AN INTERESTING BUD-SPORT IN 



THE WASHINGTON NAVEL ORANGE 



Of Our Commercial Varieties of Oranges, None Is More Erratic and Prone to 

 the Production of Sports than the Washington Navel 



Robert W. Hodgson, University of California 



THE work of Mr. A. D. Shamel 

 and others has called attention to 

 the frequency with which bud- 

 sports are found in Citrus and 

 has indicated the importance of bud 

 selection in the maintenance of our 

 standard varieties. There is little doubt 

 but that the genus Citrus represents one 

 of our most unstable classes of com- 

 mercial fruits, and this tendency to the 

 production of bud-sports or mutations 

 is apparently heightened by environ- 

 mental conditions in California. Of 

 our commercial varieties of oranges, 

 none is more erratic and prone to the 

 production of sports than the Wash- 

 ington Navel. Thus in the fifty years 

 we have known this variety, there have 

 appeared no less than six additional 

 well defined strains of more or less com- 

 mercial importance, namely, the Aus- 

 tralian or Florida navel, the Navelencia, 

 Golden Buckeye, Golden Nuggett, 

 Thomson's Improved and Smith's Wil- 

 low Leaf. Many O't'hers have doubtless 

 occurred, but being decidedly inferior 

 to the original strain, have not been 

 propagated and still others exist in in- 

 dividual trees, but have not been rec- 

 ognized by growers. 



The characters involved in the muta- 

 tions are not always of a visible nature, 

 but may be qualities such as "yield," or 

 time of maturity, or acid-sugar ratio, 

 and it is, of course, characters such as 

 these that are of the greatest importance 

 from the commercial standpoint. Mr. 

 Shamel has devised what he calls the 

 performance record to indicate trees 

 possessing the quality of high yield, and 

 the best of such trees are selected as 

 "mother" trees from which buds are 

 cut for propagation purposes. The prin- 



cipal objection to the performance rec- 

 ord is that it fails to indicate mutating 

 trees. Thus a tree may have several 

 sport limbs and be decidedly unsatis- 

 factory for the selection of bud wood 

 and still yield relatively high, which con^ 

 dition is in no way- indicated from the 

 performance record sheet. 



The writer recently ran across such 

 a tree, in an orchard near Riverside, 

 possessing a single limb quite unlike the 

 remainder of the tree. The vigor and 

 habit of growth of this branch, the 

 leaf shape and color, and the quality and 

 form of the fruit are very different 

 from the rest of the tree. The sport 

 limb occurs rather high up in the tree 

 and toward the end of what was appar- 

 rently a typical fruiting branch. At the 

 point where the mutation took place the 

 branch increases in diameter. The mu- 

 tant limb has a greatly increased vigor 

 of growth over the parent strain, as 

 indicated by the increase in size of the 

 stem as well as by the large, vigorous 

 leaves, and an abnormal amount of fine 

 twiggy growth. This vigor is also evi- 

 denced by the fact that the sport branch 

 has acted as a sucker and has succeeded 

 in starving the growth on the parent 

 limb behind the point where the muta- 

 tion occurred. All of this growth has 

 died back, apparently from lack of 

 nourishment. Indeed, the general elTect 

 of the limb on the tree has been of 

 such a nature that the owner thought 

 it was a mistletoe. (Fig. 2.) 



The habit of growth is markedly 

 weeping, the limb drooping until it 

 touches the ground, although it origi- 

 nates at a height of seven feet or more. 

 The branches are long and slender and 



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