Lemon Tree Diseases
and Insect Problems

Some lemon tree diseases you may encounter when growing dooryard citrus. Citrus anthracnose fungus. Citrus Tristeza virus. Bacterial canker. How to treat lemon tree disease.

An Unhealthy Meyer Lemon Tree

Meyer lemon trees were found to be asymptomatic hosts for citrus tristeza virus some years back. Most growers destroyed their trees and Improved Meyer Lemon was used to replace the original Meyer lemon trees. Today, even if you purchase a tree labeled as Meyer, don't worry, it's the improved version.

Tristeza causes stem pitting and quick decline. It will reduce the crop or kill the tree. The disease is spread by aphids.

Citrus canker is a bacterial infection which causes yellow scabs on the leaves and fruit of lemon trees. It can cause the tree to drop its fruit prematurely and lose leaves.

There is currently no cure. To control the disease, spray infected trees with a copper based fungicide every 3 weeks from April through July.

Root rot is probably the disease lemons are most susceptible to. Citrus roots need a lot of air. When the soil is kept too wet, they can't breathe properly. Root rot sets in and causes the tree to decline slowly. The leaves will turn yellow or light green and eventually fall. Trees are most vulnerable during the winter.

Citrus Anthracnose

Anthracnose fungus affects not only citrus but many garden crops. There is no cure. This page is about identifying and choosing a fungicide treatment for anthracnose disease.

There are a few other lemon tree diseases but they are unlikely to trouble dooryard citrus so I won't list them.

Lemon Tree Problems

Leaf miner damage on citrus leaves.

Lemon tree care is simple and you won't have many problems. The few lemon tree problems I've had are listed here.

Leaf miners - These are insects that make gray trails in the new leaves. This is unsightly but does not damage the tree. You can spray the tree with horticulural oil if it gets out of hand.

Photo by Jonathan Armstrong, University of Southern California, Bugwood.org

  • Orange Dog caterpillars like to feed on citrus leaves. Orange Dogs are the caterpillar of the beautiful Giant Swallowtail butterfly.
  • They are an inch or so long and look like a bird dropping.They give off a stink when provoked but are otherwise not harmful. They will, at times, chew a lot of leaves off your trees.
  • As I deliberately plant butterfly host plants in my yard, I do not take steps to stop the feeding. I've never had a tree damaged beyond recovery by the Orange Dogs.
  • You may feel differently and wish to spray. Safer Brand 5160 Caterpillar Killer with BT is a natural insecticide that will eliminate the worms without harming you.
  • Citrus thrips - Citrus thrips damage only the rind of the fruit. Home growers may ignore mild infestations of Scirtothrips citri but commercial growers will want to control the insects as marred skin renders the fruit unsaleable.

  • Yellow leaves on lemon trees - This can be caused by a variety of things. If the tree is kept too dry or infected with tristeza leaves will yellow. The most common cause is lack of iron. Check to see if your fertilizer contains iron.
  •  Leaves also turn yellow when they get old and are ready to fall from the tree. Once a leaf turns yellow, there is no way to make it green again. If you correct the problem, the new growth will be healthy and green. You can pick the yellow leaves off or wait for them to fall naturally.
  • More Lemon Tree Info:

    Lemon Varieties
    Different types of lemon trees. Most lemon tree varieties produce sour fruit but there are also a few sweet lemons.

    Go from Lemon Tree Diseases to Lemon Tree Fertilizer
    Order lemon tree fertilizer here. Fertilizing is an important aspect of growing lemon trees. Lemons have the ability to flower and fruit almost continuously if they are fed following these instructions.

    Go from Lemon Tree Diseases to Botanical Journeys Plant Guides Home

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