536 EXPERIMENT STATION RECOED. [Vol.36 



made of the effects on vigor aud fruitful ness of various degrees of dormant 

 pruning, summer iiruning at different times, and combinations of dormant and 

 summer pruning. Tlie worli of other investigators is reviewed and a biblio- 

 graphy of related literature appended. 



The results of the pruning work as a whole are in accord with those pre- 

 viously reported by the senior author (E. S. R., 35, p. 142). Although heavy 

 annual dormant pruning has resulted in stronger terminal growth, the gain in 

 total length of growth and in increase in trunk diameter has been less than 

 with lightly pruned trees. Heavy dormant pruning appears to be primarily 

 of value for developing a frame work during the first two or three years of 

 the tree's life and for stimulating fruit production in middle-aged trees that 

 are only in a fair state of vigor. As previously noted all classes of summer 

 pruning have been inferior to dormant pruning. 



The authors have also conducted experiments to determine the effects of 

 ringing on the growth and fruitfulness of apple trees. Ringing of trees caused 

 heavy crop production the season following the operation but so impaired the 

 vigor that no crop was produced the second or third years, and at least three 

 seasons were required to restore the tree to normal conditions. 



Apples: Production estimates and important commercial districts and 

 varieties, H. P. Gould and F. Andrews (U. S. Dept. Agr. Bid. 485 {,1911), pp. 

 48, figs. 16) . — A statistical study of the apple industry of the United States con- 

 taining estimates relative to the production aud distribution of the principal 

 varieties in the country as a whole and in the individual States, including also 

 ail outline of the distribution of the apple industry in each State and the 

 varieties grown. Estimates are also given of the proportion of early and late 

 apples produced in each State and of the annual production of apples as a 

 whole in the United States from 1890 to 1916, inclusive. A portion of the data 

 have been previously noted (E. S. R., 32, p. 438). 



Preliminary observations on the ripening of Bartlett pears, W. V. Cruess 

 and P. M. Stone {Mo. Bui. Com. Hart. Cal., 5 {1916), No. 12, pp. 425-429).— 

 Data are given on some preliminary tests conducted at the California Experi- 

 ment Station to ascertain whether the proper time for picking pears to be 

 shipped may be determined by a simple chemical test. The results thus far 

 secured indicate that a minimum size may be of more value than a chemical 

 test in deciding the time of picking. 



Navel persimmons, J. E. Coit (Cal. Citrogr., 2 {1916), No. S, p. 9, fig. 1). — 

 Some Japanese persimmons observed in California that have a small secondary 

 fruit included within the primary fruit are here illustrated and described. 



The common honeybee as an agent in prune pollination, A. H. Hendrick- 

 SON {Calif omia Sta. Bui. 274 {1916), pp. 127-132, figs. 2).— During the past three 

 years the station has been conducting pollination studies with plums and prunes 

 in the Santa Clara Valley. This bulletin comprises a progress report on that 

 part of the project dealing with the honeybee as a factor in prune pollination. 



Because of the conflicting reports of the value of interplanting such varieties 

 as the French prune and the Imperial prune, and also because of a noticeable 

 lack of bees and other insects in the prune orchards of the valley during the 

 blooming period, an experiment was planned in which a tent of white mosquito 

 bar was placed over a pair of adjoining French and Imper'al prune trees as 

 nearly as possible of the same age and size. A hive of honeybees was kept 

 in this tent throughout the blooming period. A similar tent inclosed a pair of 

 French and Imperial prune trees, from which bees and other insects were ex- 

 cluded throughout the blooming period. Observations were made on the set 

 of fruit under these tents and also on trees of these varieties exposed to normal 

 conditions. 



