McSorley, R., K.-H. Wang, and G. Church. 2004. Fumigant alternatives to me- Weingartner, D. P., J. R. Shumaker, and G. C. Smart, Jr. 1983. Why soil fumi- thyl bromide for managing nematodes and weeds in snapdragon. Proc. gation fails to control potato corky ringspot disease in Florida. Plant Dis. Fla. State Hort. Soc. 117: (in press). 67:130-134. Obenauf, G. L. (ed.). 2002. 2002 International Research Conference on Me- thyl Bromide Alternatives and Emissions Reductions. Methyl Bromide Al- ternatives Outreach, Fresno, CA. Proc. Fla. State Hort. Soc. 117:305-307. 2004. MANAGEMENT OF CYCAD AULACASPIS SCALE, AULACASPIS YASUMATSUI TAKAGI CHRISTINE EMSHOUSEN1 (Walters et al., 1997). The infected area included Fairchild Montgomery Botanical Center Tropical Botanic Garden and Montgomery Botanical Center, 11901 Old Cutler Road both of which have collections of rare and endangered Miami, FL 33156-4242 cycads. Concern for their collections led these two gardens to seek an identification of this pest so control measures could CATHARINE MANNION AND HOLLY GLENN be established (Howard et al., 1999; Walters et al., 1997). University of Florida, IFAS Initially, the scale insect was thought to be Psuedaulacaspis Tropical Research and Education Center cockerelii (Magnolia white scale), which is common in the area. Homestead, FL 33031 However, the control methods often used for P. cockerelii did not seem to be effective and the infestations of scale appeared to be Additional index words. Aulacaspis yasumatsui, cycads, Florida more intense than in the past (Howard et al., 1996; Walters et ornamentals, ornamental diseases al., 1997). Dr. Avas B. Hamon, Division of Plant Industry, Flori- da Department of Agriculture and Consumer Services, Gaines- Abstract. Since it was first introduced into south Florida in 1995, ville, identified the scale pest as Aulacaspis yasumatsui Takagi Aulacaspis yasumatsui Takagi (cycad aulacaspis scale) has (cycad aulacaspis scale). The identification was confirmed by been attacking popular landscape cycads and spreading rapid- Dr. Douglas R. Miller Systematic Entomology Laboratory, ly. This pest is now found in Florida, Texas, Hawaii, Puerto USDA-ARS-SEL, Beltsville, Md. (Howard et al., 1996). Rico, U.S. Virgin Islands, and Guam. Plant death and damage After the scale’s identity was confirmed, a survey of south caused by A. yasumatsui is having a marked effect on the or- Miami was conducted in Oct. 1996 to evaluate the extent of namental cycad industry and has become a major concern for the scale infestation (Howard et al., 1999). From Oct. 1996 to nursery professionals. The spread of A. yasumatsui to other June 1998, (Howard et al., 1999) examined hundreds of in- countries through plant sale and trade is also a serious con- cern as it could threaten native cycad populations. Previous re- fested cycads in the south Miami area. By 1997, cycad aulacas- search on 1 gallon potted cycads indicated that an insect pis scale (CAS) infestations had been discovered in Miami growth regulator, pyriproxifen, applied as a foliar spray provid- Beach and cities north of Miami. By the following year, CAS ed excellent control of this pest and did not cause any plant tis- had spread to Broward County, and by 1999, CAS had been re- sue damage. An additional study was conducted to evaluate ported in Palm Beach County, Hong Kong, Hawaii, and the the effectiveness of pyriproxifen on light and dense infesta- Cayman Islands (Weissling et al., 1999). Most recently, CAS tions of A. yasumatsui on cycads ranging in size from 1 foot to has been reported to be attacking cultivated C. revoluta on the approximately 10 feet tall growing in a landscape situation. We island of Guam and there is concern that if it is not controlled, observed that pyriproxifen provided excellent control of A. ya- it may spread to the native C. micronesica (Marler, 2004). sumatsui on lightly infested plants, adequate control on dense- This pest has spread rapidly and has a wide host range ly infested plants, and did not cause any plant tissue damage. among cycads (Howard et al., 1999). If uncontrolled, it is a threat to the ornamental cycad nursery industry as well as a In 1995, residents of south Miami first began to notice a threat to native cycad populations around the world. white scale insect infesting Cycas rumphii Miq. and C. revoluta Initially, pesticides and oils recommended for armored Thunb. which had, until then, been low maintenance cycads scales were used to manage CAS. This has included foliar ap- (Walters et al., 1997). By 1996, this pest had infested many plications of horticultural and fish oils, insecticidal soap, or C. rumphii and C. revoluta in an area at least several square ki- drenching with dimethoate (previously sold as Cygon) or lometers in south Miami (Howard et al., 1996; Weissling et al., malathion (Walters et al., 1997; Weissling et al., 1999). 1999). Plants were quickly covered in layers of live and dead Disadvantages of these methods of control quickly be- scale that looked like a white crust. The cycads rapidly began came apparent. Applications of horticultural or fish oils are ef- to lose leaves as the scale infestation continued. Within a year, fective in controlling CAS only when infestations are light and many large plants in the southern Miami area were dying good foliar spray coverage is possible. In addition, oils need to be applied weekly or at least biweekly until the infestation is 1Corresponding author. under control (Hodges et al., 2003; Walters et al., 1997). Proc. Fla. State Hort. Soc. 117: 2004. 305 Conversely, dimethoate and malathion can more quickly C. angulata R. Br., C. taitungensis C.F. Shen, C. edentata De control a heavy infestation of CAS although use of Laub., and Stangeria eriopus (Kunze) Baill. With the exception dimethoate or malathion has its own disadvantages. They are of C. edentata, one plant of each species was sampled. S. eriopus broad-spectrum insecticides, which can be toxic or dangerous was included in this study because we have observed heavy in- if used inappropriately. In addition, many suppliers have festations of CAS on this species at MBC. MBC was selected for stopped carrying dimethoate. Both dimethoate and the location of this study because there are more than 3000 malathion can cause phytotoxicity to new growth on cycads cycads in the ground and available for scientific study. (Emshousen and Mannion, 2004). The spray solution was mixed at a rate of 12 fl. oz. product In more recent years, University of Florida, IFAS research- per 100 gal of water in accordance with the Distance label. ers have evaluated some of the newer classes of insecticides The mixed solution was applied as a foliar spray to both sur- for control of CAS. Research trials conducted at the Tropical faces of leaves, cones and trunk. The spray was applied with a Research and Education Center showed that two systemic in- 300-gal high-pressure sprayer until the point of runoff. secticides recommended for scale control, imidacloprid After 40 d, Mannion and Glenn removed two samples from (Merit or Marathon) and thiamethoxam (Flagship) did not each of the nine plants. One sample from each plant was taken provide adequate control of CAS (C. Mannion, University of from a heavily infested area, such as a leaf base, and a second Florida, personal communication). sample was taken from an area with a lighter infestation, such Pyriproxifen (Distance), an insect growth regulator, has as a distal leaflet. Twenty female scale insects were examined also been evaluated and shown to provide excellent control of on each sample for mortality of the females and eggs. CAS. There are several main differences between pyriprox- ifen and broad-spectrum insecticides. Pyriproxifen does not Results and Discussion provide a contact kill, but rather inhibits production of viable eggs by females, sterilizes females, and inhibits metamorpho- Pyriproxifen’s ability to control female scale and eggs was sis of immature scale. Since pyriproxifen is a narrowly target- encouraging. One hundred percent of female scale and eggs ed insect growth regulator rather than a broad-spectrum on the lightly infested sample of S. eriopus were dead. Of the insecticide, it is less likely to disrupt any control by biological nine samples taken from lightly infested portions of the sam- parasitoids. It is also less likely to inadvertently harm either pled plants, six samples contained 90% or greater female the applicator or the immediate environment. Since py- mortality and female scale with all dead eggs. All samples tak- riproxifen breaks the life cycle of the scale by preventing de- en from lightly infested portions of sampled plants contained velopment, it takes a full life cycle before control of the pest at least 75% female mortality and 75% of females with all can be established. dead eggs (Table 1). Based on these results, pyriproxifen C. Mannion and H. Glenn first began evaluating pyriprox- broke the scale life cycle and was able to provide a high de- ifen for control of CAS at TREC in 2002. They initially exper- gree of control on lightly infested areas of the plants. imented with foliar applications applied to C. revoluta in 1- Pyriproxifen did not control scale as well on densely in- gallon pots. Female scale on leaf samples were examined un- fested samples. Of the nine samples taken, two samples, S. eri- der a microscope for mortality of females and eggs. Results in- opus and C. media, showed excellent control of CAS by dicated that, although pyriproxifen was slower to act in pyriproxifen (89% or greater female scale mortality and fe- controlling CAS than some broad-spectrum insecticides, males with all dead eggs). Five samples, C. bougainvilleana, 100% of eggs and 99% of female scale examined were dead C.