FOREST TREE BREEDING 

 Breeding work with white pine, aspen poplars and two-needled pines 

 were the main projects. Some work with chestnut was started. 



White Pine 

 A co-operative seed- source study, covering the entire range of eastern 

 white pine, was organized with four forest experiment stations in the United 

 States. Seeds from three localities in Canada were collected for tkis study and 

 distributed to the other stations. The acquisition of new materials comprised 

 76 clones of eastern and western white pine, and three population samples of the 

 latter species. Scions from young trees, resistant to blister-rust, were grafted 

 on young planted stock at Dorset, Ontario, to make the plantation resistant to 

 this disease in the future. Successful methods of fall grafting outside and of bare- 

 root grafting in the spring were worked out and put into use. Forty-two inter- 

 specific crosses out of 62 made in 1954 yielded viable seeds. Thirty-three new 

 such crosses were made in 1955, Hybrid seedlings resulting from several 

 crosses made in previous years showed very high resistance to blister rust in 

 this year's inoculation tests, as compared with native white pine. Hybrids of 

 our native species with Balkan white pine seem especially promising in this res- 

 pect. 



Aspen Poplars 

 The production of aspen-like hybrids, suitable for planting in southern 

 Ontario and easy to propagate from stem cuttings, is the chief aim of this project. 

 By means of exchange with other poplar breeders and through our own collections, 

 62 new clones and three populations have been obtained. In breeding for industrial 

 use, 37 new hybrid populations were produced. Of these, several made with 

 aspen pollen from southern Europe showed outstanding vigour. Pollen of silver 

 poplar was also received from southern Europe and used in several promising new 

 hybrid combinations. In breeding for early flowering to produce dwarfing stock 



