The tree looks like it had improper pruning cuts with cutting into the branch collar. It looks like the typical sap flow we see on trees when pruned in late winter (birch, maples, etc.). The sap does not harm the tree, but I can't be sure it if there is a pathogen present on the twigs. Poplars are very susceptible to a variety of pests and diseases. I don't see the typical herbicide damage, but again knowing what the neighbor applied to the lawn last year would really help. Laura
Check for any softening in the wood around the bleeding area that might indicate an infection of some kind. Most likely though the tissue will be firm. The bleeding area may get very brightly colored (orange or pink) eventually if yeasts and other fungi start to colonize the sap. This is a common cosmetic (and often, for clients, disturbing) phenomenon. The colored growth will disappear when the sap stops flowing and dries up. Hope this helps.
Brian (:))
Check for any softening in the wood around the bleeding area that might indicate an infection of some kind. Most likely though the tissue will be firm. The bleeding area may get very brightly colored (orange or pink) eventually if yeasts and other fungi start to colonize the sap. This is a common cosmetic (and often, for clients, disturbing) phenomenon. The colored growth will disappear when the sap stops flowing and dries up. Hope this helps.
Brian (:))
