BUREAU OF PLANT INDUSTRY. 171 



of rice in the State, and produced 1.110,000 and 1,665,000 bushels, 

 respectively, with an estimated farm value of approximately 

 $7,000,000. 



FLAX. 



Flax hreeding. — Studies of an extensive series of hybrids have been 

 conducted in cooperation with the North Dakota and Wisconsin Ex- 

 periment Stations. Some of these hybrids w^ere made to determine 

 the inheritance of plant and seed characters and others to obtain 

 wilt-resistant strains. 



Flax culture. — Experiments in growing flax on breaking in North 

 Dakota during a three-year period have been completed and the 

 results published. The varieties proved best adapted are those of the 

 Russian seed-flax type now widely grown in the flax belt. Home- 

 grown or domestic seed is better than that imported. Early seeding, 

 between May 1 and June 10, is much more profitable than later 

 sowing, although where a catch crop must be sown, flax sometimes 

 does well when sown still later. 



EXPERIMENTS IN BLUEBERRY CULTURE. 



About 15,000 hybrid blueberry plants produced in the green- 

 houses at Washington have been grown to fruiting age in the co- 

 operative blueberry plantation at AVhitesbog, 4 miles east of Browns 

 Mills, in the pine barrens of New Jersey. From these plants four 

 have been selected and placed in the hands of nurserymen for propa- 

 gation and distribution. The first of the selected hybrids will be 

 on sale in the spring of 1921. The largest berries on these selected 

 hj^brids are three-fourths of an inch in diameter. They are of de- 

 licious flavor and have good shipping qualities. Additional selected 

 hybrids which have produced berries up to four-fifths of an inch 

 in diameter are now in process of propagation. The crops produced 

 on the cooperative plantation at Whitesbog indicate the great promise 

 of blueberry culture as an agricultural industry. 



FRUIT IMPROVEMENT THROUGH BUD SELECTION. 



This activity has continued during the past year as in previous 

 years and has been confined primarily to the further accumulation 

 of individual-tree performance records and similar records on 

 progeny trees which have been propagated from particular parent 

 trees of known production performance. This line of work in 

 California lias been carried on for a considerable period of years on 

 the Washington Navel, Valencia, and Rubv oranges, on the"^ Lisbon, 

 Eureka, and Villafranca lemons, on the Marsh grapefruit, and on 

 the Dancy tangerine. 



Incident to the citrus bud-solection work, certain important pro- 

 duction studies have been made. These relate to pruning and to 

 methods of applying organic manures. Pruning investigations car- 

 ried on from 1914 to 1919, inclusive, have been based on three differ- 

 ent degrees of pruning; namely, heavy, medium, and light. These 

 studies have been carried on witii the Washington Navel orange, the 

 Marsh grapefruit, and the Eureka lemon. The result of the pruning 

 work, as measured by the product, has been consistently in proportion 

 to the extent of the pruning. The very heavily pruned trees have 



