Why Does My Avocado Look Unhealthy?

Does the fruit have brown or purplish, scablike lesions?

Have the leaves been skeletonized and webbed together?

Are the leaves wilting and are yellow on an entire branch?

Are the leaves pale green to yellow and dropping?

Does the tree declines, leaves are stunted and pale and there is no new growth?

Are the fruits discolored or scarred, twigs may develop red or yellow discoloration, or rectangular cracks may develop in the bark?

Do the trunk or branches have small holes in them, and the limbs are dying or breaking off?

Are the leaves pale and mottled?

Are the leaves stippled with yellow, and the foliage is webbed?

Are the trunk and the branches of your avocado oozing sap through the lesions?

Fruit scab is a fungal disease that can infect avocados. Scab is a superficial skin fungus and not otherwise harmful to the plant. No treatment is necessary unless the infection is so severe that fruit is deformed. For severe infection, apply copper sprays in early May and twice more at 4-5 week intervals.

These symptoms can indicate Avocado caterpillars or omnivorous leafroller caterpillars. The yellowish-green avocado caterpillar is the larva of a reddish-brown moth. Omnivorous leafrollers, yellowish-green caterpillars with a stripe down their backs, are the larvae of dark brown moths. Natural enemies, such as Trichogramma wasps, often keep these pests sufficiently in check. For heavy infestations, spray BTK. Also, look for and crush caterpillars and masses of eggs.

A soilborne fungus Verticillium causes a disease called Verticillium wilt. There is no way to save a tree once it has this problem. Don't plant avocados in soil that has sustained other Verticillium-susceptible crops such as tomatoes, peppers, and eggplants. If you suspect Verticillium fungi may be in your soil, solarize it for 1-2 months over the summer before planting Verticillium-susceptible plants.

San Jose scale causes these symptoms. Look for the small, ash-colored to sooty black bumps of San Jose scale clinging to the bark. Colonies of these sucking, immobile insects cling to the bark and weaken trees by sucking sap. Control scale with dormant oil spray applied in late winter.

Root rot can be caused by overwatering or by poorly drained soil, but the disease may take years to develop. There is no cure. Replant in well-drained soil or on a raised mound of soil. ‘Grande’ and ‘Martin’ are rootstocks resistant to this problem.

Sunblotch is a serious, incurable disease of avocado trees. Infected trees are also often stunted, but some trees show no symptoms at all, aside from a reduction in yield. Once contracted, sunblotch cannot be cured, but by purchasing certified disease-free stock and practicing good tool sanitation, you can stop the spread of sunblotch.

If the trunk or branches have small holes in them the culprits are borers. Numerous borers attack woody plants, mining the inner bark and wood of branches and trunk. Prune off borer-infested branches. If you see borer holes in your trees, probe into them with a flexible wire or inject a solution of parasitic nematodes. After treatment, seal holes with putty.

Lace bugs are flat, dark-colored insects with lacelike wings that feed on the undersides of leaves. They cause leaves to turn yellow, then brown and eventually die. Treat plants with a commercial pyrethrin spray or dust if the damage is severe.

Spider mites are known to cause problems to avocados. You can control spider mites by spraying plants thoroughly with water 2-3 times a day for several days. For severe infestations, spray plants with insecticidal soap or pyrethrin.

Oozing lesion is caused by cankers. Cankers can be caused by several different kinds of fungi. Mildly affected plants will recover if you remove and destroy all affected branches. Heavily affected plants can't be cured and you should remove the whole plant. Avoid damaging your plant with lawnmowers, trimmers or pruning tools because the wounds are the best place for cankers to start.

If the fruits have been gnawed or eaten, the culprits may be birds, squirrels, rats or other small animals. Use traps or physical barriers to get rid of rodents, netting may be necessary for birds.