December 5, 2007

South Texas Sago Palm Pest Headed North

Writer(s):
Rod Santa Ana, 956-968-5585,r-santaana@tamu.edu
Paul Schattenberg, 210-467-6575,paschattenberg@ag.tamu.edu

Contact(s):
Molly Keck, 210-467-6575, mekeck@ag.tamu.edu
Dr. Boris Castro, 956-968-5581, b-castro@tamu.edu
David Rodriguez, 210-467-6575, dhrodriquez@ag.tamu.edu

SAN ANTONIO – A pest known to be a threat to landscape plants in South Texas appears to be making an unwanted appearance farther north, according to Texas Cooperative Extension experts.

"We’ve learned that there are instances of cycad aulacaspis scale infestation in and around the Bexar County area," said Molly Keck, Extension entomologist and integrated pest management specialist for the county. "This can cause serious damage to sago palms, which are very popular landscape plants in the area."

The sago palm is not actually a palm but a cycad, said David Rodriguez, Extension horticulturist for Bexar County.

"Sagos have become a very popular landscape plant in South and Central Texas due to their palm-like appearance and generally hearty and slow-growing nature," he said. "They typically don’t have many insect problems, but the aulacaspis scale pest can do serious damage. And if left untreated, it can kill the plant."

Cycad aulacaspis scale is also known as Asian cycad scale and sago palm scale. The pest originated in Thailand and was introduced into the U.S. in Florida in the 1990s.

The pest was reported in the Rio Grande Valley in 2004, said Boris Castro, Extension entomologist with the Texas A&M University System Agricultural Research and Extension Center at Weslaco. In 2006, it reached outbreak levels there.

“Currently this scale continues to cause tremendous economic losses here in the Rio Grande Valley,” Castro said. “The landscape industry has lost millions of dollars in sales and in expenses to control this pest. And while infestations don’t appear to be as heavy this year, the damage is more visible now, especially in sago palms growing in the lower Valley, nearer the coastal area.”

The tiny, white, flat, scale-like pest damages sago palms by sucking the juices out of their leaves, also called fronds, Keck said.

"One of the initial indicators of a possible infestation by this pest is yellow spots on the leaves," she said. "The insect can reproduce quickly and prolifically, so the infestation can spread rapidly and possibly kill a plant within a month."

The insect has a waxy exterior that resists penetration, making it difficult to control through many insecticides, she said.

"It also has no known natural enemy to help keep its spread in check," she said.

Castro, one of the authors of the Extension publication "Pest Management Suggestions for Cycad Aulacaspis Scale in Landscapes," added there are several effective cultural and chemical controls for the pest.

Education and vigilance are key to reducing plant damage, he said.

“Stay informed about the latest information about this very destructive pest and keep an eye out for early infestations,” he said. “They are much easier and cheaper to treat when infestations are still low. Once infestations become severe, your options are reduced to either heavy pruning or total destruction of the plant.”

For homeowners, pressure-wash spraying both sides of the plant fronds is an effective means of dislodging the scales, he said, as is the regular application of an insecticide labeled for use against the pest.

There are several low-cost insecticides available at garden centers for controlling scale insects, Castro said. Homeowners can manage the pest by using horticultural spray oils or insecticidal soaps.

Castro also suggested pruning any infested fronds and disposing of the cuttings in a double-sealed plastic bag to prevent reinfestation.
Keck noted the only reports of cycad aulacaspis scale in Bexar County to date have been of sago palms already planted for landscape use.

"There’s been nothing reported about a possible infestation in a sago palm at a nursery, commercial greenhouse or other commercial landscaping business," she said.

Although "green" industry businesses generally do a good job of identifying and managing pests, Rodriguez suggests carefully inspecting the fronds of any sago palm intended for home or commercial landscape use.

"Look for tell-tale signs such as the typical yellow spots and give it a close look to see if you can find any clusters of small, scale-like shapes, which are predominantly found on the underside of the fronds" he said. "If you find them, inform the nursery manager and the Texas Department of Agriculture. And if you have a plant you suspect has the scale, you can bring a sample to your local Extension office for evaluation.”

Homeowners should also inspect their sagos on a regular basis to determine if any scales are present, he added.

While there don’t appear to be too many instances in Bexar County where the pest has been spotted, it is important to know that the wind can spread the pest or it can "hitch a ride" on gardening tools, as well as spreading through more direct means of contact and infestation, Keck added.

Extension continues to work with other agencies and organizations to monitor the scale situation and develop long-term solutions to controlling this pest, noted Castro.

Free information on management of cycad aulacaspis scale http://insects.tamu.edu/extension/publications/epubs/CAS_control_tips-landscape4.pdf