I grew a grapefruit out of seed about two years ago. It was doing fine until its most recent growth spurt. The leaves are all gnarled, and some of them rotted and fell off. It has gone through a tremendous growth spurt in the last 3 months growing as much as it has in the previous two years. Some of the bottom leaves are developing dry areas, as well. You can see from the pictures what the problems are. Any suggestions as to what the solution is?
I can't see detail good enough to tell for sure, but you probably have citrus leaf miners. If so, you can probably see the little tracks left as the leaf miners work their way through the leaf under the surface layer. They are very small-- the moth is only about 2 mm long, the larvae can be seen with a magnifying glass and the pupate by rolling a cocoon in a fold along the edge of the leaf. The only thing that can kill the larvae is a systemic pesticide that is taken up by the tree, but you can only use that on non-bearing trees. Horticultural oil will usually prevent the moth from laying eggs since they do not like an oily leaf, and there is a pesticide --spinosad-- that will kill the moth and is not persistient.
