542 FUNDAMENTALS OF FRUIT PRODUCTION 



self fruitful in certain localities in California. ^^"^ It has been found 

 that most sparingly self fruitful pear varieties generally mature fruits 

 with few or no good seeds and that these fruits are distinctly inferior 

 in size to those of seed-bearing fruits of the same varieties resulting 

 from cross pollination. Pears generally should be so planted as to 

 secure the benefits from crossing. 



So far as known the more common pear varieties are interfruitful 

 and one variety is as good as another in cross polhnation if it blossoms 

 at the right period. 



Parthenocarpy is not uncommon in pears but none of the varieties 

 of commercial importance in America is parthenocarpic regularly. 



Quince. — Circumstantial evidence points clearly to the conclusion 

 that the commonly cultivated varieties of the quince are self fruitful. 

 This is supported by the results of investigations of Dorsey in New York 

 (data unpublished). 



Peach. — Experimental work with the peach at the Missouri/^^ 

 Delaware, ^^ and Virginia^^ Stations indicates that practically all the 

 commonly grown varieties are self fruitful. Furthermore there is no 

 evidence of any gain in size of fruit from cross pollination. The grower 

 is safe, therefore, in planting entire orchards to a single variety. 



Almond. — The work of Tufts ^^g ^^s shown that all almond varieties 

 that were tested are generally self sterile under California conditions, 

 though in occasional seasons certain varieties will set a fairly good crop 

 with their own pollen. This self unfruitfulness is due to incompatibility 

 rather than to imperfect pollen, for the pollen proves satisfactory on the 

 pistils of certain other varieties. Certain varieties were found also to be 

 interbarren; I.X.L. and Nonpareil will set practically no fruit when 

 interplanted and the same is true for plantings of Languedoc and Texas. 

 Plum. — Plum varieties vary greatly in their abilities to mature fruit 

 without the aid of cross pollination. Waugh^^^' ^^^> ^^'^> i" reported 

 practically all the commonly cultivated varieties of the Japanese and 

 American species to be self sterile; this -has been confirmed by the inves- 

 igations of others.^^' ®^' ®*' ^^' ^^^ On the other hand, a considerable 

 number of European varieties, including Giant, Green Gage, Italian, 

 French and Blue Damson have been found partly or completely self 

 fruitful in Oregon, ^^ and Sutton^^^ reported 18 out of 39 varieties to be 

 fully self fruitful and five more partly self fruitful in England. 



Hendrickson^^ and MarshalP^ reported all Japanese varieties tested 

 as interfruitful and Waugh^^^ found both Japanese and American varieties 

 generally interfertile. Some exceptions, however, have been recorded. 

 Thus Whitaker and Milton, both seedlings of Wildgoose, are interbarren 

 and, curiously enough, both are fertile with Sophie; however, Sophie 

 used as the pistil parent is fertile with neither. ^^^ Dorsey" obtained 

 only eight mature fruits from 1327 flowers of the Compass pollinated 



