64 BULLETIN 815, U. S. DEPARTMENT OF AGRICULTURE. 
eliminated ibe danger of the unintentional propagation of worthless 
strains of the Lisbon lemon. Whensuch bud wood is used it naturally 
results in its being obtained from the most heavily fruited trees, as 
these trees have more available fruit wood than trees of vegetative 
or poor-fruited strains. When bud wood is taken from fruitJ bear- 
ing wood of performance-record trees the danger of propagating un- 
desirable strains is greatly reduced. : 
THE ISOLATION OF STRAINS THROUGH BUD SELECTION. 
The orchards of the Lisbon lemon variety include trees of many 
diverse strains which have originated from bud variations. In this 
bulletin the description and characteristics of some of the important 
strains are presented. Some of these strains, on account of their low 
and inferior production, are not worthy of propagation. Other 
strains produce fruits low in acidity, with little or no juice, of unde- 
sirable ee , of coarse texture, or with some other undesirable 
characteristic. A mixture of strains in any commercial orchard is 
undesirable a is likely to depreciate the value of the orchard. 
The first step in these investigations was the determination of the 
relative value of the different strains of the Lisbon lemon for com- 
mercial production-in California. The next step was the isolation of 
the important strains through bud selection. This was accomplished 
by propagating from performance-record trees those which were 
typical of the different strains and in this propagation using only 
fruit-bearing bud wood with typical fruits attached to the ee stick. 
The oidest “DS which have been propagated from typical trees in 
the performance-record plats are now 5 years old from time of plant- 
ing. The young trees are now bearing commercial crops of fruit, and 
performance records are being obtained from many of them. 
While the progeny data obtained are incomplete as yet, a sufficient 
amount of information has already been secured to warrant the state- 
ment that each of the important strains of the Lisbon variety has 
been isolated through careful bud selection. This does not mean 
that individual! tree variations are not encountered in these young 
trees, because variations within the strains are found which are simi- 
lar in degree to those of the parent trees. However, there has been 
no mixture of strains, and in every case the same differences which 
characterize the parent trees are found in their progenies. 
TOP-WORKING UNDESIRABLE LEMON TREES. 
The investigations have shown that in many lemon orchards there 
are a number of healthy unproductive trees of undesirable strains. 
These unproductive trees usually can be successfully top-worked by 
using bud wood selected from fruit-bearing wood on superior per- 
formance-record trees. Figure 12 shows typical fruit-bearing lemon 
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