UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1477 
Washington, D. C. 
October, 1S27 
VARIETAL CHARACTERISTICS OF PLUMS IN THE PACIFIC STATES 
IN RELATION TO PRUNING 
By C. F. Kinman, 
Associate Pomologist, Office of Horticulture, Bureau of Plant Industry 
CONTENTS 
Page 
Importance of pruning operations 1 
Explanations of terms used 4 
Growing habits of plum trees in rela- 
tion to pruning 4 
Fruiting habits in relation to growth. 9 
Habits of growth of fruit spurs 9 
Effect of low summer temperatures 
on wood growth 13 
Page 
Habits of growth and production of 
some plum varieties grown in the 
Pacific States 14 
Varieties of the Prunus trifiora 
group and its derivatives or 
hybrids 14 
Varieties of the Prunus domes- 
tica group 21 
Comparison of bebavior of plums 
under eastern and western condi- 
tions 36 
IMPORTANCE OF PRUNING OPERATIONS 
Probably nowhere in the United States is the pruning of deciduous 
fruit trees more important or more varied than in the plum-growing 
sections 1 of the Pacific States, where this important fruit industry 
is distributed over a large area. In this region the summer rainfall 
is very' light, soils and temperatures are variable as between different 
fruit-growing sections, and only large fruit is profitable for ship- 
ment to distant markets. Pruning has become a very important 
factor in obtaining the regular production of large fruit and in 
maintaining the vigor of the trees. It has become one of the prin- 
cipal operations of orchard management, and the variations in the 
operation which may prove beneficial in different sections and with 
the different varieties are of great interest and importance. 
A greater number of varieties in general cultivation are included 
in the plum and prune-producing industry than may be found with 
almost any other commercially grown fruit in this region. As each 
variety possesses its peculiar and usually striking habits of growth 
and production and responds in its peculiar way to local environ- 
ment and treatment, it is essential that the pruner have an intimate 
1 For information on plum culture, see Kinman, C. F. plum and prune growing in 
the pacific states. U. S. Dept. Agr. Farmers' Bull. 1372, 59 pp., illus. 1924. 
27428°-27 1 1 
