FLORIDA STATE HORTICULTURAL SOCIETY 



these self- and close-pollinations are not 

 eftective in fruit setting. There is what 

 we may call an incompatibility in the 

 processes of fertilization which follow 

 pollination. Interplanting is hence neces-^ 

 sary to provide for the pollinations which 

 do result in fertilization. But there may 

 also be cross-incompatibilities : two well- 

 known varieties of sweet cherries, the 

 Bing and the Xapoleon. are reported to 

 be not only self-incompatible but cross- 

 incompatible as w^ell. 



It is to be noted that incompatibilities 

 are not to be determined by an examina- 

 tion of the fiower. or by any lalx)ratory 

 tests of the pollen, as pollen sterility in 

 intersexes may often be determined, but 

 only by the results of properly controlled 

 pollinations combined with the results ob- 

 tained in orchard plantings. 



It is now evident that manv varieties of 

 Apple. Pear, Cherry, Plum, Blackberry, 

 Almond, and Feijoa are self-incompatible 

 to some degree. Certain varieties of these 

 fruits, of which the Wealthy apple may be 

 mentioned, appear to be rather highly 

 self-compatible, but in many cases even 

 these varieties will produce larger yields 

 of better fruit when there is cross-ferti- 

 lization. 



During the past ten years, especially, 

 evidence has been accumulating as to what 

 varieties of our fruits are or are not self- 

 fruitful. The evidence is very often con- 

 flicting and this has been accepted by 

 most horticulturists as proof that "self- 

 sterility is not a constant factor in any 

 variety." It is said that "the same tree 

 may be self-sterile at one time and self- 

 fertile at another or the same variety may 

 be self-fertile in one localitv and self- 



sterile in another." Such behavior is 

 credited to important varieties as the 

 Kieffer and Bartlett pears and the Yellow 

 Xewton and Rhode Island Greening va- 

 rieties of apples. Xo doubt in many in- 

 stances other causes of unproductiveness 

 are wrongly attributed to self -incompati- 

 bility and also that cross-pollination may 

 have occurred where it was not expected. 

 It is not at all certain that the differences 

 in fruit production observed in these cases 

 were due to variations in the one factor 

 of self-fertilization. But unless experi- 

 ence shows that a clonal variety of these 

 much cultivated fruits is decidedly fruit- 

 ful, the safe course for the grower is to 

 interplant rather liberally. 



Perhaps an important advance in hor- 

 ticulture will be the combining of a high 

 degree of self-compatibility with high 

 quality of fruit and other desirable qual- 

 ities through further breeding of all of 

 the various fruit crops in which incompa- 

 tibilities are now marked. This would 

 allow solid block plantings with the ad- 

 vantages in orchard management that this 

 brings. It would make yields of fruits 

 less dependent upon insect pollination in 

 that the self- and close-pollinations would 

 be sufficient. 



But possibly the ultimate and most ideal 

 goal of the horticulturist is to develop 

 fruits like the X^avel Orange which ma- 

 ture fruit without any pollination ; the 

 problems of pollination and fertilization 

 are then entirely eliminated in the matter 

 of securing yields of fruit. 



It is to be emphasized that the abundant 

 yields of fruit by a new seedling or by 

 plants vegetatively propagated from it 

 when grown in trial orchards or nursery 



