Slime Flux

What to Look For

A fresh infection appears as wet slime or white staining on the main trunk; usually originating from a wound such as a broken or pruned branch. Older infections appear as a yellow-brown discolouration on the trunk or a light-grey/white crust. Slime that drips on to grass or vegetation beneath the infection may cause dead patches. This conditions is very common among Winnipeg’s elms.


Bacterial wetwood or slime flux is caused by various species of bacteria and occurs just under the bark. Bacteria enter the tree through pruning wounds, bark cracks or branch crotches and interact with the sugars in tree sap. This results in the creation of gas and pressure builds beneath the bark until it extrudes through cracks or wounds in the bark. The slime is toxic to the surrounding cambium and may prevent the wound from completely healing itself, though it does not appear to significantly affect tree structure or strength.

 Prevention & Treatment

Be careful when pruning to avoid wounding branches. Protect trees from root damage and soil compaction. Periods of drought may increase the occurrence of slime flux, so watering during drought conditions is recommended.