The paprika-
colored
daylily is
Quannah and
the other is
called Trahlyta.

Asian Cycad Scale

The spring issue of the Master Gardener bulletin (published by the University of Florida) gave us some excellent background and possible treatment for the Asian Cycad Scale. Originating in Thailand and southern China, it is believed to have been accidentally introduced into Florida through the illegal importation of cycads. Since being discovered in the mid-1990's in Miami, the pest has moved rapidly across the state.

I know for sure it's in central Brevard County because both the sagos two doors down from me were almost totally white with scale a few months ago. Since then, the yardmen are using the “cut it all back because we don't care how it looks” method. I don't know if they're using any chemical treatment or not, but they do have a couple funny looking sagos.

The family of plants affected is called cycads. This family includes king and queen sagos, cardboard palms and coonties. The sagos appear to be most vulnerable. Asian cycad scale has been observed on several other cycads, but does not attack them as severely. A list of other species of cycads that are reported to be attacked are listed at Featured Creatures.

Scale insects hatch into a "crawler" stage capable of movement. When they find a suitable spot on a plant, they insert their mouthparts, called stylets (think drinking straw) into the plant and start feeding. Shortly afterwards they begin to create a covering over themselves. They will stay this way until they die.

The pest appears to be spread short distances by wind dispersal of crawlers and long distance by transport of infested plants. If left untreated, the pest will kill its plant host. At its worst, an infestation of this pest can completely coat a medium-sized sago within months and kill it within a year. Heavy investations can include up to 3,000 scales per square inch in several layers. The Asian cycad scale can also infest the roots of cycads. Treatment has to be undertaken both above and below ground.

The University of Florida is always testing ways to defeat this exotic invasive. They feel the most consistently effective treatment is horticultural oils. Be cautious of spraying any chemical in the heat of the day. Spraying earlier in the morning or later in the evening will help avoid damage. Research indicates that the effectiveness of the oil is increased by using Malathion-in-oil rather than oil alone.

Research shows that to prevent new generations of scale from hatching and to control the pest, spray every other week in warm weather and once a month in cold weather. Best results are obtained using a fine spray, so pump-up sprayers using adequate pressure to get into the nooks and crannies are preferable. Any gaps in coverage allow the population to rebound quickly. Treat the soil every other month.

For severe infestations, you may want to remove all the fronds from the sago before beginning chemical application. Please note, this is not recommended as a standard treatment - only on severe infestations. Once the fronds are removed, it's easier to spray the Malathion-in-oil. If you do trim the fronds, bag them, plus other clippings, in plastic bags and secure. They should go to a regular landfill and not be put out with debris that will go to a recylcing facility.

The University of Florida research facility, however, does say that all is not lost. This is just a scale insect, although it's a tougher one to control than what we gardeners are used to. We just need to be diligent and if we use chemical treatment, then we must be very thorough.