8 MASS. EXPERIMENT STATION BULLETIN 317 



little more may be used. If the fertilizer is mixed with about three times its 

 weight of dry sand before being applied, it is less likely to cause injury. 



The third year and thereafter the fertilizer can be broadcast between the rows 

 and the amount gradually increased until five to six hundred pounds to the acre 

 are used when the bushes begin to bear. This heavy fertilization of the bearing 

 bushes is recommended because long, vigorous shoots are necessary for the 

 production of the largest and best berries and because very vigorous growth 

 is needed to replace the large amount of wood removed in pruning. 

 The following mixture is recommended: 



Nitrate of soda 640 pounds 



Concentrated tankage 640 pounds 



Superphosphate 300 pounds 



Sulfate of potash 420 pounds 



This mixture should be applied in the spring when the bushes start to grow. 

 A thorough cultivation after the fertilizer has been applied is beneficial. 



Pruning 



Pruning is one of the most important operations in the growing of blueberries. 

 The purpose of pruning is to produce as many good vigorous shoots as possible 

 in the top of the bush, to keep vigorous new shoots growing from the base of the 

 plant, to prevent the bush from overbearing, and to stimulate the production of 

 large berries. It must be done in the winter or early spring before growth starts. 



The bushes need little or no pruning the first two years in the plantation. 

 Only the short, weak branches need be removed. The bushes should not be 

 allowed to bear during this period because this will greatly reduce growth and 

 delay the production of a commercial crop. Therefore the fruit buds are re- 

 moved during the pruning operations. If any are missed, the flowers may be 

 pruned off when the bushes come into bloom. 



To prune bearing bushes correctly, one must know their bearing habit. The 

 fruit buds are produced on the terminal portion of the shoots. They are formed 

 in the axils of leaves during the summer, remain dormant during the winter, 

 then bloom and produce fruit the following summer. Fig. 3 shows at (a) the 

 terminals with their fruit buds. Fig. 5 shows shoots with their fruit buds (a) 

 and leaf buds (b). 



The pruning treatments given to the different varieties vary according to the 

 character of their growth. Varieties producing many shoots from the base 

 require more thinning out of this growth than those which grow few such shoots. 

 Varieties which branch freely need more thinning out in the top than those 

 which do not. Varieties with fruit buds on the terminal two-third's or three- 

 fourths of the shoots require more cutting back than those with fruit buds on 

 only the terminal third or fourth of the shoots. Therefore, the following outline 

 of pruning practice is given as a general guide and not as a set of rules. 



First, remove or cut back a few of the older branches such as (b) in Fig 3. 

 These branches when they are three or four years old tend to produce many 

 short, weak shoots which yield small berries. 



Second, remove all branches which are so near the ground that the fruit 

 would get dirty. 



Third, remove the shorter, weaker shoots to prevent crowding of the branches. 



Fourth, cut back shoots with too many fruit buds. Three or four such buds 



