Report on Poplar Hybridization Ii 1937 and 1938

Abstract

The results of further progress in a poplar hybridization project initiated in 1935 with the aim of producing valuable hardy and disease resistant material of rapid growth for the production of wood of high quality for industrial purposes, and of value for shelterbelts in the Prairies are reported. It has, been possible to cross the native aspens of Eastern and Western Canada with several exotic aspens and their hybrids with silver poplar, and to obtain hybrid material of great promise for these purposes. Some western balsam poplars have also been crossed with exotic species and have yielded hybrids of promise forshelterbelts. An attempt to cross an aspen with a cottonwood has so far yielded indifferent results. The cress of a basket willow with a cottonwood wan not successful. Hardiness. disease resistance, and good propagability from stem: or root cuttings are a t present the most importa n t characters used in evaluating the young hybrids.T H E OBJECT of this report is to outline the further development of the poplar hybridization project initiated in 193 5 and described previously (Heimburger, 1936). I t is an attempt to produce new varieties of aspen poplars, suitable for reforestation on upland soils and yielding good, sound wood for the manufacture of match stock, veneer, and pulp. The new varieties should be fully hardy, resistant to several important diseases damaging the native aspen poplars, and should possess superior growth characters as compared with the native asFcns. Since hybridizatioil and selec. tion are the methods most commonly employed with such outstanding results in breeding work with other plant material, these methods are here applied to the development of superior aspen poplars. In inore recent years the desirability of producing suitable tree varieties for shelterbelts in the Prairies has become increasingly apparent and some of the efforts are there. fore directed towards the breeding of aspens and other poplars for these purposes also.In 1935 and 1936 it was found that the European silver poplar (Populus alba L.) and its natural hybrid with the European aspen (P. tremula L.), the so~called gray poplar (P. canescens Sm.) could be crossed successfully with the native amens (P. tremuloides Michx. and P. grandidentata Michx.). The u cross between the two native aspens, P. tremuloides x grandidentata was also successful. HYBRIDS OF 1936In the fall of 1936 the hybrid seedlings described in the previous report were carefully dug out and their roots prepared into cuttings, care being taken to keep the cuttings from each seedling separately. Each bunch of root cuttings thus represented a singe clone (Schreiner, 1939). The material was then trans, ferred to the nursery of the Petawawa Forest Experiment Station and planted. The possibility of propagating aspen poplars by means of fall-planted root cut, tings had been ascertained in previous tests with root cuttings of native aspens.all planting of root cuttingsbf aspen poplars as compared with spring plant, ing has the advantage of affording b...

Disease biology and histopathology of bronze leaf disease: a threat to cultivated aspens, white poplars and their hybrids

“…Cash & A.M. Waterman) M.E. Barr (Barr, ; Cash & Waterman, ), has damaged and killed aspen, grey and white poplar cultivars, and hybrids in section Populus of the genus Populus growing in plantations and landscape plantings in the north central and north‐eastern United States, as well as the Canadian Provinces of Ontario, Quebec, Saskatchewan, Alberta and Manitoba (Dance, ; Heimburger, ; Kawchuk et al., ; Northover & Desjardins, ; Robbins, Ostry, & Prey, ; Smith, Blanchette, Ostry, & Anderson, ). The Swedish columnar aspen ( Populus tremula L. “Erecta”) and Tower poplar, P .…”

“…The European white poplar ( P. alba ) was introduced into North America almost entirely as female populations and can readily hybridize with bigtooth and trembling aspen (Barnes, ; McComb & Hansen, ; Spies & Barnes, ). In early hybridization trials, it was reported that many of these hybrids were highly susceptible to dieback caused by stem and leaf diseases (Heimburger, ) and later Heimburger () described a serious unknown disease of P. alba hybrids with bigtooth and trembling aspen that he suggested was a “genetic barrier” to hybrid aspen species. The disease he described is now known as BLD (Heimburger, ).…”

Comparative reproductive ability of bigtooth and trembling aspen and their hybrid

“…Change in the Hybrids reach reproductive maturity by 15 years parental germ plasm may be undesirable for the of age and seeds of some natural hybrid clones opposite reasons. Heimburger (1940) reported exhibited a high percentage of germination that the rather poor growth and high suscep- (Andrejak and Barnes 1969). Fertile seeds also tibility to dieback of the hybrid "makes it unhave been obtained from several hybrid females suitable for any direct use in forestry."…”