Citrus leafminer Phyllocnistis citrella
August 12th, 2009
Is your orange tree a little ugly right now? I get a lot of questions related to this particular problem. In the summer and fall, leaves on citrus trees are distorted by the activities of citrus leafminer larvae. The leafminer is a relatively new pest of citrus in California having first being identified here in 2000. They are now a common pest of citrus trees around the world. Luckily, they do not do serious damage to established trees and they have many natural enemies. The larvae affect new, succulent growth. They do not damage older leaves that have hardened off. The citrus leafminer leaves a distinctive curving path as it carves its way through the leaf. These leaves then tend to become misshapen and distorted. This is unattractive. However, those leaves can still photosynthesize and provide food for the tree. Therefore, on young trees it is best not to remove the affected leaves. On more mature trees the affected growth can simply be cut off. While citrus leafminer makes trees less attractive it is often best to leave the trees alone and allow beneficial insects to keep the pests in check. Spraying trees is an option but should only be used in severe cases on very young trees. Even organic sprays can kill beneficial insects that are natural predators of citrus leafminer and other common garden pests. So I recommend doing everything you can to reduce stress and encourage healthy new growth. Maintain a layer of mulch around trees, plant a variety of flowering plants to provide habitat for beneficial insects and provide adequate water. If you need more personalized advice, I’m available to help or for more information check out the University of California integrated pest management site. The University of California provides great scientific information that is helpful to gardeners of all levels of expertise.