110 BULLETIN 697. U. 5. DEPARTMENT OF AGRICULTTTRE. 
fruiting they have all proved to be of the Marsh strain. In other 
words, an improved Marsh strain has been isolated and established 
and brought into fruiting. The trees of this improved strain are 
very uniform and their production is of the best grade and quality. 
Variation within the strain has been reduced through bud selection 
and from the commercial standpoint it has been eliminated. Doubt- 
less further improvement in this strain can be effected through 
further bud selection in succeeding bud generations, and experiments 
of this character are now under way. The most important step. 
however, the establishment of a superior strain, has been effected. 
Owing to a lack of opportunity, no attempt has yet been made to 
isolate an inferior strain, except in the case of the seedy strains. 
A limited propagation of this commercially worthless strain has been 
made experimentally and has shown that it. too. can be isolated and 
established by the selection of buds from trees persistently bearing 
fruits of this character. There is every reason to believe that the 
other strains can be similarly established, and in an experimental 
way this work is now being done. Such propagations are of no 
commercial value except that they further illustrate and demonstrate 
the importance of careful bud selection in the propagation of the 
variety. 
Owing to the fact that the commercial grapefruit industry in Cali- 
fornia is still in its infancy, the careful selection of buds from trees of 
the Marsh strain for all future propagations will likely result, through- 
out the State as a whole, in the development of trees of a u ni form 
character and the production of crops of proved quality and value, 
an achievement unequaled in the history of any other citrus variety 
now grown commercially. 
TCP- WORKING UNDESIRABLE TREES. 
Healthy trees of undesirable strains can be successfully top-worked 
and replaced by the valuable Marsh strain through the use of buds 
selected from trees of that strain. This operation has been success- 
fully performed on trees 12 years old. Doubtless older trees can be 
as successfully top-worked by the use of similar methods. 
The selection of trees of the Seedy. Bell, and Rough strains for 
rebudding can usually be based on an inspection of the fruits. In 
the case of trees of the Alternate-Bearing and the Unproductive 
strains their selection should be based on performance records for 
two or more seasons, preferably an even number. 
Two or more of the main limbs of the trees to be top-worked 
should be used as foundations for the new trees. All branches 
interfering with the work of budding should be cut away. The select 
buds should be inserted in the limbs, two or more in each, about 12 
inches from the trunk of the tree. After the buds have united with 
