BREEDING OF VEGETABLES 



259 



retained its resistance when grown in Iowa but seemed to lose it 

 when grown in Oregon, on the Pacific Coast. No very satisfac- 

 tory explanation has been offered for this phenomenon. It is 

 possible that a similar condition exists with flax wilt. 



FIG. 62. A strain of Hubbard squash isolated by self-fertilization which is 

 comparatively uniform for the production of large fruits of uniform shape. 

 Minnesota Exp. Sta. (Courtesy of Bushnell,) 



Flax strains resistant to wilt seem to lose their resistance when 

 grown for a few years in wilt-free soil. 



Breeding Cucurbitaceae. Each botanical species of this 

 family in most cases constitutes a freelv inter-crossing group of 



FIG. 63. A small fruited strain isolated from a commercial variety of Hubbard 

 squash by self-fertilization. Minnesota Exp. Sta. ( Courtesy of Bushnell.) 



varieties. The monoecious character of the plant encourages 

 cross-fertilization. In spite of these facts the authors believe 

 that in some cases progress may be made by breeding methods 



