The Poplar Breeding Program in Belgium was initiated in 1948 by the Swedish Match Company. From the first beginning the decision was taken to elaborate a long range planned poplar breeding program on the basis of controlled crossings incorporating in the programme the major poplar species Populus nigra, Populus deltoides, Populus trichocarpa and Populus maximowiczii. During a first period 1948-1971 a large genepool collection of Populus nigra was established and over 75.000 seedlings out of full-sib crossings between essentially native clones are produced, with the special aim to rebuild new native populations of the with extinction menaced species Populus nigra. The species Populus nigra is susceptible to very susceptible to different leaf diseases, susceptible to very susceptible to the bark and shoot disease of Discosporium populeum (= Dothichiza populea) but in general very resistant to Xanthomonas populi (= bacterial canker). To safeguard the species for future breeding work it's advisable to select the best remaining clones of the species in each of the more or less restricted geographical area's and use these clones for controlled intraspecific crossings and for introduction in a network of local seed orchards with always the special aim to reconstruct local populations. Since there exists for the most dangerous diseases, Melampsora species and Discosporium populeum different races with a different geographical distribution and a different degree of virulence and aggressiveness and since cuttings and plants of Populus nigra can be carriers of the Discosporium populeum fungus, export of such material over long distances should be avoided and we strongly advise only to restrict to the exchange of seeds and 'in vitro' plantlets.
