The stems turn brown inside then rot.The plant is growing in gritty soil in a raised bed and the drainage is very good.I guess it is a fungus a bit like a erodium version of the dutch elm disease and the phenomenon was very fast.May be it is the same disease that killed my dianthus last autumn.
Any idea what it is and how to get rid of it?
HELP pleeeeease there is a hole collection at risk!!!!