August, 1945 



Carter: Wetwood of Elms 



411 



through wounds made b\' the removal of 

 branches, fig. 4, through cracks in crotch- 

 es, fig. 5, and trunks, fig. 6, and through 

 other trunk injuries. This exuding of sap 

 is commonly called fluxing. The sap or 

 flux as it oozes out of diseased wood is 

 colorless to tan but turns dark upon ex- 

 posure to air. When abundant bleeding 

 occurs, the flux flows down the trunk, 

 wetting and soaking large areas of bark, 

 figs. 5 and 6. When it dries, it leaves a 

 light gray to white incrustation on the 

 bark, fig. 7. Ogilvie (1924), who worked 



J\ 



Fig. 8. — Crack in elm trunk wood around 

 which a pocket formed between bark and 

 wood. Such pockets develop when sap and gas 

 seep out through cracks in the wood. 



in England on elm and other trees, suggest- 

 ed that fluxing sap contains calcium car- 

 bonate and forms a white incrustation on 

 the bark upon drying. In some cases, 

 especially when fluxing is prolific or long 



k-^^K '•■'•Wm continued, air-borne bacteria, veasts and 



''''•'"^^^"' J^aH fungi contaminate the oozing sap, ferment 



^Bjfl/ ■■ <l^^9 * "^' '"^"d produce the malodorous material 



commonly called slime flux. Hence slime 

 flux, in the coinmon sense, is the material 

 resulting from an entirely external putre- 

 factive condition which develops only after 

 bleeding has occurred. 



The wetwood flux, when it exudes from 



the tree, is toxic to the extent that it is 



Fig. 7.— Dried flux showing on the bark of capable of retarding or preventing callus 



an elm after the trunk crack from which it formation, and it frequentlv kills back the 



came had closed. cambium at the base of a cut where a 



