34 BULLETIN 1483, U. S. DEPARTMENT OF AGRICULTURE 
ISOLATION AND PROPAGATION OF SUPERIOR STRAINS 
Most of the limb variations which have been studied are appar- 
ently regressive in nature, and their fruits are less desirable for com- 
mercial purposes than those of the Valencia strain. On account of 
the rank growth of some of them and the development of an unusu- 
ally large number of large and vigorous-growing nonfruiting 
branches which were formerly considered to be particularly desirable 
as sources of buds for propagation, the proportion of the trees of 
these strains has increased rapidly where systematic bud selection 
has not been practiced in the propagation of this variety. For this 
reason it was formerly considered by some growers that the Valencia 
variety was " running out " in the Southwest and that some new 
variety must be developed to take its place. 
Recent observations of Valencia orchards where the buds for the 
propagation of the trees were carefully selected from superior- 
yielding and uniformly fruiting parent trees give conclusive evi- 
FlG. 21. — Fruits of the Dry strain of the Valencia orange from a tree which was 
propagated from a similar limb variation. Riverside, Calif., June, 1923. (About 
three-fourths natural size) 
dence that the undesirable strains have been practically eliminated. 
So far as known, these commercial progenies of selected parent trees 
have not developed a single markedly variable tree, and only a very 
small proportion of individual-fruit and limb variation has been 
observed in any of these orchards. In some of these progeny plant- 
ings more than 50 per cent of the trees are now considered to be 
satisfactory sources of bud wood for further propagation, as com- 
pared with 1 per cent or less in orchards where systematic methods 
of bud selection were not used in the propagation of the trees. These 
tests, together with related commercial progeny plantings, show 
that it is possible to isolate a uniform and productive strain which is 
to be desired in commercial fruit growing. 
The application of the results of these investigations has led to 
improved yields and the more profitable culture of the Valencia 
orange. The business of growing this fruit has been stabilized 
through the isolation and propagation of the best strain and the 
elimination of the undesirable ones. Indications at present are that 
