CALIFORNIA AVOCADO ASSOCIATION 



23 



The Eureka lemon on a trifoliate stock is very markedly dwarfed while Valencias 

 grow to good sized trees. The Florida rough lemon is usually a good stock while 

 the Chinese lemon is commonly recognized as a poor stock. Different reactions 

 on the bud caused by the influence of different stocks are well known to exist. 

 When, therefore, such marked differences are found to exist in our sour and 

 sweet orange seedlings that we are using as stocks, is it any wonder that the budded 

 trees in the nursery, even when selected buds are used, should grow differently and 

 produce large and small trees, and that these differences should continue to exist 

 when the same trees are grown in the orchard ? 



The evidence now available very strongly points to the conclusion that the 

 differences in size of nursery trees, such as those taken for the experiment outlined, 

 are mainly to be attributed to the different nature of the seedling stocks used. If 

 this is true, and it is entirely in line with the evidence as well as with common 

 sense and judgment, it immediately becomes an element of fundamental impor- 

 tance in citrus propagation. 



I would be remiss in caution and duty if I did not call your attention to the 

 fact that one very important link in the chain of evidence is yet lacking, that is, 

 the growing of good buds on known stocks of these various types to prove that 

 certain ones give better growth than others. This evidence, however, is partially 

 supplied by our known experience of the reaction of buds on different stock such 

 as referred to above. 



Will the small trees continue to remain small? Certainly the evidence thus 

 far indicates that this is very likely. It's a good bet that they will. Dr. Reed 

 of the Citrus Experiment Station carried out a series of experiments with a consid- 

 erable number of sunflower plants that has a bearing on this phase of the problem. 

 In this group of sunflowers, exact measurements of height were made of each 

 plant every week from the time it was a few inches high until it reached maturity. 

 The' analysis of the data of growth obtained showed a well marked tendency of 

 the plants to retain their same relative rank as to size throughout the period of 

 growth. Plants which were small at maturity were generally small in the begin- 

 ning, and those which were large at maturity had a well marked superiority from 

 the start. The evidence indicated that height and vigor of growth were deter- 

 mined not by chance but by some definite inherent factor in the plant itself. The 

 same is doubtless true with citrus seedlings of the various species, such as those used 

 for stocks, and if the cause of the different sized nursery trees is to be attributed 

 primarily to the influence of the stocks as seems probable, then it is also probable 

 that the difference is due to causes inherent in the different stocks and that the same 

 relative rate of growth and size will be maintained in the majority of the plants. 



While the evidence is yet incomplete, we are probably justified from what 

 evidence we have, in speculating somewhat as to what this means in our fruit indus- 

 tries. Frequently, almost every tree in an orchard will be a fine good grower and 

 fruiter, giving a uniform orchard. Again, an orchard equally well handled may 

 be very ununiform, having some good trees, some poor ones and some of inter- 

 mediate character. This difference could be accounted for by assuming that the 

 good orchard chanced to be from trees grown on stock that happened to come from 

 seeds of good stock trees, or that they had been taken from a nursery where in 

 filling the order of size only the large trees had been dug, which would be the 

 ones naturally of good vigorous stocks. The remaining slower growing trees from 

 such a nursery would ultimately reach the required size and be sold and planted 

 in another orchard which would likely give an uneven orchard with good and 

 bad trees. 



