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Notes on the Palmetto Weevil, Rhynchophoru5 Cruentatus (Coleoptera: Curculionidae)1

Notes on the Palmetto Weevil, Rhynchophoru5 Cruentatus (Coleoptera: Curculionidae)1

The cyclical nature of the color response was probably needed under conditions to identify the level of due to the leaching and uptake of nitrogen, denitrification nitrogen in the soil solution which corresponds to moder or volatilization of ammonia (NH3) which is associated with ate growth, acceptable color and little or no leaching soil urea application (3). The magnitude of the color de into the ground water. Relate work being conducted at a cline 4 weeks after treatment was reduced at the higher number of institutions for nursery crops grown in contain nitrogen rates; however, fertilizer cost increases, excessive ers needs to be expanded to include the affects of fertiliza shoot growth may result and turf may be injured when tion on plant growth, leaching and runoff on landscape applying more than 1 lb N/1000 ft2 in one application in sites. hot weather (2). This could become important if the fer tilized plant was growing in a turf area and the material Literature Cited was surface broadcast applied over the turf. If more than 1 lb N/1000 ft2 were to be applied to a turf area, consider 1. Dasberg, S. 1987. Nitrogen fertilization in citrus orchards. Plant and ation should be given to placing the material below the soil Soil 100:1-9. surface. 2. Hamilton, D. F., M. E. C. Graca, and S. D. Verkade. 1981. Critical effects of fertility on root and shoot growth of selected landscape Hibiscus leaf color was found to be sensitive to nitrogen . J. of Arboricul. 7:281-290. rate. Moderate growth and acceptable leaf color was main 3. Katyal, J. C, B. Singh, P. L. G. Vlek, and R. J. Buresh. 1987. Efficient tained by applying 1 lb N/1000 ft2/application (5 lbs N/1000 nitrogen use as affected by urea application and irrigation sequence ft2/year). Wright and Hale (2) stated that 3.5 lbs N/1000 Soil Sci. 51:366-370. 4. Morton, T. G., a. J. Gold, and W. M. Sullivan. 1988. Influence of ft2/yr was adequate for shade tree growth with no growth overwatering and fertilization on nitrogen losses from home lawns. increase at the 7 lb rate. Ponder et al. (6) reported nitrogen J. Environ. Qual. 17:124-130. rate from 0-8 lbs N/1000 ft2/yr hadno effect on tree 5. Neely, D. 1984. Grass competition for nitrogen around landscape growth. Citrus, world-wide, is considered not to respond trees. J. Environ. Hort. 2:86-88. to applications of nitrogen in excess of 4 lbs N/1000 ft2/yr 6. Ponder, H. G., C. H. Gilliam, E. Wilkenson, J. Eason, and C. e. Evans. 1984. Influence of trickle irrigation and nitrogen rates to Acer rubrum (1). Yearly applications of nitrogen in excess of 4 to 5 lbs L. J. Environ. Hort. 2:40-43. N/1000 ft2 may not be warranted and could cause ground 7. Still, S. M., C. W. Gilliam, andM. E. Watson. 1980. Effects of nitrogen water contamination due to leaching. Leaching losses of fertilization on Acer rubrum 'Red Sunset' grown in containers. Hort inorganic N from turf subjected to fertilization (5 lb N/ Sci. 15(5):641-642. 8. Terman, G. L. 1979. Volatilizastion losses of nitrogen ammonia from 1000 ft2/yr) and irrigation (1.5 in/wk) practices associated surface applied fertilizers, organic amendments, and crop residues with home lawn care in New England didnot appear to Adv. Agron. 31:189-223. pose a threat to drinking water (4). Higher application 9. van de Werken, H. 1984. Fertilization practices as they influence the rates have not been tested for ground water contamina growth rate of young shade trees. J. Environ. Hort. 2:64-69. tion, but most research shows little or no growth response 10. Wright, R. H. and E. B. Hale. 1983. Growth of three shade tree genera as influenced by irrigation and nitrogen rates. I. environ. to yearly rates above 5 lbs N/1000 ft2. Further study is Hort. 1:5-6.

Proc. Fla. State Hort. Soc. 101:101-107. 1988.

NOTES ON THE PALMETTO , RHYNCHOPHORU5 CRUENTATUS (COLEOPTERA: )1

Robin M. Giblin-Davis and F. W. Howard transplanted mature cabbage palmetto, University of Florida, IFAS (Walter), at one survey site in Broward County, FL. Experi Fort Lauderdale Research and Education Center ments demonstrated that this weevil is not a primary invader 3205 College Avenue of healthy palm trees but is attracted to and infests stressed, Fort Lauderdale, FL 33314 dying, and aged palms. Because palms may suffer stress as sociated with the transplanting process, and roots of cabbage Additional index words. Sabal palmetto, cabbage palmetto, palmettos regenerate slowly, recently transplanted palms are , Canary Island , chemical con at extended risk of invasion by the palmetto weevil. trol. Prophylactic measures for reducing this risk during and fol lowing transplanting of cabbage palmettos and Canary Is Abstract. Research is reported concerning the biology, ecology, land Date palms, Phoenix canariensis Hortorum ex Chabaud, and control of the palmetto weevil, cruen- are discussed. tatus (Fabricius). This weevil caused losses of about 8% in The largest weevil in the continental U.S. is the pal metto weevil, (Fabricius) (18) (Fig. Florida Agricultural Experiment Station Journal Series No. 9447. This research was supported by aU.S. Department of Agriculture Special 1). Unfortunately, size, 1.9-3.0 cm (3/4 to 1 3/16 inches Grant in Tropical and Subtropical Agriculture, 86-CRSR-2-2841 to long), is not its only claim to fame (18). This weevil has R.M.G-D. This paper contains research results of experimental pesticide been shown to be an important pest of stressed cabbage applications, but it does not offer recommendations for pesticide use. All palmettos, Sabal palmetto (Walter), andCanary Island Date uses of pesticides must be registered by federal or state authorities, or both, before their uses could be recommended. Consult the Cooperative palms, Phoenix canariensis Hortorum ex Chabaud (9). Rhyn Extension Service for current pesticide registration information and re chophorus cruentatus belongs to the family Curculionidae, commendations. subfamily Rhynchophorinae (= Calendrinae) and tribe

Proc. Fla. State Hort. Soc. 101: 1988. 101 Fig. 1. Adult female palmetto , Rhynchophorus cruentatus, showing natural size and color pattern variability (bar = 2 cm). Photo by Jim DeFilippis

Rhynchophorini (15). The family Curculionidae (snout consumers. We have harvested larvae from the field as weevils) is estimated to include over 60,000 species of bee heavy as 6 grams, although the average last instar larva tles that feed upon a very diverse variety of plant species weighs between 3.5 to 5 grams (8). We are aware of no one (5). Part of their overall success as a group is attributed to who eats the larvae of the palmetto weevil in the U.S. How the elongation of the stomal region into a snout which ever, the larvae of the palm weevil, R. palmarum (Linneaus), bears tiny mandibles at its apex used for preparing ovipos- have been consumed and are considered a delicacy by ition holes and for feeding (5). In addition, the larvae of some South American natives (18). The last instar larva weevils are endophytic, feeding inside the plant host where migrates into an area of the host that is fibrous, such as they are protected from predators, the environment, and the periphery of the stem or the petiolar bases of the insecticides. leaves, to prepare a cocoon from the palm fiber. The larva enters the prepupal stage (Fig. 3A) within the cocoon and then molts to the pupa (Fig. 3B). Within several days to 2 Palmetto Weevil Life Cycle weeks, depending upon the temperature, the adult (Fig. Rhynchophorus cruentatus has a complete life cycle 3C) ecloses from the pupa. The adults will often sit several (holometabolous) with an egg, several larval instars (Fig. days in the cocoon before emergence. 2), prepupal (Fig. 3A), pupal (Fig. 3B), and adult stages The average number of live palmetto weevils of all (Fig. 1). In nature, the life cycle of the palmetto weevil can stages recovered per lethally infested cabbage palmetto was take less than 84 days to complete (9) and there can be 48 ± 68 (range = 1-214) (n = 9 palms) (9). Adjustments more than one generation per year in southern Florida for larval and pupal mortality suggest that 23-32 new (multivoltine). The eggs are laid deep in the petiolar bases adults will be produced from an average lethal infestation of host leaves or in wounds or cuts in the host palm. In the in a cabbage palmetto in southern Florida (9). The adults laboratory, an average palmetto weevil female can lay 26 are long-lived; males survived 87 ± 41 days (range = 6- ±15 eggs (range = 0-48) with a 42 ± 19 day oviposition 150) and females survived 74 ± 16 days (range = 40-113) period (range = 0-70) (8). The eggs hatch in 69 ± 17 when confined on pineapple slices (8). The average weight hours (8). The weevil larvae grow and molt several times of newly-emerged adult males was 1.14 ± 0.22 g (range while consuming increasingly larger volumes of plant tis = 0.83-1.65) (n = 20) compared with 1.14 ± 0.27 (range sue. The larvae have large mandibles and are voracious = 0.61-1.50) (n = 20) for females (8). The adult male

102 Proc. Fla. State Hort. Soc. 101: 1988. ture and Consumer Services, Division of Plant Industry, Gainesville were surveyed by Giblin-Davis and Howard (9) to better understand the host range of the palmetto weevil. Cabbage palmetto, Canary Island Date palm, P. dactylifera, sp., sp., Roystonea sp., sp., palm, and sp. were reported with larvae, pupae, or both, suggesting that under the right conditions R. cruentatus could use these palms as hosts. The most com monly reported palms with weevil infestations were cab bage palmetto and Canary Island Date palm. Berger (1) reported that palmetto weevil larvae could complete their life cycle when placed into the saw palmetto, Serrenoa repens (Bartram). Giblin-Davis et al. (8) have demonstrated that the palmetto weevil can be reared completely on sugarcane or on pineapple-sugarcane.

Cabbage Palmetto

The cabbage palmetto (Fig. 4) which is the state tree of both Florida and South Carolina, has become increasingly popular for mature transplantation into urban landscapes (Fig. 5) (9). The cabbage palmetto survives well in a variety of habitats within its geographical range which includes most of Florida, north from the Keys to Gainesville, to the southeastern coast of North Carolina and to the west into the panhandle of Florida (4). Cabbage palmettos are rela tively inexpensive (ca. $50.00 wholesale) (6), require low maintenance once established (17) and have high trans planting survivorship. Also, they are not susceptible to the mycoplasma induced lethal yellowing disease (11). In an age of rapid development and instant landscapes the cab bage palmetto has found a niche. In nature, palms are rarely observed with infestations of the palmetto weevil. In fact, the palmetto weevil was once considered a rare and novel catch for entomologists.

Fig. 2. Container of last instar palmetto weevil larvae harvested from However, in recent years, the palmetto weevil has caused a dead cabbage palmetto that had been recently transplanted (bar = 2 considerable damage to newly transplanted mature cab cm). Photo by Jim DeFilippis bage palmettos and date palms (9). In addition, it is re ported as an occasional pest of very old Washingtonia sp. palms on the west coast of Florida. Results from a survey possesses tubercles on the rostrum which contrasts with of recently transplanted cabbage palmettos in Broward the relatively smooth rostrum of the female (18). In very County, FL demonstrated an 8% mortality rate due to small individuals, this sexually dimorphic character is less these weevils (n = 290 palms) (9). Experiments that were reliable and the genital capsule must be examined to con firm gender. Both sexes vary in color from all black to recently conducted at the Ft. Lauderdale Research and almost all rust colored or maroon with black markings. Education Center demonstrated that healthy mature cab bage palmettos that were enclosed with a bag containing

Palmetto Weevil Distribution and Host Range ten males and ten females of field-collected palmetto weevils were not infested after 84 days, whereas stressed There are 10 described species in the genus Rhyn- cabbage palmettos (cut with a chain saw) nurtured the chophorus and all are known or suspected to use palms as weevil life cycle. This experiment was repeated with Ca hosts (16). Seven of the described species of Rhynchophorus nary Island Date palms potted in 7.4 liter containers with are considered major pests of coconut palms, Cocos nucifera similar results (9). Thus, the palmetto weevil is not a pri (Linneaus), in different geographical locations throughout mary attacker of palms, but an opportunist that preys upon the world (16). The palmetto weevil has been reported stressed palms. Cabbage palmettos have slow root regener from South Carolina south through Florida to the Florida ation following transplant excavation (2) that makes them Keys and west through the southern parts of the Gulf attractive and vulnerable to attack by the palmetto weevil States into Texas (16). Fossil evidence (19) suggests thati?. (9). A cut, wounded, or stressed palm is attractive to pal cruentatus may have been present in southern Florida as metto weevils during most of the year in southern Florida far back as the Pleistocene (ca. 1 million years ago), al (18). All species of Rhynchophorus appear to be attracted to though there are some questions as to the authenticity of mechanical wounding or stress (12). The recent increase these fossils. in palms killed by R. cruentatus in Florida is probably due Over 250 collection and identification records from to an increase in the transplanting of stressed mature 1918 through 1987 at the Florida Department of Agricul- palms.

Proc. Fla. State Hort. Soc. 101: 1988. 103 Fig. 3. Different stages of the palmetto weevil found within the cocoon; A) prepupa, B) pupa, and C) newly-emerged adult leaving the cocoon (bar = 2 cm). Photo by Jim DeFilippis

Symptomology Control

The symptoms of a lethal palmetto weevil infestation We have conducted experiments concerning the effi can vary, but most commonly involve a general and ir cacy of different commercially available insecticides for the reversible decline of the younger leaves. At the latter stages control of palmetto weevil adults (9). The following mate of infestation the larval feeding damage and associated rot rials were tested: Lindane 25% wettable powder (WP), 0.6 is so severe that the structural integrity of the crown is g (AI)/liter (1 lb formulated/50 gal water) (Miller Chemical compromised and the palm top falls over under its own & Fertilizer Corp. Hanover, PA 17331); chlorpyrifos 50% weight, producing the characteristic "popped neck" condi WP (Dursban 50W), 1.2 g (AI)/liter (1 lb formulated/50 gal tion (Figs. 5 and 6). If the heart leaf is tugged at this stage, water) (Dow Chemical Co. Box 1706, Midland, Ml 48674); it detaches easily with evidence of larval tunneling and or propoxur 70% WP (Baygon), 21.0 g (AI)/liter (2.5 lb for larvae, pupae in cocoons (especially at the petiolar bases mulated/50 gal water) (Mobay Chemical Corp. Box 4913, and sometimes at the periphery of the stem), or adults Kansas City, MO 64120); dimethoate (Cygon 400), 1.2 g (Fig. 7). Even months after the death of the palm it is easy (AI)/liter (15 fluid ounces formulated/50 gal water) (Amer to find the telltale signs of palmetto weevil cocoons (Fig. ican Cyanamid Co. One Cyanamid Plaza, Wayne, NJ 3C). We have not observed a non-lethal infestation (9) as 07470); and methomyl 90% WP (Lannate), 1.0 g (AI)/liter was suggested by Woodruff (18). Unfortunately, by the (0.46 lb formulated/50 gal water) (E. I. du Pont Nemoirs time weevil damage can be accurately diagnosed there is & Co. Inc., Walker's Mill, Wilmington DE 19898). These little hope for successful treatment. Thus, the most tenable materials were sprayed to run-off onto pineapple tops, al strategy for control involves protecting the palms during lowed to dry, and weevils (one male and one female) placed their "window of vulnerability" with a prophylactic insec onto the pineapple top in a screened container. The ticide treatment or a physical barrier, such as a nylon mesh weevils were then monitored regularly for mortality. All of net. the above compounds at the prescribed rates were effective

104 Proc. Fla. State HorL Soc. 101: 1988. Fig. 4. Healthy, mature cabbage palmetto, Sabal palmetto. Fig. 5. Recently transplanted mature cabbage palmettos; note pal Photo by R. M. Giblin-Davis and F. G. Bilz metto weevil-infested palm exhibiting "popped-neck" condition. Photo by R. M. Giblin-Davis and F. G. Bilz at killing the weevils when compared to an unsprayed con land Date palms can wholesale between $1000.00 and trol, but methomyl failed to produce 100% mortality after $4000.00 (6) and may justify the investment. Because a 168 hours (9). The mean time to mortality was less than weevil-infested cabbage palmetto can contain from 1 to 24 hours for lindane, chlorpyrifos, and propoxur, and 42 over 200 weevils of different stages, it is imperative that as hours for dimethoate. Lindane is recognized as a relatively soon as a weevil-infested palm is diagnosed it should be persistent insecticide and would be a logical first choice for removed and destroyed to reduce the potential for future prophylactic control because of the relatively long time that attacks in an area. a cabbage palmetto remains vulnerable after transplanting. Broschat and Donselman (3) suggested that root prun Some of the other species of Rhynchophorus can be con ing cabbage palmettos 2-3 months prior to transplantation trolled by some of the compounds that we tested for effi will stimulate the production of new roots from the trunk cacy against R. cruentatus. For example, a prophylactic leaf and that this will give the palm a head start once trans axil treatment of a mixture of 5% BHC (lindane) or 5% planted. They also suggested that the root pruning of palm chlordane and sand (225 g per palm) was 80-90% effective species that branch at cut roots 6-8 weeks prior to trans at controlling R. ferrugineus Oliver in southeast Asia (14). plantation would reduce stress. Any reduction of stress An application of 50-200 ml of 0.08% dimethoate was re should lessen the host apparency to palmetto weevils and commended for control of R. phoenicis (Fabricius) in thereby reduce successful attacks. (13). Griffith (10) recommended destruction of palms in We are continuing research on the palmetto weevil with fested with red ring nematodes and weevils and use of the support of the U.S. Department of Agriculture because baited traps or trap trees treated with 0.1% methomyl for its larger cousin, the palm weevil, R. palmarum, occurs in control of R. palmarum. Cuba, and from Mexico south to Brazil (15, 16, 18). In We realize that many contractors will probably not see Mexico, Central and , and Trinidad this the justification for the extra time and money required to species vectors the red ring nematode, Rhadinaphelenchus spray prior to and during the first six months after trans cocophilus. This nematode causes the lethal red ring disease planting a cabbage palmetto. However, mature Canary Is- of , oil palms, and date palms (10). That the pal-

Proc. Fla. State Hort. Soc. 101: 1988. 105 Fig. 6. Characteristic "popped-neck" condition in recently trans Fig. 7. Palmetto weevil infested cabbage palmetto that was chain sawed planted mature cabbage palmetto with lethal infestation of palmetto in cross-section to expose extensive larval tunneling and damage in the weevils. Photo by R. M. Giblin-Davis stem and crown of the host palm. Photo by R. M. Giblin-Davis

metto weevil may serve as a vector for the red ring 7. Giblin, R. M., K. Gerber, and R. Griffith. 1987. Comparison of Rhyn nematode could make the weevil a more damaging pest if chophorus species as vectors of the red ring nematode, Rhadinaphelen- the nematode were ever introduced into the southeastern chus cocophilus. J. Nematol. 19:524. U.S. (7). The more that we know about the palmetto weevil 8. Giblin-Davis, R. M., K. Gerber, and R. Griffith. 1989. Laboratory rearing of Rhynchophorus cruentatus with notes on R. palmarum (Col- and its vector potential for this nematode, the better pre eoptera: Curculionidae). Fla. Entomol. (in press). pared we will be if it is ever introduced to Florida. 9. Giblin-Davis, R. M. and F. W. Howard. 1989. Vulnerability of stressed palms to attack by Rhynchophorus cruenatus (Coleoptera: Cur culionidae) and its insecticidal control. J. Econ. Entomol. (in press). 10. Griffith, R. 1987. Red ring disease of coconut palm. Plant Disease 71:193-196. Literature Cited 11. Howard, F. W., D. L. Thomas, H. M. Donselman, and M. E. Collins. 1979. Susceptibilities of palm species to mycoplasmalike organism-as 1. Berger, E. W. 1907. The palmetto weevil (Rhynchophorus cruentatus sociated diseases in Florida. FAO Bull. Fitosan 27:109-117. Fab.). Fla. Agr. Exp. Sta. Rept. 1907: XXXIX. 12. Lever, R. J. A. W. 1969. Pests of the coconut palm. FAO Agricultural 2. Broschat, T. K. and H. M. Donselman. 1984. Regrowth of severed Studies. No. 77. Food and Agricultural Organization of the United palm roots. J. Arboriculture 10:238-240. Nations, Rome. 3. Broschat, T. K. and H. M. Donselman. 1987. Factors affecting palm 13. Mariau, D. 1968. Methodes de lutte contre le rhynchophore. transplant success. Proc. Fla. State Hort. Soc. 100:396-397. Oleagineux 23:443-446. 4. Brown, K. E. 1976. Ecological studies of the cabbage palm, Sabal 14. Mathen, K. and C. Kurian. 1966. Prophylactic control of Rhyn palmetto. IV. Ecology and geographical distribution. Principes 20:148- chophorus ferrugineus Fabr., the coconut weevil. Indian J. Aerie. Sci. 156. 36:285-286. 5. Daly, H. V., J. T. Doyen, and P. R. Ehrlich. 1978. Introduction to 15. O'Brien, C. W. and G. J. Wibner. 1982. Annotated checklist of the biology and diversity. McGraw-Hill, New York. weevils (Curculionidae sensu lato) of North America, Central America, 6. Galletta, K. (ed.). 1988. PlantFinder: Guide to foliage and ornamental and the (Coleoptera: Curculionidea). Memoirs of the plants. Betrock Publishing, Inc. Ft. Lauderdale, FL. October Issue. Am. Entomol. Inst. No. 34.

106 Proc. Fla. State Hort. Soc. 101: 1988. 16. Wattanapongsiri, A. 1966. A revision of the genera Rhynchophorus 18. Woodruff, R. E. 1967. A giant palm weevil, Rynchophorus cruentatus and Dynamis (Coleoptera: Curculionidae). Dep. Agr. Sci. Bull., (Fab.), in Florida (Coleoptera: Curculionidae). Fla. Dept. Agr. Div. Bangkok 1:1-328. Plant Industry. Entomology Circ. No. 63. 17. Watkins, J. V. 1970. Florida landscape plants, native and exotic. Uni 19. Young, F. N. 1959. Fossil from the Vero pleistocene. Coleop- versity of Florida Press, Gainesville. 368 pp. terists' Bull. 13:103-106.

Proc. Fla. State Hort. Soc. 101:107-110. 1988.

IRRIGATION OF LANDSCAPE ORNAMENTALS USING RECLAIMED WATER

John R. Parnell damage to plants and reclaimed water reuse. They quickly Public Utilities Department realized that the unique reclaimed water irrigation system City of St. Petersburg offered an unprecedented opportunity for the City to con P. 0. Box 2842 duct original research on the effects of this new resource St. Petersburg, FL 33731 on the growth and development of ornamental plants and trees commonly used for landscaping and decorative pur Abstract. St. Petersburg's reclaimed water reuse distribution poses in Central Florida. The study called "Project Green- system supplies many residential and commercial users with leaf was initiated early in 1986. It was funded by the City, highly treated wastewater effluent for the irrigation of turf with the cooperation of the Institute of Food and Agricul and landscape areas. The higher nutrient content of reclaimed tural Sciences (IFAS) of the University of Florida. water promoted significantly greater growth than potable The Florida Department of Environmental Regulation water in salt tolerant ornamental plant species. Foliar dam (FDER) is the primary regulatory agency permitting waste- age was recorded in salt sensitive species irrigated with re water disposal and reuse within the State. Woehicke and claimed water containing 400 + ppm chlorides by the over Adams (6) outline the FDER quality requirements for head spray method. Growth media and tissue analyses effluent reuse water which are designed to eliminate public suggest that drip irrigation methods produce greater growth health problems and result in a minimum impact on the responses and reduced foliar damage than overhead sprays. environment. Nutritional requirements for vegetative The experimental plants included, Avocado [Persea ameri- growth were not taken into consideration when the limits cana Mill.), Boston ( exaltata (L) Schott), for the various parameters were promulgated. Crape myrtle (Lagerstroemia indica L), Dwarf azalea Baldwin and Comer (1) discuss general aspects of the (Rhododendron sp. cv. Celestine red), Formosa azalea (Rho use of reclaimed water in Florida for the irrigation of dodendron sp. cv. Formosa), Hibiscus (Hibiscus rosa-sinensis urban and residential landscapes. A brief communication L), Burford holly {Ilex cornuta "Burford"), Chinese privet by Fitzpatrick (3) also mentions the use of reclaimed water (Ligustrum sinense "variegata"), Laurel oak {Quercus by commercial growers. Other papers, (4) (5) describe the laurifolia Michx.) and Sweet viburnum ( Viburnum odoratis- effects of using different growing media and fertilizer simum). rates with reclaimed water as an irrigant for a variety of tree species.

In 1987, the City of St. Petersburg, Florida, became the Materials and Methods first major U.S. coastal municipality to achieve zero waste- water discharge to surrounding surface waters. An instru Ten experimental plots were set up each containing 12 mental segment of it's pollution abatement program was replicates of each of 10 species of plants. These included, the development and placing into service of the largest Avocado (Persea americana Mill.), Boston fern (Nephrolepis fully functional urban reclaimed water reuse irrigation dis exaltata "Bostoniensis"), Crape myrtle (Lagerstroemia indica), tribution system in the U.S.A. Only 146 customers were Dwarf azalea (Rhododendron sp. cv. Celestine red), Formosa connected to the system in 1981. This number rapidly in azalea (Rhododendron sp. cv. Formosa), Hibiscus (Hibiscus creased to over 6,000 residential and 200 municipal and rosa-sinensis), Burford holly (Ilex cornuta "Burford"), commercial users in 1988. Consumption rose from 4 to 24 Chinese privet (Ligustrum sinense "variegata"), Laurel oak million gallons per day (mgd) in the same time interval. (Quercus laurifolia) and Sweet viburnum (Viburnum odoratis- Further expansion of the system is still possible as 45 mgd simum). of reclaimed water are presently available from the four All plants were grown in 3 gallon plastic containers. wastewater treatment plants that serve the City. The growing medium consisted of commercial horticul Between 1983 and 1986, St. Petersburg, experienced tural mix (two thirds peat with not more than 15% nor less highly abnormal climatic conditions. Nineteen consecutive than 10% sand, one third cypress chips and dolomite to months had extremely low rainfall from October 1983 on adjust pH to 6.0 ). One tablespoon of 14-14-14 Osmocote wards, severe freezes occurred in December 1983 and Feb and one teaspoon of 2% Oxydiazone pre-emergent her ruary 1985, and a hurricane brushed coastal St. Petersburg bicide were added to each pot at the outset of the experi in September 1985. These climatic factors damaged or kil ment. led many sensitive landscape ornamental plant species and Three variables were investigated in various combina created a significant increase in the demand for reclaimed tions as shown in Table 1. Irrigant chloride concentration irrigation water. was 15 ppm in potable water, 180 to 200 ppm in reclaimed Throughout 1985, City officials became increasingly water supplied to the City nursery from the Southwest concerned over alleged connections between vegetative wastewater treatment plant and over 400 ppm in reclaimed

Proc. Fla. State Hort. Soc. 101: 1988. 107

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