Slime fluxes and resinous exudations can be caused by a number of different things. Essentially a slime flux is a leaking of fluid from under the bark. It is frequently a dark colour which stains the stem as it flows to the ground. A resinous exudation is similar, though tends to be associated with conifers which contain resins as a defence mechanism. When the tree is injured resin bleeds from the injury forming a sticky barrier to ingress by fungal and bacterial infection. This will eventually harden to form a crystalised covering. Chewing gum was at one time sourced from the resin of the black spruce (Picea mariana) on the East coast of the United States.
Unexplained leaking of resin, where a wound is not present, like a slime flux, is likely to be an indicator of an underlying illness within the tree. Cankers (discussed previously) may be the source of the flow, but equally such leaking can be caused by root diseases such as Phytophora (the cause of so called ‘sudden oak death’). Unexplained exudations are difficult to diagnose and would likely require further investigation.
