Fruit tree genetic resources and disease resistance.Since 1975, the Plant Pathology Station bas been collecting fruit tree cultivars which were formerly grown in Belgium. The number of accessions is now over 2 500, mostly of apples, pears and plums, all of which are planted in the open on dwarfing or semi-dwarfing rootstocks. One third of the material was recovered from old, often endangered collections in horticultural schools and to a minor extent from collections abroad, and two thirds from old orchards on faims and in gardens. A preference was given to material originated in Belgium either as landraces or as cultivars produced by recognized breeders from the part two centuries. The initial aim, which is still a priority, was to evaluate a broad range of old cultivars for useful characters, with an emphasis on disease resistance. As the collection expanded, a conservation objective also developed. From 1985 on, the Station started to reintroduce in the nursery trade and to recommend for home-growing the better cultivars emerging from the evaluation. Fifteen cultivars were released up to now, among which ten apples, four plums and one peach cv. Corresponding technical leaflets were also edited. The project had a multiform social impact ever since the outset. Both the collecting work and réintroduction process were a Ovide success with the public, which led a number of commercial growers to experiment with some of the recommended apple cultivars. As a further step in the utilization of genetic resources, the Station bas been producing yearly since 1988 several thousands of hybrid seedlings from interesting old apple cultivars with the aim of creating new material of commercial value with low disease susceptibility.