194 REPORT OF STATE BOARD OF HORTICULTURE, 



POLLINATION IN ORCHARDS. 



By Prof. (t. W. Fi.etchkk. 



1. VARIOUS REASONS WHY Fl^OAVERS DO XOT SET. 



All observing fruitgrowers have seen trees which blossom full but do not 

 set a fair amount of fruit: many have found their orchards unprofitable for 

 this reason. It is a pi-actical point to know the causes of this loss and the 

 best way to prevent it. 



NOT ALL THE FLOWERS CAN SET FRUIT. 



In the first place, but a small percentage of the blossoms set fruit any- 

 way, even in the most favorable seasons and with the most productive varie- 

 ties. In blossoming time a Japanese plum tree is a mass of white, carrying 

 scores of flowers on a single branch: yet scarcely a dozen fruits may set on 

 that twig, and some of those must be removed or the ti^ee will overbear. In 

 the pollination work at Ithica in 1899, forty-seven hundred and twenty-five 

 untouched blossoms, including apples, pears, plums, and apricots, set but six 

 hundred and seventeen fruits. The blossoms counted were those on the tree 

 at large, and were used for comparison with the hand crosses. This is about 

 one fruit for every eight blossoms: yet most of the trees set what would be 

 called a good crop. All of these blossoms were apparently uninjured by the 

 winter, and the weather during the blossoming season was very favorable for 

 the setting of fruit. 



This normal failure in the setting of fruit blossoms may be due to a num- 

 ber of causes: as poorly nourished fruit buds, lack of pollination, or winter 

 injury to the pistils which cannot be seen with the eye alone. It is usually 

 a distinct advantage to the fruitgrower, as it saves thinning. If all plum 

 blossoms set fruit, the expense of thinning would be multiplied many times. 

 Only when the failure of fruit blossoms to set becomes general does the fruit- 

 grower feel the loss and call for an explanation. 



This wholesale failure in the setting of fruit is often called self-sterility. 

 Properly speaking, a self-sterile tree is one which is self-unfruitful; it must 

 have other varieties near it in order to bear well. But it appears that self- 

 sterility in orchard fruits is often confused with the unfruitfulness resulting 

 from other causes. It would, therefore, be well to clear away this confusion 

 at the outset, in order that the discussion of self-sterijity may be better un- 

 derstood. The influences which sometimes make trees unfruitful, which are 



