Y. SELF-FERTILITY OF THE GRAPE.* 



S. A. Beach. 



SUMMARY. 



Cultivated American grapes show remarkable differences in the 

 degree of self-fertility of different varieties. Many of them fruit 

 perfectly of themselves. Others form no fruit when cross polli- 

 nation from other varieties is prevented. Most varieties are found 

 between these two extremes, being neither fully self-fertile nor 

 completely self-sterile. 



With many varieties the degree of self-fertility is not an un- 

 changeable characteristic, even when the vines appear to be in 

 a normally productive condition; but varies under differences of 

 environment. Many other varieties which have been under ob- 

 servation show practically no variation in this respect. Usually 

 when any variation in self-fertility is observed with a variety it 

 is confined within rather narrow limits. In exceptional cases rather 

 wide variations are seen. 



Investigations to determine the degree of self-fertility of a 

 variety should be made with vines in a normally productive con- 

 dition because variations in the amount of fruit which sets may 

 be due to an unproductive condition of a portion or all of the vine. 

 It is desirable, also, that a large number of clusters be tested for 

 each variety and that the tests be made in more than one locality 

 and in more than one season. 



One hundred and sixty-nine cultivated varieties were included 

 in these investigations. They are classified, according to the de- 



* Reprint of Bulletin No. 157. 



