374 Bulletin 181. 



The great and growing Kieffer pear industry in the eastern 

 United States warrants a fuller discussion of this variety. Many 

 large blocks of Kielier are being planted with no other varieties 

 intermingled, and it is an important point to know whether this 

 practice will give the best results. Eight blocks of Kieffer in New 

 Jersey and Delaware have been reported as completely or partially 

 unfruitful because of self-sterility, and there are also many solid 

 blocks of Kieffers 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, par- 

 ticularly since the pollen of other varieties is likely to give better 

 fruit, as will be seen later on. 



Selecting the Pollinizee. 



Let us suppose that we intend to plant a large block of an uncer- 

 tain variety, as Kieffer, because it has distinct merit as a market 

 sort. We wish to plant it with some other variety to make it fi'uit- 

 ful. There are two points to be considered when selecting a polli- 

 nizer for Kieffer or for any other self-sterile variety ; the choice 

 should not be indiscriminate. These are simultaneous blooming and 

 mutual affinity. 



The first and most important point is that the two shall blossom 

 together, since the only way in which a pollinizer can make a self- 

 sterile variety fruitful is by supplying it with pollen. This means 

 that the pistils of the self-sterile variety must be receptive when the 

 stamens of the pollinizer are ripe, which is possible only with simul- 

 taneous blooming. 



The comparative blooming of varieties is more or less a local 

 problem. Differences of latitude, altitude, soil, nearness to large 

 bodies of water, and weather conditions during the blooming season 

 not only hasten or retard the time of blooming but also disturb the 

 order in which the different varieties open. Varieties blossoming 

 together at one place may not at another. The best that can be 

 done in the way of generalizing on the question of simultaneous 

 blooming for cross-pollination is to make a chart for each well 

 marked geographical district. To this end several hundred fruit- 

 growers have kindly taken notes the past two seasons, and when 



