CARTER: THE WETWOOD DISEASE OF ELM 19 



Efforts have been made to cure wetwood by treating affected 

 trees internally and externally with chemical compounds. None 

 of the treatments reported to date has been successful. 



A tree treated with chemical compounds should not be pro- 

 nounced cured unless the wetwood organism in the tree has been 

 killed. Fluxing is arrested on some wetwood-affected trees by the 

 sealing of wounds with callus growth. Whether or not a tree has 

 been cured can be determined only by laboratory tests on speci- 

 mens from the discolored heartwood and older sapwood. Suitable 

 samples for laboratory tests can be obtained with an increment 

 borer. If the bacteria are still alive in the discolored wood, al- 

 though fiuxing has ceased, the tree has not been cured ; only the 

 fluxing has been arrested. 



