La variabilité du pouvoir pathogène de Nectria ditissima agent du chancre du hêtre

Variability in the pathogcnicity of Nectria ditissima Tul. cause of beech canker . Four mycelial strains of Nectria ditissima Tul. were inoculated into young beeches of two different provenances. The size of bark necrosis was assessed monthly from December to June. The strains can be separated into three groups of aggressiveness according to the size of the necrosis, its persistence and also the hormonal disturbances resulting from pathogenesis. The results reported here suggest a differential interaction between N. ditissima and its host Fagus sylvatica.     

Influence des sels fondants sur les arbres et autres végétaux Rapport présentéà la division Forêts de la Commission des Communautés européennes à Bruxelles

Effect of thawing salts on trees and other vegetation . Report to the Forestry Department of the Commission of the European Communities at Brussels. The effects of the chemical composition, the quality, the consumption and the sequences of application of thawing salts, on the soil, on trees and on other vegetation are described. Some conclusions and recommendations are given.     

Production d'hydrolases dégradant des polyosides pariétaux par Rigidoporus lignosus,un des agents du pourridié blanc de l'Hévéa

Cell wall-degrading enzymes produced by Rigidoporus lignosus in vitro and in vivo. Secretion of 3 polysaccharide degrading enzymes (cellulase, xylanase, endopolygalacturonase) by R. lignosus, responsible for white root rot of Hevea, was studied in culture and during pathogenesis.     

Etude de la relation entre la pluviosité et l' accumulation du fluor dans les forêts résineuses soumises à une pollution fluorée

On the relationship between precipitation and fluoride accumulation in coniferous forests under fluoride influence . In forests under the influence of airborne fluorides a relationship of the form F = 2.92 C^1.137/P^0.508 was found. The fluoride accumulation F relates to the F-contents in dry matter of fir needles (ppm), C means F-output in tons and P precipitations in mm.y^?1.     

Méthode ?estimation de la hauteur de pourriture dans le tronc des épicéas sur pieds attaqués par le Fomes annosus (Fr.) Cooke

Estimating the height of decay in standing Norway spruce attacked by Fomes annosus (Fr.) Cooke. A method is given for estimating the height of decay due to Fomes annosus in standing Norway spruce. A good correlation is provided by the height of the decay and, at the 1,30m level, the diameter and stage of the decay. The data were obtained using Pressler borings.     

La pourriture des faines causfée par Rhizoctonia solani Kühn: Incidence de cette maladie après les fainées de 1974 et 1976. Traitement curatif des faines en vue de la conservation

Rot of beechnuts caused by Rhizoctonia solani Kühn. Disease incidence after the 1974 and 1976 mast years. Curative seed treatment before storage. Rot of beechnuts by Rhizoctonia solani Kühn, occurred throughout French beech forests after the masts of 1974 and 1976. The site conditions and the climatic conditions of November and December determine the incidence of disease which is notably reduced by soil cultivation before the mast. Thermotherapy - 24 hours at 36–38°C at 100 % relative humidity - was shown to be a curative treatment of seeds before storage.