Proc. Ha. State Hort. Soc. 112:247-250. 1999.

INTEGRATED MANAGEMENT OF PALM PESTS

Thomas J. Weissling and Timothy K. Broschat Table 1. Pests of landscape palms in . University of Florida, IFAS Common name Species Damage severity Fort Lauderdale Research and Education Center 3205 College Avenue Palm aphid Cerataphis palmae aesthetic Fort Lauderdale, FL 33314 Mealybugs several species aesthetic Scales several species aesthetic Additional index words. IPM, nutrition, transplanting, pal Whiteflies Aleurodicus dispersus, aesthetic A. atratus metto , silky cane weevil. mite Aceria guerreronis aesthetic Spider mites several species aesthetic-severe Abstract. Though founded in agricultural production systems, Royal palm bug Xylastodoris luteolus severe integrated pest management (IPM) has been adapted for use in The palm cixiid Myndus crudus disease vector the management of some urban pests. However, compared to Palm leaf skeletonizer Homaledra sabaUlla aesthetic agriculture, the urban environment presents unique concerns Banana moth Opogona sacchari severe to many individuals. Although few urban pests cause econom ic damage, management is usually based on an individuals tol Palmetto weevil cruentatus lethal erance to their presence, or the damage they do to lawns and Silky cane weevil Metamasius hemipterus severe-lethal ornamental plantings. Often, landscape pests do not need to sericeus be managed as their damage is aesthetic and through time, Greenhouse thrips Heliothrips haemorrhoidalis aesthetic problems generally dissipate. Several factors are discussed Caterpillars several species aesthetic for consideration in the management of palm pests, such as Grasshoppers several species aesthetic methods to grow palms that reduce stress and potential attack by pests. In addition, monitoring and types of pest damage are discussed. Damage and management of several principle palm pests are also discussed. One of the first steps in any IPM program is to prevent pest establishment and outbreak. Growing a healthy plant can The urban environment is comprised of many unique and help alleviate pest problems in many situations. Likewise, diversified habitats. and related pests within good palm health can help prevent pest problems, and assist urbanized areas can be found infesting structures, land in palm recovery after a pest outbreak is controlled. Palms scapes, gardens and lawns. Unlike pest management in crop can be stressed by a number of factors including poor instal production systems, treatment thresholds in homes and other lation site, improper transplanting, poor care following trans structures aregenerally very low and are almost always based planting, or they simply are not adapted for the climatic or on tolerance rather than economics. Similarly, there is a very edaphic conditions of south Florida. low to zero tolerance for pests that cause aesthetic damage to Site Selection. Palms have wide-ranging habitat and edaphic ornamental plants and turf. Therefore, pest control in the ur requirements. Prior to installing a palm, determine if condi ban environment, a $1.4 billion a year industry in Florida, is tions at the site of installation will limit the success of trans generally accomplished by remedial and preventative applica planting, or if future problems may arise. Potential problems tions of fast-acting insecticides within, under, and around may include drainage, and light levels. Carefully choose the structures, and in the lawn and landscape. The amount of in right species of palm for the site rather than trying to force a secticide used and associated health and environmental con particular palm species to work in a site in which it will not cerns regarding applications within urban areas presents thrive. unique considerations. Species Selection. Carefully consider your choice of palm Integrated pest management (IPM) has found its way species, not only in terms of site selection, but in terms of fu from agricultural settings to the urban environment, and with ture maintenance and potential for loss. For example, majesty some effort, IPM programs have proven adaptable for use in palms require substantial nutritional inputs and would not be structural and landscape pest management. In this article, we a good choice in areas where maintenance is minimal. Selec will provide an overview of an integrated management pro tion should also be made on disease and pest susceptibility. gram for pests of installed palms. Palm species vary in their resistance to the phytoplasma dis Several arthropod species are pests of ornamental palms ease lethal yellowing (Howard and Harrison, 1996). Lethal in Florida (Table 1) (Meerow, 1992; Howard, 1999). Few ac yellowing is by far, more important as a palm mortality agent tually kill their host through their actions but many are of than insect pests. concern because they cause aesthetic damage during palm Specimen Selection. Carefully inspect palms for sign of dis production and after installation in the landscape. In Florida, ease, stress or insect pests when buying and before installa one insect species is lethal to palms; the palmetto weevil, tion. Often, we inadvertently import pests into a relatively Rhynchophorus cruentatus, whose larvae bore into the stem and pest-free landscape via infested plant material. crown (Giblin-Davis and Howard, 1989). Installation. Once a species and site has been decided up on, the tree needs to be carefully removed from its container or from the ground and installed. Do not install a tree deeper than the depth at which it was originally grown. This practice Florida Agricultural Experiment Station Journal Series No. N-01789. results in a slow decline in tree health. After installation, the

Proc. Fla. State Hort. Soc. 112: 1999. 247 specimen must be properly supported. Never use nails to at Sap-Feeding. with piercing-sucking or rasping tach support boards to the palm trunk. See Meerow and mouthparts feed on the sap of their host. In general, their Broschat (1992) for a complete guide to transplanting. feeding activity is not injurious to the plant unless high pest Fertilization. Palms and other landscape ornamentals can populations are present. Damage is generally observed as be most effectively fertilized by broadcasting a 2N-lP-3K-lMg chlorotic spots on the leaves, which may be confused with plus micronutrients fertilizer over the entire ornamental signs of nutritional deficiency. Sap-feeding pests include landscape area at a rate of 1.5 lbs/100 sq ft of canopy area or aphids, mealybugs, scale insects, whiteflies, mites, thrips, and landscape bed area. Applications should be made every 3 the royal palm bug. months. The fertilizer used should have 100% of their N, K, Boring Borers can be very damaging and even lethal to and Mg in controlled release form to maximize their effec palms. As larvae, boring insects move through the tree dam tiveness to the plants and minimize their impact on the envi aging tissues. This injury can severely stress trees or create ronment. We suspect that proper fertilization may help to pathways for pathogens to enter trees. Some borers may even reduce pest problems but this still needs to be explored. See consume the "bud" of meristem killing the palm. Boring pests Broschat (1999) for more information on fertilization. include the banana moth, silky cane weevil, and the palmetto Pruning. Landscape managers often remove healthy, weevil. green palm leaves for aesthetic purposes. Removal of green Disease Vector. Only one insect in Florida is known to vector palm leaves is generally not advised as it removes photosyn- a lethal palm disease. The palm cixiid, Myndus crudus, is a thetic material and nutrients resulting in tree stress planthopper that vectors lethal yellowing disease (Howard et (Broschat, 1994). In some instances, such as the Canary Is al, 1983). At present, there is no evidence for any other vec land , pruning of green leaves creates wounds at tors of lethal yellowing in Florida. tractive to the silky cane weevil and palmetto weevil. Management Pest Monitoring For the most part, palm pests cause minor damage and in- All palms and other landscape plants should be routinely secticidal management is usually not necessary. Through monitored for plant health, pest problems, and conditions time, many pest populations decline due to the appearance of that may lead to pest problems. Weekly scouting is recom natural enemies or a change of season. However, from time mended. Personnel doing pest control must have an under to time, populations increase to injurious levels and a man standing of the biology, and ecology of the plant community agement tactic must be deployed. Although insecticides are and its pests as well as biological control organisms that attack readily available and easy to use, consider some alternatives: pests. They must also have an awareness of how both the plant 1. Natural enemies: Predators and parasitoids can be pur and pest is regulated or influenced by other factors in the sur chased from a variety of supply houses to augment existing rounding ecosystem. This is the knowledge/information ele populations. There are several advantages to the use of bio ment of IPM. A good estimate of populations helps to make logical control organisms for pest control and very few disad better decisions. The pest manager must also be in touch with vantages. changes occurring. 2. Nematodes: Entomopathic nematodes in the genera The most commonly used method of monitoring is visual Steinernema and Heterorhabditis are commercially available for counts on plants. Usually we are drawn to injury and this is a management of some pests, such as the silky cane weevil and good place to start. Keep track of the information that you the banana moth. While effective, their utility can be limited collect. Note particular problem areas and be sure to visit by temperature, ultra violet exposure, and desiccation. these spots every week. 3. "Soft insecticides ": So called soft insecticides such as soaps and horticultural oils are often very effective for management Action Thresholds of sap-feeding pests such as aphids, mealybugs and scale in sects and are less toxic to humans and the environment. In agricultural situations, many pests are not managed un 4. Microbial insecticides: Probably the best known microbial til their populations reach a certain threshold. These thresh product is Bacillus thuringiensis (BT). The actual formulation olds are based on the type of injury a pest does as well as the does not contain the live pathogens, rather a toxin produced cost of control. In the landscape, we often fall into a situation by the bacteria when cultured anaerobically. Bacillus thuring where we have zero tolerance for pest damage. In reality, iensis is effective against caterpillars. Also available is a fungi, most palm pests cause only aesthetic damage. Their activities Beauveria bassiana for control of various Homoptera. Abamec- do not injure the palm but may make the foliage appear less tin, and avermectin are toxins produced by fermentation of than perfect. These pests can usually be left untreated and certain fungi. These products are usually effective against sev their populations will sometimes diminish through time. eral pests, including spider mites. Some pests are serious, but various tactics can be used to man age their populations. Principle Pests and Management

Principle Classes of Pest Injury Palm Aphid. Female palm aphids are relatively sedentary and are surrounded by a white, wax ring on their body. Thus, Defoliation. Defoliation of palm leaves by insects with chew they appear as scale insects. Palm aphids infest young leaves ing mouthparts, can, under high pest pressure result in plant and can be present in high numbers. Generally they cause lit injury through loss of substantial photosynthetic material. tle if any injury to landscape palms. However, like other However, damage is usually more unsightly than injurious. aphids, they excrete honeydew which supports the growth of Pests that defoliate palm leaves include various grasshoppers sooty mold. When monitoring, look for ladybird on and caterpillars. leaves infested by palm aphids. Ladybird beetles usually do an

248 Proc. Fla. State Hort. Soc. 112: 1999. excellent job reducing palm aphid populations. Insecticidal Infestations can be difficult to detect and personnel scout soaps are also effective at controlling this pest. If using a insec ing for pests need to inspect plants carefully. Debris and ex ticide, consider a systemic product to reduce mortality of bio crement produced by larval boring within above ground logical control organisms. portions of infested plants may be pushed out of holes. In ad Mealybugs. Mealybugs are usually a problem only for dition, pupal cases are often pushed out of the soil at the base greenhouse and shadehouse producers. However, they can of plants to facilitate adult emergence. Unfortunately, infesta occasionally be found on landscape palms infesting the leaf tions go unnoticed until damaged fronds or stems fall over. axils. Mealybugs can be controlled by a wide range of prod Control tactics involve the application of insecticides to ucts including insecticidal soaps and horticultural oils as well control the larvae or adults, or application of beneficial nem- as systemic insecticides. A naturally occurring predator, the atodes to control larvae. Two species of entomopathogenic mealybug destroyer (Cryptolaemus montrouzieri), is also effec nematodes appear to be effective at killing banana moth lar tive at reducing populations. vae, Steinernema carpocapsae and Heterorhabditis bacteriophora. Scale Insects. Various pests, such as the thread scale, mag Palmetto Weevil. The palmetto weevil, R. cruentatus, is closely nolia white scale, coconut scale, and Florida red scale appear associated with the cabbage palmetto (), a palm on palms on occasion. Generally infestations cause little inju native to the southeastern U.S. In addition, the native saw pal ry but their presence can be distracting. Scales are tiny insects metto (Serrenoa repens) appears to be an acceptable alternate covered by a waxy shell. This shell often reduces the effective host. Several other palms, most of them introduced species, ness of contact insecticides. Predators and parasites can be have been observed with larval infestations. These include the purchased for scale control but their effectiveness can vary. If Canary Island Date Palm {), P. dactylifera, using an insecticide, a systemic product is recommended. sp., sp., royal palms (Roystonea sp.), La- Spider Mites. Spider mites are usually a problem only in taniasp., coconut palm (Cocos nucifera), and sp. greenhouse or interior conditions. However, populations Giblin-Davis and Howard (1989) determined that the pal may occasionally appear on palms in the landscape. A preda metto weevil attacks dying sabal palms and that infestation is tory mite, Phytoseiulus persimilis, is effective for reducing pop usually associated with transplant stress. Dying palms emit ulations of the two-spotted spider mite. In addition, products semiochemicals that work synergistically with male-produced containing avermectin are usually effective at controlling spi aggregation pheromones to attract to the available re der mites. source (Giblin-Davis et al., 1996b). However, while R. cruenta Royal Palm Bug. Royal palm bugs feed on freshly opened tus normally appears to infest only dying palms, they will leaves of royal palms causing scattered yellow spots on the attack and kill recently pruned, or transplanted Canary Island lower leaf surfaces. As feeding pressure increases, leaves turn date palms. In addition, lethal infestations of R. cruentatus brown and wilted. New leaves emerge about once a month have been observed in well-established Canary Island date and under heavy infestation [up to 300 bugs per leaflet (F. W. palm plantings that appear to be healthy. Unfortunately, Howard, pers. comm.)], a large portion of the crown may be feeding damage by the larvae of this weevil is difficult to de damaged. Royal palm bugs rarely, if ever, kill palms but their tect before the apical meristem of the palm has been de damage is unsightly. Palms less than 12 feet tall are seldom at stroyed and the tree dies (Giblin-Davis and Howard, 1989). tacked. Symptoms of a palmetto weevil infestation vary, but com Other than some general predation by miscellaneous ar monly involve a general, often irreversible decline of leaves. thropods such as spiders, insecticidal control is the only In palm species with upright leaves, such as the Canary Island known reliable method of controlling the royal palm bug in date palm, the older leaves begin to droop during the early Florida. Chemical control with a contact insecticide can, how stages of infestation but quickly collapse thereafter. As the in ever, be a challenge due to the height of infested palms and festation progresses, the larval feeding damage and associat problems with insecticide drift. Root drenches with systemic ed rot is so severe that the integrity of the crown is insecticides are a viable management option because their ap compromised and the top of the palm falls over. This condi plication does not require special equipment to reach palm tion is termed "popped neck". If the palm is pulled apart at leaves (Howard and Stopek, 1998). this stage, larvae, cocoons, and even adults may be found The Palm Cixiid. Although the palm cixiid is the only know within the crown region. Early detection of weevil infestation vector of lethal yellowing disease, its management does not is difficult, and treatment even in the early stages of infesta appear to reduce the incidence of lethal yellowing. tion may be too late to save the tree. Palm Leaf Skeletonizer. Feeding by the small caterpillars of Insecticidal treatment of trees infested with the palmetto the palm leaf skeletonizer results in unsightly, brown patches weevil is futile. The best recourse is to cut down infested on older palm leaves. On occasion, larval feeding on the leaf palms and destroy them before adults emerge. Prophylactic stem can cause the entire leaf to turn brown. Injury is usually treatment of recently transplanted palms with insecticides is only cosmetic and infested leaves can simply be trimmed off. an option but the costs can quickly become prohibitive unless Chemical control is often ineffective. only a few trees are to be protected. Use of a systemic product Banana Moth. Several ornamentals serve as hosts for the ba to prevent infestation is being investigated. nana moth, including bamboo palms and majesty palms. The Growers managing nursery plantings of palms may have banana moth and closely related species are typically detritus the greatest potential to control the palmetto weevil using an feeders and scavengers. However, banana moth larvae will at integrated program. First, trees should be grown using cultural tack damaged tissues and feed on nearby healthy tissue caus practices that promote vigor. This means following proper fer ing serious damage. Feeding damage can vary depending on tilization and irrigation guidelines. Trees such as the Canary Is the host plant. In bamboo palms, larvae usually feed at the land Date Palm are not adapted for the south Florida climate. base of plants where aerial roots enter the soil. Debris accumu Great care should be taken to ensure the health of these trees. lates at the base of plants from feeding in roots and petioles. Secondly, wounding of trees, such as by pruning, should be

Proc. Fla. State Hort. Soc. 112: 1999. 249 avoided. Following these two steps will help to prevent an infes Caterpillars and Grasshoppers. These pests will, from time to tation. If trees are infested with palmetto weevils, there is cur time, feed on palm foliage sometimes causing significant loss rently little if any chance of saving them. Therefore, sanitation, es of leaf material. Frequent monitoring and rapid manage as in removing and destroying infested plant material is crucial ment can prevent populations from building up to high in preventing or reducing subsequent infestations. levels. Infestations can usually be removed by hand. However, Silky Cane Weevil The silky cane weevil, Metamasius hemi- caterpillars with stinging spines should be removed with pli pterus sericeus, primarily infests banana and plantain, Musa ers. Applications of Bt can also be used to control caterpillars. spp., and interspecific hybrids of sugarcane. Infestations have also been observed in several ornamental palms such as Ca Conclusion nary Island date palm; MacArthur palm, Ptychosperma mac- arthurii; majesty palm, Ravenia rivularis; royal palm; spindle When dealing with any pest, prevention is usually the best palm, Hyophorbe verschaffeltii; and Washington fan palm (Gib- defense. In the case of palm pests, preventing stress to the lin-Davis et al., 1994). tree can help alleviate some problems. All plantings should Palms infested with the silky cane weevil are often charac be carefully and routinely monitored, not only for pests, but terized by the production of an amber-colored and gummy ex- also for plant health and biological control organisms. When udate in the stem, crown shaft or petioles, and galleries in the confronted with a pest outbreak, there are usually several al leaves, petioles and stems (Giblin-Davis et al., 1994). Typically, ternative methods of management but often most palm pests silky cane weevil infestations in palms are not lethal, although do only aesthetic damage and do not harm the palm. In many heavy infestations in highly susceptible species such as spindle cases, pests will disappear on their own. and majesty palms may be lethal. However, aesthetic problems such as the exudate running down the stem or crown shaft are Literature Cited usually of concern. Palm stress created by silky cane weevil in festation can increase the chances of infestation by the palmet Broschat, T. K. 1994. Removing potassium-deficient leaves accelerates rate of to weevil. Palmetto weevil infestations can be lethal to palms. decline in Phoenix roebelenii O'Brien. HortScience 29:823. Chemically-based management tactics are currently rec Broschat, T. K. 1999. Nutrition and fertilization of palms. Palms 43:73-76. Giblin-Davis, R. M. and F. W. Howard. 1989. Vulnerability of stressed palms ommended for control of the silky cane weevil. Giblin-Davis to attack by Rhynchophorus cruentatus (Coleoptera: ). J. etal. (1996a) demonstrated that adults were killed by labeled Econ. Entomol. 82:1185-1190. rates of acephate, carbofuran, chlorpyrifos, cyfluthrin, disul- Giblin-Davis, R. M., J. E. Pena and R. E. Duncan. 1994. Lethal trap for evalu foton, imidacloprid, isofenphos, lindane and vydate. ation of semiochemical mediated attraction of Metamasius hemipterus seri ceus (Olivier) (Coleoptera: Curculionidae). Florida Entomol. 77:247-255. The use of entomopathogens provides a promising means Giblin-Davis, R. M., J. E. Pena and R. E. Duncan. 1996a. Evaluation of an en of managing silky cane weevils. The entomogenous fungi, Beau- tomopathogenic nematode and chemical insecticides for control of Meta- veria bassiana and Metarhizium anisopliae, have gained consider masiushemipterus sericeus (Coleoptera: Curculionidae).J. Entomol. Sci., able attention as potential control agents for weevils (Pena et 31:240-251. al., 1995; Giblin-Davis et al., 1996a). Giblin-Davis et al. (1996a) Giblin-Davis R. M., A. C. Oehlschlager, A. L. Perez, G. Gries, R. Gries, T. J. Weissling, C. M. Chinchilla, J. E. Pena, R. H. Hallett, H. D. Pierce, Jr. and demonstrated that the nematode Steinernema carpocapsaewas ef L. M. Gonzalez. 1996b. Chemical and behavioral ecology of palm weevils. ficacious against larvae but not the adults of the silky cane wee Florida Entomol., 79:153-167. vil. Researchers have concluded that because of the potential Howard, F. W. 1999. An introduction to insect pests of palms, pp. 133-139. In for high weevil production per Canary island date palm in Flor M. C. Ruano (ed.), Proc. of the 2nd Int. Symp. On Ornamental Palms and Other Monocots from the Tropics. Acta Hort. 486. ida and the cryptic habitat of the boring stages of this weevil, Howard, F. W. and N. A. Harrison. 1996. Lethal yellowing of palms in Florida. chemical insecticides and entomopathogenic nematodes Posted on the UF/IFAS FLREC World Wide Web home page at http:// would need to be applied frequently and over a long period of www.ftld.ufl.edu/lyfacts.htm time for effective management of established populations. Howard, F. W. and A. Stopek. 1998. Control of royal palm bug with imidaclo Biological control is expected to provide additional, pos prid. Principes, 42:80-84. Howard, F. W., R. C. Norris and D. L. Thomas. 1983. Evidence of transmis sibly more effective, management of the silky cane weevil in sion of palm lethal yellowing agent by a planthopper, Myndus crudus (Ho- Florida and the Caribbean. However, very little is known moptera: Cixiidae). Tropical Agriculture 60:168-171. about effective biocontrol agents in the Americas and the Meerow, A. W. 1992. Betrock's guide to landscape palms. Betrock Informa Caribbean. Siequeira et al. (1996) identified predators of tion Systems, Inc., Cooper City, Florida. 153 pp. Meerow, A. W. and T. K. Broschat. 1992. Transplanting palms. University of Metamasius at the family level and stated that they were more Florida, IFAS Circular No. 1047. abundant in Brazil than were parasitoids. The predacious in Pena,J. E., R. M. Giblin-Davis and R. Duncan. 1995. Impact of indigenous sect families include Labiduridae, Histeridae, Staphylinidae, Beauveria Bassiana (Balsamo) Vuillemin on banana weevil and rotten sug Carabidae, Cicindelidae, Formicidae and Reduviidae. A para- arcane weevil (Coleoptera: Curculionidae) populations in banana in sitoid was observed and identified as a Tachinidae. Florida. J. Agric. Entomol. 12:163-167. Siqueira, H. A., R. Barreto, T. Cavalcante and M. Picanco. 1996. Controle bi- Greenhouse Thrips. Thrips are an occasional pest of palms ologico de Cosmopolites sordidus e Metamasius sp. (Coleoptera: Curculion in the landscape but damage is usually aesthetic and popula idae) em bananeoira por predadores e parasitoides. V Sicnobiol, Faz de tions tend to decrease on their own through time. Iguacu, Brasil, June 9-14, p. 161.

250 Proc. Ha. State Hort. Soc. 112: 1999.