74 



FLORIDA STATE .i.)?/nCULTUKAL SOCTFTY 



plant and then carried in its tubers to the 

 pros^eny grown from them. The success- 

 ful growing of Potatoes, particularly, in 

 the more southern states, has become in 

 large degree dependent on securing for 

 planting tubers of plants free from these 

 diseases. 



The recent advances in the knowledge 

 of such diseases now make it very doubt- 

 ful if vegetative propagation of itself ever 

 leads to the "running out" of a clonal va- 

 riety. The selection of healthy stocks 

 in the various plants in which there may 

 be yellows or mosaic disorders is becom- 

 ing well recognized as a necessary pro- 

 cedure. 



Rather special studies are needed to de- 

 termine the nature of these diseases, the 

 means of their transmission, and the meth- 

 ods of eliminating them in practical cul- 

 ture. Thus at the beginning the solution 

 of these problems rests on the shoulders 

 of the specialist in plant pathology. It 

 remains, however, for the nurseryman 

 and the grower to practice the means for 

 control. 



FRUIT PRODUCTION IN CLONAL VARIETIES 



The horticulturist needs always to know 

 when the growing of a clonal variety in 

 solid blocks will of itself reduce fruit 

 production through limiting the i)ollina- 

 tion required for the setting of fruit. It 

 is the rule among the fruit crops grown 

 at the present time that proper production 

 of fruit depends on the development of 

 seed. But the initiation of seed develop- 

 ment depends (with few exceptions) upon 

 intricate processes of fertilization which 

 in turn depend upon a pro{x.'r pollination. 



It happens that there are frequently spe- 

 cial conditions that are inherent character- 

 istics of certain clonal varieties which lim- 

 it or prevent either pollination or fertiliza- 

 tion after pollination whenever a plant 

 stands alone or when there is a solid block 

 of a single clonal varietv. 



There are so many conditions influenc- 

 ing the production of fruit that it is not 

 always an easy matter to distinguish be- 

 tween those that are incidental, or purely 

 environmental or cultural, and those which 

 pertain to the needs of a variety for pol- 

 lination. The former operate to limit 

 production when all requirements for pol- 

 lination are met. The latter operate to 

 limit fruit bearing where all environment- 

 al conditions are fully favorable to high 

 yields. The manifold and complex in- 

 fluences of climate, weather, culture, nur- 

 ture, fungous diseases, insect pests, etc., 

 are all of vital and immediate effect. They 

 have always been matters of much con- 

 cern to fruit growers. They always will 

 be of much concern. But these are not 

 factors for un fruit fulness that develop 

 or become prominent because of vegeta- 

 tive propagation. They are (juite apart 

 from the un fruit fulness that arises from 

 lack of pollination or from lack of prop- 

 er fertilization. 



Among the many cultivated plants (and 

 wild as well) there are various types of 

 sterility; the non-blooming condition, 

 sterility from hybridity, and sterility ac- 

 companying double flowers frecjuently 

 render plants decidedly or fully sterile in 

 the true sense of the term. Such plants 

 may be grown as ornamentals and be prop- 

 agated vegetatively. Their sterility, how- 

 ever, does not arise because of vegetative 



