576 STATE BOARD OF AGRICULTURE. 



fruitfuluess but at the expense of losing a considerable part of the fruit- 

 producing area in the tree. To maintain fruitfuluess by this method, 

 such severe pruning must be repeated each successive year which, of 

 course, would hardly be feasible. This explains the results often at- 

 tained in orchards tliat have been neglected, where the owner or renter 

 severely pruned such trees and by careful spraying obtained fair crops 

 for a season or two. 



Many of the orchards on the farms in this State are in the condition 

 of Group 2. Such trees usually produce an abundance of fruit spurs, 

 which, while not vigorous, are sufficiently so to produce weak fruit buds 

 usually in alternate years. A heavy bloom occurs usually biennially 

 but a very small percentage of the spurs set fruit except witli very favor- 

 able weather conditions prevailing at the flowering time and for the first 

 few weeks after flowering. When such trees fail to set fruit after heavy 

 flowering, unfavorable weather conditions, a lack of pollenizing insects, 

 infertility of the variety, insects and diseases, are a few of the most com- 

 mon reasons given for such failures in fruit setting. A most potent 

 factor, however, is a lack of vitalitj^ in the fruit spur to properl}- stimu- 

 late and nourish the setting and development of the fruit. After the 

 production of a fair crop, such trees require the following season or two 

 to recuperate and store up sufticient food for another good crop and are 

 thus referred to as biennial bearers; that is, bearing crops every other 

 year except when weather conditions interfere. 



The most productive apple orchards in the State belong to the third 

 group. The spurs produced are strong and vigorous, indicating an ade- 

 quate stored supply of food, a large conducting tissue in the spur for 

 supplying sap to the young growing fruit, and large, plump, vigorous 

 fruit buds. (See Fig. 11.) The leaves produced on such spurs are large 

 and dark-colored and tlie fruits are also of good size. Generally trees 

 producing a large percentage of such spurs are quite annual in their pro- 

 ducing habit. This may be explained by the fact that there is sufticient 

 plant food to nourish the spurs developing fruit and also to induce a 

 vigorous, new spur-growth for fruit production the following year. The 

 plant food supply is not all required to mature the crop but much is left 

 for new fruit spur development. Where a tree is under-nourished, such 

 new spur development is restricted the season a crop is being matured. 



AVhile weather conditions will always be an important factor in fruit 

 setting, it is important to know that flowers on strong spurs are more 

 apt to set fruit than those upon weak spurs. Tliis is due to the fact that 

 in weak spurs the stimulating and drawing effect of numerous seeds, 

 the formation of which requires favorable weather conditions during 

 the flowering period, seems to be necessary to supplement the natural 

 forces in attracting enough moisture and plant food to the young fruit; 

 but in strong fruit spurs the young fruits seem to obtain a sufticient 

 supply of food without this supplementing effect of numerous seeds.* 



Wlnle one cannot exercise the control over weather conditions to in- 

 sure thorough pollination at the flowering time for seed development, 

 it is possible to exert much influence over the vigor of the fruit spur 

 and thus tend to insure crops even during seasons when weather condi- 

 tions are not most favorable. This was one of the most important fac- 

 tors in determining the size of the apple crops in southern Michigan 



♦Dr. Heinicke'8 Bulletin, Cornell 393. 



