278 BREEDING CROP PLANTS 



made and 407 trees were grown. Some varieties were obtained 

 with larger fruits but these as yet have not been thoroughly 

 tested for hardiness. 



Pears have been frequently tried in the Dakotas but have 

 failed for two causes (Hansen, 1915): (1) Lack of hardiness; 

 (2) susceptibility to blight. The Chinese sandpear, Pyrus 



FIG. 64. Wolf, a hardy variety of plums which lacks quality of fruit. (Photo 



loaned by Dorsey.) 



sinensis Lindley, obtained from Dr. Sargent, of the Arnold 

 Arboretum, proved perfectly hardy and resistant to blight. 

 Various crosses between this species and cultivated pears be- 

 longing to Pyrus communis have been made. Preliminary tests 

 have shown that some of the seedlings were blight resistant and 

 hardy. These results indicate that the problem of producing 



FIG. 65. Burbank, a plum of high quality produced by Luther Burbank. It 

 lacks hardiness when grown in Minnesota. (Photo loaned by Dorsey.) 



pears for the Northwest may eventually be solved. In a some- 

 what analogous manner, Hansen (1911) has produced new plum 

 varieties by crossing the native sand cherry with Japanese plums. 

 This has resulted in a "happy combination of hardiness, rapid 

 growth and early bearing of tree, with large size and choice 

 quality of fruit." 



