128 



FUNGOUS DISEASES OF PLANTS 



(particularly the work of Waite) has shown that this disease 

 may be controlled or even practically eradicated in large regions. 

 The essential step consists in pruning out the blight in situations 

 where it may winter over. If all of the blight could be thoroughly 

 pruned out of the orchard during the fall and winter, there would 



FIG. 35. BLIGHT CANKER ON TRUNK OF APPLE, FROM INFECTED PRUN- 

 ING KNIFE. (Photograph by H. H. Whetzel) 



probably be no opportunity for infection the following season, ex- 

 cept from distant orchards. In practice the pruning out of the 

 blight during winter is not an easy process, and it requires 

 the greatest care and keenest eyesight. It would be necessary 

 to go over the orchard several times, the final observation being 

 made only a short time before the opening of the blossoms. 



