458 FUNDAMENTALS OF FRUIT PRODUCTION 



springing from terminal buds on other short growths, or spurs. Indi- 

 vidual spurs are wont to bear only every other year, though annual 

 bearing spurs are not rare and are common in trees of certain varieties. 

 More frequently, however, individual spurs fail to produce even every 

 other year, bearing perhaps only once in 3 or 4 years, or very irregularly. 

 These spurs may live many years and there is nothing in their manner of 

 growth to necessitate a deterioration in efficiency as they grow older. In 

 reality, however, they flower and, more particularly, set and mature 

 fruit, much less regularly as they increase in age.^^ Without doubt this is 

 due to unfavorable nutritive conditions induced by crowding and compe- 

 tition with other parts of the tree for food, moisture and light. Records 

 show, nevertheless, that even very old spurs may bear good fruits and that 

 when strong and vigorous they are more efficient fruit producers than 

 those that are much younger but lacking in vigor. ^^ Roberts^" has 

 reported a marked correlation between the vigor of spurs, as measured 

 by the length of each year's growth and by the number and area of their 

 leaves and performance in flower-bud formation. Spurs of medium 

 length with relatively large leaf areas and consequently with the means 

 of accumulating reserves of elaborated foods are more likely to form 

 fruit-buds. 



Heavy annual production, then, would seem among other things 

 to depend on (1) the formation of an adequate supply of fruit spurs, 

 (2) the retention of those already formed and (3) maintaining all of 

 them in a vigorous condition so that they may flower and fruit regularly. 

 These requirements plainly cannot be met or supplied by any single 

 pruning practice or by any combination of pruning practices. They 

 depend on many factors, chief among which are nutritive conditions 

 within the plant, which, in turn, are influenced most readily by ferti- 

 Uzers and various systems of soil management. Pruning, however, 

 is important in this connection. 



The Formation of Fruit Spurs. — As pointed out elsewhere, maximum 

 fruit-spur formation is encouraged by leaving the trees unpruned or by 

 pruning them very lightly. Such treatment or lack of treatment leaves 

 the largest possible number of buds from which spm-s may develop; 

 consequently an approach to this treatment is recommended to induce 

 bearing in a short time. Formerly the artificial bending of long shoots 

 was quite generally recommended to make them more fruitful through 

 the formation of fruit spurs. However, recent investigation indicates 

 that this practice is of doubtful value and certainly is not to be recom- 

 mended under average field conditions. ^^ Experimental work at the 

 Oregon Station has shown that when certain shoots are selected for 

 removal in young apple trees, new fruit-spur formation is favored by 

 leaving those that are vigorous and comparatively upright. ^^ As the 

 trees become older and possess fruit spurs in numbers sufficient to pro- 



