 1971 ses travaux sur les rodenticides, insecticides, acaricides et nématicides, ainsi que sur les affections fongiques. Depuis, 5 méthodes intéressant 7 espèces de rongeurs ont été adoptées par les 35 pays membres de I'OEPP et publiées, alors que 5 méthodes concernant les champignons et 10 méthodes les insectes et acariens sont à l'impression; par ailleurs, 29 méthodes font présentement l'objet détudes appro‐fondies.

Depuis 1976, des contacts ont été pris avec l'ASTM (American Society for Testing and Materials) dans le dessein de parvenir à une harmonisation des technologies à l'échelle inter‐régionale.
Fossorial Forms of the Water Vole, Arvicola terresths (L.), in Europe1
Authors: Meylan A.
Published: April 2008

The species Arvicola terrestris (L.) comprises 2 main life types:an aquatic form which is more common, and a form with fossorial habits which is confined to continental Europe, from the Cantabric Cordilliera to the Carpathian Mountains. However, forms inhabiting a primary wet biotope and a secondary dry one occur in a large border zone in the north of the range of the fossorial form.

The fossorial type lives underground in grassland and some types of crops. Very recently, the structure and the occupation of burrows of this subterranean rodent were studied, as well as its digging behaviour and rhythm of activity. The fossorial form of A. terrestris is very easily captured, which makes it possible to estimate its density and to follow population evolution.

This microtine shows cyclic population fluctuations and, during outbreaks, causes severe damage to grassland, both by its burrowing activity and by consuming plants. In orchards, it gnaws root systems of fruit trees, mainly of apples. Damage is also serious in gardens and in horticultural crops, especially to plants with fleshy roots. This vole does not eat cereals and does not invade forests.

Control methods generally used are surface treatment with organochlorine insecticides (banned in most countries), poisoning (but no efficacious toxic baits are available), fumigation of burrow systems and trapping.

Taxonomic research is needed for a better understanding of the status of the different life types of A. terrestris. The biological, ecological and ethological characteristics of these forms must be defined in order to develop and test adequate control methods.
The Levant Vole, Microtus guentheri (Danford et Alston, 1882). Economic Importance and Control1
Authors: Wolf Y.
Published: April 2008

The levant vole, Microtus guentheri (Danford et Alston), the only vole of major economic importance in the Middle East, is the species responsible for the often disastrous mice outbreaks known in this region since antiquity.

Population cycles of vole populations and especially the impact of mass outbreaks have been less marked in recent times as a result of changes in cultivation methods, the introduction of new, less vulnerable crops (e.g. cotton) and the elimination of various former sources of infestation and spread of voles (drainage of swamps, regulation of rivers, etc.). On the other hand, new, permanent reservoirs of voles have been created; as, for instance, in alfalfa fields and orchards with permanent vegetation cover.

Loss of crops in relation to expenditure of control in Israel is discussed. Various methods of control and rodenticides are reviewed. Organization of control operations, timing of control treatments as well as the need for forecasting impending vole outbreaks are emphasized.
FAO's Need for Rodent Ecology, Population Dynamics and Forecasting Data1
Authors: Shuyler H.R.
Published: April 2008

During the past decade, technical assistance in rodent damage control has tended to utilize less and less resources per problem, while the results expected per unit of resources used has rapidly mounted. The developing world, with its multitude of needs, lacks personnel, funds and organizational infrastructure for self‐help. The donor world, with its inflation, requires justification and the prospect of probable achievement of objectives prior to sponsoring assistance. On the basis that these trends are likely to continue, it is proposed that: 1) national rodent damage control assistance be action‐oriented; 2) multi‐country assistance rapidly evaluate damage control strategies of stubborn, common problems; 3) both national and multi‐country assistance projects be designed with the flexibility to accept unsatisfactory results in objective achievement and to move to a slower, more certain route, such as development of ecological and population dynamics data; 4) co‐operation among agencies, donors and developing countries be increased for more effective use of scarce resources; and, 5) an ad hoc advisory group of vertebrate pest control specialists meet in 1977 to give guidance in further strategy refinement for development assistance. With the hope of avoiding frequent use of the flexibility of assistance project design, data from the more developed world on ecology, population dynamics and forecasting should be examined in all developing country projects as to possible useful extrapolations which will increase the likelihood of achieving objectives within the available resources.
Forecasting of Rodent Outbreaks: Models and the Real World1
Authors: Stenseth N.C
Published: April 2008

Theoretical and practical purposes of mathematical modelling are discussed. Of these, special attention is given to large scale simulation models and regression models. It is pointed out that, for proper use of simulation models for predictive purposes, it is necessary to realize the uncertainties associated with such model predictions. These uncertainties are mainly due to insufficient knowledge of parameter values included in the simulation model. As these model predictions are made iteratively (i.e. by short time steps), biases in parameter estimates have, with increasing length of simulated time, an accumulating effect on the biases in the output variables.

Regression models are described and methods for finding the best mathematical model are discussed. Assumptions regarding statistical properties of the data from which the regression model is constructed are discussed. It is pointe out that valid predictions are made only within the domain defined by the data Examples of regression models for forecasting rodent outbreaks are discussed. Some further developments are proposed.

Results from a model emphasizing spatio‐temporal heterogeneity in a heterogeneous region are discussed. Based on this model conclusions regarding what type of landscapes are likely to cause rodent outbreaks are deduced. Furthermore, proposed control treatments are suggested by analyzing the model. It is concluded that larger regions should be composed of suitable and non‐suitable rodent habitats interminded with each other. It is suggested that treatments for increasing the local extinction rate be applied uniformly over the whole region, but varyjng in time as much as possible and not correlated with the density in local habitats nor in the entire region. Within these limits, treatments should be applied during periods of low mobility and low reproduction.