My little kumquat (1.2m tall) was doing very well, apart from attack by citrus leaf miner, for which I sprayed with a systemic insecticide some while ago. Later, it started bearing a good crop of flowers.
More recently, the leaves have started falling off, while still green. They first develop a central brown blotch, and they are not fully withered when they drop off. I can find plenty of web sites that show all sorts of leaf problems, but none match these symptoms. The remaining leaves seem to be more firmly attached, and do not have the brown blotch. ...So it is the older leaves that are most-affected. In principle, this sounds a bit like normal shedding of the old leaves, except: the brown blotch, no sign of the usual yellowing preceding leaf-fall, happening all of a sudden, and all the flowers and fruitlets have dropped off, too.
I wonder if it is my fault. Most of the irrigation goes down a 50mm pipe straight to the roots, but I recently increased irrigation, including at the surface. The base of the trunk has been getting wet, and has been exposed to the hot sun. I'm afraid I may have cooked the wet base of the trunk...
Yesterday, I ceased surface watering, and I built a little cairn around the base of the trunk (close, but not touching), to keep the sun off (see photo).
I would appreciate any opinions on:
- identification
- treatment
- significance for adjacent Citrus, Prunus and olive trees
Regards,
Mike