FRUITS 219 



of Northern plums (^Primus Aynericana and Prunus 

 nigra) are also but little planted. 



A few varieties of plums root readily from cuttings, 

 and one of these, the Mariana^ has been extensively 

 used as a stock on which to bud the other kinds. 

 At the present time most commercial plum orchards 

 in the South are on these stocks. 



Besides the diseases and insects discussed under 

 peaches, plums are subject to another serious trouble, 

 known as black knot (Ploivriglitia). This is a 

 fungous parasite causing unsightly black, gall-like 

 swellings on the twigs and branches. When these 

 become numerous, they greatly sap the vitality of the 

 tree, and in extreme cases even cause its death. It 

 can be quite thoroughly controlled by carefully 

 pruning out the diseased branches and spraying the 

 tree in early spring with Bordeaux mixture in order 

 to prevent new infection. 



Neither apricots nor cherries, the other two im- 

 portant stone fruits, succeed well at the South. 

 Apricots bloom so early as to be very subject to 

 injury from late frost ; while climatic conditions do 

 not seem favorable to the growth of cherry trees, and 

 it is useless to plant them south of Tennessee and 

 Kentucky, except in the mountains and the red clay 

 foothills of the Piedmont region. 



Apples (^Pyrus malus). — At the South apples 

 do not have the same preeminent commercial im- 

 portance as at the North, but they can be grown, 

 at least for home use, in practically all parts of the 

 cotton belt. A few varieties will even grow and bear 

 fruit along the Gulf coast and in Florida, though 



