Lemon trees belong to the citrus family. According to CitrusTreeCare.com, the lemon itself is technically a berry. Lemon trees grow best in warm climates, as they are one of the most sensitive citrus plants. Pests and bacteria can damage the trees and fruit. Always consult an expert in your area for advice in the growing, care, and curing of lemon trees and any problems that may arise.
Attacks by Asian citrus leaf miners occur when the developing leaves are approximately 1 inch long. Stunted growth and distorted leaves are signs of infestation. According to Texas Citrus and Subtropical Fruits, the bugs will not kill the lemon trees. However, damage to the lemon fruit may appear. Spray citrus oil to ward off the bugs. Apply the spray when new growth begins to develop.
Scales are small insects. They are most commonly found on the new wood of the tree, but can also be found attached to fruit and foliage. These insects show up as waxy bumps on the lemon trees. They cause the leaves to drop and turn color by sucking sap from the tree, and leave behind a sticky substance that attracts ants. Control and eliminate scales by spraying an insecticide recommended by your local citrus expert.
Signs of the bacterial infection canker on lemon trees are halo shaped yellow scabs and lesions on the leaves, twigs and fruit. In addition to causing blemished fruit and leaf loss, canker can be fatal. It is highly contagious and is spread by humans, birds, air and insects. Prevent canker by spraying lemon trees with liquid copper fungicide. Destroy infected trees to prevent spreading this disease.
Excessive rain and wet soil can lead to root rot. Oozing dark brown patches of bark on the lemon tree trunk are signs of root rot. Root rot dries, cracks and kills the bark, and can also cause fruit to brown and decay. Control root rot by removing all leaves and damaged fruit when they fall from the tree. Keep branches no lower than 2 feet off the ground. Spray the lemon trees with fungicide when root rot is diagnosed. Spray again in the spring.
Orange dog caterpillars eat lemon tree leaves. Chewed and partially eaten leaves are signs that caterpillars are present. One option to rid the tree of these pests requires removing the caterpillars by hand and destroying them. Alternatively, consult a local gardening center for a recommended insecticide and frequency of application.