bluuebunny/crossref_metadata_2025 huggingface dataset:
«Septoria ‐ the lurking threat to wheat yields»
Authors: BAKER Elizabeth A.
Published: April 2008

A review of Septoria diseases of wheat is given with particular emphasis on the resistance of this host to Septoria nodorum Berk. Following a general historical outline, the effects of glume blotch on the wheat plant are described, including symptoms and physiological changes. Brief reference is made to epidemiological studies, and then resistance breeding and genetic studies are discussed. The role of antifungal compounds in resistance is dealt with in more detail, and with reference to the author's own research results. It is concluded that no single mechanism of resistance of wheat to S. nodorum emerges and that the resistance factors appear to be varying quantitatively rather than qualitatively.
Detection of Peronospora manshurica (Naum.) Syd. in Seeds of Soybean, Glycine max
Authors: PATHAK V.K. , MATHUR S.B. , NEERGAARD P.
Published: April 2008

Out of 140 soybean samples tested from 17 countries, 42 originating from Brazil, Colombia, Iran, Korea, Malaysia, Thailand and the United States were found to be contaminated by oospores of Peronospora manshurica (Naum.) Syd. Oospores are generally present as a crust on the seed coat, and are easily detected during visual examination; however, individual spores may stick to the surface of non‐crusted seed, and these spores are detectable only by examining surface washings.

A new method for testing the viability of oospores by the tetrazolium chloride test is described. Viable oospores turn orange‐red. In all oospore collections, viability tested by this method was generally higher than germination recorded in water. One to 2‐year‐old oospores showed 30 to 39% viability, while an 8‐year‐old collection had about 20% viable spores. Oospores collected from 1‐year‐old seed treated with captan showed 6 to 11 % viability.
An Evaluation of the USDA Preshipment Clearance Program for Propagative Material1)
Authors: SANTACROCE N.G.
Published: April 2008

One of the programs utilized by PPQ‐APHIS‐USDA2) to prevent the introduction of hazardous pests and pathogens is known as preclearance. Preclearance relies more on inspection at origin than it does on inspection upon arrival or entry into the United States. Two such programs have been developed by PPQ for plant materials. One, established in 1951, is for bulbs, while the other, established in 1975, is for a few ornamental crops. The USDA, in co‐operation with the Plant Protection Services of the Netherlands, Belgium, France, Italy, Fed. Rep. of Germany, Israel and South Africa, has been performing preclearance for bulbous plant propagative materials. Flower bulbs are being precleared in all of the above countries at the request of the exporter's groups of the respective countries. The objective of this clearance is to facilitate the entry of this material, reduce the chances of introducing plant pests and diseases into the United States, and save APHIS manpower at US ports of entry. This is achieved by having USDA personnel working cooperatively with foreign plant protection services in the inspection of material in the field and packing houses in the country of origin. Detection and elimination of plant pests and diseases is a co‐operative effort for mutual benefit of both parties.
A Review of Methods Used in the Laboratory Diagnosis of Fireblight1)
Authors: MILLER HJ.
Published: April 2008

Most well–known laboratory methods which can be used in the diagnosis of fireblight, as well as more recent developments in identification, have been discussed. They vary from the use of simple culture media to the use of immunofluorescent microscopy. The use of any one method alone is not advised, but by combining methods, accurate and rapid diagnosis is possible. In order to minimize diagnostic errors, especially among less experienced workers, the use of 5 % sucrose–nutrient agar for bacterial isolation followed by serological control is recommended. For further information reference is given particularly to the procedures described by Lelliott at the first EPPO Conference on Fireblight held in 1967 at Canterbury.
Fireblight Inoculum: Sources and Dissemination1
Authors: BEER S.V.
Published: April 2008

Understanding the disease cycle of fireblight requires knowledge of the sources of inoculum and means of dissemination. In regions where the disease is endemic, hold–over cankers are the most important source of primary inoculum. Dissemination of primary inoculum occurs by rain or by crawling or flying insects. Often, blossoms infested with Erwinia atnylovora (Burrill) Winslow et al. provide secondary inoculum that is disseminated by pollinating insects or by rain. Later in the growing season, secondary inoculum produced in infected tissues may be disseminated by rain or by sucking and biting insects. Relatively rare sources of inoculum and inefficient means of dissemination may be responsible for introducing the pathogen to areas where fireblight has not been found previously. E. amylovora may be carried to new locations in intimate association with host tissues (infected nursery stock), in association with vectors (insects, birds or man), or by wind as “strands” or in airborne water drops. Every effort should be made to prevent introduction of E. amylovora into areas now thought to be free of fireblight. Attempts to eradicate the disease from several new areas in northern Europe have been unsuccessful. Because weather conditions and the host plants present in southern Europe are especially conducive to severe damage from fireblight, plant protection personnel are advised to prepare now for the possible introduction of disease. Personnel should be trained to recognize the disease and plans should be drawn to contain it or to manage host plants to minimize disease losses.
Warning Systems for Fireblight1)
Authors: BILLING Eve
Published: April 2008

The ideal warning system should indicate conditions favouring inoculum production and dissemination, infection and subsequent symptom expression. It should give guidance on the best times for inspections to be made and for chemical control measures to be applied. The choice of system is governed by the crop, the climate and economic considerations. New systems must be developed to deal with new situations. Most previous systems have been concerned with the spring blossom periods of pear and apple, but systems for assessing fireblight activity at other times in the growing season are being developed. This is especially important in Europe where the blossom periods of susceptible ornamental hosts extend into July and where, in some countries, summer blossom on pear may be present throughout the season. Monitoring of inoculum levels on cankers, blossoms or shoots has proved valuable where economy in the use of sprays has justified its use; sprays are usually withheld until the pathogen is detected.

Warning systems based on weather data are broadly in agreement but differ in detail. Sprays during bloom are often withheld until maximum temperatures exceed 18° C (or mean temperatures reach 14.5 —‐ 16.5° C) and there is precipitation or high humidity (> 60 % RH) at the same time. Some workers would spray immediately after moderate rain (e.g. 2.5 – 5.0 mm) when inoculum was known to be present. Spray applications immediately after damaging storms are the general rule. Proper evaluation of warning systems is difficult and is only possible in areas where fireblight is endemic and where adequate field records can be obtained.
Prevention and Control of Fireblight1
Authors: MEIJNEKE CAR.
Published: April 2008

A review is given of the possible measures against fireblight in countries which so far do not have the disease (the “have–nots”) and in countries which do (the “haves”).

In the “have–nots”, precautions can be taken by putting into practice our knowledge of susceptibility and sensitivity of host plants in non–commercial as well as in commercial plantations. Some guidelines are given. Planting of the most susceptible non–commercial host plants should be avoided whilst testing and breeding programs for resistance should be stimulated.

In the “haves”, an attempt should first be made to eradicate the disease. Some remarks are made about this point. When eradication has proved to be impossible, special attention should be given to the health of the source material for nurseries. This point is worked out in some detail. Also in the “haves”, preventive measures can and should be taken, inside and outside nurseries and orchards. These measures are specified. In cases where infection is found, the foci should be destroyed as soon as possible, without exception in nurseries and orchards, and preferably also outside these holdings. A number of remarks about this point are made.

Only by practising an integrated policy by a combination of the measures mentioned can one achieve a maximum of control and a minimum of damage by this disease.
Problems in Chemical Weed Control1
Authors: STRYCKERS J.
Published: April 2008

Despite the abundance of herbicidal substances, there is still a long way to go in order to solve the multitude of weed control problems. It is necessary to develop a logical systematic approach to master all the existing information. Substances suspected for good reasons of developing injurious effects or dangerous decomposition compounds should not be used. However moderate use of herbicides with clear advantages can for many reasons be defended.

Herbicide performance can be much influenced by the method of application. Sometimes inter– and intra–specific differences in susceptibility or in tolerance can complicate the use of herbicides. Biological, mechanical and physical weed control must, by integration with chemical control, maintain weed growth at levels below those interfering with the objectives of the cultural system.
Recent Progress in the Biological Control of Weeds1
Authors: WAPSHERE A.J.
Published: April 2008

The recent progress in biological control of weeds is such that three main branches can now be distinguished: 1) classical, 2) inundative, 3) total vegetation. For each branch a brief account of modern methods is detailed, the advantages are outlined and examples of recent programmes are given. For classical biological control, safety, effectiveness and virulence of the agent are prime requirements; for inundative control, safety, virulence and manipulability are necessary attributes of the agents; for total vegetation control manipulability is the major criterion.
Systems Analysis Applied to Crop Protection1)
Authors: GUTIERREZ A.P. , WANG Y. , JONES R.E.
Published: April 2008

This paper reviews the biological problem of crop protection from a systems analysis point of view, and discusses the commonalities in the biological and mathematical form of the population models used to describe the interactions between trophic levels (e.g. herbivore–plant). The historical development of the mathematical models is presented. The uses of these models in crop production are discussed.
Systems Analysis and Dynamic Simulation1)
Authors: WIT C.T. DE , RABBINGE R.
Published: April 2008

The state–variable approach to systems analysis and dynamic simulation is based on the assumption that the state of each system at any moment may be quantitatively characterized and that changes in state may be described by mathematical equations.

The basic distinction between state, rate and driving variables in this approach is illustrated by examples

The conflict resulting from the large number of state variables that may be distinguished in any ecological system and the small number that can be handled in simulation models is treated and attention is given to the distinction between unique and recurring systems, especially with reference to the problem of model evaluation.
Digital Simulation Languages: Problems and Possibilities1)
Authors: ELZAS M.S.
Published: April 2008

When faced with a model to be simulated on a computer, one is in general faced with a series of problems, to which answers are quite often difficult to find. These problems include:

1) Can we construct a mathematical approximation of the model in such a way that the resulting formulation can be implemented as a computer for simulation purposes ? 2) Will the above mathematical formulation guarantee a result on an ideal (perfect) machine ? 3) Will the chosen method of simulation withstand the non–ideal characteristics of an actual machine ? 4) Will it be possible to compute results to the computing sequence that is created for the simulation ? 5) How does one choose the right language that is to be the programming vehicle for the simulation ? 6) Can one describe every simulation problem in any of the languages for specific classes of problems ?

This paper tries to give an insight into the possible answers to these questions and endeavours to provide the reader with some basic knowledge about the possibilities available and the problems to look for when setting up simulation experiments by programming them with simulation languages for digital computers.
CROPS: a GASP IV Based Crop Simulation Language1)
Authors: MILES G.E. , PEART R.M. , HOLT D.A. , PRITSKER A.A.B. , BULA R.J.
Published: April 2008

CROPS is a GASP IV based simulation language which emphasizes the development of the equations which model crop physiology. The CROPS philosophy of physiology is to first divide the crop into constituents (carbon, nitrogen, phosphorus, potassium and water) and then partition the crop into compartments (leaves, grain, stems, and roots). Flows of constituents between compartments are illustrated by system dynamics diagrams. A crop model consists of the equations which describe these constituent flows and which are totally user–specified in separate FORTRAN functions.

The CROPS coding (which is a specially written set of GASP IV user routines) accomplishes all other tasks normally required in a crop simulation. CROPS automatically processes weather data, collects and reports statistics on crop growth rates and relative growth rates, and prints status reports on simulated crop conditions. In addition, all GASP IV support routines (plots, histograms, etc.) are available to the CROPS user. A reference manual, which provides complete documentation, and a mini–tutorial, which introduces the reader to using CROPS, are also available.
Variation du microclimat d'une culture en fonction de ses caractéristiques biologiques1
Authors: PERRIER A.
Published: April 2008

Sommaire

On utilisera pour souligner aussi bien le rôle des facteurs climatiques dominant que celui des caractéristiques biologiques de la plante, structure ou régulation stomatique, un modèle analytique du couvert, basé sur les équations de transfert. Ce modele permet d'illustrer, de préciser et de quantifier la variation des principaux paramètres que sont la vitesse du vent, la température et l'humidité tant au sein du couvert qu'au–dessus. Le röle particulier de la pluie et des irrigations sur le microclimat sera mis en évidence, ainsi que le röle de la densité de population et de la hauteur du couvert considéré.

Enfin, on soulignera, compte tenu de la répartition verticale du feuillage, comment ces variations microclimatiques peuvent être trés diversifiés selon la hauteur considérée au sein du couvert.
Bond Graphs and Minicomputers in Greenhouse Climate Control1)
Authors: BOT G.P.A. , DIXHOORN J J. VAN
Published: April 2008

This paper is concerned with the modelling and simulation method used in greenhouse climate control. A bond graph is a topological diagram, clearly representing any kind of physical network. In this case, the bond graph models the heat and vapour flows between compartmented components and the coupling between heat and vapour flow.

The bond graph can easily be converted into a differential equation model to be solved, for example, by CSMP. In the present case, however, the bond graph was used as a direct input to an interactive simulation program on a minicomputer. The method was applied to model an experimental greenhouse described by STANHILL et al. 1973.
Simulation of Epidemics: Problems and Applications1
Authors: ZADOKS J.C.
Published: April 2008

A review is given of some disease simulation models. There have been 2 schools of thought in simulating disease progress with time. Three further models have simulated disease progress in time and space. The accuracy of the models depends, in part, on the time span (in generations or in days) covered and the overall multiplication over that time span. In these respects, models differ considerably. Spatial models can be used to study the epidemiological effect of multiline varieties and mosaic patterns of varieties. Disease simulation models can be used for guidance in research, disease forecasting, plant breeding strategies, supervised and integrated control, but much further development, including sensitivity testing, is needed.
Simulation of Epidemics Caused by Venturia inaequalis (Cooke) Aderh.1
Authors: KRANZ J.
Published: April 2008

We discuss simulation of apple scab epidemics based on analog computer models, multivariate regression analyses, and systems analyses. Details of underlying models and their scope for applications are emphasized. Monomolecular growth functions by Bertalanffy and Gompertz in analog computers permit fast simulation of disease progress curves. The models derived from multivariate analyses of field experiments on apple scab epidemics simulate closely the changes in infection rates. EPIVEN, our comprehensive and self–generating simulator of apple scab epidemics is reviewed and compared to a reduced model, also based on elements of the system “apple scab epidemic”.
Modélisation de transports horizontaux (spores, pollen)1)
Authors: ITIER B. , PAUVERT P.
Published: April 2008

Sommaire

A partir d'un mod&le analytique de diffusion, nous calculons l'evolution horizontale et verticale des concentrations et des flux d'aerosols emis par une sur‐face ou un couvert vegetal. Ce modele s'applique i deux cas particuliers:

‐ soit concentration constante au‐dessus de la zone d'emission,

‐ soit flux d'hission constant sur toute la zone.

Les flux de concentration en aerosols sont calcules tout d'abord sur la zone d'kmission et i l'inttrieur de sa propre couche limite de diffusion. Dans un deuxikme temps, on s'interesse i ces mCmes quantites au‐deli de la zone d'tmis‐ sion de maniere i calculer les retombees.

Pour une mCme concentration sur la zone d'emission et une mCme rugositt de surface, ces retombees dependent de quatre paramPtres: la vitesse du vent, la vitesse de sedimentation des aerosols, la dimension de la zone d'emission et la distance i cette zone.

Reference est faite i un exemple d'application concernant quelques maladies i dissemination anemophile telles que l'oldium de l'orge et la rouille du bli et nous discutons ducomportement des particules en fonction de valeurs <(seuil)> de la vitesse du vent.
Management of Cotton Pests1
Authors: GUTIERREZ A. P.
Published: April 2008

The interplay between plant carbohydrate balance and various kinds of insects damage is described for cotton growth and development in a general way.
A Data Bank on Crop Losses: First Experiences1)
Authors: RIJSDIJK F.H. , ZADOKS J.C.
Published: April 2008

The third of a series of Agro–ecological Atlases on Cereal Growing in Europe, published under the auspices of the European Cereal Atlas Foundation, will deal with pests and diseases of cereals. Information was collected and stored in a data bank before processing. Data processing leads to two kinds of outputs:

1. Loss maps of Europe show the mean annual loss due to each cereal pest and disease by means of isoloss curves;

2. Risk maps of Europe for selected pests and diseases show the relative risk incurred by the cereal crop in each climatic area as determined by the climate of that area, areas with equal risk being separated by isorisk curves.
Optimal Integrated Control of Alfalfa Weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae)1)
Authors: SHOEMAKER Christine A.
Published: April 2008

The use of optimization methods to determine single and multidimensional economic thresholds for insect pests in discussed. A review of previous applications of optimization methods to pest management problems is followed || by a detailed description of an application to alfalfa weevil management. This model uses dynamic programming to determine the best combination of chemical, cultural and biological means for control of the alfalfa– weevil. The model includes stochastically varying weather patterns, seven weevil age–classes, three parasite age–classes, and five alfalfa plant components. The decision variables include times of harvest and insecticide applications over a three–year period. The multi–dimensional economic thresholds calculated depend upon parasite density and weather, as well as upon alfalfa–weevil density. Results for central New York, USA, are presented.
Dynamique des populations de doryphores. Etude de 1971 à 1979 sur le littoral ouest du Cotentin1
Authors: LOUVEAUX A. , PIGANEAU P.
Published: April 2008

Des dénombrements de populations de doryphores ont été effectués pendant neuf années consécutives le long d'un parcours fixe d'une centaine de kilomètres. Ils ont fait l'objet d'une analyse multidimensionnelle en composantes principales, permettant de résumer graphiquement l'ensemble des observations faites pendant cette période et de regrouper les données qui ont des affinityés entre elles. Une gradation des contaminations est observée entre 1973 et 1979; elle trouve son apogée en 1976‐1977. Les adultes de printemps sont alors suffisamment nombreux et actifs sur le littoral pour que quelques individus atteignent Jersey. Le danger potentiel de recontamination des Iles de la Manche par le doryphore reste done actuel. Les analyses ont montré que, dans la plupart des cas, les cultures visitées au cours d'une année se caractérisent par un méme type de développement de l'insecte, lent ou rapide. L'uniformité de développement, lorsqu'elle est observee sur l'ensemble des cultures visitées, indique que les facteurs climatiques ont certainement une influence prépondérante. Certaines Iocalités du littoral révélent cependant des caractéristiques qui leur sont propres et influent sur la multiplication du doryphore.
Vingt‐cinq années de lutte et d'avertissements agricoles contre le doryphore de la pomme de terre dans le Département de la Manche (1950‐1975)
Authors: PORTIER G.
Published: April 2008

Face aux arriveées sur les plages des Iles Anglo‐Normandes de doryphores de plus en plus abondantes en provenance du littéral français, le Ministère français de l'Agriculture, en accord avec l'Organisation Européenne pour la Protection des Plantes, décida de limiter une zone de protection dans le Département de La Manche (face aux Iles de Jersey et de Guernesey) afin de les protéger de toute invasion. Cette mesure a été prise en raison de la grave menace que le ravageur faisait peser sur les exportations de pommes de terre des deux ǐles vers la Grande‐Bretagne. Depuis vingtcinq années, les populations du ravageur sont maintenues à un niveau suffisamment bas pour éviter leur diffusion du Cotentin aux lies Anglo‐Normandes. De plus, un dispositif d'avertissements mis en place dans le Cotentin permet d'alerter par télégramme et en temps utile les Iles de Jersey et de Guernesey lorsqu'il y a danger.
The Introduction of Perillus bioculatus into Europe to Control the Colorado Beetle
Authors: JERMY T.
Published: April 2008

From the end of the 1950's attempts to introduce the predator Perillus bioculatus have been made in several European countries. This article reviews the main results of studies carried out during the last two decades on the ecology, behaviour and cultural enemies of the predator as well as on its practical use. The species has not yet become established anywhere in Europe, presumably due to some of its ecological and behavioural characteristics. Its direct use against the Colorado beetle by repeated mass release into potato fields has not proved feasible.
Problems of Estimating the Need for and Timing of Control Measures Against Pests and Diseases of Crops1
Authors: HULL R. , DUNNING R.A.
Published: April 2008

The problems are as numerous and diverse as the biology of the various organisms causing damage to crops. They are compounded by the differences in reaction of crops cultivated in different ways, by weather sequences over long periods or short periods and the interactions of all three factors;noxious organisms, crops and weather.

To ensure that control measures are economically justified, their need must be assessed on the basis of probable crop loss if no precautions are taken. The relationship between the intensity and timing of the infestation of the crop by the noxious organisms, crop damage and crop loss must be determined. In some instances, this is straight forward;in others, very complicated.

The assessment of the probability of infestation may be based on existing population levels, on intervening weather, on crop examination for the start of infestation, on the occurrence of critical environmental conditions, or on the transport of inoculum. Having developed a warning system, how is the information conveyed to the grower? Warning systems are based on past experience, but how stable are they ? Pathogens change, crop cultivation practices change, available controls change. The problems of estimating the need for and timing or control measures are likely to be continuing ones for the biologist and crop specialist.

Les problèmes sont aussi nombreux et diversifyés que la biologie des organismes nuisibles eux‐mêmes. Les réactions dissemblables des cultures soumises à différents modes de culture, les séquences méteorologiques à court et a long terme ainsi que les interactions entre L'organisme nuisible, la culture et le temps sont autant d'élements qui ajoutent à la complexite des phénomenes.

La justification économique dune méthode de lutte repose sur I'évaluation de la perte de récolte a laquelle il faut s'attendre en I'absence de protection. Cette évaluation, plus ou moins diffcile, tiendra compte de I'importance et de la durée de la contamination en fonction du dommage que subit la culture et des pertes de récoltes qui en résultent.

L'évaluation de la probabilityé d'une infestation peut reposer sur la densité de la population au moment du contrble, les conditions météorologiques prévalentes, la detection d'une attaque primaire de la culture, L'apparition de conditions critiques dans une biocoenose, ou la possibilityé de dissemination de L'inoculum. Lorsqu'un système d'avertissement a éte développé, la question est de savoir de quelle faGon L'information peut atteindre le cultivateur. Les systemés d'avertissement sont basés sur des expériences acquises, mais quelle est leur fiabilite ? L'organisme change de méme que les modes de culture et de lutte. I1 s'ensuit que I'evaluation de la necessite et du moment de I'intervention phytosanitaire doit être continuellement reconsideré par le biologiste et I'agronome.
Forecasting and Warning in Danish Agriculture1
Authors: WAGN O.
Published: April 2008

In Denmark, the principle is maintained of forecasting and warning against pests and diseases which are not easily recognized by the farmer himself. The forecasting and warning system is based upon close cooperation between the farmers' unions, a well‐organized network of plant husbandry advisers and the State Plant Pathology Institute in Lyngby. Most field data are collected by the advisers and forwarded to Lyngby from where announcements on current attacks are distributed as appropriate. Realizing the considerable local variations in the occurrence and course of the attacks, plant pathologists mainly notify the advisers, who can then intervene, if necessary, with a local warning for their own districts. Potato blight, however, is an exception, country‐wide forecasting being broadcast every year. This may also be the case with warnings againts aphids. Potato blight forecasting has been in operation since 1935 and warnings against aphids in beets (causing virus yellows) since 1957. Each year about 10 different pests and diseases are warned against.

Au Danemark, le principe prévaut d'assurer les prévisions et les avertissements pour les déprédateurs qui ne sont pas facilement dépistés par I'exploitant. Le système se base sur une coopération étroite entre les syndicats dexploitants, un réseau bien organisé de conseillers agricoles, et 1'Institut national de phytopathologie à Lyngby. Les observations de plein champ sont realisees par les conseillers qui transmettent les resultats a Lyngby. L'Institut assure alors la dissemination des informations sur les attaques en cours. Compte tenu de la forte variation regionale de L'incidence et de I'evolution des attaques, les phytopathologues avertissent les conseillers qui decident s'il y a lieu d'emettre des avertissements dans leur district. Le mildiou de la pomme de terre, cependant, est considere au niveau national et, suivant les cas, egalement les pucerons. Les previsions contre le mildiou sont en place depuis 1935, et contre les pucerons de la betterave (vecteur du yellows virus) depuis 1957. Chaque années, une dizaine de ravageurs et maladies font L'objet d'avertissements.
Possibilités de prévisions écoclimatiques par L'interprétation d'images‐satellite en infrarouge1
Authors: MUELLER W.
Published: April 2008

La photographie aérienne « classique » ou par satellites, en infrarouge (IR) surtout, offre des possibilités nouvelles en matière de prévision écoclimatique à moyenne et à grande échelle. Ces données peuvent être intégrées dans un modèle prévisionnel reproduisant la dynamique des populations des ravageurs et des parasites. L'utilisation de L'IR, dit véritable, permet d'établir une cartographie thermique des surfaces et, dans certains cas, d'enregistrer les courant d'air à proximité du sol. Dans le cas du satellite ERTS 1, L'utilisation de simples filtres (MSS 5 et 7) permet de cartographier les plans d'eau et, par superposition chronologique de photos, il est également possible de tirer quelques conclusions quantitatives sur le bilan hydrique, la variation de L'humidité du sol et L'état de la végétation qui font partie intégrante de la prévision.

Aerial photographs, whether obtained by classical or satellite methods, offer new possibilities for ecoclimatological forecasting on a medium or large scale. This is particularly the case for infra‐red photography. This forecasting can readily be integrated into larger scale models for parasite population dynamics. The use of true infra‐red photography allows thermic mapping of the ground, and, under certain conditions, mapping of air currents near the ground. Simple filters (MSS 5 and 7 for the ERTS 1 satellite) make it possible to map water surfaces, and, by superposition, to come to conclusions on water balance, variations in soil moisture, and the state of vegetation ‐ all useful in forecasting.
Agrometeorological Conditions Determining the Occurrence of Potato Blight (Phytophthora infestans de Bary) in Poland1
Authors: UTRATA A.
Published: April 2008

Using phytopathological and climatological data covering the period 196 1 ‐ 1965, the author considers the problem of the influence of chosen meteorological factors during June‐September on the intensity of potato blight. Multiple regression equations are given for average conditions and for selected soil groups comprising either districts with adequate water conditions or those with a predominance of soils that are usually too dry. The influence of soil type on the hazard index of potato blight is shown. By using the mean values of the meteorological factors for the period 1930‐ 1961 in the equations, hazard index maps of potato blight distribution in Poland are plotted. The equations, together with the data on the empirical probability that the disease may occur (resulting from the meteorological conditions), can also be used for forecasting the disease intensity in a given year.

L'auteur a étudié les effects du climat sur le mildiou de la pomme de terre en cherchant à dégager la relation entre certains paramétres météorologiques et l'épidémiologie de la maladie. Ces études ont été entreprises de juin à septembre durant la période s'étendant de 1961 à 1965. Une régression multiple a pu être établie pour des conditions moyennes et pour certains types de sol, dans des régions à conditions hydrologiques differentes. Il est démontré que le risque de mildiou est influenceé par le type de sol et que, par référence à la période 1930–1961, les valeurs moyennes des facteurs météorologiques peuvent être utilisées pour établir des cartes indiquant le risque de mildiou en Pologne. Les équations de régression, ainsi que les donneés sur la probabilityé de L'apparition de la maladie, en fonction de conditions météorologiques données, peuvent être utilisees pour prédire Ie niveau d''attaque pendant L'année considérée.
Some Problems in Using Meteorological Data to Forecast the Timing of Insect Life Cycles1
Authors: BAKER C.R.B.
Published: April 2008

Sources of error in using accumulated temperatures for estimating the timing of events in insect life cycles, such as adult emergence and egg hatching, have rarely been examined in detail. There are two sources of error, one in the calculations, the other in the observations. Errors in the calculations arise from using the wrong base temperature, from using the daily arithmetic mean temperature in the calculation of the daily effective temperature on occasions when the mean is not appropriate and, occasionally, in using the linear relationship between temperature and growth where a non‐linear relationship would be more appropriate. Errors in observations arise mainly from attempts to employ standard meteorological measurements rather than measurements made from sites where the insects normally live. Temperature measurements in the soil at different depths on the flat and on north and south slopes, on the bark of trees and on the leaves of plants have been converted into estimates of insect development to demonstrate the effect of local differences in microclimate. It is strongly emphasized that day‐degrees as units of effective temperature in temperature summation calculations are physiological units of growth and not physical units of heat energy input.

Les sources d'erreurs résultant de L'utilisation de la somme des températures pour prévoir le déroulement des cycles évolutifs des insectes (éclosion des adultes, ceufs, etc.) n'ont guère étéétudiées de rnanière approfondie. De L'avis de L'auteur, ces erreurs peuvent provenir de I'observation et du calcul. En ce qui concerne ce dernier, L'utilisation dune fausse température de base, résultant du recours à une moyenne arithmétique de la température quotidienne établie à tort, est préjudiciable. D'autre part, le résultat peut être faussé lorsqu'il est recouru à une relation linéaire entre la temperature et la croissance alors qu'il serait préferable de tenir compte d'une relation non linéaire.

Les erreurs d'observation concernent principalement L'utilisation de données météorologiques à caracère général, au lieu de se référer à celles qui prévalent au site même où se trouve L'insecte. La détermination de la temperature du sol à des profondeurs différentes, sur terrain plat ou incline vers le nord ou le sud, ainsi que de la température de l'écorce des arbres ou des feuilles des plantes rvele L'influence du microclimat sur le développement des insectes. Il est souligné que le degre‐jour, utilisé dans les calculs de sommes de témperatures, est une unite physiologique de croissance et non une unité physique dabsorption d'énergie thermique.
Standardization of Pest Assessment1
Authors: WALKER P.T.
Published: April 2008

The first need in forecasting, in decision making in pest management on an economic base, for research and in breeding for resistance, is a good method of pest or disease assessment. This should be standardized, quantitative, repeatable, quick and simple, and give details of the signs of attack and effect on the crop.

Examples of this approach from drafted or published FAO Crop Loss Assessment Methods are given, one for assessment of nymphs and bugs of the Sunn pest complex on cereals, one on Dacus fly on olives, and one on Aonidiella scale on citrus leaves.

The need for continued international cooperation in developing, publishing and testing assessment methods is stressed.

Une méthode fiable d'avaluation de L'incidence des ravageurs et des maladies constitue l'élément fondamental sur lequel doivent pouvoir s'appuyer les prévisions, la sélection de cultivars résistants et toute autre décision prise dans le cadre dun système de lutte integrée. Les techniques normalisées, simples et rapides, mises en ceuvre pour apprécier la signification des déprédateurs, devraient également faire état de la symptomatologie et de L'effet que ceux‐ci exercent sur la culture. L'auteur cite des exemples de méthodes d'valuation des pertes de récoltes publicées par I'OAA ou en voie d'étude en se référant plus particulièrement au dénombrement des nymphes et des adultes de differentes espèces d'Eurygaster et Aelia sur céréales, et a ceiui de Dacus oleue sur olivier et d'anonidiella aurantii sur feuilles d'agrumes. Le developpement, la publication et l'évaluation des méthodes exigent une cooperation internationale suivie.
Techniques d'étude des contaminations des tavelures des arbres fruitiers à pépins1
Authors: GEOFFRION R.
Published: April 2008

Dans toutes les régions fruitiéres françaises, les tavelures du poirier et du pommier sont de redoutables maladies, pouvant provoquer, en L'absence de traitements, des dégâts trés sérieux. Dans les exploitations fruitiéres, il est utile, pour déterminer le moment des traitements préventifs, de savoir si une contamination peut se produire et, éventuellement, quelle en sera la virulence. II est également souhaitable de savoir si une contamination s'est produite, pour prevoir la date d'apparition des premiers symptômes. A l'aide de ces renseignements, les arboriculteurs peuvent alors fixer la date et la fréquence des traitements préventifs et empêcher ainsi L'installation de la maladie sur leurs arbres. Les Stations d'avertissements agricoles du Ministère de L'Agriculture transmettent aux exploitants des informations qui leur permettent de prendre dans ce domaine toutes dispositions utiles; ainsi, les risques de contaminations primaires sont régulierèment précisés. Pour cela, les Stations utilisent les renseignements climatiques, biologiques et phénologiques transmis par le réseau de leurs postes d'observations. L'étude de la maturité des peritheces et de la projection de leurs ascospores fixe L'absence, le début et le maximum du danger éventuel. L'arret des projections permet de suspendre les interventions contre les attaques primaires. Des appareils de type Vuittenez sont utilises par les Stations d'avertissements. L'estimation des risques de contaminations secondaires fait intervenir L'etude des conditions climatiques, la vitesse du développement des arbres, les dates probables d'apparition des taches de la maladie. II est précisé de quelle façon ces différentes données sont mises en valeur par les Stations d'avertissements qui assurent la diffusion des recommandations aux intéressés.

Apple and pear scab, if not treated, can cause considerable losses in France, especially in the damp and rainy West and Southwest, even if dry springs and summers have recently tended to reduce infection. Treatment without adequate biological information leads to fungicide wastage, without even a guarantee of adequate protection. The recent introduction of systemic fungicides may allow fewer treatments to be made, during disease incubation periods, and information on the probability of outbreaks becomes even more important. The warning stations inform growers of the risk of primary contamination on the basis of climatic, biological and phenological data collected by their network of observation posts. Study of the maturation of perithecia and of ascospore discharge fixes the beginning of the danger period and its maximum, the end coinciding with the completion of ascospore release. This risk of secondary contamination is forecast on the basis of climatic conditions, rate of tree development and the dates of probable lesion appearance. The information is made known by post, radio, television and telephone.
Méthodes de détermination des risques concernant ies insectes nuisibles au colza1
Authors: LECHAPT G.
Published: April 2008

Les coléoptères nuisibles au colza sont surveilles en France á lapos;aide d'un réseau d'observateurs qui communiquent au Service de la Protection des Végétaux les données suivantes, jour par jour: stade végétatif du colza, insectes piégés dans les cuvettes jaunes (altises, charancons, méligèthes), insectes présents en culture, ou dégats observés. Aprés plusieurs années d'observations, il apparait que la cuvette, maintenue au niveau supérieur de la végétation, rend trés bien compte des vols de colonisation des insectes. Ces vols sont liés à de grands i'acteurs climatiques (températures et insolations) et se produisent de façon simultanée sur des régions assez étendues. Leur détection est done possible avec un nombre réduit de postes d'observations (3 par département par exemple), ou même en se basant sur des releves météorologiques. Lapos;intensité des risques au niveau de petites régions ne pourrait être appréciée qu'avec un nombre beaucoup plus important de postes, compte tenu de la tres grande hétérogénéité des sols et microclimats de notre pays.

The coleopterous pests of oilseed rape are monitored in France by a network of observers, who send the following daily information to the Plant Protection Service: growth stage of the crop, insects caught in yellow dishes (flea beetles, weevils, pollen beetles), insects present on the crop, damage observed Several years of observation show that dishes placed at the level of the top of the crop provide an excellent indication of the colonization flights of the insects. These flights are determined by climatic factors (temperature and insolation) and occur simultaneously over wide areas. They can thus be detected with a limited number of observation stations (for example, three per department) or even predicted from meteorological data. However, the risk at the more local level can only be estimated with a larger number of stations, in view of the great heterogeneity of soils and microclimates in France.
An Approach to Forecasting the Incidence of Potato and Cereal Aphids in Scotland1
Authors: TURL Lindsay A. D.
Published: April 2008

Many potato and cereal infesting aphids in Scotland are either completely cr partially anholocyclic. This makes forecasting their first appearance and abundance on crops difficult, when compared with holocyclic species such as Aphis fabae Scopoli. This paper describes an analysis of the early movement of nine aphid species, commonly found on potatoes and cereals in Scotland, in relation to winter and early spring climate. Data on their early movement have been extracted from the catches in three of the sjx.12–2.rn suction traps now operating in Scotland in cooperation with the Rothamsted Insect Survey. The particular importance of early spring temperature has been established. The extension of this work to develop a predictive forecast of summer activity of anholocyclic aphid species is discussed.

En Ecosse, une forte proportion de pucerons des pommes de terre et des céréales est entièrement ou partiellement anholocyclique. Ceci complique la prévision sur le moment de leur première apparition et sur leur abondance par rapport aux espéces holocycliques telles qu'Aphis, fabae. Cette étude concerne les déplacements précoces de neuf espéces de pucerons retrouveés fréquemment sur les pommes de terre et les céSreales. Les données sur les deplacements ont été obtenues à partir de trois des six piegès à succion de I2,2 m installes en Ecosse en cooperation avec le « Rothamsted Insect Survey », Il est apparu que la température printanière revêt une importance particuliere. Les recherches se poursuivent dam le but d'établir des prévisions sur le développement estival des espèces anholocycliyues de pucerons.
Forecasting Aphids in Field Crops (Swiss Model)1
Authors: SUTER H.
Published: April 2008

A new prognostic system for aphids in field crops, based on long‐term ecological investigations, was developed in Switzerland during the years 1971 ‐ 1976 and tested successfully in practice in 1975 and 1976. Within the region, population densities of aphids and mortality caused by predators, parasitoids and fungus diseases were measured weekly at different places. Sampling was started in early spring (parthenogenetic overwintering of the aphids was never observed) in permanent and temporary grassland and continued in annual field crops after aphid migration. Typically, in years during which aphids caused damage (1973, 1975, 1976), there was a late progression of aphid population densities in permanent grassland in spring. But, during years without damage (1971, 1972, 1974), an early and intensive aphid development was observed in permanent pastures in spring. Thus, the intensity of the spring development of aphids in permanent grassland is of general importance for the development of the pests later on in annual field crops. This conclusion was considered in the forecasting system for which guidelines have been developed, enabling the Regional Plant Protection Services to establish exact prognoses. Farmers can then start making observations in their fields, in order to find the right moment for insecticide applications.

Un nouveau systemè de prévision pour les pucerons des grandes cultures a été developpe en Suisse au cours des annees 1971–1976; il repose sur des recherches écologiques de longue durée et sa mise en place en 1975 et 1976 s'est révelée très utile. Les densités de populations de pucerons dans la région ainsi que la mortalité occasionée par les prédateurs, les parasitoides et les maladies ont été déterminées chaque semaine à des sites differents. L'échantillonnage commence au printemps (L'hivernation des populations parthénogenétiques n'a jamais été observée) dans les prairies permanentes et temporaires et se prolonge dans les cultures annuelles apres la migration des pucerons. Les annees au cours desquelles les pucerons ont provoqué des déghts importants (1973, 1975, 1976) sont caractérisées par un developpement tardif des populations de pucerons dans les prairies permanentes au printemps. A L'inverse, les annees caractérisées par I'absence de dommages (1971, 1972, 1974) ont vu un developpement printanier intensif des pucerons dans ces mêmes sites. Ainsi, L'intensité de ce développement exerce une incidence sur l'évolution ultérieure du ravageur dans les cultures annuelles. Cette conclusion a été incorporée dans les directives pour la prévision dont I'établissement a permis aux services regionaux de la protection des végétaux detablir un pronostic precis. Les agriculteurs peuvent ensuite observer leurs champs afin de determiner la date optimale pour le traitement chimique.