Ficus trees tend to be very healthy trees with few problems. However, a number of problems can affect ficus, especially if you are growing them outdoors in United States Department of Agriculture (USDA) Hardiness Zones 10b and 11. Ficus growing indoors occasionally, but very infrequently, suffer from these diseases and problems. Most indoor ficus trees drop leaves due to temperature changes, but do not have problems with most diseases.
Nematodes are soil organisms that can attack the roots and damage some ficus trees. Not all nematodes are harmful, but those that attack can cause the tree to lose leaves and eventually die. Nematodes can be controlled by planting companion flowers that emit natural substances that discourage nematodes. Marigolds are a common flower that repels nematodes. In some cases, however, you may need to use chemical pesticides. If your soils test positive for nematodes and you are having trouble with your ficus, consult your local county agricultural extension for advice specific to your area.
Although not a problem in the United States, the stem borer (Batocera rufomaculata) can be a problem in India. The Batocera rufomaculata feeds on the branches and can sometimes kill ficus trees. In Venezuela, the fig borer (Azochis gripusalis) feeds on new growth and can, eventually, tunnel down and destroy the tree's roots.
Crown gall starts as a swelling on trunks, stems and leaf veins of ficus trees. These swellings eventually enlarge and begin to look like corky growths on the ficus tree. These growths can eventually grow together and deform the trunk or roots. In some case, you may need to remove and destroy severely infected trees. However, in mild to moderate infections, you can try cutting the galls off repeatedly to see if the tree can be saved. If you choose this method, be sure to sterilize your tools before working on other trees.
Xanthomonas Leaf Spot
Xanthomonas leaf spot is generally caused by water pooling on leaves and allowing the xanthomonas bacteria to develop on the tree's leaves. They tend to form between leaf veins and often have yellow borders around the edges of the roundish infection. In many cases, you may need to remove and destroy the tree to prevent spread to other trees. You can try commercial bactericides on single, indoor trees. Increasing fertilizer rates and watering near the roots to keep the leaves dry is a good way to prevent this bacterium.