2 BULLETIN" 914, TJ. S. DEPAETMENT OF AGEICULTUEE. 



hybrids have fruited and four of them have been selected and ap- 

 proved as worthy of introduction into agriculture. Propagation 

 material from these four hybrids has been placed in the hands of 

 nurserymen for commercial propagation. 



Miss T^Hiite has also brought together at Whitesbog a very remark- 

 able collection of selected wild blueberry plants. Several of thes-e 

 have been used as breeding stocks in the blueberry development 

 work carried on by the department. 



In the present bulletin are included such results of the experiments 

 and experience at W'^shington, Whitesbog, and other points as con- 

 stitute a brief practical guide for persons desiring to take up blue- 

 berry culture. 



SPECIAL REQUIREMENTS. 



Success in blueberry culture rests especially on the recognition of 

 two peculiarities in the nutrition of these plants: (1) Their require- 

 ment of an acid soil; (2) their possession of a root fungus that ap- 

 pears to have the beneficial function of supplying them with nitrogen. 



If blueberries are planted in a soil with an alkaline or neutral 

 reaction, such as the ordinary rich garden or fertile field, it is use- 

 less to expect their successful growth. In such a situation they 

 become feeble and finally die. Blueberries require an acid soil, and 

 they thrive best in that particular type of acid soil which con- 

 sists of a mixture of sand and peat.^ (PI. I.) 



Good aeration of the soil is another essential. It is commonly 

 but erroneously supposed that the highbush or swamp blueberry 

 {VacciniuTTb coryTribosum) ^ the species chiefly desirable for culti- 

 vation, grows best in a permanently wet soil. It is to be observed, 

 however, that the wild plants of the swamps occupy situations 

 which, though perhaps submerged in winter and spring, are exposed 

 to the air during the root-forming period of summer and autumn; 

 or, when growing in permanently submerged places, they stand on 

 a hummock or in a cushion of moss which rises above the summer 

 water level and within which the feeding roots of the bush are 

 closely interlaced. In actual culture, moreover, it has been found 

 that the swamp blueberry does not thrive in a permanently wet 

 or soggy soil. 



Although some species of Vaccinium, such as the common low- 

 bush blueberry of the northeastern United States, Vaccinium angus- 

 tifolium (called V. 'pennsylvanicum by some authors), grow and 



^ The degree of soil acidity best suited to blueberries is about specific acidity 100, cor- 

 responding to a hydrogen ion concentration, Ph=5. See a paper by Edgar T. Wherry, 

 " Soil Acidity and a Field Method for Its Measurement," published in the technical 

 journal Ecology, vol. 1, pp. 160 to 173, July, 1920, with a colored plate. The same 

 subject is treated more fully by Dr. Wherry in the general appendix to the Smithsonian 

 Eeport for 1920, also with a colored plate, under the title " Soil Acidity — Its Nature, 

 Measurement, and Eelation to Plant Distribution." 



