My willow is oozing a white, foamy substance from its bark....What kind of care should I be taking?
Tri Colored Willow Tree
This sounds like bacterial wetwood, aka slime flux or alcohol flux. Willows are prone to this disease. Bacteria produce gas which makes the sap foamy and often foul-smelling. Check with your state extension service for recommended treatment in your area. Here is what New Mexico extension has to say on the topic. http://aces.nmsu.edu/ces/yard/2000/081200.html