Question
Leaves are turning yellow and falling off my two dwarf lemon & lime trees. The lime tree leaves are also curling and have decay spots on them.  Trees are in large pots on patio; watered 2xweek; Phoenix AZ area.  Newly acquired spring 2008.  What can I do to treat the problem?

Answer
Hi Sharon,  If the leaves are falling off in the center and staying on on the ends,  it could be getting ready to fruit, as lemon and limes are everbearing.  The curling of the leaves is the leaf minor which will stop laying her eggs when it gets cold and the leaves will come out nice again till it gets too hot.   If the leaves are falling off all over it may not be getting enough water. Plants dry from the outside in in a container so make sure you water the outside rim and not always the center of the plant  .Black on the ends of leaves means too much water or white veins going down the center of the leaves.   .kathy