444 



The Journal of Heredity 



evidence accumiilatcd in the course of 

 these observations, that the variation 

 in this type can be controlled by bud 

 selection, so that by this means the 

 variety can be conserved, maintained, 

 and improved. 



In the consideration of the practical 

 problem of maintaining the navel orange 

 \'aricty by bud selection, it has been 

 found necessary not only to select trees 

 from definite individual tree perform- 

 ance records, but also to make limb 

 selections as well. This is done by 

 cutting the budwood from the select 

 trees with the ripe fruits attached and 

 using only budwood from the limbs 

 which produce the typical or standard 

 Washington navel orange fruits. This 

 budwood is of the preceding year's 

 growth and while it is of small size, has 

 been successfully used commercially. 

 The buds from this source have been 

 found to produce equally good if not 

 better trees than those propagated 

 from the larger and more rapidly 

 growing wood. 



TREE RENEWAL 



Of the observations made in the 

 navel and other orange districts of 

 Brazil, one of the most interesting to 

 the writer was the method of tree 

 renewal practiced by the orange growers. 

 We found existing a general belief that 

 after fifteen or twenty years orange 

 trees became unproductive and un- 

 Ijrofitable. In such cases the tree tops 

 are cut off and new tops grown from the 

 old trunks. In the case of badly 

 diseased and dying trees, they are cut 

 back severely, sometimes to a point 

 just above the bud union. Where the 

 trees were in fair condition of vitality 

 but decadent, only the smaller limbs 

 are cut off, leaving the main limbs as a 

 framework for the growth of a new top. 

 The amount of tree top cut off is 

 governed by the condition of the trees. 

 The renewed trees were found to be 

 surpri.singly healthy, vigorous-growing, 

 and productive. Many of the orange 

 growers claimed that the fruits borne by 

 these renewed trees were of better 

 quality than those borne by original 

 trees. 



In consequence of this practice of 



tree renewal, no very old na\'el orange 

 trees were found; the oldest was said 

 to be about 40 years of age. However, 

 in some cases, evidence was discovered 

 where such trees had been renewed as 

 many as four times, indicating that the 

 trunks were from 60 to 80 years of age. 

 The method of tree renewal practiced 

 by the Brazilian navel orange growers 

 is chiefly of interest in that it tends to 

 confirm the soundness of the principle 

 of pruning based on the systematic 

 renewal of the fruil-bcaring wood in 

 citrus trees. 



BUDDING 



Another interesting practice observed 

 in the Bahian navel orange districts 

 was the budding of stocks set in per- 

 manent orchard places. While the 

 general method of propagation followed 

 in the past at Bahia has been that of the 

 ordinary nursery, the majority of the 

 newer orchards were found to be prop- 

 agated by budding the stocks in place. 

 Certain advantages for this method of 

 propagation are claimed by the Brazilian 

 orange growers: e.g., a more rapid 

 growth of the budded tree, earlier 

 fruiting, and greater resistance to dis- 

 eases, as compared with the ordinary 

 transplanted nursery trees. The stocks 

 are budded higher than is the usual 

 practice in this countr}' — 15 or 20 

 inches above the ground, and arc usu- 

 ally about two years old when budded. 

 The liudding is done at all times of the 

 year, but is said to be most successful 

 during November, December, and Janu- 

 ary, the spring and summer seasons in 

 Bahia. A shield bud is used as a rule, 

 the budsticks being about the same 

 size as the stocks to be budded. 



BUD VARIATIONS 



Bud variations were found in the 

 Bahian navel orange, but a])parently 

 are not so frequent as in the California 

 Washington navel orange trees. Dis- 

 tinct types of trees, as shown by habit 

 of growth and other characteristics, 

 were observed in all the orchards ex- 

 amined. On individual branches, leaf 

 variations were very frequent. For 

 instance, the variation of the petiole 

 was particularly noticeabk-. 'I'hc> jietiole 



