No. 2, March, 1921] HORTICULTURE 153 



995. Partridge, N. L. Growth and yield in apple trees. Proc. Amer. Soc. Hortic. Sci. 

 16: 104-109. (1919) 1920. — Studies made at the Delaware experiment station on the growth 

 and yield, during the previous three years of ten-year-old Jonathan, Yellow Transparent, 

 and Stayman Winesap apples, indicated strongly that there was a very consistent relationship 

 between the growth that the tree made and the amount of fruit produced. It was shown 

 that if the growth was smaller in 1918 than in 1917, the yield was larger in 1918; and the 

 reverse was also true. Thus the author states, "There is an alternate habit of growth as well 

 as an alternate habit of bearing in these trees. However in the case of the tree with an 

 increasing yield this is not the case." It was suggested, however, that when trees with in- 

 creasing yields finally had sufficient fruit produced in some year to depress the growth, such 

 trees would then fall in the biennial habit of bearing and growth. — E. C. Auchier. 



996. Pierce, G. W. The almond industry. Monthly Bull. California State Commission 

 H or t. 8:355-357. 1919. 



997. PoPENOE, WiLso.v. The natural groups of mangos cultivated in Florida. Proc. 

 Amer. Pomol. Soc. 1917: 70-81. 5 pi., 5 fig. 1918. — The varieties of mangos now grown in 

 Florida have been classified by the autjjor into a natural classification. The different varie- 

 ties which resemble one another in certain general characters have been placed in groups 

 according to these natural resemblances. In defining the groups, consideration was given 

 to characters of growth, foliage, inflorescence, fruiting habits, and the fruit itself. — Two 

 main divisions of the several groups are first made; namely, (1) bark rough; leaves having 

 commonly 18 to 24 pair of primary transverse veins; and (2) bark smooth; leaves having 

 commonly 2G to 30 pairs of primary transverse veins. — In the first division are included the 

 following groups: Mulgoba, Alphonse, Sandersha, Madras, and Julie groups. — In the second 

 division is included the one group — Cambodiana. — Detailed descriptions of each group are 

 given in the paper, and the varieties which fall in each group are enumerated. — E. C. 

 Auchier. 



998. Rice, W. H. Orchard sanitation. New Zealand Jour. Agric. 20: 238-242. 1920.— 

 A general discussion showing the importance of sunlight, air circulation, drainage, cultiva- 

 tion, and general cleanliness in orchard practices. — .V. J. Ciddirtgs. 



999. Roberts, R. H. Studies in biennial fruiting. Proc. Amer. Pomol. Soc. 1919: 28-33. 

 1918. — Careful studies were made at the Wisconsin experiment station concerning the bien- 

 nial fruiting of certain apple varieties. The effects of blossom formation, spur growths, and 

 leaf areas during one year on the amount of bloom the following year were noted. The 

 author's general conclusions are as follows : "While no definite solution of the off-year question 

 is attempted, two statements bearing upon this matter can be made as a result of the investi- 

 gations. — (1) Biennial blossoming and fruiting is not due to a constitutional habit of the tree. 

 If it were due to a definite plant habit, successive blossoming could not have been induced 

 by blossom removal. Investigations with other plants show that blossom-bud production is 

 associated with the amount of plant-foods present. Qualitative tests indicate the same 

 condition in the apple. The off year, then, evidently results from a condition of nutrition 

 within the plant and not from a growth habit. — (2) Annual bearing by successive blossoming 

 of individual spurs cannot be expected. When the spur produces blossoms and develops 

 them to the point of setting fruit, it seldom blossoms again the next year. The develop- 

 ment of blossoms to the stage at which the fruit can be said to have set together with the 

 presence of excessive numbers of blossom spurs, seems to be the determining factor in the 

 ability of the spur to blossom in successive seasons. If annual bearing can be produced, 

 it must apparently be brought about by having a double system of spurs, which fruit in alter- 

 nate seasons. How this may be accomplished fully cannot be stated further than to refer 

 to the condition as pointed out before, that excess growth as well as very weak growth was 

 associated with the failure to form blossom buds. The normal blossom spurs are usually 

 one-eighth to one-half inch in length. If their growth is increased to one to two inches, they 



BOTANICAL ABSTRACTS, VOL. VII. NO. 2 



