Kay Easton wrote:

In article , Ken Riley
writes

We are currently carrying in and out of the conservatory (out in the
evening into the warm living room, back into the light conservatory
for the day) a 12inch twig. It had leaves on when we bought it in the
spring and has had lots of flowers but by November we were singing
"four leaves on my lemon" then "three leaves on my lemon". Two weeks
ago the last leaf fell off and on Monday last the pathetic little
half-inch green lemon hit the carpet. Is there any hope for it? Are
we wasting our time carrying it in and out?

Probably, though it may re-shoot if you are very lucky.

Don't throw it out until is is warm enough for it to live outside. I have
had "dead" plants recover from apparently lifeless sticks before. As long as
it is green there is still some hope for next year.

Two things seem to go for citrus:

scale insects - you will see round shiny brown lumps abut 1/8 inch long
on the twig which can be pushed off with a fingernail

Red spider - any fine cobwebs on what remains?

Probably the latter. They seem to be martyrs to it and attract them from
everywhere.
I have even had to spray mine with soft soap in late autumn to keep control
of rsm.

The main symptoms are that all the leaves will drop off if left untreated.

Remove anything you can see, wipe the twig with a damp tissue, and hope.

I also suspect it doesn't much like being moved in and out of warmth.
Thermal shock is bad.

Provided it is kept frost free it may be better off being left somewhere out
of drafts and slightly on the dry side. Not likely to lose much water if it
is entirely without leaves. Mine still has plenty of flowers even now but is
kept in the main living room against a south facing floor to ceiling picture
window.

I am still a bit vague on the correct feeding regime for citrus plants. Any
recommendations ?

Regards,
Martin Brown