On compare quelques modeles de croissance permettant de decrire la progression des symptomes de la maladie due a Phytophthora parasitica var. nicotianae. On determine si les plantes sont atteintes par P. p. de facon aleatoire ou non dans le temps, a l'interieur des rangs

SUMMARYFusarium oxysporum f. sp. nicotianae was grown on cell walls from the roots of the flue-cured tobacco cultivars ‘Coker 298’ (resistant to Fusarium) and ‘Virginia Gold’ (susceptible to Fusarium). All plants were grown in a split-root system and Meloidogyne incognita eggs were applied to one-half of the root system of certain ‘Coker 298’ plants. The amounts of polygalacturonase, cellulase, polygalacturonate transeliminase, pectinmethyl transeliminase, polymethyl galacturonase and amylase enzyme activities and soluble protein concentrations produced by the fungus on cell wall preparations from these roots did not differ statistically. However, there was a strong tendency for greater enzyme activity production on cell walls from the nematode-infected roots than on walls from nematode-free roots.