Report of the Department of Lands and Forests for fiscal year ending March 31, 1950 Page 130 



development of the cone prior to its emergence from the bud has been traced. Con- 

 cerning this basically important matter little or nothing has been known hitherto. 

 The work of 1949 brought this part of the project to a conclusion. 



In connection with the destruction of formed cones and seeds by insects, the 

 data of 1949 confirms Dr. Duff's previously reported view that the insect attacks are 

 correlated with the cycle of seed production. It is obvious that if seed orchards are 

 to be established reliable methods of insect control will have to be worked out. 



In defining the optimum conditions for seed production in culture, progress 

 has been made in ( 1 ) the discovery and bringing into culture of what appear to be 

 highly productive seed strains or races of red pine, and (2) the experimental treatment 

 of existing plantation stands, such as thinning, pruning, fertilizing, hormone treatment, 

 and protection from insects. 



Forest Tree Breeding. The work, initiated in 1946 under the direction of Dr. 

 C. Heimburger, is concerned principally with the selection, breeding and propagation 

 of white pine and poplar. Incidental to the above is the establishment of an arboretum, 

 essentially for the preservation of authentic material for breeding and genetical 

 research. 



(1) White Pine: This species, for many years the mainstay of the lumber 

 industry in Ontario, is recognized as one of the most valuable in the province for 

 forestry purposes. Nevertheless, its culture is handicapped by blister rust and weevil. 

 The white pine project is concerned primarily with the discovery and development 

 of superior stock, highly resistant to attack by these enemies. The main effort is still 

 centred on the assembling of breeding materials, testing and evaluation of the same, 

 and improvement of methods of vegetative propagation. In the course of the year 

 breeding material was received in exchange from Denmark, California, Wisconsin, 

 eastern States and British Columbia. This has been used with native and other 

 stocks in grafting and pollination. Outside grafting was further improved and its 

 use extended. Experimental outside fall grafting was started. Inoculation experi- 

 ments showed the western pine much easier to infect than the eastern species. 



(2) Poplar: The increasing use of poplar for pulp and lumber warrants con- 

 tinued investigation of the breeding potentialities of these species. The aim of this 

 project is to produce a rapidly growing hybrid with wood of superior quality, adapted 

 to the relatively poor sites of Ontario, and resistant to disease. In addition, it is 

 proposed to evaluate poplar material for windbreak planting in the southern part 

 of the province. Experience in hybridization indicates that the most promising com- 

 binations are Populus alba x P. grandidentata ; P. alba x P. tremula; P. tremuloides x 

 P. tremula and reciprocals. 



The selection of elite material for these crosses is important. Such material 

 was sought both here and abroad. Grafting experiments indicated that native aspens 

 are not compatible; but that the European P. tremula can be successfully grafted on 

 both our P. grandidentata and P. tremuloides. August budding showed considerable 

 promise as a means of propagation. 



(3) Arboretum: The arboretum of native and foreign species, started in 1948, 

 continued to expand rapidly in 1949. It consists of breeding materials for present and 

 future use. It is planned to continue the acquisition of seeds, scions and plants, with 

 emphasis on the white pine and poplars, and other economically important trees. 



