DETERMINING NEED OF CROSS-POLLINATION 395 



self-pollination, whereas the term self-sterile is employed if no 

 viable seeds are produced when self-pollination occurs. 



It can thus be seen that a variety may be both self-fruitful 

 and self-fertile, or self-fruitful and self-sterile. Sometimes 

 two varieties are found neither of which will fertilize the other. 

 These are called intersterile. 



When the above facts are known, it is apparent that if 

 certain self-unfruitful and intersterile varieties are planted in 

 large blocks, and in a section where there are no nearby or- 

 chards of other varieties, such varieties will bear practically 

 no fruit, even though they may bloom profusely. 



3. Determining Need of Cross-Pollination. 



(a) Apples. 



(6) Pears. 



(c) Plums. 



(d) Cherries. 



(e) Peaches and apricots. 



(/) Quinces. : 



(a) Apples, The following apple varieties appear to be 

 self-unfruitful in most states where studies have been made, 

 and should not be planted alone in solid blocks: 



Group I 



Akin 



Arkansas Black 



Arkansas (Mammoth Black 



Twig) 

 Cortland 

 Delicious 

 Golden Delicious 

 King David 

 Mcintosh 

 Northern Spy- 

 Ohio Nonpareil 

 Opalescent 

 Red June 

 Eed Spy 



Rhode Island Greening 



Roxbury Russet 

 Scarlet Pippin 

 Stark 

 Starking 



Stayman Winesap 

 Summer Rambo 

 Sweet Delicious 

 Tompkins King 

 Twenty Ounce 

 White Pearmain 

 Williams 

 Winesap 

 Winter Banana 

 Wolf River 

 Yellow Bellflower 



