Non-native ficus hedges and trees are under attack by fig whiteflies. First observed in Homestead in 2007, fig whiteflies have since spread through Miami/Dade County and north to Broward County, leaving a wide path of defoliation along streets and property lines. A loss of leaves is the most obvious symptom of a whitefly infestation.
Researchers at the University of Florida report that fig whiteflies are seriously injuring host plants by sucking juices from them, which causes wilting, yellowing, stunting, leaf drop, or even death. Fig whiteflies are distinct from and more destructive than the rugose spiraling whitefly.
The adult whitefly resembles a very small moth with a yellow body and white wings with a faint grey band in the middle of the wings. Immature states (eggs and nymphs) can be found primarily on the underside of the leaves. The underside of infested leaves look like they are dotted with small, silver or white spots, which are actually the empty “skin” of the pupae after the adult, emerges.
The life cycle of the fig whitefly, also called ficus whitefly, is approximately one month. Eggs, which are usually laid on the underside of leaves, hatch into a crawler stage. The crawler wanders around the leaf until they begin to feed. From this point, until they emerge as adults, they are immobile and remain in the same place on the plant.
Although efforts to understand and control this pest are ongoing, there are several potential options:
- First you have to determine if you already have fig whitefly. If the leaves of your ficus have not started falling off, shake your plant to see if small, gnat-like whiteflies emerge. You can also check the underside of the leaves for whiteflies in immature stages when they appear as small tan to light green discs with red eyes. A magnifying glass is helpful for detection.
- Monitor your ficus plants for early signs of an infestation, because it will be easier to manage the pest before it builds high populations and causes major damage.
- If you detect fig whitefly, you may want to consider a two-step treatment. The first step is to spray the hedge to immediately kill the adult whitefly population. Spraying is only effective for 7 to 10 days.
- The next step involves applying a systemic insecticide to the root zone. This can be done by what is called “soil drenches.” Mix the insecticide with water and pour it onto bare soil within the root zone of the plant. It is very important that the drench is applied to bare soil, not mulch or fallen leaves. Most systemic insecticides will offer protection for 6-9 months.
- If your ficus does not show signs of whitefly, you should still apply systemic insecticide.
Imidacloprid is the most popular and seems to have the greatest effect. It is the active ingredient in Bayer Advanced Tree and Shrub Insect Control, which is readily available at garden centers.
Systemic insecticides recommended include Clothianadin, Thiamethozam, Imidacloprid and Dinetefuran.
Foliar application should be limited and only used for controlling the whitefly population immediately, while giving time for the systemic chemicals to work.
It is important to note that the most ficus shrubs and trees becoming infested are not native to South Florida, so don’t blame Mother Nature for this nuisance. Most ficus plants used for landscaping are native to India, Asia and Africa.
Using insecticides to control fig whiteflies poses environmental concerns, including the unintended consequence of killing butterfly larvae as well as natural enemies of fig whiteflies, like wasps. An environmentally friendly solution to the fig whitefly problem is to replace non-native ficus plants with plants native to South Florida.
This page includes information provided by the University of Florida Tropical Research and Education Center.