Flower and Fruit Thinning 241 



easily set parthenocarpic fruit in response to auxin sprays can be 

 thinned in this way. 



These treatments provide several advantages to the pomologist. 

 They can be used to remove excess truits several weeks after full 

 bloom whereas most other chemical thinning agents can be used only 

 at full bloom. This permits the grower to wait until the major threat 

 of late frost has passed, and also to wait until the time that he can 

 estimate the extent of loss due to natural fruit drop. The sprays offer 

 the advantage of great saving in labor and permit much more accurate 

 timing than hand thinning will permit. Such sprays can effectively 

 break the biennial bearing habit and greatly increase the quality of 

 the fruit harvested. 



It is evident that fruit thinning with auxin sprays is not at all 

 precise and small differences in the vigor of the tree will be largely 

 reflected in the amount of thinning obtained. Therefore it is very 

 difficult to predict how much thinning a given spray will bring about. 

 Nevertheless, the growers find this treatment a useful one for biennial 

 bearers, for even if excessive thinning does result, a larger crop can be 

 expected the following year; and when insufficient thinning is ob- 

 tained, the grower still reaps a higher quality crop and can expect a 

 small, high quality crop in the off-year as well. 



