Citrus leafminers have been regular visitors to Tri-Valley gardens over the past few years. They burrow into the citrus leaf and cause extensive damage to tender new growth. The leafminers thrive in the fresh fall flush of new growth starting August-ish.

Leafminers originate when the tiny adult moth lays her eggs, they hatch, and the leafminer larva burrows below the leaf surface. They hide between the upper and lower leaf surfaces. Younger trees are especially vulnerable. Older trees have tougher leaves so they may be OK without aggressive treatment, but younger trees can lose all their leaves if not treated.

Prevention can be the best cure. Discouraging an overabundance of new growth can be helpful in reducing damage. Our grower recommends a steady, light supply of citrus food monthly as opposed to heavy feedings three times a year, as is common but produces vulnerable soft growth.

Hanging leafminer traps can be helpful for knowing when to spray. Hang traps in at least one of your citrus trees and, monitor them frequently so you can spot the arrival of adult moths. Adult moths happen to be relatively small at just 1/4″ long.  Some have reported the traps alone have been helpful in minimizing the problem.

Protect Pollinators

A concern when applying any pesticide is protecting bees. Only spray plants after the citrus trees have bloomed, so bees are not drawn to the blossoms while at the same time you spray. Citrus trees, for the most part, have long past their bloom period now, but pinching out flower buds if they appear after spraying will prevent the bees from visiting a plant that could cause harm.

Captain Jack’s is our go-to organic spray. It has shown to be an effective treatment for the leafminer, especially when applied early. Try to time sprays between the time adult moths arrive and young leafminers are visible.

Citrus trees are growing new foliage this month. Watch for leafminer activity then spray every 10-14 days. Pinching out affected leaves as soon as damage is detected helps limit citrus leafminer damage.

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