THE THINNING OF FRUIT 111 



nently injured as a result or may at least require several 

 years again to bear fruit in quantity. This difficulty may be 

 obviated by nature through a lack of setting of the blossoms 

 and indeed this is connnon, notably with peach trees just 

 reaching the bearing age. However, when a natural abscis- 

 sion does not take place, it is desirable to thin the fruit. 



It would probably be difficult to cite a season when the 

 above principle was so evident as after the winter of 1917- 

 18. Winter-injury was common throughout the northern 

 poi-tions of the country and the testimony of a vast number 

 of growers was that the trees that bore heavily in 1917 

 suffered the greatest injury from the following winter and 

 many were killed outright. Hence not only young but also 

 mature trees may have their vigor maintained by judicious 

 and sj^stematic thinning. 



99. Thinning to secure more regular bearing applies 

 more particularly to the poach than to the other tree-fruits. 

 In experiments with mature apple trees, the results have 

 usually been negative. This is explained on the grounds that 

 the fruit-ljuds have started to differentiate as such before the 

 thinning and hence it can have no effect. Writers have, 

 however, often urged that annual bearing was one of the 

 greatest advantages to l)e gained by thinning. This seems 

 most reasonable, and the teachings of plant physiology 

 woukl give it some support. Just why the peach should be so 

 responsive in this direction and the apple be unaffected is not 

 clear unless it is due to a longer period of fruit-bud formation 

 and type of bearing. 



Walker reports as follows in regard to the peach: ^ ''The 

 trees on which the first lot (which had been thinned) grew 

 had a strong set of fruit buds for the next season's crop; the 

 trees on which the second lot (unthinned) grew were scarcely 

 able to live." 



1 Walker, E. Ark. Agr. Exp. Sta. Bull. 79. 1903. 



