286 BREEDING CROP PLANTS 



The seed plot method is here outlined by means of a diagram. 



DIAGRAM OF FARMER'S METHOD OF MAINTAINING THE PURITY OF SELF 



FERTILIZED CROPS 



Canadians register seeds as 1st, 2nd or 3rd 

 generation seed according to the source of the 

 seed and the number of generations away from 

 the H. S. P. (Hand Selected Seed Plot.) 



For the tobacco crop there is no necessity of a seed plot. 

 The grower should select good-type plants in the field and save 

 these for seed production. The best growers insure the produc- 

 tion of self-fertilized seed by covering the inflorescence before any 

 of the flowers open, with a 12-lb. manila paper bag. It is 

 necessary to remove the bag from time to time to shake out the 

 dead parts of the corolla so that the seed will not become damaged. 

 Ten or twelve plants handled in this manner furnish sufficient 

 seed for a large acreage. 



If the farmer is troubled with flax wilt he can easily over- 

 come this difficulty by seed selection. All that is necessary is 

 to select from a plot on which the wilt disease is causing con- 

 siderable loss those plants which appear to be free from the dis- 

 ease. Experiments carried on by Bolley at the North Dakota 

 Station which have been recently corroborated (Stakman et al, 

 1919), have shown that a wilt-resistant type can be produced 

 by three years of continuous selection. Methods of producing 

 wilt resistant seed are presented here in diagrammatical form: 



