io6 Bulletin 393 



Effect 0} slow and of rapid drying of leaves on detached spurs with 

 uncoated fruit and on detached spurs with vaseline-coated fruit. — Spurs with 

 leaves and fruits were taken from the orchard and put in the laboratory. 

 About half of the fruits were coated with vaseline, while the others were 

 left untreated. Some spurs with the fruits coated and some with 

 uncoated fruits were exposed in the laboratory with the cut ends in 

 water; others of each lot were exposed in the same place but without hav- 

 ing access to water. 



After eight days the leaves on the spurs with their cut ends in water 

 were green and turgid. The vaseline-coated fruits had all fallen from 

 these spurs, while the uncoated fruits remained attached. In both cases 

 the fruits were fully turgid. The leaves on spurs not having access to 

 water v/ere dried up and the fruits were shriveled, but both the vaseline- 

 coated and the normal fruits remained attached. 



Effect of a saturated and of a dry atmosphere on abscission of fruit on 



detached spurs 



A number of spurs with leaves and fruits were brought into the labora- 

 tory and placed in a heavy paper sack, after which they were thoroly 

 moistened by immersing them in water and then allowing the water to drain 

 off thru perforations in the bag. They were given the same treatment every 

 day for a week. Another lot of spurs was obtained at the same time, but 

 they were accidentally overlooked when the others were moistened. 

 At the end of the week, the spurs in the bag that had been moistened 

 every day had lost all their fruit; the leaves were turgid and green, and 

 remained attached to the spurs. The spurs that had not been moistened 

 had lost all their leaves, which were yellow and crisp, but the fruit re- 

 mained attached to the spur. The fruits in the himiid atmosphere of the 

 moistened bag remained firm, while those in the dry bag had shriveled. 

 Similar observations were subsequently made. 



SUMMARY 



The facts and observations contained in the foregoing pages may be 

 summarized as follows: 



1. From two-fifths to four-fifths of the total number of flowers are 

 lost during the early drop. 



2. In some varieties practically all flower-bearing spurs set fruit after 

 the first drop ; in others almost half of the spurs fail to develop fruits. 



3. The proportion of spurs that set fruit after the first drop varies 

 considerably on different trees of the same variety and on different lim.bs 

 of the same tree. 



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