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Deformed, twisted citrus leaves

Question: Hi chuck I have a lime tree with most of the leaves twisted and with slime clear like if a molusk were snail were passing throughout the leaves what this could be an what will be the best product to treat it?



You have a very common but not too harmful citrus leafminer. It will not kill trees but will deform the leaves. There is no good treatment because by the time you see the damage the culprit (a small caterpiller inside the leaf) has dropped to the ground to pupate. It is one of those pests in Florida that we must tolerate. There are parasitic insects that prey on the leafminer and these parasites have reduced the leafminer population to some extent. The biggest problem, however, is the leafminer wounds the leaves making them more susceptible to both citrus canker bacteria or citrus greening bacteria, which are big problems now in Florida.

Here is an excerpt from a University of Florida publication

Citrus Leafminer

Adults of the citrus leafminer (Phyllocnistis citrella) are tiny moths that hide within the canopy during the day and emerge at night to lay eggs individually on young, expanding leaf flushes. The egg first appears as a tiny dew drop, usually alongside the midvein on the underside of an unexpanded leaf. The larva emerges directly into the leaf tissue, mining first along the midvein, then back and forth as it makes its way to the leaf margin, where pupation occurs.

Leafminer populations decline to their lowest levels during the winter, due to cool temperatures and the lack of flush for larval development. Populations of leafminer build rapidly on the spring flush, although their presence is not apparent until late spring, as populations increase while the amount of new foliage decreases. Throughout the ensuing warm season, leafminer populations vary with the flushing cycles, and subsequent flushes are often severely damaged. The summer period of high leafminer damage coincides with the rainy season when canker spread is most likely.

Citrus leafminer greatly exacerbates the severity of citrus canker caused by Xanthomonas axonopodis pv. citri. This insect is not a vector of the disease. Nevertheless, leafminer tunnels are susceptible to infection much longer than mechanical wounds. Tunnels infected by canker produce many times the amount of inoculum than in the absence of leafminer. Control of leafminer should be optimized in areas where infection by canker is high. Natural enemies already present in Florida have responded to leafminer infestations, causing up to 90% mortality of larvae and pupae. These natural enemies include the introduced parasitoid Ageniaspis citricola that has established throughout most of Florida and is responsible for up to 30% of this mortality, mostly later in the year.