It was suffering from a fungal infection which shows itself as brown spots on the leaves. It's happened several times before to a lesser degree and, although there's no cure, the infected leaves can be simply cut off leaving the unaffected ones on the plant.
However, this time around, every single leaf was discoloured. Previously, these infections had also started during the winter months, particularly in prolonged wet periods, but last winter and early spring had been remarkably dry.
I first thought perhaps that yucca were monocarpic, i.e. they flower only once and then die, but then I remembered I'd seen very much larger specimens in flower in the Canary Islands, and in that climate it seemed unlikely they'd reached such a size without flowering several times before.
So what to do with the plant ? A bit of research on the internet seemed to suggest that the top of the plant could be cut off and, with a bit of luck, it may respond by producing new shoots from the side of the trunk.
So in late April, during a spell of warmer weather, this is exactly what I did, cutting the whole head off the plant and leaving a bare stump of 300 mm height.
|the freshly cut stump ...|