CALIFORNIA AVOCADO ASSOCIATION 



21 



of choosing buds for propagation from uniformly highly yielding trees of good 

 standard type. Is this all of the story or are other factors involved, which we 

 should know about and guard against in growing citrus trees? 



It is a well knowTi fact that nursery trees as they are normally grown, when 

 two years old and ready for sale, exhibit great diversity in size, the trunks fre- 

 quently ranging from % inch to 1 Yl inches in diameter. Does this variation in 

 size of trees of the same age mean anything, or is it purely accidental? All of 

 these trees are ordinarily sold and planted. Probably these differences in size are 

 due to the same or similar causes as those responsible for the differences in size of 

 bearing orchard trees. 



A nursery grown at the Citrus Experiment Station for experimental purposes 

 was planned with the idea of producing as uniform trees as possible. The sweet 

 seedling stock used was thus selected when it was planted in the nursery, many of 

 the small trees being discarded. Through the kindness of Mr. Shamel, the buds 

 used for propagation were taken from some of his best record trees of standard type 

 in order to further insure uniformity. Valencia and Washington Navel oranges. 

 Marsh Seedless grapefruit and Eureka lemon were the varieties grown. When 

 this nursery was two years old and ready for orchard planting the trees were found 

 to show the same variations in size of buds that have been referred to as being 

 universally present in ordinary nurseries. Had buds been taken indiscriminately 

 from ordinary trees this variation would have been passed by as normal. As it 

 was, this fact led to a test of the different sizes of trees to determine, if possible, 

 whether they were of any importance in growing an orchard. Eighteen large, 

 eighteen small and eighteen intermediate sized buds of each variety were selected 

 and planted in comparison rows in the variety orchard at the Citrus Experiment 

 Station, Riverside, California. These trees were all dug "bare root" to see that 

 the roots were normal and not injured or diseased. All were normal and thor- 

 oughly healthy so far as could be determined. They were planted in the orchard 

 in June, 1917. The severe heat coupled with "bare root" planting injured so 

 many of the Eureka lemons that this variety was eliminated from the experiment. 

 The Navels, Valencias and Marsh Seedless grapefruit stood the transplanting very 

 well and are still growing. 



These trees have now been in the orchard lYi years and are 4 J/2 year old 

 buds. They still retain the same comparative difference in size just as markedly 

 as when they were transferred from the nursery. 



To get some indication of the comparative average size of the tops of the 

 different groups, the top diameter of each tree was measured east and west, north 

 and south and the height from the lowest branch to the top of the foliage. These 

 measurements for each tree were multiphed together to give the volume of the 

 cube that would enclose the top. The averages of these figures for each group in 

 each variety are given in the following table: 



While admittedly such figures are not exact measures of the top volume, 

 they are believed to represent fairly accurately the comparative sizes of the trees 

 in each group. 



To what factors could this variation be due, and is it of any importance in 

 citrus propagation? A difference in the soil or in the nutrition available might 



Large 

 54,174 

 29,003 

 26,343 



Intermediate 



Small 



Navels 



Valencias.. 

 Grapefruit. 



20,185 

 15,606 

 15,827 



12,541 

 12,953 

 10,642 



