I am based in Melbourne, Victoria and own a small 'Variegated Lisbon Lemon' tree. It is about 5 foot high and initially when purchased, featured approx. 8 or 10 healthy mature lemons. Between Feb and late Oct 07 the tree held no fruit, however since early November 07 it has produced and is currently growing 18 - 24 very small 'baby' lemons.

On return today from a 5 day break away, we found 10 or so of said 'baby lemons' on ground (we watered before going away and do so approx. 1 - 2 times per week on average whilst at home during Spring and Summer months). The leaves and branches - on most of the upper-half of the tree, are covered with brown and yellow 'blisters' and there are hundreds of ants crawling over same area.

Any advice/knowledge as to what this condition is and how I go about rectifying the situation would be greatly appreciated.

Many thanks in advance...