16 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 50 



face of the bark. This treatment prevents toxic sap from being 

 taken into the current-season wood and should prevent addi- 

 tional wilt. 



Special care should be taken to assure proper drainage of the 

 toxic sap and gas from the tree affected with wetwood. There is 

 no hard and fast rule for determining where drains should be 





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Hi 



mr/^ 



PRUNING CUT 





DRAIN HOLE 



-DRAIN PIPE 

 •DRIPPING SAP 



Fig. 16. — Fluxing: at pruning wounds may be stopped by a hole bored 

 into the diseased wood where toxic sap and gas have accumulated. The hole 

 should be 6 to 14 inches directly below the wound and slanted so that the 

 toxic sap will flow out through the opening. A short piece of threaded 

 pipe, inserted in the hole only far enough to be firm, will carry the toxic 

 sap away from the tree. 



installed. Effective drainage is usually obtained by installing a 

 drain a short distance below the fluxing region. In some cases, a 

 drain installed at the base of the trunk of a large elm has stopped 

 the fluxing of several wounds along the trunk. A fluxing wound, 

 made where a branch has been removed, usually can be drained 

 through a hole three-eighths to one-half inch in diameter bored 

 6 to 14 inches directly below the fluxing region (Fig. 16). 



A fluxing crack in a trunk or in a branch crotch may or may 

 not respond to the same treatment. In some cases, it may be nec- 

 essary to bore several holes before satisfactory drainage is ob- 

 tained. A crack in the wood may not be directly beneath the crack 

 in the bark through which the sap is fluxing. A bark crack and a 

 wood crack may be so located that a hole bored directly beneath 

 the bark crack will not be directly beneath the wood crack, and 

 effective drainage will not result. As a rule, it is best to bore the 

 drainage hole to one side and about 6 to 14 inches below the flux- 



