Sometime between last month and today, my orange tree has half died. Half twiggy and dead and half luscious and alive.  If the recent frost is the culprit,  I would have expected to find dried-up leaves and fruit. Moreover, frost would not know to pick on fruit from just that one branch, would it? Or has this half-dead tree been masquerading as a wholly healthy one for months? Or have I been so absent minded not to have noticed.