568 



Missouri Agriadtural Report. 



age to many orchards in Illinois. It has since been reported as 

 doing considerable damage in several other states in the middle 

 west. It is due to a parasitic organism gaining entrance into the 

 tree through broken or injured places in the bark. This parasitic 

 invasion extends not on and into the bark, but also into the wood, 



even into the heart wood. This 

 canker is readily distinguished 

 from others because of its char- 

 acteristic appearance. The sur- 

 face of the diseased patches, 

 especially the ends of the patches, 

 is dotted with stromata or pus- 

 tules in which the spores are 

 are born, giving to the cankered 

 area a pitted or blistered appear- 

 ance. If the dry bark be re- 

 moved from the dead portion of 

 an old canker these markings will 

 be plainly seen on the wood. 



Infections may take place 

 through any broken place in the 

 bark, but the most usual place 

 of infection is through wounds 

 made in pruning. Infected areas 

 extend most rapidly along the 

 length of the branch and may in- 

 volve a single branch or the en- 

 tire tree. 



The best treatment of canker 

 consists of extreme care in work- 

 ing about the trees, using every 

 precaution to prevent injuring or 

 breaking the bark, either with 

 picking ladders, harness or culti- 

 vating tools. Cut made in prun- 

 ing should be smooth, made close 

 to the trunk or main branch and 

 well protected with paint. It is 

 possible that some temporary benefit may be obtained from cutting 

 out new cankers and protecting the cut surface well against the 

 weather, but owing to the nature of the disease it is not likely that 

 permanent control can be had in that way. 



lllinoi.s app 



L- u I r r.iiik(.T ( blit-Lcr 

 canker). 



