CARTER: THE WETWOOD DISEASE OF ELM 



17 



ing bark crack (Fig. 17 and 18). This hole should be directed 

 toward the probable location of the crack in the wood or toward 

 the center of the heartwood. The drainage hole should have suffi- 

 cient slant to allow the wetwood sap to flow out, and it should ex- 

 tend through the heartwood to within a few inches of the bark 

 on the opposite side of the trunk (Fig. 19). 



CROTCH 

 CRACK 



DRAIN 

 PIPE 



Fig. 17. — Fluxing at cracks in branch crotches usually can be stopped 

 by a hole bored into the diseased wood. The hole should be bored to one side 

 and 6 to 14 inches below the base of the crack so that it will cross the crack 

 in the underlying wood. It should be slanted so that the toxic sap will flow 

 out through the opening. A drain pipe should be inserted in the hole. 



TRUNK CRACK 

 DRAIN HOLE 



DRAIN PIPE 



:— DRIPPING SAP 



Fig. 18. — Fluxing through a crack in the bark of a trunk should be 

 treated as for a crack in a branch crotch (Fig. 17). The crack in the under- 

 lying wood may not be directly beneath the fluxing crack in the bark; the 

 drain hole should be bored so that it will cross the crack in the wood. 



