When deciduous trees lose their foliage, somtimes it gives us the opportunity to spot defects and issues otherwise not at all discernible (by virtue of the foliage obscuring vision). In the case of the below hybrid black poplar, this was indeed the case, for atop the structure sat some blackened and weathered fruiting bodies (sporophores) of the common wood-decay fungus Cerioporus squamosus (formerly Polyporus squamosus).
Clearly, the heavy pruning the tree has suffered previously facilitated (one would expect) in the ingression of penetrative hyphae, following the germination of a spore upon the exposed sapwood, given this species’ typical colonisation strategy (sapwood exposed – unspecialised opportunism). To be honest, it’s in fact rather typical of poplars (and willows, as well as some maples) to have some quite awesome decay columns following heavy pruning, and thus this poplar fits the stereotype quite nicely.
What’s next for this poplar? One would at least propose a reduction, and potentially push a heavier one, though the sporophores are isolated to this one region and therefore perhaps the other limbs are not colonised. Granted, this is perhaps wishful thinking, as there is a good chance the entire upper crown is colonised, and either the colonies didn’t fruit or the fruiting bodies fell and were then moved (as there could be more than one secondary mycelium – where two separate and genetically-different hyphal structures meet and reproduce spore sexually via basidia).
It always pays to look up.