Fig are small, attractive trees that produce small fruit that some consider irresistible. There are several varieties of fig, and most of them are susceptible to a variety of diseases. But few of them affect the fig's leaf, making diagnosis a relatively easy task.
Fig rust is a common leaf disease that causes light orange spots on fig leaves. As the disease progresses, the spots grow larger and the affected leaves eventually drop. To treat fig rust, prune the affected leaves. Then, in early May or June when the leaves have reached full size, spray the fig with two applications of neutral copper spray administered in one-week intervals.
Fig mosaic is a fig tree leaf disease caused by a virus. Affected leaves develop large yellow spots, and lightened veins are smaller than the other leaves on the tree. Eventually, leaf and fig production become severely reduced. Since fig mosaic is a virus, the only remedy is to plant another, uninfected fig tree.
Botrytis blight is a fungal disease that often crops up after an unusually cool and wet spring or summer season. The leaves and fruit of an affected fig tree develop brown spots that may house silver-gray fungal spores. To control the infection, prune all affected plant material immediately and remove any leaf litter from the base of the tree. To protect the tree from further infection, apply a neem oil spray to the tree in early spring.