BUD VARIATION IN THE EUREKA LEMON. 
81 
of the typical parent trees have been uniformly transmitted. Varia- 
tions in some of the individual trees in these progenies, similar in 
degree to those of the parent trees, have been found. However, no 
mixture of strains has been discovered so far in the progenies. There- 
fore, it can be safely stated at this time that it is practicable to iso- 
late the different strains through bud selection 
based upon individual-tree performance, records 
and intimate tree knowledge. 
TOP- WORKING UNDESIRABLE TREES. 
The healthy unproductive lemon trees of 
undesirable strains in bearing orchards can 
usually be successfully top-worked through 
the use of bud wood selected from desirable and 
superior performance-record trees. Figure 18 
shows two such bud sticks before they have 
been cut from the parent tree. Three bud 
sticks cut from the tree and ready for use are 
illustrated in figure 19. 
The top-working is usually best done during 
the months of April, May, and June. As a 
rule, in the instances under observation, the 
best results have been obtained during May 
and early June. Fall top-working is not usu- 
ally done on account of possible frost damage 
to the tender growth, except that it is the 
practice of some growers to insert buds in the 
trees to be top-worked during the late fall 
and allow the buds to remain dormant un- 
til spring. The advantage claimed for this 
method is that if any of the buds do not unite 
with the limbs in which they have been in- 
serted and die during the winter new buds can 
be used in the spring, resulting in a more uni- 
form stand than with spring budding. Obser- 
vations during the course of these investigations 
do not bear out this contention, so that spring 
budding is strongly recommended for top- 
working. 
The trees selected for top-working should be so pruned as to allow 
free access to the limbs in which the buds are to be inserted, as shown 
in figure 20. The limbs for top-working should be selected from the 
standpoint of furnishing a strong and suitable framework for the 
new tops. Usually from three to five such foundation limbs are 
necessary for the best results. The best place for the insertion of 
135336°— 20— Bull. 813 6 
Fig. 19. — Typical fruit -bear- 
ing bud sticks from a lemon 
tree of the Eureka strain. 
The bud sticks after being 
cut and trimmed should be 
packed in slightly mois- 
tened sphagnum moss and 
held in a cool room until 
needed for use. (One-half 
natural size.) 
