Asian Scale

The Palm Society of South Texas (PSST) is providing the following information as a public service in an attempt to help highlight a serious problem that is affecting many of our members and fellow palm/cycad collectors. PSST is not attempting to take credit for any of the work cited below or any of the links provided. On behalf of PSST, we hope the promulgation of this information may some how help control this epidemic.

Sincerely, PSST

Attached are several links below including articles from agricultural extensions in Florida and Texas. Additionally some articles from other newspapers and some interesting treatment methods for homeowners.

Following the links is an email received from a Master Gardener in Nueces County


From: Linda T. Collins

Sent: Friday, January 14, 2005 5:04 PM

Subject: Asian Cycad Scale

I attended a tree conference in Corpus Christi, Texas on January 11, 2005. One of the speakers was Dr. Michael Womack, County Extension Agent for Nueces County, Texas. He spoke about the Asian Cycad Scale, and here is some good information about it. Asian cycad scale has been found on Padre Island September 3, 2004 If your sago palms look like they've been sprayed with artificial snow in preparation for the Christmas holidays, you've probably got a major problem recently discovered in the Coastal Bend. The pest on your sago is known as cycad Aula-caspis scale or Asian cycad scale.

Asian cycad scale first entered Florida in 1996 and rapidly moved throughout that state. It is one of the few major pests known to affect sago palms and other cycads. Scales are sucking insects that often appear like small immobile scabs on the plant leaf. Soon after the insects hatch they insert their straw-like mouth parts, known as a stylet, into the leaf and start sucking. Shortly afterward, they produce a waxy white coating over themselves and stay there until they reproduce and die. Heavy infestations can result in layers of scales numbering as many as 3,000 per square inch, producing the dense white flocked appearance.

Infestations usually begin on the underside of leaves and then move to the upper side and stems. A medium-sized sago can be completely coated with scale within a couple of months. Asian cycad scale is also unlike other scales in that the crawlers can attack roots and have been found up to 24 inches deep. I recently learned about this insect problem at a conference from an extension entomologist with the University of Florida's Institute for Food and Agricultural Sciences. Within two weeks of returning, I had a report of something killing sago palms on Padre Island. Since then, Texas Cooperative Extension and the Texas Forest Service are coordinating a public awareness program with the assistance of Master Gardeners to provide treatment information. Further investigation with local nurserymen revealed that the problem has been around for about two years. In 2003, Asian cycad scale also was found by Texas Department of Agriculture inspectors on a shipment of sago palms from Florida about a year ago, but the department believed that all infested plants were quarantined and then either treated or destroyed. The spreading of the problem can happen in a number of ways. More than likely, the crawlers have moved by wind, people, animals, and lawn maintenance equipment. If fronds are cut from an infected sago palm and then the same clippers are used on a healthy plant, the crawlers and/or its eggs can infect the other plant. Clippers and equipment used around Asian cycad scale-infested sago palms needs to be cleaned using a 10 percent bleach solution before moving to a pest-free plant. University of Florida entomologists recommend soaking tools for 10 minutes in 10 percent bleach solution (one part bleach to nine parts water). While this may not be practical, especially in commercial situations, a quick dip doesn't apparently kill these critters.

Commercial landscape maintenance personnel are recommended to have two to three sets of clippers that can be alternated in bleach to minimize time delays. Infected fronds should be double-bagged in plastic bags and incinerated or buried far away from other cycads, and not just simply sent to a landfill and ground into mulch. Luckily, the insect is essentially stationary so you don't have to worry about a swarm of Asian cycad scale moving across the Coastal Bend. It takes several months of heavy infestation to weaken a sago palm to the point of death, but some of these hardy cycads have already fallen victim to the Asian cycad scale.

How do you control it? Simply removing the white fronds usually doesn't provide control since the crawlers are also found on the roots and will quickly result in re-infestation. Frond removal is not recommended except on severe infestations. The most consistently effective treatment is spraying infested plants every two weeks with lightweight horticultural oil but spray coverage must be thorough to both the top and bottom of fronds. Combining oil treatment with Malathion can increase its effectiveness. The pre-mixed product known as Malathion-in-oil is commercially produced, but homeowners can mix their own in a pump-up sprayer as long as the label directions on both bottles are followed. Systemic insecticides such as imidicloprid (Merit) or acephate (Orthene) have not proven to be consistently effective.

After the fifth or sixth bi-weekly application, plants need to be sprayed down hard with a garden hose to loosen dead scales. Preventative monthly treatments can then be used to keep the pest in check until biological control populations are established. The key is to treat thoroughly. The major infestation appears to be localized on the Padre Island in the Eaglesnest and Hawksnest Bay Drive areas; however, it may be in other areas of Padre Island, Corpus Christi or the Coastal Bend without our knowledge. It is extremely important to document the infestation to aid in coordinated control efforts. If you see the flocked appearance on the underside of your sago palm leaves, please call the Master Gardener Hotline at

361-767-5250.

A fact sheet on Asian cycad scale has been developed to help homeowners identify and treat the problem. These publications are available at area nurseries and from Texas Cooperative Extension. Dr. Michael Womack is a horticulturist with Texas Cooperative Extension in Nueces County. He said that it had come into Texas by way of Florida, and if anyone sees any of it here in south Texas, to be sure to contact him.