LUTHER BURBANK 



of bark and wood (called gummosis) , to which the 

 cherry is peculiarly liable. 



Hybridizing with wild species, intelligently and 

 systematically carried out, might produce vari- 

 eties of cherry that would show exceptional re- 

 sistance to insect pests as well as inherent vitality 

 that makes for healthiness in the tree. 



It has long been my belief that a solution of 

 the problem of protecting our fruit trees from 

 both insect and fungus pests must eventually be 

 found in the development of the qualities that 

 make for immunity of the trees themselves, 

 rather than in the resort to such expedients as 

 spraying and "gasing." In this regard the plant 

 experimenter may well take a leaf from the note- 

 book of the physician, who has learned that im- 

 munity to disease often depends more upon vthe 

 condition of the patient than upon the presence 

 or absence of disease germs. 



It is possible, furthermore, that the cherry may 

 be hybridized even more widely, and that a fruit 

 differing markedly from any cherry hitherto pro- 

 duced may thus be developed. An inkling of the 

 possibilities in this direction is given by some ex- 

 periments made recently by Professor N. E. Han- 

 sen, of the South Dakota Experiment Station, who 

 has cultivated a variety of wild "fruit, called the 

 Sand Cherry, Prunus Besseyi, which is a dwarfed, 



[100] 



