Pollination in Orchards. 373 



Varieties Which Are Often Self-Sterile. 



Self-sterility is not a constant character with any variety, It is 

 influenced by the conditions under which the tree is grown, as are 

 the size, shape and color of the fruit. The adaptation of a variety 

 to soil and climate has much to do with its self-fertility, and if a 

 tree is poorly nourished it is more likely to be infertile with its own 

 pollen. No one can separate varieties of fruit into two definite classes, 

 the self-sterile and the self-fertile. Thus Bartlett and Kieffer are 

 often self-sterile, but there are orchards of both which are self-fertile. 

 The same may be said of many other varieties. The best that can 

 be done, therefore, is to give a list of those varieties which tend to 

 be more or less self-sterile and which it would be unsafe to plant 

 alone. 



Following is a conservative list of these risky varieties, drawn 

 both from experimental work and from the reports of over five 

 hundred fruit growers who have favored mo with their experience. 

 Pears: Angouleme (Duchess), Bartlett, Clapp, Idaho, Kieffer, 

 Kelis. Apples: Bellflower, Primate, Spitzenburg, Willow Twig, 

 Winesap. Plums: Coe Golden Drop, French Prune, Italian 

 Prune, Kelsey, Marianna, Minei-, Ogon, Peach, Satsuma, Wild 

 Goose, and, according to Waugh and Kerr, all other varieties of 

 native plums except Robinson. Peach: Susquehanna. Apricot: 

 White Nicholas. Cherries: Napoleon, Belle de Choisy, Reine 

 Hortense. Most of these varieties are self-fertile in some places, 

 but the weight of evidence shows them to be uncertain. 



It must not be inferred that all other varieties are always able to 

 set fruit when planted alone. Tliere are some, however, which 

 have exceptionally good records for fruitfulness when planted in 

 solid blocks, other conditions being favorable. Among these are : 

 Apples: Baldwin, Ben Davis, Fallawater, Janet, Oldenburg, 

 Rhode Island Greening, Red Astrachan, Smith Cider. Plums: 

 Burbank, Bradshaw, DeSoto, Green Gage, Lombard, Robinson and 

 some of the common blue Damsons. 



All this goes to show that the problem of self -sterility is as much 

 a study of conditions as of varieties. We can set no limits ; we can 

 only indicate tendencies. 



