22 



ANNUAL REPORT 1919 AND 1920 



cause variation in size, but this cannot be the main cause of the variation in size of 

 these trees as they showed the difference in the nursery and continue to show it 

 2 Yl years after transplanting into the orchard. In the orchard they are planted 

 close together on uniform soil and are treated alike so the difference cannot be 

 attributed to local soil condition or nutrition. 



Is the difi^erence due to the character of the bud union? The buds seem to 

 have healed nicely in all trees used and exhibit no characters that would indicate 

 a difference here. 



Is it due to the roots having been injured thus resulting in dwarfing the tree? 

 The roots were all examined when the trees were transplanted and all were found 

 to be healthy and uninjured. Any injury or disease contracted since the trees 

 were transplanted could not be limited to the small tree rows only. 



Is it due to the kinds of buds used? All that can be said regarding this is 

 that the buds were carefully selected from trees of known record and standard 

 type. It does not seem that the difference is to be explained in this way although 

 this possibility cannot be entirely eliminated. 



The only other factor that is likely to be the cause of the variation is the 

 influence of the stocks used. The sweet orange stock used was merely ordinary 

 sweet orange seedlings grown from unselected seed, the only extra precaution 

 taken being merely to discard the small seedlings when transplanting from the seed 

 bed. About fifteen percent, of the total number of seedhngs were discarded at 

 that time. The universal custom pursued at present is to use either sweet, sour, 

 grapefruit, lemon or trifoliate orange stock without reference to any particular 

 kind within these great groups. Are the variations within the ordinary lots of 

 sweet and sour orange seedlings sufficiently great to be assumed to account for 

 these variations in size of nursery trees? Fortunately some evidence has been 

 secured bearing on this point. 



In 1915 the writer, with the help of Mr. W. M. Mertz and Mr. E. E. 

 Thomas, made an examination of one sour orange nursery and selected sixteen 

 seedlings that appeared to show different characters. At the same time in the 

 same nursery four different types were selected in a bunch of sweet seedlings. A 

 more detailed examination would doubtless have revealed many more types but the 

 only object in view at that time was to add "freaks" to the variety orchard. Buds 

 were cut from each of these seedlings and two sour orange stocks were budded 

 with each t5^pe. The trees from these buds are now AYl years old from the bud 

 and have been set in the variety orchard for 2 Yl years. All of the types selected 

 present marked differences in size, foliage, character of branching and the like. 

 The good vigorous types in the case of the sour orange selections are five times, 

 or more, larger than the slow growing dwarf types. Two trees out of sixteen of the 

 sour orange types selected have lost the typical aroma of the sour orange, so far as 

 the leaves are concerned. The four types of the sweet orange also differ in similar 

 way in size and fohage characters. 



The great extent of this range of variation within the different species -is shown 

 equally as well by the large number and range of the named varieties that are 

 grown. 



In sweet orange and sour orange seedlings, usually or at least frequently, 

 grown from seed of unknown origin, and coming from different trees, we are not ■ 

 dealing with a homogeneous lot but with lots in which every individual differs 

 from every other individual and yet our policy has uniformly been to use all; good 

 and bad alike, for propagation. Is it any wonder under these conditions that our 

 trees, though grown from the best selected buds should be variable in the groves? 



