· John Heider's Answer
· Elaine-A tree with yellow or cupped leaves, or leaves that don't look perky after watering can indicate excessive watering and soggy roots. Give your tree water less often. Citrus prefer infrequent, deep watering to frequent, shallow sprinklings. Creating a watering basin around the tree's drip line can aid in deep watering. Deeper watering promotes deeper root growth and strengthens your tree. Generally, once or twice a week deep watering works well for a tree in a container. Be sure to adjust your watering based on weather conditions. If this is a newly planted tree it could be experiencing some transplant shock. Usually yellowing and dropping of leaves will happen if this is the case. The tree will sprout new growth in a short period of time. Keep it moist, but not wet. Too much water can cause root rot.
Yellowing leaves usually indicate lack of fertilizer or poor drainage, too much water. If you haven't fertilized lately you can fertilize using a citrus/avacodo food. These fertilizers will usually contain trace minerals like iron, zinc, and manganese, that will also help in the yellowing of leaves.
If no spotting of leaves or signs of insects are apparent checking for too wet a soil and fertilization should help with the yellowing leaves.
Hope this helps.