TREE PHYSIOLOGY 



217 



develop, other changes occur, and toward spring the ovary 

 enlarges and ovules are formed. By early spring all th« 

 flower parts are developed and simply await the opening of 

 the buds to expand into flowers. 



Pear. Differentiation in the pear usually starts about the 

 middle of July and proceeds much the same as in the apple. 

 The order of differentiation of the different fruit buds is like-- 

 wise quite similar to that of the apple. 



Peach. Most investigators report that the first noticeable 

 differentiation in the peach occurs in the latter part of July,. 



Plum and Cherry. The time of differentiation seems ta 

 vary somewhat with the different species of plums. Thus, 

 varieties of the Americana species differentiate about the first 

 week in July, those of the Japanese plums about the second 

 week in July, and one variety at least of the Hortulana 

 species, the Whitaker, a wild goose plum, showed no sign of 

 fruit-bud differentiation in Virginia until the first week in 

 September. Cherry buds seem to differentiate about the first 

 week in July. 



Quince. In Wisconsin, observations seemed to show that 

 the beginning of flower parts could first be seen in the quince 

 during late summer or early autumn. 



Summary and Conclusions Concerning Fruit-Bud Differen- 

 tiation. It can be seen that most fruit buds are formed nor- 

 mally quite early in the season. Thus it seems reasonable that 

 any treatments such as fertilization, pruning, and soil culture, 

 designed to influence tree growth and fruit-bud formation, 

 would be more effective if given in the spring and early 

 summer. 



It should also be kept in mind that the fruit buds are 

 formed the year preceding that in which the crop is borne. 



TREE PHYSIOLOGY AND NUTRITION 



Fruit trees as well as other plants grow, thrive, and are pro- 

 ductive when adequate amounts of water, mineral or soil foodsy 

 and air foods are available, provided that other environmental 



