252 THE CHIEF SOUTHERN AGRICULTURAL CROPS 



always pack their own fruit. It is often bought on 

 the tree by shippers who run their own packing 

 houses, or if not sold, it may be taken to some cen- 

 tral cooperative packing house. 



A large number of varieties are in cultivation, but 

 for a detailed discussion of them the reader must 

 consult some of the really excellent special works on 

 orange culture. Two quite distinct groups may be 

 recognized : the common or round orange ( Citrus 

 aurantimn) and the Mandarin or kid-glove orange 

 (^Citrus nohilis). The Washington navel, which is 

 the seedless orange so extensively grown in California, 

 does not succeed well in Florida, and whether or not 

 it will be a success in the West Indies is still an 

 open question. In Florida each section has its fa- 

 vorite kinds, many of which have been selected from 

 among the best native seedlings. In the compara- 

 tively new orange regions of the West Indies it is 

 still difficult to decide what varieties it will be most 

 profitable to plant. Many very excellent seedlings 

 occur in these countries and it is probable that in 

 the future each island may develop its own market 

 varieties by selecting its best native seedlings. 



The orange is subject to a considerable number of 

 serious diseases and insect pests, only the more im- 

 portant of which can be briefly considered. 



The ''die back" has already been mentioned in the 

 discussion of fertilizers. It is a functional trouble not 

 caused by any parasitic organisms but resulting from 

 some derangement of nutrition. It is usually caused 

 by overstimulation with nitrogenous fertilizers. The 

 leaves, which are at first very large and dark green, 



