REVIEWING THE CASE 



401 



least two varieties are interplanted when planting the orchard. 



Sweet, sour, and Duke cherry varieties vary as regards 

 their interfruitfulness. Varieties of these three groups will 

 intercross, but, as a rule, pollen of the Duke cherries does not 

 cause as satisfactory a set on either sweet or sour cherries as 

 pollen from varieties within their own groups. Pollen of sweet 

 cherries will cause satisfactory sets on sour cherries, but as a 

 rule the sweet cherries bloom too early to be satisfactory pollen- 

 izers for the sour. Sweet cherries will also fertilize the Dukes 

 satisfactorily if their blossoming periods overlap. Likewise, 

 pollen of the sour cherries will fertilize both the sweet and Duke 

 cherries if their blossoming periods coincide. For early-bloom- 

 ing Dukes, sweet cherries should be satisfactory pollenizers, 

 whereas sour cherries should be more satisfactory for the late- 

 blooming varieties. 



{e) Peaches and Apricots. With a few exceptions, all im* 

 portant peach varieties that have been studied have been found 

 to be self-fruitful. The variety J. H. Hale, however, has been 

 shown to be self-unfruitful and practically no crops are borne 

 unless pollen from other varieties is available (Fig. 159) . Like- 

 wise, the June Elberta appears to be self-unfruitful for all 

 practical purposes, and the Late Crawford is usually bene- 

 fited by cross-pollination. The pollen of almost any variety 

 w^hich blossoms at the same time as these varieties causes a 

 good set. 



All varieties of apricots tested, including Blenheim, Lewis, 

 Montgamet, Moorpark, Royal, and Tilton, appear to be suffi- 

 ciently self-fruitful to set commercial crops. 



(/) Quinces. Although very little evidence has been se- 

 cured relative to quince pollination, the data available indicate 

 that the varieties commonly grown such as Champion, Orange, 

 Meech, and Rea are sufficiently self-fruitful to set satisfactory 

 crops with their own pollen. 



4. Reviewing the Case. From the preceding discussions 

 of fruit pollination and fertilization, it can be seen that, with 

 the possible exceptions of sour cherries, quinces, some of the 



