New Pest in Town Targets Ficus

Leaves showing signs of a ficus whitefly infestation.
February 11, 2013 | 6:00am

A variety of whitefly, whose cousins make a mess of citrus trees and hibiscus, has made its first appearance in our county, and this one targets the widely popular ficus plants. County agriculture officials are asking for help from the public and growers in reporting any evidence of infestation.

The ficus whitefly’s arrival was confirmed after a landscaper turned in a sample found while working in the San Diego neighborhood of Allied Gardens in early December. Inspectors from the County of San Diego Department of Agriculture, Weights and Measures (AWM) then surveyed the surrounding square mile and found further signs of the insect.

“It is a big deal,” said Dr. Tracy Ellis, the County entomologist. “It’s a bad pest.”   

The whitefly affects the plant in several ways. First, it sucks the juice out of the leaves, drying them out. Second, it creates a lot of honeydew, a pleasant-sounding term for what is in fact the insect’s excrement. Unlike some whiteflies that affect only one side of the leaf, the ficus whitefly leaves both sides coated in the sticky white specks of waste.  The honeydew in turn is fodder for a type of mold. The sooty mold blocks sunlight from reaching the leaves, preventing photosynthesis. 

Those factors together can cause a heavy loss of leaves, and if it goes on long enough, kill the plant off.

“It could handle this every once in a while,” Ellis said. But over time, “it’s going to start stressing the tree, and the tree will die.”

It will unfortunately keep spreading.
-Dr. Tracy Ellis, County entomologist

The ficus genus includes hundreds of species of trees and shrubs, from common houseplants to the mighty Moreton Bay fig, a specimen of which is the massive tree outside Balboa Park’s Natural History Museum.  The ficus whitefly likes them all but is especially fond of the extremely popular Ficus benjamina, typically known as the weeping fig or Benjamin’s fig.

No one knows how the ficus whitefly arrived in San Diego. Ellis says it’s likely it hitched a ride to California on some plants, possibly from Florida where it’s heavily established. Shortly before it turned up in our county, it was discovered in Los Angeles.

It’s noteworthy when a new bug appears that targets a plant found as widely as the ficus. But discoveries of invasive insects are almost routine. Ellis said nearly a dozen new pests make their way into California each year that become established, and this is one of them.

“It will unfortunately keep spreading,” Ellis said. ”We have to learn to keep living with these.”

AWM has alerted local nurseries about the ficus whitefly and is working with them to make sure they don’t inadvertently push it into new areas by selling infested plants. The department will also be looking for recommendations from the University of California, which develops methods for controlling agricultural pests. 

Ellis said it’s likely nature will provide some help controlling the spread of the pest. Predators and parasites will begin attacking the whitefly and limit its population. But they will only put the brakes on the expansion, not bring it to a halt.

If one of your plants appears to get ficus whitefly, Ellis said you can wash off the leaves with a high-powered stream of water.  She said it would be extremely helpful if residents, landscapers or growers who find suspected ficus whitefly bring a sample to the AWM offices in either Kearny Mesa or San Marcos. The lab workers need a six to 10-inch branch with infested leaves, placed inside a zip-locked gallon plastic bag. View office addresses and phone numbers