64 BULLETIN 815, U. S. DEPARTMENT OF AGRICULTUEE. 



eliminated the danger of the unintentional propagation of worthless 

 strams of the Lisbon lemon. When sueh bud wood is used it naturally 

 results in its beuig 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 fruit-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 origuiated from bud variations. In this 

 bulletm 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 m acidity, with little or no juice, of unde- 

 sirable shapes, of coarse texture, or with some other undesirable 

 characteristic. A mixture of strains in any commercial orchard is 

 undesirable and 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 strams 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-bearmg bud wood with typical fruits attached to the bud stick. 

 The oldest trees which have been propagated from typical trees in 

 the performance-record plats are now 5 years old from time of plant- 

 ing. The yoting trees are now bearing commercial crops of fruit, and 

 performance records are being obtauied from many of them. 



While the progeny data obtained are incomplete as yet, a sufficient 

 amount of information has aheady 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 



