Our Black Jack fig tree is in its second year. This past year, it developed a brown-leaf problem. About 15 percent of the young tree was affected. The leaves eventually dry up and fall off.
New leaves did grow back in. I took a leaf to my local nursery. They didn't know what was wrong, but recommended I flush out the soil.
It doesn't seem to be helping. No fruit developed, either.
Al Ramirez, Sacramento
According to UC master gardeners, two publications from the University of California "Pests of the Garden and Small Farm" and "The Home Orchard" do not specifically address the problem you described.
"Sunset Western Garden Book" indicates that you are in the correct zone to grow figs. An Internet search, including the UC Integrated Pest Management site, did not reveal any brown-leaf problems associated with figs.
Maybe you are not giving your young tree enough water during its growing season, and possibly not frequently enough. Or the root zone is not thoroughly watered. Check to see how far moisture is penetrating the soil by pushing a long screwdriver into the dirt at the drip line around your tree.
There is another possibility. Fig leaf rust, a fungal disease caused by Cerotelium fici, can cause fig leaves to develop brown or rust-colored spots, usually on the underside of the leaves.
The leaves will gradually change from green to yellow to brown. Eventually, they die and drop off, preventing the tree from producing fruit.
Rust winters over in the dead leaves and mulch around your tree. It becomes active again after spring rains as the weather warms. To stop it from coming back in spring, thoroughly clean up the tree debris and dispose of it. Replace the mulch, too.
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