200 HORTICULTURE FOR SCHOOLS 



provisions was supplemented by funds from several states. 

 At the present time the work of control has apparently 

 resulted in the eradication of the disease. 



What has been said about the control of canker illus- 

 trates very well some fundamental features of disease 

 control. Constant watchfulness, the destruction of diseased 

 trees wherever practicable, and the maintenance of rigid 

 quarantines, are the three means most likely to be effective 

 in the case of all new diseases, especially if eradication is at 

 all possible. 



293. The future of the citrus industry. A considerable 

 acreage is yet available for citrus planting; but year by year, 

 some localities prove to be better than others for the citrus 

 fruits, and there is a slow but natural process of adjustment 

 going on. This is mentioned because it is true not only of 

 oranges but of other fruits as well. Under the spell of a 

 temporary enthusiasm the planting of some type of fruit will 

 be pushed far beyond the limits of the regions adapted to it ; 

 then will come adverse seasons; many plantings will be 

 neglected and will perish, but a few in especially suitable 

 locations will persist. Thus the industry is extended. The 

 process is hard on those who are carried away by their tem- 

 porary enthusiasms, to the loss, it may be, of all they possess. 



294. The pomelo. Even a brief discussion of citrus fruits 

 would be incomplete without some mention of the pomelo, 

 known commercially as grapefruit. The fruit is borne in 

 clusters of three to twenty, hence perhaps its popular name. 

 It was brought to Florida by the Spaniards in very early 

 times, and at first was grown in gardens merely as an orna- 

 mental plant. It is only in the last quarter of a century that 

 the pomelo has assumed commercial importance. This some- 

 what bitter fruit has proved both wholesome and appetizing, 

 and has come to be widely used as a breakfast and salad dish. 

 The Florida pomelos are preferred in the market, although a 

 considerable quantity of the fruit is raised in California. Its 



