On Sat, 12 Nov 2011 17:47:20 +1100, Richard Sherratt
wrote:

We planted a dwarf lemon about three years ago. It flowers, but not
abundently and seems to produce a few little starter fruits about 2 to
3mm in diameter, but they all drop off after a few days. If you touch
one that's sstill attached, it dropos off immediately. It's a "Lots
A' Lemons".

It's in in a terracotta pot with internal measurements 520mm dia by
510mm deep. The pot previously had a cumquat bush that thrived
(cumquat marmalade in big batches - yum), but I totally replaced the
old dirt with terracotta potting mix.

The pot's sitting on a paved surface and might not drain particularly
well.

It's been fed and watered according to the instructions on the tag
that came with it. It might have been over-watered for the first year
before I bought a soil moisture meter. It's had leaf miner attacks
which we handled by spraying and removing affected leaves. Some of the
leaves turn yellow.

Any thoughts?

Could be overwatering or deficient in nitrogen (lemons are heavy
nitrogen feeders)? That potting mix may well be clapped out by now, or
possibly wasnt that high in nutrients to begin with.

You're in Melbourne, but I'm guessing the weather is fairly warm and
the tree hasnt been exposed to frost?

I'm leaning towards lack of nitrogen...