376 Bulletin 181. 



tils of the self-sterile variety readily and also develop them into high 

 grade fruit? At present but little is known about this matter. 

 Taking iirst the possibility of cross-pollination between varieties of 

 different species, there seems to be no doubt but that many varieties 

 of native, Japanese and domestic plums will fertilize each other. 

 Orchard experience in many places indicate this ; as when Satsuma 

 is used to j^ollinate Coe Golden Drop in California prune orchards. 

 Several successful crosses between the three were also made at 

 Ithaca the past season. Among these are Abundance X Grand 

 Duke (Fig. 84), Georgeson x Wayland, Berckmans x Coe Golden 

 Drop, Coe Golden Drop X Satsuma. That is, if w^e wish to use 

 Satsuma as a pollinizer for Coe Golden Drop, or Lombard for Wild 

 Goose, the probability is that the combination would w^ork, if the 

 two varieties bloom together ; but since the three groups usually 

 bloom at somewhat different periods there can be no general cross- 

 pollination outside the limits of the species. 



Numerous crosses and common orchard practice have also shown 

 that the European pears, as Bartlett, and the Sand pear hybrids, as 

 Kieffer, will fertilize each other regularly when they bloom together. 

 Several Kieffer fruits from Bartlett pollen and Bartlett fruits from 

 Kieffer pollen w^ere secured in the crossing work of 1899. In fact, 

 my experience has been that if Kieffer pollen is put on the pistils 

 of our common pears, of the European class, it will usually produce 

 larger fruit than pollen from most varieties of that type. Kieffer 

 is a good pollinizer for Bartlett, Angouleme, Clapp, Nelis and like 

 varieties, w^hen they bloom together. In Fig. 81, compare the size 

 of the Seckels which received Kieffer pollen with those which had 

 Lawrence pollen. The specimens shown are typical of thirty fruits 

 secured from these two crosses in 1899. 



It is necessary to study not only the mutual affinity of varieties 

 belonging to different species, but also of varieties of the same 

 species. Some varieties will not fertilize each other, though blos- 

 soming at the same time. Kerr has found that Whitaker plum will 

 not fertilize Wild Goose nor will Early Bed lielp Caddo Chief. 

 Again, the pollen of some varieties will give better fruit than that 

 of others when used on the pistils of self -sterile or even on self- 

 fertile varieties. Tliere is very little definite knowledge as to what 



