248 



AGRICULTURE ON THE PACIFIC SLOPE 



Root rot. This is a decay of the roots and lower "part 

 of the trunk and may be caused by fungi entering from 

 the soil or by fungi entering from wounds made by prun- 

 ing and working their way downward. It attacks the 

 apple, almond, and the stone fruits. 

 Some of the toadstool fungi (figure 147) 

 seem to be the cause of at least a 

 part of this trouble. The best way of 

 checking it is to avoid wounds, and to 

 HBr paint over wounds with tar to prevent 



the fungi from entering. (Washington 

 Experiment Station, Bulletins 59, 83.) 

 Gum disease of citrus -trees. This 

 disease shows itself on the trunk of the 

 tree. Gum breaks out through the 

 bark. The cambium (see page 87) is 

 injured and the tree may die. The 

 root is not usually affected. The cause 

 is usually found to be some unfavorable 

 soil condition, especially irregularity 

 in water supply. 



Beet blight or curly top. A peculiar 

 disease of the sugar beet ; the leaves are 

 stunted and curl in a peculiar way. 

 The roots become blackened in rings 

 inside and the whole crop is sometimes 

 lost. The cause is not known. 



Club foot. This disease is found on 

 the roots of cabbages, turnips, and rad- 

 ishes, producing large swellings or tumors. (Washington 

 Experiment Station, Bulletin 83.) 



Sour sap of stone fruits. Fruit trees sometimes die quite 

 suddenly while in full leaf, commonly in the early spring. 



FIG. 148. Effect of 

 beet blight; the 

 beet is blackened 

 inside in rings. 



