APPENDIX. 201 



have done careful work alonu- this line. Among these are Goff, Waugh, 

 ("raig, Kerr. Crandall, and Heideman, on orchard fruits: Beach, Earle. 

 T. V. Munson, Whitten, and Green on grapes. The California and Oregon 

 .state boards of horticulture are also making a special inquiry on the self- 

 .sterility of prunes. 



VARIKTIES WHICH ARE OFTEN SELF-STERILE. 



Self-Sterility is not a constant character with any variety. It is influenced 

 hy the conditions undei' which the tree is grown, as are the size, shape, and 

 <-olor of the fruit. The ada])tion 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 classe.s. the self-sterile and the self-fertile. Thus, Bartlett 

 and Kieflfer 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 live hundred fruitgrowers 

 who have favored me with their experience. Pears: Angouleme (Duchess)* 

 Bartlett, Clapp. Idaho, Kietfer. Nelis. Apples : Bellefleur, Primate, Spitzen- 

 berg. Willow Twig, Winesap. Plums: Coe (iolden Drop. French prune, 

 Italian prune, Kelsey. Marianna. Miner. Ogon, Peach, Satsuma, Wild Goose, 

 and according to Waugh and Kerr, all other varieties of native plums except 

 llobinson. Peach: Susquehanna. Apricot: White Nicholas. Cherries: 

 Napoleon, Belle de Choisy, Heine Hortense. Most of these varieties are 

 .self-fertile in some places, but the weight of evidence shows them to be 

 imcertain. 



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

 when planted alone. Thei-e are some, however, which have exceptionally 

 good records for fruitfulness when planted in solid blocks, other conditions 

 l^ing favorable. Among these are. Apples : Baldwin, Ben Davis, Fallawater, 

 Janet, Oldenburg. Rhode Island Greening. Red Astrachan. Smith Cider. 

 Plums : Burbank, Bradshaw. De Soto, 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. 



The great and growing Kieflfer pear industry in the Eastern United States 

 warrants a fuller discusion of this variety. Many large blocks of Kieflfer 

 are being planted with no other varieties intermingled, and it is an impor- 

 tant point to know whether this practice will give the best results. Eight 

 blocks of Kieflfer in New .Tersey and Deleware have been reported as com- 

 pletely or partially unfruitful because of self-sterility, and there are also 

 many solid blocks of Kieffer in the same states -which bear well, Kieffer is 

 unreliable, especially on the Delaware peninsula. A large block of Kieffer 

 may be productive, but it does not pay to take the risk, particularly since 



