182 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 



BLUEBERRIES. 



Distinct procuress has been made in the breeding of superior varie- 

 ties of bkieberries. About 25,000 hybrids have now been fruited in the 

 testing plantation at Whitesbog, 4 miles east of Browns Mills, N. J. 

 -Many of them have produced berries three-fourths of an inch in diam- 

 eter, several four-fifths of an inch, and one of them this year reached 

 almost seven-eighths of an inch. Among these large-berried hybrids 

 several have been selected for propagation. The progress of blue- 

 berry culture is evidenced by the fact that during the season of 1922 

 nearly a thousand bushels of blueberries were picked at Whitesbog 

 and that these sold in the open market in New York at prices about 

 75 per cent higher than those of wild blueberries. In the fall of 

 1921 more than 250,000 cuttings of selected blueberries were made 

 by nurserymen. 



AVOCADOS. 



It is becoming more and more evident that the future of avocado 

 growing in the United States depends in large measure upon secur- 

 ing good commercial varieties which are more frost resistant than 

 most of those now cultivated in California and Florida, One of the 

 most promising methods of producing such varieties is by plant 

 breeding; another is the introduction of the hardiest commercial 

 sorts from high elevations in tropical America. The bureau has 

 lately introduced from the mountains of Ecuador several choice 

 varieties of the Mexican avocados which seem likely to prove of real 

 value. In addition, every effort is being made to aid plant breeders 

 engaged in developing new forms through hybridization by supply- 

 ing them with other material of this nature, including the hardy 

 wild relatrv-es of the avocado and superior varieties of the Guatemalan 

 race which may be utilized in crossing with hardy forms of the Mexi- 

 can to produce forms combining hardiness with good commercial 

 characteristics. 



NURSERY INVESTIGATIONS. 



In view of the fact that this country has been so dependent upon 

 foreign sources for many of its fruit stocks, an attempt has been 

 made to find out whether American sources of seed and American- 

 grown stocks may not be produced which will have all the merits of 

 the imported stocks. Furthermore, the fact has been impressing itself 

 more and more that the wide seedling variation in the stocks that 

 were in general use must have a very much greater influence on the 

 merits of the trees propagated on them than has been supposed. 

 The desirability of vegetative propagation of the better stocks is 

 therefore assuming much importance. 



APPLE-STOCK EXPERIMENTS. 



In comparing the development of American-grown and foreign- 

 ^rown apple seedlings, representative lots were secured from prac- 

 tically all the sources that w^ere available. For example, sample lots 

 of imported French crabs were obtained ; also French crab seedlings 

 grown in Kansas and in Iowa ; seedlings from Minnesota-grown seed 

 raised in Minnesota; seedlings from Minnesota-grown seed raised 



