bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring the Health Status of Pest Populations as a Contribution towards the Establishment of Economic Thresholds
Authors: Franz J.M.
Published: April 2008

Knowledge of pest population dynamics is required to assess the future abundance of a pest, the losses to be expected and the economic threshold. Mortality of pests caused by diseases can greatly influence their development and a valuable assessment can therefore only be based on healthy individuals. Examples of monitoring the health status are usually taken from the forest and from such insects that develop slowly and allow an assessment of the epizootic before the damaging final instar has been reached (caterpillars, sawflies). In agriculture, the tendency of reducing crop rotation increases the permanence of regulative forces and is consequently favourable. This allows for a more precise prediction on the development of epizootics. Recent observations show that appropriate sampling of aphid populations designed to determine their health status in respect to fungal epizootics can greatly increase the accuracy of the forecast on future trends in population dynamics.
Economie et innovation technologique en agriculture
Authors: Simantov A.
Published: April 2008

SOMMAIRE

L'importance de la place qu'occupe l'économie dans l'agriculture moderne est essentiellement fonction de l'accélération du changement structurel et éthique de nos sociétés. II est plus facile de rationaliser la production lorsque celle‐ci peut être augmentée sans être confinée dans des limites restreintes, comme c'est le cas en agriculture. Faute de coordination entre la technique et l'économie, les progrès technologiques peuvent conduire à des impasses, comme cela a été le cas à la suite de l'augmentation poussée de la teneur du lait en matières grasses. Il est done indispensable non seulement d'assurer cette liaison, mais également de définir les programmes de recherches en tenant compte des différentes disciplines concernées. A l'intérieur même du secteur agricole, les procédés et les techniques ne peuvent se développer et s'améliorer que si l'ensemble de la technologie progresse de manière harmonieuse. En ce qui concerne les risques, il apparaît que les exploitations les plus développées sur le plan technologique sont très vulnérables à la conjoncture économique.
Results of Polyhedral Virus Applications Against Neodiprion sertifer Geoffr
Authors: Donaubauer E.
Published: April 2008

In 1972 several experiments were carried out in Lower Austria to study the effect a very early application of a polyhedral virus suspension may have on Neodiprion sertifer Geoffr., feeding on the needles of Finns nigra austriaca and P. silvestris. The results show that spraying in the Li‐stage prevents a major loss of needles, thus confirming the outcome of the 1971 experiments. Especially for young trees or trees that were already partially defoliated the previous year, an early application is of great importance. The effect equalled the result obtained with a malathion‐containing insecticide. With older trees spraying in the L2‐L3 stage still gave good results.
Aerial Application of Bacillus thuringiensis (Dipel) against Colotois (Himera) pennaria L. in Comparison with ULV‐Application of Various Insecticides 1)
Authors: DONAUBAUER E. , SCHMUTZENHOFER H.
Published: April 2008

In spring 1972 experiments were carried out in Lower Austria with the Bacillus thuringiensis isolate Dipel in order to assess its effectiveness in controlling Colotois pennaria L. infesting oak and other broad‐leaved trees. The results obtained compared favourably with those produced by the insecticides Nexion2), malathion and Dipterex3), although both malathion and Dipterex yielded higher mortality.

Similar results were obtained when B. thuringiensis was used to control Stilpnotia salicis L., feeding on poplar trees. Neodiprion sertifer Geoffr. and Pris‐tiphora abietina Christ., however, were not affected.
The Economic and Technical Evaluation of New Pesticides 1)
Authors: Lever B.C. , Strong W.M.
Published: April 2008

This paper describes the high costs and risks associated with pesticide research and highlights the need to refine methods of identifying research targets and of determining the economic viability of chemicals that have shown biological activity.
Are the Present European Phytosanitary Regulations in Forestry Satisfactory ?
Authors: Roll‐Hansen F.
Published: April 2008

The pathogens which present the greatest potential dangers to European and Mediterranean forest trees are mainly to be found in remote areas such as those parts of the American continent and East Asia where the climate and tree species are similar to those in Europe. In general, inspections are not sufficient to guarantee that a consignment is free from known, and especially from unknown, pathogens.

Phytosanitary regulations should therefore be based on the prohibition of the importation of living plants (not seeds). The prohibition of the importation of all conifers (not seeds) from all countries outside Europe and the Mediterranean area is proposed. All European and Mediterranean countries should agree upon effective and co‐ordinated phytosanitary regulations.
Progress Achieved in the Implementation of Integrated Control Projects in the USA and Tropical Countries1
Authors: Smith R.F. , Huffaker C.B. , Adkisson P.L. , Newsom L.D.
Published: April 2008

General accomplishments of a large co‐operative research program in the United States is reviewed. Examples of the developments of integrated pest control for the cotton and soybean agro‐ecosystems are given. The uses of simulation models are emphasized. Progress of integrated control in tropical countries is discussed.
Organization of Plant Protection in Norway and Research Orientation1
Authors: Fjelddalen J.
Published: April 2008

Research in the various crop protection disciplines is carried out at the Central Norwegian Plant Protection Institute near Oslo: it includes studies on pesticide efficacy, problems of uptake, breakdown and residues. This agency is further in charge of the extension of practical knowledge and has a supervising capacity for the Plant Inspection Service.

Some of the various problems which are of major concern for Norway are reviewed and ways for a proper integration of chemical and alternative methods studied.
Problèmes nationaux et internationaux liés aux produits stockés 1)
Authors: Domenichini G.
Published: April 2008

Sommaire

La multiplication des industries de transformation des denrées alimentaires et le développement des entreprises chargées de leur commercialisation posent en termes nouveaux la question de la conservation des stocks avant leur consommation. Les problemès sérieux qui se font jour, liés aux risques de contamination par les ravageurs ou par les résidus de pesticides, nécessitent un effort de coordination de la part des instituts scientifiques et des organismes internationaux. Cette collaboration devrait porter ses fruits dans différents domaines d' activité: recherche, formation professionnelle, vulgarisation des techniques.
Integrated Control in the Netherlands 1)
Authors: Brader L.
Published: April 2008

In the Netherlands the need for an ecological approach in pest control has led to the establishment in 1958 of the Research Group on harmonious control of arthropod pests later renamed into Research Group on integrated control of arthropod pests which has several sections. This Group is part of the National Council for Agricultural Research of the Organization for Applied Scientific Research (TNO). There is a close co‐operation between many Research Institutes towards developing integrated control of which the TNO Research Group is the co‐ordinating body. The research priorities have been clearly defined and the ways leading to a practical implementation of integrated control studied.
The Assessment of Economic Losses due to Late Blight of Potato1
Authors: James W. C. J.
Published: April 2008

The development of a method which reliably estimates the loss for any given level of disease is a prerequisite to the development of a rational disease control program. Such a method was developed between 1953‐1970 using results from field experiments; it led to a multiple regression equation in which the yield loss is the dependent variable. The decrease in marketable tubers because of their reduced size was also considered.

The method of estimating yield loss due to late blight is currently being used in conjunction with a disease simulator.
A Comparison of Various Methods for Competition Studies Between Crop Plants and Weeds1
Authors: Koch W.
Published: April 2008

The assessment of economic thresholds of weeds is difficult because there are so many interactions between the various species and the crop. In addition, a precise forecasting of the weather is needed when pre‐emergence treatments are performed since the conditions prevailing at that moment will be decisive for the abundance of weeds.

Still, there are various possibilities to assess the crop losses resulting from weed competition and attention is drawn to the following two approaches: 1) Long‐term assessment in relation to the total weed population in a region, and 2) Competition studies between individual weed species and crop plants in pots or in field experiments.

The advantages and disadvantages of the various methods are discussed and the data obtained critically evaluated. It appears that the application of average values to a special situation remains for the moment highly uncertain.
Aperçu économique de la protection phytosanitaire des vergers français soumis à la lutte intégrée 1)
Authors: Milaire H.G.
Published: April 2008

Sommaire

La mise en place d'une vaste demonstration de lutte intégrée en vergers dans le sud‐est de la France bénéficie de l'appui financier du Ministère de l'Agriculture depuis 1967. Les structures organiques de cette action sont décrites.

L'activité des techniciens spécialisés qui fournissent un appui logistique au second degré auprès des conseillers agricoles et des producteurs de fruits, tout en restant en liaison constante avec les centres de recherches et les services d'applkation, est indispensable pour assurer le développement de l'entreprise. Elle a notam‐ment stimulé diverses études immédiatement utilisables dans la pratique.

Des résultats probants sont obtenus en vergers de pommiers et de pêchers par l'application d'une lutte dite dirigée, qui constitue la phase de transition entre la lutte traditionnelle et la lutte intégrée. lis se traduisent par une diminution de l'ordre de 50 % du nombre des interventions insecticides et acaricides. Les données économiques correspondantes sont présentées et discutées. Outre l'aspect strictement économique, les utilisateurs apprécient la maîtrise que leur confèrent les connaissances écologiques.
Essais de lutte chimique contre Aonidiella aurantii (Mask.)
Authors: ET G. Liotta , Mineo G.
Published: April 2008

Sommaire

Les essais de lutte chimique contre Aonidiella aurantii (Mask.) sur citronniers en Sicile ont été réalisés à l'aide d'une série de produits organo‐phosphoriques en partie mélangés avec des huiles blanches, et compareés à l'efficacité des huiles blanches appliquées seules. II est apparu que les meilleurs résultats sont obtenus contre les larves et les jeunes femelles, alors que pour les femelles matures il n'a pu être enregistré une mortalité suffisante. L'analyse statistique n'a pas révélé de différences significatives entre l'efficacité de l'huile blanche et celle des autres produits testés.
RESUME:Studies on the Chemical Control of Aonidiella aurantii (Mask.)
Authors: Liotta G. , Mineo G.
Published: April 2008

Aonidiella aurantii (Mask.) which was accidentally introduced in Sicily in 1968 has since become a dangerous pest requesting special treatments in citrus groves. Experiments have been carried out on Citrus lemon to evaluate the efficacy of several organophosphorous compounds partly in mixture with white oil and this latter applied sole (cf. table 1). The results obtained against young females are set out in table 2; they show excellent results with almost all compounds whereas the same pesticides had a rather poor effect on mature females (cf. table 3).

It is concluded that the replacement of white oils by organophosphorous compounds is not justified providing that the control is directed against larvae and young females. This means that a proper timing is essential to obtain a satisfactory mortality, thus avoiding the use of detrimental broad acting pesticides.
Pheromones in Stored Product Insect Trapping and Pathogen Dissemination1
Authors: Burkholder W.E. , Boush G.M.
Published: April 2008

The generally restricted habitats of stored product insects provide an ideal situation for control attempts with pheromones and pathogens. Problem areas can be located and monitored with traps containing pheromones and insecticides and controls can be applied in localized areas. The method is economical, effective and reduces the hazards involved with blanket application of pesticides.

Another method that promises to be successful utilizes pheromones in an inoculation device that contains a pathogen. The insects that are attracted become contaminated with the pathogen and may subsequently spread it throughout the population. In this way the pathogen will be spread to a multitude of population niches. Preliminary studies have indicated that few, if any, insects survive the infection, that the disease is highly contagious and that males will become inoculated with spores in pheromone‐pathogen baited inoculation devices and will transmit the spores by contact to females.
Methods for Detection of Potato Cyst Nematodes1
Authors: Southey J.F.
Published: April 2008

Methods are reviewed for inspection of growing potato crops and of soil sampling for detection and estimation of potato cyst nematodes (Heterodera rostochiensis Woll. and H. pallida Stone). Modifications of the Dutch soil‐sampling method are now widely used in Europe, including U.K. The statistical principles of soil sampling for Heterodera cysts are discussed. It is concluded that the efficiency of the method for detection is best improved by increasing both the quantity of soil examined and the number of sampling points per area sampled; the quantity is the most important factor which determines the level of infestation that can be detected. The area represented by a standard sample should be the same as that for which a separate decision will be made; variations in this area are unimportant because in effect one is sampling from an infinite population. It is concluded also that effective systems of control on potato‐growing land, and removal of soil from exported plants and potatoes, offer better prospects than soil sampling for preventing transport of cysts; a combination of these methods provides the best safeguard, e.g. for seed potatoes.
Reflections on Heterodera rostochiensis1
Authors: OOSTENBRINK M.
Published: April 2008

In 1955, the EPPO Heterodera rostochiensis Conference held in Wageningen (Anon., 1955) came to conclusions and recommendations which are analyzed together with other papers issued by EPPO between 1951–1959.

In the course of the 18 years which elapsed since the Conference, major advances have been made in the following fields:

– Origin, spread and distribution of the nematode, numerical dynamics and distribution of the nematode.

– Numerical dynamics and genetic density and flexibility of nematode populations.

– Breeding resistant potato varieties.

– Development of new nematicides and integrated control.

– Ecological limitations.

Progress achieved along these lines is reviewed.
Host‐plants of Heterodera rostochiensis Woll. and the Breeding for Resistance1)
Authors: Huijsman C.A.
Published: April 2008

The two most important aspects of the host‐parasite relation of the potato and the tomato versus Heterodera rostochiensis Woll. are discussed. Many transitory forms between very poor and good hosts have been found in wild and primitive forms of these crops. The nature and the mode of inheritance of forms are described and their consequences for breeding work discussed. Several patho‐types are found and it is argued that many more exist.

Much variation has also been found in the amount of damage in good hosts when heavily attacked. Some varieties, both in potato and in tomato, have been found with a high degree of tolerance to damage.
Chemical Control of Heterodera rostochiensis Woll.1)
Authors: Ouden H. den
Published: April 2008

In Dutch field experiments with Heterodera rostochiensis Woll. systemic nematicides at low and high nematode densities resulted in unfavourable cost/ benefit relations, as compared to other control procedures; on average, a 50 % reduction of the maximum multiplication of the nematode was observed. In England, better results were obtained at high nematode densities when higher dosages of nematicides were worked into the soil at a depth of 15 cm.

In order to obtain a better effect of the mostly used contact nematicide DD‐mixture at a moderate dosage, a special treatment of the soil surface with the non‐fumigant dazomet was combined with the fumigation. On clay soil more than 99 % kill of stem nematodes was obtained with 30 g dazomet + 50 ml DD‐mixture per m When 10 g dazomet was added a 80% kill of Rolylenchus uniformis (Thorne) could be obtained on sandy soil; this was equivalent to 2 applications of the DD‐mixture alone. The combined treatment offers the great advantage of increasing the chances by 3 times to make the appropriate choice of the year for the treatment. Eggs of R. uniformis and H. rostochiensis are less susceptible to DD‐mixture than free living larvae and adults.
Thoughts on Quarantine Problems
Authors: Mathys G.
Published: April 2008

Plant quarantine is a part of crop protection strategies and has generally not received the scientific support it deserves neither has the usefulness of quarantine actions which are a matter of public policy been verified. Experience shows that introduction of exotic pathogenic organisms often fails in establishment because the complicated sets of biological conditions needed are not met; however, with increased frequency of introductions, the probability of meeting the right combination of circumstances increases. This is of fundamental importance in quarantine.

Protecting a bio‐geographical area rather than individual countries against emigrant pests and diseases is a prerequisite for a successful quarantine. It is explained how this approach is currently implemented within the EPPO area on the grounds of scientific data.

A major breakthrough in evaluating the potential hazards inherent in emigrant pests has been made in the United States through mathematical modelling. Many gaps in the biological knowledge remain and there is a clear need for collaborative action on a global scale.
Health Aspects of Pesticides and their Residues1
Authors: Bressau G.
Published: April 2008

Various important factors in the evaluation of the acute and chronic toxicity of agricultural pesticides are discussed. Special attention is drawn to the residues in food and fodder of active ingredients, including their degradation and reaction products. A general evaluation of the effects of pesticides on roan, animals and the environment is only possible if their properties and behaviour in the different fields of application and under various conditions are known. This is illustrated by a few examples.

Manufacturers (especially involved in residue analysis), chemists, toxicologists, biologists, advisors, farmers and operators dealing with pesticides are faced with many questions and problems which can only be solved through close cooperation. Public authorities and responsible organizations have to elaborate national and international guide‐lines, rules and regulations, which have to be constantly improved and adapted to the latest state of knowledge ‘for the sake of safety and efficacy.’

The expression « health aspects » is often used as a synonym for « toxicological aspects ». In order to avoid misunderstandings, it is pointed out that toxicology is merely one important part of general health aspects; this is illustrated by some examples.
Taxonomy of Potato Cyst‐Nematodes1
Authors: Stone A.R.
Published: April 2008

Potato cyst‐nematode pathotypes fall into 2 groups distinguished by morphological and biological differences, corresponding to the species Heterodera rostochiensis Wollenweber, 1923 (the golden nematode) and H. pallida Stone, 1973. The species may most readily be distinguished by differences in length and knob shape of second stage juveniles' stylets, by differences in the cuticular pattern of the female or cyst perineum (the region between vulva and anus) and by the colour of the maturing female. Both species occur in the United Kingdom, continental Europe, South America and elsewhere, and include pathotypes able to develop on potato cultivars bearing genes for resistance.
Désherbage et environnement1
Authors: Mathys G.
Published: April 2008

Sommaire

L'étude des répercussions des herbicides sur la biosphère a suscité un vif intérêt depuis que la sauvegarde de l'environnement est devenue une préoccupation prioritaire. La documentation qui s'y réfère est encore fragmentaire; elle concerne l'impact de ces produits sur la faune sauvage, les poissons et les abeilles, ainsi que sur le sol et l'eau en général. Il est fait état des recherches dans ces domaines et des conclusions que l'on peut en tirer. L'eau demeure un point vulnérable dans le cadre des applications de certains herbicides en raison des dangers de contamination par la dérive et des possibilités d'infiltration dans les zones de captage d'eau potable.
Recent Developments in Deciduous Orchard Pest Management in the United States1
Authors: Glass E.H.
Published: April 2008

A realistic appraisal of insect and mite control on apple suggests that the existing status of almost total reliance on chemicals is very precarious. During the past 10 to 15 years integrated systems of biological control of mites and chemical control of insects have been developed. The most common integrated system makes use of predacious phytoseiid mites resistant to insecticides used for the control of major pests.

In the United States, there are currently 4 federally funded apple pest management projects (Washington, Pennsylvania, Michigan and New York). While there are differences among these in their scope and structure, they all aim at implementing new pest management systems on a commercial level and to train fruit pest managers.

The pest problems on apples in North America, which include insects, mites, fungal, virus and bacterial disease organisms, weeds and mammals, are very complex and difficult to solve. Chemical control of insects has been practised on this fruit since before 1900 with considerable success but there have been problems of acquired resistance and destruction of parasites and predators by certain insecticides and fungicides. As a result mites and a few insects have become greater problems than formerly. Currently organophosphates are being used as the basic control agents for most insects. Phytophagous and some predacious mite species are now resistant to these materials. Chemical control is needed in all commercial apple planting to prevent severe fruit damage.

During the past 10 to 15 years successful integrated systems of biological control of mites and chemical control of insects have been developed in several widely scattered apple‐growing areas. Fruit growers are using these more or less depending upon the severity of mite problems and the availability of effective acaricides. The most common integrated system makes use of predacious phytoseiid mites which have developed resistance to insecticides essential to controlling major insect pests of apple. All pesticides known to be harmful to these mites are avoided during critical periods. In Pennsylvania an integrated system employing the chrysomelid beetle, Stethorus punctum, is used. In this case, the predator is preserved by using reduced dosages and limited spray coverage.

Considerable progress has been made in recent years in reducing the quantity of insecticide used on apple. The basis for the reduction has been the use of very effective insecticides which essentially eliminate major pests from orchards. This level can be maintained by reduced schedules, i.e., applying treatments only when pests are present as indicated by monitoring and inspections. The development of sex pheromone traps has enabled excellent progress in this direction.

Currently there are 4 federally funded pest management projects in important apple‐producing regions. The objectives are to implement new pest management systems on a commercial level and to train fruit pest managers.
Orientation de la protection des plantes en Autriche1
Authors: Kahl E.
Published: April 2008

En Autriche, la protection des plantes repose sur la loi de 1948, adaptée à la situation particuliére du pays qui est composé de 9 provinces. Les dispositions intéressent la production et le commerce; une attention particulière est vouée à l'application des pesticides qui sont assujettis à l'homologation et doivent répondre aux critères d'efficacité et de sécurité. Ainsi, ce système est conçu de manière à mettre à la disposition de l'agriculture et de la sylviculture des produits répondant aux exigences d'une lutte économique sans qu'il en résulte des effets indésirables pour l'homme, les écosystèmes et l'environnement en général.
The Feasibility of Environmental Control for the Protection of Stored Grain
Authors: Calderon M.
Published: April 2008

Relevant data on the possibilities of changing the stored grain environment, for the sake of better preservation of grain in storage, are reviewed. The grain bulk is regarded as an ecosystem, in which the impact of damaging organisms can be controlled by ambient conditions. The influence of humidity, temperature, composition of atmospheric gases, atmospheric pressure and light is discussed. Lowering humidity and grain temperatures are well known effective and practical ways for the prevention of storage damage. The modification of atmospheric gas compositions has been subjected to very extensive research, on which new methods for insect control could be based. Lowering the absolute pressure in storage containers has detrimental effects on storage insects; the practical implementation of this technique is discussed. Research on the effects of changing light conditions on stored grain insects is in its earliest stage, but shows promise. Studies on an integrated approach using several environmental elements for the containment of grain insects and microflora are proposed.
Quelques problèmes de pathologie dans les rotations céréalières1
Authors: Cassini R.
Published: April 2008

Sommaire

En France, le maïs est souvent produit en monoculture ou placé en tête d'un assolement réduit à la rotation maïs‐blé, avec quelques variantes. D'autre part, cette culture s'étend vers des zones climatiques plus marginales à la faveur des nouveaux hybrides. Ces conditions, auxquelles s'ajoute l'uniformité des variétés, sont favorables au développement des maladies.

Deux types de problèmes sont examinés dans le cadre de cette évolution; ils se rattachent aux affections suivantes: 1) les maladies communes au maïs et aux céréales à paille, comprenant notamment Fusarium roseum (Link) Sn. et H., et 2) les maladies spécifiques du maïs; elles se réfèrent àHelminthosporium turcicum Pass., H. maydis Nisikado et Miyake, race T et Kabatiella zeae Narita et Hiratsuka.

Les possibilités de lutte contre ces différentes maladies sont examinées ainsi que les mécanismes qui peuvent être rendus responsables de leur virulence et de leur extension.
Crop Rotation, Monoculture and Soil Ecology1
Authors: Hoestra H.
Published: April 2008

Crop rotation and monocultural systems are discussed in relation to disease management and control. The ecological basis of both systems is examined. In crop rotation the leading principle is that in the absence of host‐plants parasite populations invariably decline below threshold levels, mostly within a few years.

Knowledge of the behaviour of parasite populations in the soil is becoming vast, especially in the case of plant parasitic nematodes. Analysis of soil samples for nematodes and fungi often helps the farmer to plan rotation schemes. From the ecological point of view, crop rotation is interpreted as a system of interrupted monocultures.

Monocultural practices cannot be applied so universally as crop rotation, but in a number of cases monoculture is feasible, e.g. with cereals. In the equilibrium situation between host‐plant (e.g. cereals), parasite (Gaeumannomyces graminis [Sacc.] v. Arx & Olivier) and the antagonists of the parasite, growth of the crop is satisfactory. These cases illustrate the role of antagonists, and it is proposed to investigate more systematically monocultures in relation to antagonisms. This may lead to more opportunities for biological control of soil‐borne diseases.
Present Status of Research on Insect Growth Regulators for the Protection of Stored Grain1
Authors: Hoppe T. , Suchy M.
Published: April 2008

Two insect growth regulators of the juvenile hormone type, namely 6,7‐epoxy‐3‐ethyl‐(p‐ethylphenoxy)‐7‐methylnonane, cis/trans mixture (compound A) and 6,7‐epoxy‐3,7‐dimethyl‐1‐[3,4‐(methylendioxy)‐phenoxy]‐2‐nonene (compound B) have been tested for their persistence when treated on stored grain. The interim results of this trial showed inhibition of adult emergence of Ephestia kühniella Zell., Plodia interpunctella Hübn., Tribolium castaneum Herbst and Rhyzopertha dominica F. even 8 months after treatment. The gas‐chromatography residue determination of compound A showed a reduction of 27 % of the original concentration within 8 months. No effect of compound A on the endosperm of the grain or taste of flour and bread could be found in the Bakery School in Lucerne.
Diseases in Reduced Cultivation and Direct Drilling Systems1
Authors: Yarham D.J. , Hirst J.M.
Published: April 2008

Mould board ploughing, long the foundation of arable agriculture, has been replaced on many British farms by reduced cultivation systems not involving the inversion of the soil. There is also an increasing interest in direct drilling into untilled soil. The change to such techniques may be expected to influence the incidence of certain cereal diseases. Increases in Rhynchosporium secalis (Oud.) Davis and Septoria spp. have been noted in non‐plough situations where infected debris is left on the soil surface. Effects on other diseases are more complex and may be mediated through the effects of cultivation technique on time of sowing, crop establishment, weed control, pest incidence and other factors including the physical nutritional and microbiological characteristics of the soil.
Some Consequences of Cereal Monoculture on Gaeumannomyces graminis (Sacc.) Arx & Olivier and the Take‐all Disease1
Authors: Cunningham P. C.
Published: April 2008

Studies were made of isolates of Gaeumannomyces graminis (Sacc.) Arx & Olivier var. tritici J. Walker from different length crop sequences of wheat and barley following permanent grassland. Studies were done on the influence of cropping intensity of soils, natural and steam disinfested, on disease expression from added inoculum. Efforts were also made to detect interactions between isolates and soils from the same and different cropping sequences. Investigation of variability in the pathogen related to virulence and specificity as well as to saprophytic traits.

In general, mean virulence of isolates increased up to the point where approximately peak disease levels occurred in the field, and diminished subsequently. Host specificity of isolates from a monospecies system was also pronounced at this point whereas it was not evident in the first 2 crops; it did not increase further after the 5th or 6th cereal of a single species. There was evidence of loss of competitive saprophytic ability in isolates from long sequences as against those from 1st, 2nd and 3rd crops after permanent pasture. A differential sensitivity response from Gliomastix murorum (Cda.) Hughes var. felina (Marsh) Hughes was observed with isolates from 1 to a 3 year sequence compared with isolates from sequences of 4 to 8 years. Isolates from a 1st to a 3rd crop restricted colony growth of G. murorum in culture whereas those from 4th to the 8th cereal were overgrown by this fungus. Isolates from the 1st cereal after grass darkened considerably with age, those from a 2nd less so and those from a 3rd successive crop remained almost totally hyaline; those from longer sequences darkened considerably but were very variable for this trait. The influence of soil from more intensively cropped cereal sequences, which was destroyed by steam disinfestation, was to depress disease levels from applied inoculum. This soil inhibitory effect set in between the first and 3rd cereal.
Anatomie fine de Cercosporella herpotrichoides Fron dans les gaines foliaires de froment. Observations sur la percée des parois des cellules‐hôtes 1)
Authors: Rassel A.
Published: April 2008

Sommaire

D'une étude en microscopic électronique de Cercosporella herpotrichoides Fron parasitant des gaines foliaires de froment, il résulte que le métabolisme du champignon est particulièrement actif. L'attention est attirée sur les phénomènes d'autophagie, de turn over de substances de réserve et sur la percée des parois pectocellulosiques des cellules‐hôtes.

Des cellules mycéliennes de C. herpotrichoides ont été observées à l'intérieur de cellules de gaines foliaires de froment et classées en 5 catégories d'âge. Les observations ont porté plus particulièrement sur les cellules jeunes et adultes.

La paroi émet un exsudat. Les parois transversales sont munies de pores septaux ouverts ou bouchés entourés de corps de Woronin. La membrane plasmique donne lieu à la formation de lomasomes et d'invaginations isolant des portions cytoplasmiques appauvries. Le cytoplasme contient des particules α et β de glycogène, des mitochondries, un réticulum endoplasmique peu développé, des inclusions claires dépourvues de membranes et vraisemblablement des peroxysomes. Les vacuoles contiennent généralement un gros globule et de petites vésicules issues de bourgeonnements du tonoplaste. Des phénomènes d'autophagie par séquestration de matériel cytoplasmique dans des doubles membranes et des vacuoles ont été repérés.

La percée des parois cellulaires de l'hôte s'accompagne toujours d'une réduction du diamètre du filament mycélien à l'endroit de passage. Dans les vaisseaux, elle a lieu au niveau des ponctuations. Après un choix thigmotropique du site de pénétration et adhérence du parasite à la paroi grâce à l'exsudat émis, la percée se fait par voie enzymatique. Des phénomènes de pression sont suggérés.

On peut conclure de ces observations que, dans les conditions de l'essai, le métabolisme du parasite est particulièrement actif.
Fungi and the Decrease of Cereal Cyst‐nematode Populations in Cereal Monoculture1
Authors: Kerry B.R.
Published: April 2008

Populations of the cereal cyst‐nematode decrease when cereals are grown frequently or continuously because the females that develop on the roots between May and July fail to produce eggs, or produce a smaller number than expected. Consequently, cysts in the soil after harvest are fewer and contain fewer eggs. The role of fungal parasites and competitors in limiting populations of cyst‐nematodes is reviewed. Parasites of eggs and females of Heterodera avenae Woll. were widespread in British cereal fields, an Entomophthora‐like fungus and Verticillium chlamydosporium Barron & Onions being the most common species found. Although fungal parasites may be the cause of the failure of the nematode to increase, it has not yet been established unequivocally.
Amélioration de la résistance du blé au piétin‐verse, Cercosporella herpotrichoides (Fron)1)
Authors: Vandam J.
Published: April 2008

Sommaire

La maladie du piétin‐verse, causée par Cercosporella herpotrichoides (Fron) est favorisée dans notre pays par des conditions climatiques particulières, jointes à la simplification des assolements céréaliers. De nombreux travaux ont permis de mettre au point des épreuves de résistance en serre, en chambre de végétation et en plein champ.

Aucune variété de blé tendre n'opposant une résistance élevée à la maladie, les genres et les espèces voisins ont étéétudiés. Quelques lignées de Triticum monococcum et d'espèces tétraploïdes semblent présenter un certain intérêt. Au sein du genre Aegilops, A. ventricosa constitue une excellente source de résistance et son utilisation a déjà permis d'obtenir des résultats très encourageants.

D'autre part, au cours des travaux de sélection, il est nécessaire de surveiller avec attention l'évolution de la virulence des souches du parasite.

La maladie du piétin‐verse causée par C. herpotrichoides revêt une importance croissante dans les cultures de blé. En Belgique, son extension est favorisée par les conditions climatiques et par la simplification des assolements céréaliers. De nomhreux travaux ont permis de mettre au point des épreuves de résistance en serre, en chambre de végétation et en plein champ. L'examen du matériel en cours de sélection exige l'utilisation d'une méthode indirecte d'appréciation des symptômes.

Au sein de l'espèce T. aestivum, il ne paraît pas possible de trouver des géniteurs pouvant conférer une résistance suffisante à la maladie. Dans les genres et espèces voisins, quelques lignées de T. monococcum et des blés tétraploïdes semblent présenter un certain intérêt Parmi les espèces du genre Aegilops, A. ventricosa s'est révélé de loin le plus résistant

L'évolution de la virulence des souches de C. herpotrichoides peut poser de graves problèmes aux sélectionneurs. Des études portant sur l'interaction souche hôte ont révélé la chute de la résistance d'A. squarrosa vis‐à‐vis de certaines souches isolées du parasite.

L'amélioration de la résistance peut être basée sur l'utilisation de transgressions de resistance chez les blés tendres ou d'intergression des caractères de résistance provenant d'espèces voisines. Cette dernière technique a permis la création, en France, du géniteur VPM: (A. ventricosa T. persicum) T. aestivum cv. Marne 3 (Maia, 1967), qui semble le plus intéressant parmi les blés tendres.

La réussite d'une sélection ayant pour but la création de lignées résistantes et de bonne valeur agronomique implique que des travaux soient menés simultanément en pépinière classique et en parcelles infectées artificiellement.
Effect of Foliar Application of Urea on Rhizosphere and Rhizoplane Microflora of Wheat1)
Authors: Vuurde J.W.L. van , Schippers B.
Published: April 2008

The effect of urea leaf treatment on plant growth and rhizosphere microorganisms was studied under controlled environmental conditions with spring wheat at 2 growth stages, and at 2 inorganic nutrient levels of the soil. The increase in dry weight of shoots and roots was inhibited by the urea treatment. Treatment of seedlings also resulted in a delay in the formation of tillers and nodal roots, especially in low fertilized soil. A temporary increase of rhizoplane bacteria was demonstrated after 7–9 days due to a stimulation of fast growing strains. A quantitative effect on rhizoplane fungi was only apparent, on day 9 after treatment of seedlings, as a decrease in total numbers and coincided with the increase in numbers of bacteria and actinomycetes. At this time the numbers of fungi known to be early root colonizers like Penicillium spp. and Mortierella spp. decreased after initially being stimulated, while numbers of late colonizers like Fusarium spp. and Trichoderma spp. increased after 9 days after initially being reduced in comparison with the control. Investigation of the rhizosphere effect (R/S) of wheat by the soil dilution plate method and fluorescence microscopy showed a 200% increase in total numbers of micro‐organisms in the rhizosphere soil when the former method was used, but a 10–30% reduction when fluorescence microscopy was employed.
Eyespot in Winter Wheat: Effects of Crop Rotation and Tillage, and the Prediction of Incidence1
Authors: Maenhout C.A.A.A.
Published: April 2008

Eyespot in winter wheat is an important disease in the Netherlands. Symptoms can be found in almost every wheat crop. Italian ryegrass was shown to be a host crop and is able to maintain a high level of inoculum in the soil.

In rotations with winter wheat every other year, ploughing compared with cultivating the soil in autumn resulted in a lower incidence of eyespot and a higher yield in the following wheat crop. A system of predicting the incidence at the beginning of May in order to indicate the necessity of chemical control is outlined.
La pourriture des racines de maïs causée par Fusarium moniliforme Sheldon1
Authors: Paul V.
Published: April 2008

Fusarium moniliforme Sheldon, qui agit en tant qu'envahisseur primaire, provoque la pourriture des racines de maïs sans l'intervention d'autres espèces fongiques. Les hyphes du champignon se répandent dans les tissus par voie inter et intracellulaire. La lyse des parois de l'hôte par F. moniliforme entraîne évidemment la pourriture des racines du maïs.

F. moniliforme forme des appressoria globuleux et pénètre ensuite dans les raciness de maïs en perforant directement la paroi des cellules épidermiques. Le mycélium se propage par voie inter et intracellulaire dans les tissus sous‐jacents. Dans de nombreux cas, les points de contact entre le champignon et la paroi de l'hôte sont marqués par des formations globuleuses riches en composés pectiques. Les hyphes pénètrent à travers des ponctuations dans des faisceaux conducteurs. La lyse des parois cellulaires de l'hôte par F. moniliforme entraîne évidemment la pourriture des racines du maïs.
Occurrence and Pathogenicity of Fusarium Species in Cereals in Finland1
Authors: Uoti J.
Published: April 2008

Several Fusarium species occurred abundantly in spring cereal seed samples studied in 1966, 1968 and 1972 in Finland. A total of 17 species of Fusarium were isolated and identified. The most frequently isolated species were F. avenaceum (Fr.) Sacc., F. culmorum (W. G. Sm.) Sacc., F. poae (Peck) Wr. and F. tricinctum (Cda) Sacc. These species were found in more than 40% of the seed samples from 1972.

The same 4 Fusarium species in addition to F. graminearum Schwabe were used in the pathogenicity test. Artificially inoculated spring wheat and barley seeds were grown in the field during the growing season of 1973. Of these 5 species F. culmorum was clearly the most pathogenic. This species significantly lowered the shooting percentage and the yield of both cereals. Foot rot assessment also revealed F. culmorum as the most damaging species. Natural soil‐borne infection obviously increased the foot and root rot, and thus the soil‐borne F. culmorum strongly affected all treatments. In the harvested seed F. poae dominated in all treatments, but F. culmorum still occurred most abundantly in the seed lot harvested from plots originally inoculated with this species.
Experience of Brown Rot Caused by Pseudomonas solanacearum (Smith) Smith in Sweden1
Authors: Olsson K.
Published: April 2008

Brown rot (Pseudomonas solanacearum [Smith] Smith) infection of 5% or less was found in potatoes from some fields in Southern Sweden at about 56° N in the years 1972 and 19732). The fields were irrigated with water from small streams. The pathogen has been isolated from a wild host, Solanum dulcamara, growing at the water's edge in one of the streams. The wild host is perennial and bacteria can overwinter in this host. Overwintering also occurred in artificially infected S. dulcamara at 59° N. No overwintering in soil has hitherto been demonstrated, in spite of experiments with artificially infested soil. Infections have probably originated from imported potatoes.
Experience of Ring Rot Caused by Corynebacterium sepedonicum(Spieck. et Kotth.) Skapt. et Burkh. in Sweden. Particularly Detection of the Disease in its Latent Form)1
Authors: Olsson K.
Published: April 2008

As it is difficult to detect ring rot in its latent form as well as in badly decayed tubers and in potato haulm, a diagnostic technique has been developed. With the help of a Turmix blender and a little water, a suspension is made of the suspected material. The suspension is inoculated into eggplants. Gram‐staining of bacteria in sap from petioles of leaves showing symptoms is used to confirm the diagnosis. Some results obtained with this method applied on potatoes and potato haulm are described.
Field Observations on Blackleg in England1
Authors: Lapwood D.H.
Published: April 2008

Inoculation of seed tubers with Erwinia carotnvora (Jones) Bergey et al. var. atroseptica (van Hall) Dye before planting resulted in early death (especially with sprouted seed), blackleg stems and decreased yields. Apical inoculations had most, and stolon inoculations the least, effect on growth and yield. Even plants without blackleg symptoms were more stunted and had fewer stems than plants from uninoculated seed. Rotting of seed tubers often stopped in dry weather and started again later, probably caused, or assisted by, insects breaching the wound barrier.

Many other organisms can also rot seed tubers including Phytophthora erythroseptica Pethybridge (pink rot), Fusarium spp. (dry rot), Verticillium spp. (wilts) and Rhizoctonia spp. (black scurf).

The bacteria have been shown to spread along rows underground and to different stocks within the same field, presumably in air, but season to season spread by the potato digger has not been demonstrated.
Plant Protection and Production in Modern Society1
Authors: Brader L.
Published: April 2008

Many currently existing agricultural production techniques have been developed in total reliance on effective chemical pest control. Today, however, it is becoming clear that chemical pest control has a number of limitations, and its ever increasing costs may well make it a limiting factor in agricultural production. This has already occurred in a number of cotton growing areas.

The need for increased world food production will require improved pest control methods. If no special precautions are taken, we will undoubtedly end up in many other crops with a situation similar to that of cotton.

In view of the reduced availability of new pesticides, those currently available should be used in the optimal way. At the present time, the integrated pest control approach is the best means of accomplishing this. The introduction of such programs will require official support through legislation or technical assistance.

In the future, various new developments in pest control are to be expected. Greater reliance will be placed on the use of computer science. Further effort will be needed in areas such as crop loss assessment, stored product pests, technical assistance to farmers and pesticide selectivity. Closer international collaboration on plant quarantine matters and pesticide registration are essential for the future of pest control.
Economic Conflicts in Plant Protection: Individual Versus Social Decisions1
Authors: Regev U.
Published: April 2008

We are becoming increasingly aware of the unintended harm caused by the use of chemical pesticides to man, crops, livestock, and the environment. The major side‐effects of pesticides are ecosystem disruption, increasing pest resistance and environmental pollution. Market structure (prices) does not include these effects and, for this reason, the individual farmer has no incentive to consider them in his pest control decisions.

This leads to conflicting economic interests between the individual farmer who uses excessive pesticides to maximize profits, and society, which considers environmental quality and other external effects as part of the costs of pesticides, and thus desires lower levels of pesticides. A case study of resistance to pesticides by the Egyptian alfalfa weevil shows that the farmers' pest control decisions lead to faster development of resistance than would be deemed desirable by the society.

Economic analysis of the costs of resistance serves as the basis for estimating needed investment in new pest control means, of which the most desirable ones are environmentally neutral: some form of biological control and/or host‐plant resistance.