286 Plums and Plum Culture 



planted on the assumption that they will require cross- 

 pollination. 



Choosing varieties for pollination. — The only re- 

 maining question is what varieties shall be chosen for 

 mutual cross-fertilization. This involves several con- 

 siderations. Investigation of the subject shows that 

 this mixing of varieties should not be made carelessly. 

 Some varieties will pollinate each other, while some 

 will not. The selection of varieties for proper cross- 

 pollination should be controlled by certain general 

 principles. The most important matters to be con- 

 sidered in selecting a pollenizer for a given variety 

 seem to be the following four: (a) Blossoming season, 

 (b) mutual affinity, (c) amount of pollen borne, (d) 

 value of the pollenizer as a fruit-bearer. 



The first requirement is absolute. If two varieties 

 do not blossom at the same time they cannot pollinate 

 one another. The second one is very important in 

 some cases. The third is apparently less often of 

 practical consequence. The fourth consideration is 

 not a matter of pollination properly, but is often of 

 more practical importance to the fruit grower than 

 some of the others. 



Blossoming seasons. — The most important require- 

 ment, in order that two varieties shall pollinate each 

 other, is that they blossom at the same time. It if 

 therefore necessary to have a somewhat extensive 

 knowledge of the blossoming seasons of plums. Along 

 with other investigations, I have collected a consider- 

 able mass of data relative to this question. The best 

 way to make this available seems to be to tabulate it 

 in some such manner as that shown in the following 

 ■'blossoming chart," republished from the eleventh an- 

 nual report of the Vermont Experiment station. In 

 this chart the first column gives the names of the varie- 

 ties in the order of their blossoming. The second col- 



