THE NEXT GENERATION OF EUROPEAN PLUM CULTIVARS RESISTANT TO PLUM POX VIRUS

Plum growing in Sharka infested regions is only successful with Sharka resistant cultivars. The cultivar `Jojo', up to now the only cultivar which is absolutely Sharka resistant in the field, was introduced by the University of Hohenheim in 1999. The resistance is based on a hypersensitive response to the Sharka virus (Plum pox virus, PPV). Since its release a number of new hypersensitive clones were bred within the Hohenheim breeding program that have different ripening times, better quality and higher fruit weights. These include interesting clones with early, midseason and late ripening times. A particular breeding aim is the combination of resistance and high fruit quality. Crosses of hypersensitive genotypes with the cultivars `Hanita', `Felsina' and `Fellenberg' gave promising seedlings. There are some clones that combine a high degree of hypersensitivity resistance with excellent fruit quality. Clone Nr. 7346 will soon be introduced as new cultivar. Crosses of `Jojo' with `Haganta' resulted in two PPV resistant clones with fruits larger than 50 g. Some clones originating from the cross `Jojo' $\times$ `Hauszwetschge' vary in ripening times and are also very interesting. Some of the very promising hypersensitive hybrids are very similar to `Common prune' in shape, colour, size and taste. These promising clones cover more than six weeks of ripening time. Their fruits are resistant to fruit flesh damage caused by excessive heat as fruit mature which is a current problem with fruits of `Common prune'. These clones will be introduced as new PPV resistant cultivars. They will allow growers to sell fruits of `Hauszwetschge' (i.e. `Common prune') and very similar fruits from the middle of August until the beginning of October     «

Plum growing in Sharka infested regions is only successful with Sharka resistant cultivars. The cultivar `Jojo', up to now the only cultivar which is absolutely Sharka resistant in the field, was introduced by the University of Hohenheim in 1999. The resistance is based on a hypersensitive response to the Sharka virus (Plum pox virus, PPV). Since its release a number of new hypersensitive clones were bred within the Hohenheim breeding program that have different ripening times, better quality an...     »