In article ,
Martin Brown wrote:

I find that a lot of rosemary grown in the UK is infected with some sort
of fungus that kills off a few branches every year - making it
effectively self pruning. The leaf nodes on the affected branches show a
sort of white fur not unlike woolly aphid but with straight fur. Shortly
afterwards the stem goes brown from the tip and dies back. I prune them
out as soon as I spot any signs of trouble. YMMV

I don't think that it's an infection in the rosemary, initially. In
my garden, it's a similar rot but affects everything from the root
upwards. I am pretty sure that the rosemary is weakened by weather
(and rich soil), and what kills it is just whatever opportunistic
fungi happen to be local to the soil.

Whatever. The solution is to keep renovating it - layering is the
easiest, but people good with cuttings may prefer those. There are
some very old rosemary plants, so that isn't always needed, but it
seems to be unpredictable whether they will be long-lived or not
(though I am pretty sure that it's mainly location-dependent).


Regards,
Nick Maclaren.