We have a well-established (perhaps, 50 years) Meyer lemon, which is a prolific bearer, despite the presence of a quite severe black-spot infestation when we 'inherited' it 2 years ago. The black spot we now have pretty well under control, by spraying and thinning of the branches. Last summer (it is now spring here, see below), the tree was subject to fruit-fly attack, which we also attempted to curb by spraying. The current, heavy, crop is badly affected (perhaps 25%) by the presence of brown lesions (similar to the sunburn lesions reported elsewhere, e.g. from Arizona) on one side of the individual fruits which eventually turn spongy-rotten. What is the likely cause of this problem? We are in Canberra, Australia, which has a relatively mild continental climate (frosts in winter, with temperatures seldom lower than 6 C; summer temperatures getting into the low 30s). Could the problem with the fruit be due to frost? Or could it be due to fruit fly (which one would hope would be neutralised by the frosty conditions)?
