346 



MANUAL OF FRUIT DISEASES 



times witches'- 

 brooms are formed ; 

 these may attain 

 a diameter of two 

 feet. 

 Cause. 



The Pacific Coast 

 rust fungus may 

 properly be called 

 Gymno sporangium 



FIG. 96. - Pacific Coast rust on pear-fruit. Ubocedri. Sporidia 



developed from teliospores on the incense cedar are blown 

 for a considerable distance to the pear and other pomaceous 

 fruits, where they cause infection. Within a few days after 

 the pear is inocu- 

 lated by sporidia, 

 spots become visi- 

 ble on the affected 

 organ as a result 

 of infection. 

 Within a month 

 or less after inocu- 

 lation mature secia 

 are present. 

 From the secia 

 great numbers of 

 seciospores are pro- 

 duced. These are 

 liberated and are 

 carried by the 

 wind to the incense 

 cedars, where in- 

 fection results. 

 The mycelium of 



FIG. 97. 



Pacific Coast rust of pear ; telial stage on 

 incense cedar. 



