DIRECTIONS FOR BLUEBERRY CULTURE. 15 



temporary stimulation of vegetative growth, is likely to cause serious 

 injury later. For those desiring to experiment with fertilizers the 

 following acid mixture is recommended, applied at the rate of 1,000 

 pounds per acre, or one-fifth of a pound per square yard : 



Pounds. 

 Acid phosphate (high grade, about 16 per cent available phos- 

 phoric acid) 600 



Sulphate of potash (50 per cent potash) 200 



Sulphate of ammonia (20 per cent nitrogen) 200 



(Muriate of potash may be substituted for sulphate of 

 potash.) 



This and similar acid mixtures have been used with success on 

 blueberry plants in both pot and field experiments, with no evidence 

 thus far of cumulative injurious effects. However, as no fertilizer 

 is required to make the swamp blueberry fruit abundantly and con- 

 tinuously in suitable peat and sand soils properly handled, the use 

 of fertilizers in commercial plantations is not at present advocated. 



The swamp blueberry does not require a yearly pruning. When 

 one of the stems of a bush becomes unproductive from injury or old 

 age it should, of course, be cut out. If a large part of a bush needs 

 removal it is better to cut all the stems to the ground and let the 

 plant send up new shoots, all of the same age, to form a wholly new 

 and symmetrical top. 



YIELD AND PROFITS. 



By proper manipulation in the greenhouse, seedling blueberry 

 plants can often be made to ripen a few berries in less than a year, 

 but they do not come into commercial bearing in field plantations 

 until they are 3 to 4 years old (Pis. XIV, XV, XVI), when the 

 plants are 1 to 3 feet high. They then increase slowly to full size 

 and full bearing. Wild bushes of the swamp blueberry live to great 

 age, often 50 to 100 years, still bearing heavily, and they often 

 attain a height of 6 to 8 feet when growing in full sunlight; still 

 more when shaded. Individual stems may remain productive for 

 10 to 25 years. When dead they are replaced by new and vigorous 

 shoots from the root. 



The field plantings resulting from the recent experiments in blue- 

 berry culture are too young to show the mature yield. Fortunately 

 however, there is, near Elkhart, Ind., a small blueberry planting of 

 mature age. The returns from this plantation set forward our 

 knowledge of yields by at least a decade. The plantation is about 

 2| acres in extent. It was started in 1889 in a natural blueberry 

 bog, which was first drained and then set with unselected wild-blue- 

 berry bushes. The plantation was profitable from the first, but 

 exact records of yield and receipts are available only for the years 

 1910 to 1915, when the plantation was 21 to 26 years old. The data 

 are shown in Table I. 



