THE POLLINATION OF ORCHAED FRUITS. 75 



be self-fertile, although some were shown to be self-sterile. A 

 great deal of work has been done in determining the character- 

 istics of varieties in this regard. It is now possible to find in 

 various books and bulletins more or less complete lists of the 

 varieties of plums, pears, apples, grapes and other fruits in com- 

 mon cultivation classified according to their self-fertility or self- 

 sterility. I will not stop to present such lists here. It will be suf- 

 ficient for the present to say simply that it has been found that 

 plums are very largely self-sterile, cases of self-fertility being 

 altogether rare; that a majority of pears tested show more or less 

 self-sterility, and that the same is true of apples. Perhaps a quar- 

 ter of the apples in common cultivation are totally self- sterile, 

 another quarter are practically self-sterile and a third quarter need 

 cross-pollination for the best results. 



There has been some objection made to this summary way of 

 classifying varieties according to their self-sterility or self-fertility. 

 It has been said by the critics that these qualities do not belong 

 specifically to the varieties, but rest upon many external and more 

 or less incidental conditions. Self-fertility, these critics say, varies 

 with the season, climate, locality, age and vigor of the tree, etc. 

 While there is undoubtedly some truth in this view, it may be well 

 to notice that for the present it rests almost purely on speculative 

 reasoning. Nobody has made a satisfactory experiment to prove 

 any of these supposed variations, and for the present these criti- 

 cisms, though very interesting, may safely be discarded. At any 

 rate, the question is of small practical importance, as we shall see 

 further along. 



THE REMEDY MIXED PLANTING. 



The remedy for all this unfruitfulness has already been named, 

 viz.: the mixing of varieties either by planting several together 

 or by grafting two or more into one tree. This is such a sim- 

 ple and easy matter, and the risks of self-fertility are so great, that 

 it seems an altogether unjustifiable practice now to plant large 

 blocks of apples, pears or plums of any single variety. There are, 

 indeed, to be found many orchards of solid blocks of certain varie- 

 ties through the country which bear fairly well or even abundantly, 

 but they are exceptions. Solid planting is always risky, and there 

 are enough risks in the fruit business without taking any gratu- 

 itous ones. 



It has been objected by a few extensive fruit growers that mixed 

 planting is really troublesome. They say it is easier to handle a 



