FRUIT SETTING AS AN ORCHARD PROBLEM 545 



found all that he tested self fertile but reported some increase in size 

 of fruit resulting from cross pollination. In North Carolina 11 out of 

 15 varieties of dewberries were found self barren and 12 out of 16 varieties 

 of blackberries self fruitful. The varieties of Ruhus villosus generally 

 were self fruitful, those of R. trivialis self barren. There was no increase 

 in size of fruit from cross pollination in those varieties maturing fruit 

 when selfed. The Vineland (Ontario) Horticultural Experiment Sta- 

 tion* ^^ has reported that a number of the seedlings of the raspberry which 

 they have obtained in their breeding work are self sterile. Others are 

 self fruitful or partly so. A number of the blackberry-dewberry hybrid 

 varieties are partly or wholly self barren. 



The Nuts. — Data are not available on the degree of self fruitfulness 

 characteristic of different varieties of the walnut, pecan, hickory, chest- 

 nut and filbert. All are monoecious and a large majority are characterized 

 by partial dichogamy. In some the dichogamy is almost complete, 

 rendering the tree or variety self unfruitful to a marked degree. To 

 what extent, if at all, individual trees or varieties are self unfruitful because 

 of incompatibility is not known. On account of the partial dichogamy 

 that is generally found it is always a good plan to interplant two or more 

 varieties having approximately the same blossoming seasons. 



Persimmon. — The kaki, or Japanese persimmon, includes varieties 

 bearing pistillate flowers only and those bearing both pistillate and stami- 

 nate flowers. Of the varieties in the latter class some bear staminate 

 flowers regularly, others bear them sporadically. The names pistillate 

 constants, staminate constants and staminate sporadics have been applied 

 to these several groups. 



Some varieties set fruit freely without pollination and they mature 

 seedless fruits. Others require pollination and their fruits usually con- 

 tain one or more seeds. Apparently pollination is not so essential to the 

 securing of a good persimmon crop in California as in Florida. ^^ 



The differences in the size, shape, color, flavor and season of maturity 

 of seed-bearing and seedless persimmons have been discussed previously. 



There is reason to believe that most pistillate flowers of the native 

 American persimmon (Diospyros virginiana) require pollination from 

 staminate trees of the same species in order to set and mature a good crop. 

 The Japanese and American varieties of persimmon are not interfruitful.^^ 



Summary. — In the absence of definite knowledge that the variety 

 being planted is self fruitful under local conditions provision should 

 always be made for cross pollination. Even when varieties are self 

 fruitful the increase in size often obtained as a result of cross pollination 

 warrants the use of other pollenizers. In most tree fruits one of the 

 pollenizing variety is sufficient for 8 or 10 trees of the leading sort. 

 Top grafting and the use of flowering branches of other varieties at the 

 blossoming season are the most satisfactory methods of providing for 



