Leaves drying up
On several of my plants, (the tubers where potted up in January) the bottom leaves are drying up and becoming crisp (decidedly dead). Then, the next most bottom leaves are suffering from the same dreaded fate, and so on, like a chain reaction.
what is causing this? I believe the mother plants from last year had white powder mildew, but they show no other signs of this right now. (No powder, nice bright green leaves). I thought perhaps spider mites, but it has been many weeks with this condition, and I can`t see the mites, no leave damage on top, no webs with very careful inspection.
Could it be overwatering?
The leaves seem to turn very quickly, otherwise they look very healthy up until they become affected!!