DISEASES OF PLANTS 



247 



Potatoes, sweet potatoes, and carnations are attacked by 

 a similar fungus. 



The wilt of squash and pumpkin is due to bacteria. 



Scaff of apple and pear. The well-known scab of fruit 

 (figure 146) has caused great loss to pear growers and also 

 affects apples. It 

 can be checked by 

 spraying. (Idaho 

 Experiment Station, 

 Bulletin 39; Utah, 

 49, 65; Washington, 

 64, 75, 83.) 



Potato scab. This 

 well-known disease, 

 which causes much 

 trouble, is best 

 treated by dipping 

 the seed potatoes in 

 formalin. (Idaho 

 Experiment Station, 

 Bulletin 52; Wash- 

 ington, 83 ; Wyo- 

 ming, 32.) 



Split pit. This 

 is seen principally 

 in peaches. The 

 pit splits and may 

 become cracked into 



Small pieces. A good FlG 147 _ Toa d s tool fungus on cherry trees. 



deal of gum is also 



produced around the pit, and this may appear on the out- 

 side of the fruit. The cause is not known, but it does not 

 seem to be due to a parasite. 



