La fonte des semis en pépinière forestière

Damping off in forest nurseries . A survey of conifers damping off in French nurseries revealed that the principal pathogens involved were Fusarium oxysporum, Pythium spp. and Rhizoctonia solani . Larch, spruce, and pines in general were most susceptible host species. No correlation was observed between disease severity and causal agents involved with factors such as sampling year, host species, seedling age, and location of nurseries. The disease intensity, independant of soil type, was mainly related to local weather conditions prevailing at the period of seedling emergence. Disease prediction and preventive treatment were difficult to realize in practice. Improved control measures could be expected from a better understanding of disease epidemiology.