Weeping fig tree problems

I have a Weeping Fig tree in my living room. I purchased it in May of this year, and it appeared to be doing well during the hot summer. The window it is in does not give much light so I purchased a grow light. No matter what I do it is loosing leaves. Some of the leaves seem to have a very sticky substance on them, almost as if it is oozing this. A lot of the leaves that drop still look healthy but drop anyway. What is causing this and what can I do? The amount of leaf loss is much more than I would consider normal.

Answer:

You may have several problems. Although a weeping fig can grow in relatively low light, relative to corn or tomatoes that is, it still needs several hours of light of an intensity that would be found under a shade tree that is not too dense. If the window "does not give much light" as you said, how many hours is that light available? The plant needs around six or more hours of that light, if it is bright enough. You state you purchased a grow light. You didn't state which type of grow light, but I assume it was one of the "spotlight" types of grow lamps. These help some but are useful only a short distance from the plant.

If you place it too close, it will burn some leaves, but if it is not close enough it is not effective. In the case of a fairly large plant, most of the tree is too far from the light. The properly lighted portion of the tree also blocks light from the rest of the tree. So self-shading may also be part of the problem. If the lamp is helping, then leaves near the lamp should not be dropping, unless other factors are part of the problem.

That brings up the other concern I have from your description of the tree. You stated that some of the leaves have a sticky substance on them. This sounds like you have a scale insect problem. Even if you have sufficient light, the scale insects can cause the leaves to drop and, ultimately, kill the tree. Look for these insects on the branches, twigs, and leaves above those with the sticky substance. The insects will appear as brown bumps on the stem and twigs or as brown, immobile, lumps on the underside of the leaves and their petioles.

If you discover these insects, you will need to treat the tree with an insecticide, or dispose of the tree. If you have other plants nearby, check them for scale insects as well. If you have many valuable plants infested, you may choose to dispose of some and treat others.

There are various insecticides that you may choose to use. Whichever you choose, read the label before purchasing it to be sure it will kill scale and is labeled for use on the weeping fig, Ficus benjamina, or at least labeled for use on indoor ornamental plants. Insecticidal soaps should be effective but will probably require many retreatments. Unless you are allergic to soaps, there should be no health concerns with using insecticidal soaps. Horticultural oils may also be used if you can find some labeled for indoor use. However, the oils are more likely to cause damage to fabrics and furnishings, so be sure to use the oil in a manner to prevent damage to your home and furnishings. Other insecticides labeled for indoor control of houseplant insects may concern you more. Follow directions carefully, and if you are especially concerned, apply the product outside on a warm day and wait for the insecticide to dry before bringing the weeping fig and other plants back indoors. Wash your hands after treating and after handling the plants as you bring them back indoors. 

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!