FRUIT BREEDING 



279 



It will be of interest here to present briefly an instance from 

 the fruit-breeding work at the Minnesota Station in which 

 desirable new plum hybrids were obtained when the tender 

 parent, Burbank (P. triflora) was crossed with Wolf which is a 

 hardy variety of P. americana mollis. The percentage of hy- 

 brids killed during winter dormancy is taken as a basis for clas- 

 sification. It will ,be seen that some of these hybrids, as No. 8 

 or No. 9, are hardy in the bud like the staminate parent Wolf. 

 The two which have been named Red Wing and Tonka, are inter- 

 mediate in hardiness but of excellent fruit characteristics. 



FIG. 66. Tonka, Burbank X Wolf, No. 21. Has high quality and is nearly 

 as hardy as the hardy variety of Wolf. (Photo loaned by Dorsey.} 



TABLE LXXV. SHOWING THE PERCENTAGE OF BUDS KILLED IN AN FI 

 PROGENY WHEN ONE OF THE PARENTS is HARDY AND THE OTHER TENDER 1 



These few instances have been given as indicative of the 

 methods of work which are being used by some of the most pro- 

 gressive fruit breeders. Some general conclusions regarding 

 methods of work may be here given. 



1 Data furnished by M. J. Dorsey. 



