19891 HOWARDAND BARRANT:LETHAL YELLOWINGS t63

Principes,33(4), 1989, pp. 163 171

Questionsand Answersabout Lethal Yellowing Disease

F. W. HoweRD ANDC. I. Be.nnexr Uniuersity of Florida, Fort Lauderdale Research artd Education Center, 32O5 CoIIege Auenue, Fort Lauderdale, FL 33314 and Industry Board, P.O. Box 204, Kingston 10, lamaica,

Lethal yellowing (LY) diseaseis one of the disease is comparatively limited at the most serious threats to palms world- present. wide becauseit is fast-spreading,kills palms The careers of most of the members of "LY rapidly once they are infected, incurable the original Florida and Jamaica at present, and affects many speciesof researchteams" havetaken them separate palms. Thanks partly to some membersof ways. Having been associated'with the the International Palm Society, a research original LY research teams, .the authors program with a multidisciplinary team of continue to conduct research on LY as a six scientistsrepresenting the fieldsof part of the Ft. LauderdaleCenter's long- pathology,entomology and horticulture was term interest in tropical ornamental hor- establishedby the State of Florida in the ticulture and the Coconut Industry Board's 1970's at the University of Florida'sFort mission to serve the coconut industry of Lauderdale Researchand Education Cen- Jamaica. ter to try to find solutionsto this problem. Over the years,we have receivedmany The Fort Lauderdalegroup soon formed a questions on LY from growers, horticul- close working relationship with a similar turists, and others interestedin palms. The LY researchgroup which had been orga- most frequent and some of the most inter- nized in the Research Department of the esting questionsare presentedhere. Coconut Industry Board of Jamaicaby the British OverseesDevelopment Ministry. By the early l9B0's, due to changesin Wich palm speciesare rnost suscep- budgetary priorities and other administra- Q. tible to LW tive considerations,both LY researchpro- gramswere phasedout by their respective A. The coconutpalm (Cocosnucifera) and. governments. This was unfortunate. speciesof Pritchardia are the most sus- Together, the two groups had developed ceptible (Howard et al. 1979). more knowledgeof the basic nature of the However, there are different degrees of disease,as well as practical ways to man- susceptibilityamong the many varieties of 'Jamaica age it, than had been accumulatedin the coconutpalm. The Tall' variety, 100 years or more since LY had been which is the most common coconut palm known in the Region. Lethal seenthroughout the CaribbeanRegion and yellowing is still with us, and in fact, has formerly in southeasternFlorida and the spread into new localities in the last few Keys, is one of the varieties that is highly years,but the momentumof theseresearch susceptibleto LY (Harries 1971, 1974). programs has been lost and researchon In Jamaica,where this was once the prin- r64 PRINCIPES [Vor. 33

I. A plantation in Jamaica of'Jamaica Tall' coconut palms destroyed by lethal yellowing disease. cipal variety grown, entire plantationswere associatedwith certain plant diseases.Since lost to LY within periods of a year or two it has not been definitely establishedthat (Fig. l). There are more than 30 species they are mycoplasmas,they are called known to be susceptibleto LY (Table l). mycoplasmallfte organisms. o'catch" Q. What causesLm Q. How do palms LY diseo.se? A. Scientific studies have indicated that A. The mycoplasmalikeorganisms which LY is causedby mycoplasmalikeorganisms causeLY are transmittedby the American (\4LOs).Mycoplasmas are microorganisms palm cixiid, Myndus crudus. (A cixiid is that are intermediatebetween viruses and a planthopper of the Cixiidae.)This bacteria.They have beenknown for some informationis basedon fieldevidence (e.g., time as pathogensthat causecertain dis- Howardl9B0) andon experimentsin which easesof animals.In the last two decades, American palm cixiids were collectedfrom similar oreanisms have been found to be palmsin areaswhere the diseasewas active r98el HOWARDAND BARRANT:LETHAL YELLOWINGS 165 and introducedinto cagescontaining palms Table 1. List of palm taxa susceptible previouslyunexposed to the disease.Palms to lethal yellowing in Florida, and rel- in caeesinto which the insects were intro- atioe susceptibility, Iune 1989. duceJ contracted LY. Palms in similar cageskept free of these insects remained Relative Susceptibilityl healthy(Howard et al. l9B3). Further test- ing wasdone with youngerpalms and palms unknown unknown of different species with similar results Allagoptera arenaria Arenga engleri 3 (Howardet al. 1984). Borassus f.abellifer 2 mitis 2 pus cabadae I Arner- Chrysalidocar Q. Are there insectsother than the Cocos nucifera 3 ican palm cixiid that could spread LY? Corypha elata 3 Dictyosperma album 2 A. Our studiesindicate that the American Gaussia attenuata unknown palm cixiid is the principal and possibly Houea belmoreana unknown the only vector of LY in the Americas. If Hyophorbe aerschafeltii 2 there were other insect speciescapable of Latania spp. 2 I they would be Liuistona chinensis transmitting the disease, Nannorrhops ritchiana unknown limited to Iocalizedareas. In most casesin Neodypsis decaryi unknown which diseasesare spread by more than Phoenix canariensis 2 one speciesof insect, all of the speciesare P. dactylifera 3.- I taxonomicallyclosely related. Thus, if there P. reclinata P. rupicola unknown is a vector of LY additional to the Amer- P. syluestris unknown ican palm cixiid, we would expect it to be Pritchardia spp. 3 another speciesof cixiid. Except for the Rauenea hildebrandtii unknown American palm cixiid, speciesof this group Syagrus schizophylla 2 2 Caribbean Trachycarpus fortunei are quite rare on palms in the Veitchia arecina unknown Region. In conclusion,if we could control V. merrillii 2 the American palm cixiid, we could control V. montgomeryana 2 LY in most (if not all) placesin the Amer- Veitchia sp. (Sunshinepalm) 2 icas where the diseaseis present. I Susceptibility ratings based on combined obser- vations of Fort Lauderdale Research and Education Center personnel. I : slightly susceptible,2 : mod- Q. Where did LY comefrom? erately susceptible,3 : highly susceptible. A. Lethal yellowing may have originated in the Western Caribbeanarea, as there reports of what appearsto have been were In which countries has LY been in coconutpalms in the Cay- Q. this disease reported? man Islandsas early as 1832, and in Cuba, Jamaicaand Haiti in the late lB00's. Palm A. In the'WesternCaribbean Region: Cuba, speciesnative to the Americas,particularly Jamaica, the Cayman Islands, Hispaniola to the CaribbeanRegion, are almost never (Haiti and the Dominican Republic), New affected by this disease, suggesting that Providence(Bahamas), Yucatan and Quin- perhapsin past ages the diseasespread tana Roo (Mexico);in the United States: repeatedlythrough this region, thus select- Florida and Texas.In Tropical West Africa, ing out resistant strains of these palms a similar or perhaps identical diseasehas (reviewedby Howard 1983). There are beenreported in Ghana,Togo, Cameroon alsoreasons to suspectthat LY may have and Nigeria. Also, in Tanzania(East Africa) evolved in Asia (Harries I979). an LYlike diseaseis beine studied. Since I66 PRINCIPES [Vor. 33 no major differenceshave been detected Q. Wat is the current situation regard- between the diseasesof Africa and the ing LY in Jamaica? Americas, they are all referred to as LY A. In Jamaicathere were formerly an esti- (reviewedby Howard 1983). 'Jamaica mated 5 million Tall' coconut palms(Harries 1974). LY destroyedmost Q. What is the current distribution of LY of these by the l980's, and they were in Florid.a (Iune of 1989) ? replacedby'Malayan Dwarf palms.There 'Jamaica are still,some Tall' coconut A. Key'West was where LY was first dis- palms throughout the island, and they continue covered in Florida, possibly as early as to be eliminated by LY. 1937. Between1955 and 1960, an epi demic of LY eliminated about 15,000 (75%) of the coconutpalms in Key West Q. Since LY is spread.by an insect, can (Martinez and Roberts 1967). Today, a the diseasebe controlled by spraying the visitor travelling the OverseasHighway to palms with an insecticid.e? Key West will passover many islandswith abundant standsof healthy coconut palms A. Although the American palm cixiid can 'Malayan 'Jamaica (the Dwarf and Tall' be controlled by insecticideson a limited varieties and hybrids between these are basis (Reinert I977), insecticidalcontrol represented)but may occasionally spot a of the vector is not promising as a long- palm or perhaps a cluster of palms with range strategyto control this disease.We LY symptoms. Coconut palms are still \ryereable to suppresspopulations of this common on Key West, and some of the insect and bring about a reduction of 50 'Jamaica old Tall' palms (e.g., near the to 7 5% in the rate of spreadof LY in large beach on the south side of the island) sur- experimental blocks by spraying palms vived the earlier LY epidemics. Some biweeklyfor l4 months.A 50% reduction islands,e.g., ConchKey and figeon Key, in the spread means that it would take have remained virtually free of LY. twice as long for all of the palms to die. The epidemicof the 1970's and early Perhapsthe rate of spreadcould be slowed l980's on the east coast from Miami to further by more frequent applications of the Palm Beaches(Howard 1980) hassub- more toxic and more persistentinsecticides sided because few palms of susceptible to even larger blocks of palms, but large speciesare left. LY continuesto spread scaleuse of insecticidesto control this dis- among these widely separated susceptible ease would entail unacceptable costs and palms. (The extensiveplantings of coconut environmental hazards (Howard and palms along beachesare notable excep- McCoy I9B0; Howard,unpublished data). tions.) During the 1970's there were rel- atively few casesof LY on the west coast How was it d,eterminedthat LY is of Florida or on the east coast north of Q. caused by MLOs? Jupiter Inlet (Howard 1980). However, within the last few years there has been a A. Researchershave observedmycoplas- seriousoutbreak of LY in Stuart, which is malike organisms consistently in tissue the northernmost city on the east coast of samples from palms with LY symptoms, Florida with extensiveplantings of coconut but have never observedthese orsanisms palms.And within the past two years,the in healthypalms (Beakbane et al. 1972; disease killed more than three hundred Heinze et al. 1972; Plavsic-Banjacet al. coconut palms on Estero and Sanibel 1972;ThomasI974,1979; Thomasand Islandsand Ft. Myers on the west coast Norris l98l). In one experiment,tissue of Florida. samplesof palms with LY symptoms and reB9l HOWARDAND BARRANT:LETHAL YELLOWINGS r67 of healthy palms grown under identical cycle again. This raises the question conditionswere compared.Only the palms whether the insectscan transmit the MLO with LY symptoms had MLOs (Howard et to the grasses.If so, grassescould serve al. 1983). In addition,researchers injected as a reservoirof the pathogen.We have various materials into palms with LY, and attempted to investigatethis point, but our found that only tetracycline antibiotics, resultswere inconclusivebecause adequate which are known to be active againstMLOs, experimentaltechniques have not yet been suppressedthe disease.Penicillin, which is developed. effective againstbacteria, did not suppress LY symptoms(McCoy 1972, McCoy and Giaenpresent technology,what is the Gwin 1977, Hunt et aI. 1974, Steiner Q. r976). bestmethod for controlling LY in coconut plantations? A. Coconut plantations affected by lethal Can tetracycline injections be used to Q. yellowing should be replanted to certified control LW 'Malayan seednut of either Dwarf or the 'Maypan' A. The tetracycline treatment developed coconut palms, which are highly by Dr. R. E. McCoy and co-workers resistant to lethal yellowing disease(Har- (McCoyL972,McCoy et al.1976)is very ries 1970, Harries and Romney 1974). 'Maypan' effective, but involves regular injections The is a hybrid obtained by 'Malayan 'Pan- every 4 months for the life of the tree. It crossingthe Dwarf with a suppressesthe symptomsof the diseaseso ama Tall,' the latter which is significantly 'Jamaica that a palm infected with lethal yellowing more resistant to LY than the staysalive and healthy. But if the injections Tall'(Harriesand Romney 1974). We have are stopped, the infection will break out investigatedseveral sites in both countries again and kill the palm. Therefore, this where there were unusually high lossesof 'Malayan 'Maypan' treatment was neyer recommendedby the Dwarf or coconut University of Florida as a permanent cure palms to LY. We have not conclusively for LY, but as a means of saving infected determined why these losseswere so high or immediately threatened palms while at thesesites (Howard et al. 1987). How- resistant palms were planted and grown to ever, since millions of these palms in take their place. The method is generally Jamaica and many thousandso{ them in considered impractical for use in com- Florida have survived LY epidemics,they mercial coconut plantationsbecause of the are thus far the most recommendablecoco- cost and other factors. nut palms for LY-affectedareas.

Q. Someonetold me that St. Augustine Q. Are there additional resistant uari- grass is an ahernate host of LY disea.se. etiesof coconutpalm? Is this true? 'Ceylon A. The 'Fiji Dwarf,' King' (a semi- 'Ceylon A. It is plausible,but remainsto be proven. dwarf), oCuban Dwarf,' Yellow 'Indian 'Red It is known that St. Augustinegrass (Slez- Dwarf,' Green Dwarf and otaphrum secund,atum),as well as many Spicata Dwarf are varieties of coconut other speciesof grasses,serves as a host palm that appearto be resistant,based on to the immature stages of the American Iimited trials in Jamaica. These are palm cixiid (Eden-Green1978, Zener de undergoing further field tests in Jamaica, Polaniaand LopezI977). When this insect and someof them are being testedin Flor- becomesan adult, it flies to palms, return- ida with the cooperation of the Coconut ing to grassesto lay eggs and begin the Industry Board. 168 PRINCIPES lVoL. 33

Q. For landscaping use,which lethal yel- Americas are known to be susceptibleto lowing-resistant palms can be recorrl- LY (Aiphanes lindeniana, Allagoptera mended? arenaria, Gaussia attenuata and, Sya- grus schizophylla). A. In addition to the resistantcoconut palm A booklet listing the numbers of palms varieties already mentioned, there are of different species in Fairchild Tropical many speciesof palms that are suitable as Garden, their geographic origins and the ornamentalsand which are resistantto numbers lost to lethal yellowing from lethal yellowing disease. More than 30 I97l-t977 is availablefrom the Ft. Lau- specieso{ palms are known to be suscep- derdaleCenter. tible to LY (Table i). But in Florida, at least 386 speciesof palms can be grorrr. This is the number of palm speciesiden- Are the date industriesof Arizona and tified in Fairchild Tropical Garden, Miami Q. Califtrnia threatened by LY? (Howardet al. 1979). On the other hand, many of the palm speciesin the Garden A. It wasonce believed that LY wasexclu- cannot be said to have been adequately sively a diseaseof coconut palms. When tested for LY susceptibility. For example, it invaded Florida, where many speciesof during the peak of the LY epidemic in the ornamental palms are common, it was dis- Garden(1973 -I977), LY hadnot affected coveredthat it had a broaderhost ranse. ottostapfeana,a specieswhich was Even then, it was suspectedthat coconut represented in the Garden by one palm. palm was a primary host, and that the This palm is still there, leading one to sus- diseasewould not spreadoutside of tropical pect that this speciesis not susceptibleto and semi-tropical areas where LY. However,this doesnot constitulea grow. The appearanceof LY in the Rio conclusivetest of the effect of LY on this Grande Valley of Texas, where it spread species.By contrast,in 1977,,Coccothri- rapidly and devastatedplantings of Canary nax clrgenteawas represented in the Gar- Island date palm (Phoenix canariensis), den by 40 palms,none of which was lost was a grim lesson(McCoy et al. 1980). to LY. The higher the number of palms Arizona and California have imposedquar- exposedto LY, the more confidentare we antine regulations to try to prevent LY of its resistance or susceptibility to the from invading those states and affecting disease.W'e can be quite confident about the date industries and also the Canary palmsthat are popular in southern Florida, Island date palms which are an essential becauseby now they havehad ampleexpo- part of the distinctive landscape of cities sureto LY withoutsuccumbins to it. Acoe- of the American Southwest.Methods of lorrhaphe wrighrii, Chrysilidocarpus preventing and controlling LY in coconuts lutescens, Phoenix roebelenii, Ptycho- and other tropical palmsdeveloped through sperma elegans,Roystonea regia, Sabal researchin Florida and the Caribbeanwould pctlmetto, Syagrus romanzffiana, and. usually be applicable to date-growing Washingtonia robusta are very common regions.In addition,some research in Flor- in southern Florida cities and we can say ida emphasizesmanagement of LY in date with a great deal of certainty that there groves. A preliminary evaluationof sus-' hasnever been a caseof LY in thesepalms ceptibility of different date palm varieties in Florida. Notice that five of these eight hasbeen completed (Howard et al. l9B5), speciesare nativeto the Americas.In Flor- and an apparently resistant variety, the 'Halawy,' ida we found that most of the susceptible is being tested further. AIso, species are native to Asia, Oceania and Canary Island date palms grown from Africa. Onlv four speciesnative to the of different provenancesare being tested r989l HOWARD AND BARRANT:LETHAL YELLOWINGS r69 for LY resistance,with some early prom- experts doubt that this occurs. For one ising results. thing, palms infected with LY shed their . However, the possibility of seed Q. Is LY a threat to Hawaii? transmission of MLOs has not been dis- proven. A. In spite of its isolated geographic posi- tion and strict quarantine measuresprac- Und,erwhat conditionsare palms most ticed by agricultural officials, Hawaii has Q. susceptibleto LW more than its fair share of plant pests and diseases inadvertently introduced from A. We lack conclusive experimental data sometimesvery distant lands. If LY were to answer this question, but basedon field introduced into Hawaii, it would have a observations by a number of scientists, devastating effect. To evaluate the sus- palms are apparently most likely to con- ceptibility of Hawaiian coconut palms, a tract LY when grown under the following field trial was conducted at the Ft. Lau- conditions:(t) in full sun, (2) on a site with derdale Center, in which 18 palms of a grassesthat serve as hosts to immature tall variety common in Hawaii and 13 of stages of the American palm cixiid, and a dwarf variety referred to in Hawaii as (3) when given plenty of water and fertil- 'Samoan Dwarf were grown from seednut izer. Also, in our experience(4), LY spreads obtainedfrom Hawaii. For comparison, IB faster and destroys more palms if suscep- 'Jamaica Tall' coconut palms were grown tible speciesare planted in blocks or mono- from seednut obtained locally. The seed- cultures, rather than mixed with non-sus- nuts were held in a seedbeduntil two years ceptible palms or other trees. after sprouting and then were planted in a field in April 1983. The palms were Q. []nder what conditions do palms of examined frequently for disease symp- susceptiblespecies esca,pe LY infection? toms, and diagnosesby symptoms were A. Palms of susceptiblespecies grown in substantiatedby taking bud tissub samples the shade(e.g., of a large, spreadinglive from one symptomatic palm of each of the oak or similar tree) often escape the dis- three varieties and examining them under ease. In southeastern Florida extensive the electron microscopefor MLOs. 'Jamaica plantings of Tall' coconut palms MLOs were observedin tissue samples on the oceanbeaches survived the severe from all three varieties, confirming that LY epidemic of the 1970's and early our diagnosesby symptoms were correct. 1980's and are still standing.The disease After four years of field exposure to LY appeared to spread relatively slowly in (April 1987), lossesof the three varieties 'Jamaica palms surrounded by large paved areas, to the diseasewere as follows: 'Jamaica e.g., parking lots, and some Tall' Tall'-88.8%; taltrvariety from Hawaii- 'Samoan coconut palms have continued to survive 83.3%; Dwarf'-92.37o. In in such areas, while in nearby areas with addition to coconut palms, other palms in lawns the palms died from LY, In general, Hawaii would be affected by LY. W'e have the diseaseappears to spread more slciwly found, Pritchardia a native of ffinis, in areas where palms are presumably Hawaii, to be highly susceptibleto LY, as "stressed" due to lack of maintenanceor are other speciesof this genuswhen grown otherwise inhospitableenvironmental fac- in Florida. tors than in areas where they are given ample water and fertilizer, especiallyhigh Can LYbe carried in the seedof palms? Q. rates of nitrogen. For example, in Florida A. There is no evidencethat MLOs can LY spreadsparticularly fast on golf courses be tranmitted uia the seed of , and as opposedto areasof the citieswhere the 170 PRINCIPES [Vor. 33

lawns and trees are neglected by the res- tioned in Veracruz and at the experiment idents. This relationship needs further station in Chetumal, Quintana Roo (Vil- investigation. lanuevaet al. l9B7).

Q. Wat is the current status of research Acknowledgments on lethal yellowing disease? We thank Mr. JamesV. DeFilippisfor A. At the Ft. LauderdaleCenter, methods assistancein many of the field experiments of controlling the vector are being inves- at the Ft. LauderdaleResearch and Edu- tigated. A key to control of this insect is cation Center referred to in this article and that the immature stages develop on Ms. Donna S. Williams, Department of grasses,and the adults fly to palms. There Microbiology and Cell Science, University is considerable interest throuehout the of Florida, for identification of MLOs in humidtropics in the conversionof ground- the experimenton Hawaiiancoconut palms. covers of coconut plantations to improved Information on the current distribution of foragegrasses. Use of grassesthat do not lethal yellowing in Florida was developed support the American palm cixiid could in cooperationwith Mr. GeorgeH. Gwin, prevent or help control the spreadof LY. Florida Department of Agriculture and Recently, the authors completed a three- ConsumerServices (Ret.), Miami; Ms. Nina year cooperative project funded by the Woessner, Plant Recorder, Fairchild U.S. Agency for International Develop- Tropical Garden;Mr. Mike Miller, Monroe ment. This project resulted in the identi- County Cooperative Extension Service, fication of grassesthat are poor hosts of Key West; and Mr. Victor Yingst, Lee the American palm cixiid and that are valu- County CooperativeExtension Service, Ft. 'Samoan able tropical forage grasseswell-adapted Myers. Seednutsof Dwarf coco- for use as ground-cover in coconut plan- nuts were kindly provided by Mr. James tations. This work continues-at Ft. Lau- W. Mason. Aiea. Hawaii. We also thank derdale, with increased emphasison find- Dr. NigelHarrison. University of Florida, ing turfgrasses and other ornamental for reviewing the article. This is Florida ground-coversthat do not supportthe vec- Agricultural Experiment Station Journal tor of LY. Researchon varietiesof coconut SeriesNo. 9740. that are resistantto LY continuesto receive high priority in Jamaicaand Florida. Test- ing of date palms and other speciescon- Lrrrnerunn Crrnn tinue at Ft. Lauderdale. BrerneNr,A. 8., C. H. W. Surnn, exl A. G. Dr. Nigel Harrison, a plant pathologist PoSNETTE.1972. Mycoplasmasin the phloem at the Ft. Lauderdale Center, is currently of coconut, Cocos nucifera L. with lethal yel- lowing disease. attempting to develop a biochemical test J. Hortic. Sci.47:265. Elnn-Gnrex, S. J. 1978. Rearingand transmission to diagnoseLY in its pre-symptomstage. techniquesfor llaplarizs sp., a suspectedvector Pre-symptomdiagnosis of LY has been a of lethal yellowing diseaseof coconut palms in Jamaica.Ann. Appl. Biol. 89: I73 176. goal of a number of researchersfor many 'Malayan years becauseof the importance of such Hennrts, H. C. 1970. The Dwarf supercedesthe'Jamaica Tall' coconut. l. Rep-. a technique to many research problems utation and performance-Oleagineux 25:527 directed towards developing practical 531. methods of managing and preventing the 1971. Coconut varieties in America. disease. Oleagineux26: 235-242. Researchon LY is alsobeing conducted I 974. Natural symptomremission of lethal yellowing diseaseof coconut. Trop. Agric. (Trin- by the Mexican Secretariade Agricultura idad)5I: 575 576. y RecursosHidraulicos by personnelsta- 1979. The evolution,dissemination and 19891 HOU/ARDAND BARRANT:LETHAL YELLOWINCS l7I

classificatiorr of Cocos rtuciJbr L. Botanical Rev. McCoY, R. E. I972. Remissiorrof lethal yellorving 44:265-319. in coconut palm treated with tetracyclineanti- ,r.NlD. B. RoMNEY.1974. Maypan:an biotics.Plant Dis. Reptr.56: 1019 1021. F, hybrid coconut variety for commercialpro- eNl C. H. CwtN. 1977. Responseof ductioninJamaica. World Crops26: I10 III. mycoplasmalikeorganism-infected Pritchardia, HrrNzE,K.G.,H.Plrzoll,,rnoR.MARwIrz. 1972. Trachycarpus, and Veitchia palms to oxytetra- Beitrug ziir Atiologie der Todlichen Vergilbung cycline.Plant Dis. Reptr.6l: 154 158. der Kokospalme.Phytopath. 2.74:23O 237. M. E. MTLLER,eul D. S. WILLIAMS. 1980. HowARD, F. W. 1980. Population densitiesof Lethal yellowingin Texas Phoenir palms.Prin- Myndus crudus Van Duzee(Hornoptera: Cixi- cipes24: 179 lB0. idae) in relation to coconut lethal yellowing in V. J. CARRoLL,C. P. Pot,cHER,,q.nl C. H. Florida. Principes24: I74 1.78. CwIN. 1976. Field control of coconut lethal 1983. World distribution and possible yellowing with oxytetracycline-hydrochloride. geographicorigin of lethal yellowing and its vec- Phytopathology66: I 148-I I50. tors.FAO Plant Prot. Bull. 341: l0I i13. Pr.'rtrslc-BeNJec,B., P. HlNr, eNn K. Menluo- AND R. E. McCoY. 1980. Reductionin oRoscH. 1972. Mycoplasmalikebodies asso- spread of mycoplasmalikeorganism-associated ciated with lethal yellowing diseaseof coconut lethal declineof the palm, I'eitchia nerrilLii by palms. Phytopathology 62: 298 299. the use of insecticides.J. Econ. Entomol. 73: RntNrnl, I. A. 1971. Field biologyarrd control of 268-270. Haplaxius crudus on St. Augustinegrassand R. A. ATILAN0,AND D. S. WILLIAMS. 1985. Christmaspalm. J. Econ. Entomol. 7O: 54-56. Experimental establishment of {ive date palm SrrrNon, K. G. 1976. Remissionof symptomsfol- cultivars in southern Florida. Date Palm J. 4: lowing tetracyclinetreatment of coconutpalms 9l r02. affectedwith Kaincope disease.Plant Dis. Reptr. R. C. Nonnrs,eNo D. L. THoNIAS.1983. 60:617 620. Evidenceof transrnissionof palm lethal yellowing THoMAS,D. L. 1974. Possiblelink betweendeclin- agent by a planthopper, Myndus t:rudus ing palm speciesand lethal yellowingof coco- (Homoptera:Cixiidae). Tropic. Agric. (Trinidad) nuts. Proc. FloridaState Hortic. Soc. 87:502 60: 168 17l. s09. D. S. Wrrlrer,rs, eNl R. C. NORRIS.1984. I979. Mycoplasmalikebodies associated Insect transmissionof lethal yellowing to young with lethal declines of palms irr Florida. Phyto- palms.Internat. J. Entomol. 26: 331 338. pathology69:928 934. D. L. THoMAS,H. M. DoNSELMAN,AND eNl R. C. NoRRIS. 1981. The use of M. E. CoLLINS. 1979. Susceptibilitiesof palm electron microscopy for lethal yellowing diag- species to mycoplasmalike organism-associated nosis.Proc. FloridaState Hortic. Soc.93: I96- diseasesin Florida. FAO Plarrt Prot. Bull. 27: r99. 109 li7. VrrreruEve, J., J. PrNA, AND H. CARRILLO. 1987. R. ArrreNo, C. I. BARRANT,N. A. Avances sobre el control y la irrvestigaci6n del HARRrsoN,W. F. THEOBALD,aNo D. S. Wtl- amarillamiento letal en cocotero en M6xico. LIAMS. i987. Unusuallyhigh lethal yellowing SARH, Inst. Nac. Invest. Forest. Agropec., diseaseincidence in Malayan Dwarf coconut Campo Expt. Cotaxtla, Veracruz, Ver. Mexico, palms on localizedsites in Jamaica and Florida. Foll. Tec. #1, pp. 19. J. PlantationCrops l5: 86 f00. ZENNER DE Pol,qNl,r, I. AND A. Lopnz A. 1977. HUNr, P., A. J. DABEK,.qNo M. Scsurr-rNc.1974. Apuntes sobre la biologia y h6bitos del HapLax- "rnarchitez Remission of symptoms following tetracycline ius pullidus, transmisor de la sor- treatilrent of lethal yellowing infected coconut presiva" en palma africana. Rev. Colorrb. Ento- palms.Phytopathology 64: 307-3I2. mol 3Q,/2): 49 62. MARTrNEZ,A.P.exrD.A.RoBERrs.I967. Lethal yellowingof coconutsin Florida. Proc. Florida State Hortic. Soc. 80: 432 436.

CLASSIFIED

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