208 FUNDAMENTALS OF FRUIT PRODUCTION 



blossom bud formation. It is generally conceded, however, that fruit 

 bud initiation is in a way a response to nutritive conditions within the 

 plant and it has been shown that these nutritive conditions are modified 

 by the nature of the soil solution. At least theoretically, then, it should 

 be possible to influence fruit bud formation through the use of fertilizers. 



In Peaches. — In a preceding paragraph Alderman- is quoted as report- 

 ing that in his fertilizer experiments with peaches in West Virginia the 

 application of nitrogen-carrying fertilizers resulted in more than double 

 the shoot growth and hence double the amount of possible fruit-bearing 

 surface. Data on fruit bud formation on these shoots are presented in 

 the last column of Table 67. If these figures for numbers of fruit buds 

 per unit of shoot length were plotted, the curve would take the same general 

 direction as one for figures on total shoot length, though the two would 

 not be exactly parallel. In commenting on these data Alderman^ says: 

 the ' ' table . . .shows during the first 3 years a uniformly high percentage 

 of fruit buds formed on the nitrogen-fed plots and a correspondingly low 

 percentage in plots 4, 5 and 9 (those receiving nothing, potash and 

 phosphoric acid or lime only). By 100 per cent, set of buds we mean that 

 practically all the new growth is filled with double buds from base to tip 

 . . . while a 50 per cent, set would indicate that buds were found over 

 only about one-half the twig and were single in many cases." 



In Apples. — The situation is somewhat more complicated in fruits 

 like the apple that bear mainly upon spurs. However, Roberts^^^ has 

 reported that there is a distinct correlation between the annual increase 

 in length of spurs and their blossom bud formation. Both those spurs 

 making a very short and those making a very long annual growth did 

 not form many fruit buds, but, on the other hand, those that made a 

 medium growth were highly fruitful. Length was in turn correlated 

 directly with number of leaves and total leaf area and within certain 

 hmits {i.e., for the shorter spurs) there was also a correlation between 

 spur length and average leaf area. Experiments on the influence of nitrog- 

 enous fertilizers on spur length are reported by Roberts^''^ as follows: "In 

 1918 the difference in spur growth of non-bearing Wealthy was as follows: 

 check trees 4.89 mm.; nitrate of soda 11.98. In 1919, when there 

 was a larger growth on checks than usual, less difference was also noted. 

 The figures for different trees than those used in 1918 are: check 7.41; 

 nitrate 9.25." In general the influence of the nitrate was to increase 

 the length of the spurs and consequently leaf numbers and total leaf 

 areas. In the trees with spurs too short for fruit bud formation the effect 

 would be to encourage that process; in those trees with spurs averaging 

 just long enough or a little too long for maximum fruit formation the effect 

 would be to discourage it. Roberts'^^ also points out certain correlations 

 between the amount of shoot growth and the number and character of 

 fruit spurs. This suggests a further indirect correlation between fertilizer 



