In your experience are leaves retained in winter on apple branch tips a sign of blight in every case or only sometimes?
In the past I always automatically removed all such branches down to at least two or three year old wood. But this year I don’t find any blight cankers or shepherd’s crook twigs in these trees, so am not sure.
For many years, decades really, the mummified leaf at tip of apple branch in winter has reliably signaled blight once I take a closer look. Even a mummified apple stem (or apple) hanging on in winter is a red flag for me.
I hope this isn’t always the case. My trees have held leaves a lot longer than I expected. I chalked it up to a hard summer prune due to suspected hits causing excessive growth at the wrong time. I was concerned about cold damage. I guess I can add another concern to the list.
I find the leaves stay on shoots that had extra vigor during the growing season, e.g. a new graft on a big root or similar. I don’t associate it with fireblight at all.
The main clue for fireblight in the off season is black marks on the trunks or shoots. Those get a nice blowtorch treatment if big, and pruned off if small. Currently I have almost no fireblight in my orchard, many susceptible varieties were culled and I am getting plenty of sun in by pruning.