156 Journal of Agricultural Research voi. xviii, no 3 



Lyon and Keyser {5, p. 25-2g) came to the conclusion that — 



there is quite a definite relation between the per cent of yellow berries in the crop and 

 the character of the season in so far as the latter aflects the date of ripening, the com- 

 position, and the yield of wheat. 



From experimental data they find that — 

 the amount of '-yellow-berry " increases with the lateness of ripening, 

 and that— 



crops of large yield and low nitrogen content contain more ' ' yellow-berries ' ' than do 

 crops of the opposite kind. 



They conclude that — 



since it has been shown that the amount of yellow-berry increases as the ripeness of 

 the grain increases, and also with the length of time the cut grain is exposed to the 

 weather, it is impossible to lessen the loss by cutting the grain rather early and stack- 

 ing as soon as sufficiently dry. 



Roberts and Freeman (6, p. 21-35) found that in two successive years 

 there was a diminution in the amount of yellow-berry corresponding to 

 the shortening of the fall growing period on account of late planting. 

 No relation was found to exist between the spring growing period and the 

 percentage of yellow-berry, except that, in general, late ripening increased 

 it. Higher mean temperatures for the three weeks before ripening were 

 found to be correlated with low percentage of yellow-berry. Evidences 

 of hereditary tendencies were found. 



Headden (4, p. 30-37) studied the effects of different commercial 

 fertilizers on yellow-berry. His results may be summarized in his own 

 words, as follows : 



In our case it is evidently the ratio between the potassium and nitrogen which 

 determines the presence of yellow-berry. . . . The degree of mealiness or starchi- 

 ness, the yellow-berry, . . . depends upon the relative available supply of these 

 two elements. . . . The application of nitrogen, which was in the form of sodic 

 nitrate, greatly reduced the amount of yellow-berry, in some cases preventing it 

 altogether. 



Headden does not find that climatic conditions, the soil, or the 

 amount of available phosphorus affects the development of yellow- 

 berry, but states that — 



it can be greatly intensified or increased by the application of available potassium, 

 and that — 



yellow-berry indicates that potassium is present in excess of what is necessary to 

 form such a ratio to tlie available nitrogen present as to be advantageous to the forma- 

 tion of a hard, flinty kernel. ... I do not tliink that there can be any question 

 of the identity of this affection of oiur wheat with that of Kansas, Nebraska, or South 

 Dakota, and almost no question but that the opaque wheats of California and the 

 Pacific Coast States in general are identical in their character with extreme cases of 

 yellow-berry in Colorado and have the same cause. 



This last phase of the question has not yet received much attention. 

 The fact that yellow-berry is produced under apparently the same condi- 

 tions as the flinty kernels, not merely in the same field, but on the same 



