PALMS Ganodermain Florida:Elliott & Broschat Volume 45(2) 2001 Observations and M. t. Eluorr Pathogenicity AND T. K. BnoscHer Universityof Florida Experiments Fort LauderdaleResearch and EducationCenter 3205 CollegeAvenue on GsnodermcrFort Lauderdale,Floricla zonatum in 33314 USA Florida

Ganoderma butt rot of palms, caused by zonatum, is a widespread and serious disease in Florida, USA. The means by which the invades healthy palm trunks is not known. However, infection appears to begin at the center of the base of palm trunks and spreads outrvard and upwards from there, eventually producing a hard, shelf-like structure that is the basidiocarp (conk). Basidiospores produced within the conk may be the primary method for spreading the fungus in the urban landscape. Wilt symptoms are caused by the fungus rotting the xylem, as well as other trunk tissue, in the lowest 1.5 m of trunk. It is believed that most, if not all, woody palms are susceptible to this disease. Experimental attempts to inoculate healthy trees with this fungus have generally been unsuccessful.

Palms are found throughout Florida (USA)in both basidiomycete fungi that are found throughout natural and landscaped settings. They are not l the world on all types of wood - gymnosperms, grown for agronomic purposes, but are important hard- and softwood dicots, and palms (Gilbertson as ornamental . When a list of the top ten , & Ryvarden 1986). The is greatly debated diseasesof Florida ornamentals was compiled in , at the specieslevel; Miller et al. (1999) described "currently 1997, Ganodermabutt rot of palms was listed as , it as chaotic." This has been due to number two (Schubert et al. 1997). The fungal , speciesnames being added and then dropped, an genus Ganodermais a group of wood-decaying , inconsistency in criteria used for identification

62 PALMS45(2): 62-72 I'ALNlS Ganodermain Florida:Elliott & Broschat Volume45(2) 2001

1 (above). palmetto (sabal palm) with wilted and desiccatedleaves due to Canodermozonotum infection.

2 (right).Syogrus romonzoffiana (queen palm) dying from Canodermazonatum. Only the spearand one other remaingreen.

3. Basidiocarp(conk) o1 Conoderma zonatum. Note glazed reddish- brown top surfaceand whiteundersurface. The "straight"side of the conkis directly attached to thetrunk. There is no "stem" or "stalk"that attachesthe conkto the trun k.

63 PALMS Ganodermain Florida:Elliott & Broschat Volume 45(2) 2001

purposes at the specieslevel, and the fact that the vasculartissue aswell as the surrounding tissue morphological characteristics change based on has been degradedby the fungus. This becomes environment (Moncalvo et al. 1995). evident when a palm that has died or is dying from Ganoderma butt rot is cut down and cross- In Florida, Ganodermabutt rot is a lethal disease sections made of the trunk. Figs 4 and 5 are that appearsto be causedby the fungus Gqnoderma examples of the wood rotting and disease zonatum Murrill. Another fungal name that was progression pattern observed. The fungus associatedwith this diseasein the first half of the colonizes and degradesthe palm trunk tissue 20th century was Ganodermasulcatum MurrilI closestto the soil line first, expands in diameter (Murrill 1902,79O8;Childs & West 1953).Murrill at the baseand moves up the center or near-center indicated in his papers that both specieswere of the trunk. Therefore, the diseaseprogression associatedwith dead wood in Florida, and that pattern within the trunk is best described as cone- they were very similar in appearance.Recently, shaped,widest at the soil line and narrowing to a these two specieshave been grouped together as pinpoint. In general, we do not see the fungus one, G. zonatum (Gilbertson & Ryvarden 1986). extend more than 1.5 m (-5 ft) up into the palm Although G. zonatum is often referred to as a trunk. Although roots may eventually rot, member of the G. lucidum complex, it is a distinct especiallyafter the palm dies, the lethal damage speciesfrom G. lucidum (Adaskaveg& Gilbertson from the fungus appearsto be associatedwith the 1989). Information is available regarding the trunk degradation. Ganoderma butt rot is a disease morphological and cultural characteristicsof G. of mature palms (i.e.,palms with trunks) and has zonatum (e.g., Adaskaveg and Gilbertson 1989; not been observed to affect seedling or juvenile Adaskavegand Gilbertson 1988; Gilbertson & palms in natural or landscapesettings. R1'varden 1986), but little is known about the diseaseit causes.A similar basal stem rot of oil It was previously thought that the location of the palms is widespread,but is causedby a different initial basidiocarpformation was the entry point Ganodermaspecies, presumed to be G. boninense for the fungus, perhapsfrom a wound to the trunk. (Miller et al. 1999). This pathogen does not occur We do not believe that is true. The location of the in North America. Considerable information is basidiocarp is where the fungus is emerging from available on this diseasein SoutheastAsia, so we the trunk. This means the degradation is occurring have relied heavily on this information as a basis internally as the fungus moves from the lower for initiating researchin Florida. This article is a center of the palm to the outside. This is especially compilation of our personal observations and evident when a palm suspectedof being infected pathogenicity researchresults obtained since 1994. with G. zonatum, based on wilt symptoms and palms, I. OBSERVATIONS proximity to other diseased but without basidiocarpsis examined.This meansthat wounds Symptoms and Signs are not a likely factor in diseaseinitiation. Other Ganodermazonatum is a white rot fungus that external environmental factors associatedwith the produces numerous enzymes that allow it to trunk are probably not associatedwith disease degrade (rot) woody tissue, primarily lignin and development either, such as too much mulch cellulose (Adaskaveget al. 1991). As the fungus around the trunk, irrigation heads striking the destroys the palm wood internally, the xylem trunk, flowers or shrubs too close to the trunk, or (water-conducting tissue) will eventually be painting the trunk. affected. Therefore, the primary symptom that Life Cycle of the Fungus may be observed is a wilting, mild to severe,of all but the spear leaf (Figs. 1 and 2). Other The basidiocarp or conk is the most easily symptoms can best be described as a general identifiable structure associatedwith the fungus. decline - slower growth and off-color foliage. The conk is a specializedmass of fungal growth However, these symptoms alone should not be that originates from mycelia in the palm trunk. used for diagnosis of Ganoderma butt rot, since Fig. 6 illustrates different stages in the other disorders or diseasesmay also causethese development of the basidiocarp. When the fungus symptoms. Only when these symptoms are first starts to grow on the side of a palm trunk or accompanied by the development of the palm stump, it is a solid white mass that is basidiocarp (conk) (Fig. 3) can the palm be relatively soft when touched. It will have an confirmed as affected by G. zonaturu.Also, it is irregular to circular shape and is relatively flat on commonly observedthat basidiocarpswill form the trunk or stump. prior to any obvious wilting or decline symptoms. As the conk matures, a small shelf or bracket will It should be emphasizedthat this fungus is not start to form asthe basidiocarpbegins to protrude restricted to vasculartissue. The palm wilts because from the trunk. It will still be white, both on the

64 PALMS Ganodermain Florida:Elliott & Broschat Volume45(2) 2001

Thble 1. Palms documented to have been infected with Ganodermq zonqtum.

Palm Sourcez Nannorrhopsritchiqna FTG Phoenix canartensis DPI, FTG Acoelorraphewrightii FTG Phoenix dactylifera FLREC Acrocomiaaculeata FTG Phoenix reclinata DPI, FTG Adonidia merrillii FTG Phoenix roebelenii FTG Aiphanessp. DPI Phoenixsylvestris FLREC Arenga engleri FTG Ptychospermaelegans TREC Arenga tremula FTG Ptycho s p erma mac arthurii DPI, FTG qlomonens Arenga undulatifolia FTG Ptycho sp erma s e FTG Attalea sp. FTG Roystoneaaltissima FTG Bactris maior FTG Roystoneaoleracea FTG Brahea berlandieri FTG Roystonearegia DPI, FTG Brqhea brandegeei FTG Sabal causiarum FTG, TREC Brqhea dulcis FTG Sabal mauritiiformis FTG Brahea edulis x brandegeei FTG Sabalpalmetto DPI, FLREC, FTG Sabal uresana FTG Butia capitata DPI Satqkentia liukiuensis FLREC Carpentariaacuminata FLREC Serenoarepens FTG Caryota mitis DPI Syagrusoleracea FTG Chamaeropshumilis FTG Syagruspicrophylla FTG Coccothrinaxsp. FTG Syagrusromanzoffiana DPI, FLREC, Cocosnucifera DPI Syagus sancona FTG Copemiciacurtisii FTG Syagrusschizophylla FTG Dictyospermaalbum DPI Syagrusx costae FTG Dypsis cabqdae FTG Washingtoniarobusta DPI, FTG Dypsis lutescens DPI, FTG Elaeisguineensis TREC ZDPI = Diseasesand Disordersof Ptants in Florida Euterpeedulis DPI (Alfieri et aI., 1994); FTG = Fairchild Tropical Gastrococoscrispa FTG Garden, Miami, FL; TREC = University of Hyophorbeindica TREC Florida's Tropical Researchand Education Livistona benthamii FTG Center, Homestead, FL; FLREC= University of Livistona chinensis DPI, FTG Florida's Fort Lauderdale Research and Livistona merrillii FTG Education Centeq Fort Lauderdale, FL; Forestry Livistona muelleri FTG = Florida's Department of Forestry, Miami, FL. Livistona saribus Forestry

top and bottom surfaces.Eventually, it will form expanding in size at a later date. In southern, sub- a very distinct shelf-like structure that is quite tropical Florida, conks can be produced hard with aglazed reddish-brown top surface and throughout the year. In northern, temperate a white undersurface (FiS. 3). A mature conk will Florida, conks are normally only produced during have distinct zones, hence the name G. zonatum. the warmer months of May through October. We The basidiocarp will have a half-moon shape with have observed thdt:"mature, viable basidiospores the "straight" side directly attached to the trunk. are produced very eitrly in the formation of the This is referred to as a sessilebasidiocarp as basidiocarp. Sporeswere produced shortly after opposed to one that has a stalk or stipe (Figs3 and the conk began to protrude (form a shelf from the 6). Conks can be up to 20 cm (8 in) at their widest trunk, while it was still white, and long before the point and 5 cm (2 in) thick. Microscopic top turned a reddish-brown color. We believe that basidiosporeswill be produced in the "pores" the sporesare the primary means of spread of the present on the underside of the conk. When fungus, but that has yet to be proven. Recent basidiospores are dropped en mass on a white research with Ganodermain Malaysia determined surface, they will appear brownish-red in color. that G. boninensemay spreadin oil palm plantings through basidiospore dispersalor through contact The conk is considered an annual conk. Once it with long-term residual inoculum (mycelia, etc.) stops growing, it does not begin growing and in soil debris (Miller et al. 1999). The genetic

65 l),\1.\ls Canoderma in Florida:Elliott & Broschat Volume45(2) 2001

I

:l .: -I trL '^i'* :,.. \. 11...:,,,.-'--*+

.+'{, ' r\'' *Tii Fig. 4 (top). Crosssections of lower lrunl

56 PALMS Ganodermain Florida:Elliott & Broschat Volume 45(2) 2001

.r'r't ,; '^ti'rNl.^,'.i,; lrjf) '*i ;r,f \ /t.r#'i"r 71;l i*fi "button" Fig.6 (top).Three phases of basidiocarp(conk) development of ianodermazonotum. The white nearthe top of pictureis the beginningstage of the conk.The lower-rightstructure is a matureconk. The lower-leftstructure is also a matureconk, but it is an old one;the undersideof the conkis no longerwhite. Fig. 7 (bottom).Cut palmstump with numerousbasidiocaros of Gonodermozonotum formino on it.

I 67 PALMS Ganodermain Florida:Elliott & Broschat Volume45(2) 2OO1

information obtained by this research group disease.In fact, it is probably more Iogical to suggeststhat the fungus doesnot spreadby direct assume that all palms are susceptible to G. root-to-root contact between palms. zonatum.The only possibleexceptions would be palm speciesthat do not form woody trunks - The diversity and isolation of locations in Florida e.g.,Sabal minor, some Chamaedoreaspp. SinceG. where Ganoderma butt rot has occurred would zonatum kills by degrading wood, these palm support the concept of sporesas a primary method speciesmay not have any suitable tissue to serve of spread.Palms are not a plantation crop in as a substratefor the fungus. Florida, but are found in two distinct settings. One would include natural groves of non-transplanted The distribution of G. zonatum in Florida is shown sabalpalms (Sabalpalmetto). The other is the urban in Fig. 8. This information was obtained from landscape, where the majority of palms are many of the same sourcesas listed for the palm transplanted from either natural settings in host range and by contacting University of Florida Florida, date groves from south-western USA, or Cooperative Extension Service faculty in each nurseries.In urbanized southern Florida, the county. While the diseaseis more prevalent in the "soil" upon which developmentsare built, and in southern half of the state where palms are in which palms are transplanted, is dredged from greatestabundance, it is certainly not restricted to man-made lakes.It is devoid of any possibleplant that area. debris harboring G. zonatum. However, only Environments or Practices that Encourage genetic studies will definitively demonstrate how Disease Development G. zonatumspreads. To date, we have observed no common environ- After sporesare released,it is unclear exactly what mental conditions or landscape management happens next. We do not know if the practices that favor the development of become dormant in nature. In a laboratory setting, Ganoderma butt rot. The disease has been the spores do not show any dormancy and observed in natural settings (palms never germinate readily on media after being dropped transplanted) and in highly-maintained, trans- from the basidiocarp. However, in the real world, planted landscapes.It hasbeen observedon palms they may indeed become dormant or need specific that have been maintained very well nutritionally substrates,temperature, relative humidity and so (no nutrient deficiencies)and on palms that were forth for germination to occur. We do know that severelystressed by deficiencies.The diseasehas at some point in time multiple spores do been observed in well-drained settings and in germinate, mate and produce mycelia that will go swamps.The fungus has killed treesthat had no through three distinct stagesof development - apparent mechanical injuries and those that had primary, secondary and tertiary. The basidiocarp been severely damaged by weed trimmers. Soil or conk is composed of the tertiary mycelia. t)?e appearsto have no relationship with disease Host and Geographic Range either as diseasedpalms have been observed on deep sands (both silica and calcareous), muck In the Diseasesand Disorders of Plants in Florida (peat), and limestone rock. There has been no (Alfieri et al. 1994), five non-palm speciesare listed simple discernible pattern to provide clues as to under G. zonatum. It is quite possible that G. why palms become infected and die from G. zonatum was not a pathogen of these non-palm zonatum. species,but rather a saprobe that grew on the wood after the tree had died. According to Management Considerations Adaskaveget al. (1991), the only authenticated In general, the fungus will be located in the lower reports of G. zonatum are from palms. Howeveq 1.5 m of trunk. This has two implications. First, there has been one report in Florida ef G. zonatum this means that only'ihis lowei trunk portion associatedwith a cycad. Still, palms should be should not be chipped and used for mulch. If consideredthe primary hosts of this fungus. Table possible,the diseasedsection should be placed in 1 lists all of the palms known to have died from a legal landfill or incinerated.The remaining Ganoderma butt rot in Florida. This list was portion of the palm trunk could be immediately comoiled with information obtained from chipped and used for mulch in the landscape. .tumerous sourcesin Florida, as indicated in the table. Although not all palm speciesknown to be Secondly,only the lower 1.5 m of trunk will need growing in Florida have succumbedto this disease, to be protected from the fungus. However, typical the majodty of those speciesnot on this list are xylem-limited, systemic fungicides will not be relatively uncommon in Florida. Therefore, just effective unless they are capable of spreading becausea palm is not listed in this table, it is not beyond the vasculartissue and protecting all the safe to assumethat the oalm is resistant to the wood in the lower portion of the trunk. No

68 PALMS Ganodermain Florida:Elliott & Broschat Volume45(2) 2001 fungicide will be effective once the basidiocarps from Ganoderma butt rot also eventually have formed, since a large percentage of the trunk succumbs to this disease.This would indicate that is already destroyed. Since we have no means of the fungus does survive in the soil, either as predicting or determining which palms are infected plant material or spores. Therefore, it is infected with G. zonatum, this effectively never recommended to plant another palm in the eliminates the use of fungicides as a control same location as the previous Ganoderma-infested method, either preventively or curatively, for the palm. In general, no other plant tree speciesgrown present time. in Florida (pines, oaks, woody shrubs, etc.) are affected by G. zonaturz.Therefore, these would Since basidiosporesare probably the primary be replacements. We have method of spreading the fungus, we urge people aeceptable no definitive information on the length of time for zonatum to monitor their palms closely, especially after a G. survival in the soil, but it should be measured in palm has died or been removed for anlz reason. multiple years,not months. It may long The fungus will readily colonize and degradepalm be as as 10 to 30 years.It is certainly not less. stumps or dead palm trunks (Fig. 7). Once it becomes established on this dead wood, it will If an infested site must be replanted with a palm, normally produce basidiocarps with millions of follow these guidelines. Remove the stump and all basidiospores.We had never observedG. zonatum roots from the site, and then fumigate the soil. as a pathogen on the Fort Lauderdale Research This can be done by a professional pesticide and Education Center (FLREC)property until applicator using a legally registered fumigant for March 1993 when it first killed a Sabalpalmetto. the landscape. An example would be the product Interestingly, this palm was only - 30 cm away dazomet (trade name = Basamid).If the palm was from a sabalpalm stump, left when a healthy palm located in a site surrounded by concrete (e.9., a had been cut down 5 years earlier for research street median), remove all of the old soil, bring in purposes. Howeveq we had observed G. zonatum new soil and then fumigate. However, none of basidiocarpson this stump as early asAugust 1991. these procedures guarantees the new palms will More recently at the FLREC, we observed G. remain free of Ganodermazonatum. zonatum basidiocarps on dead Carpentaria II. RESEARCH acuminata trunks. These palms had died from other causes.We also noticed that there was a Introduction - Carpentariapalm in this same planting, 1 m Although it may appear obvious that G, zonatum away, that appearedwilted. When it was cut down, is a pathogen of palms in Florida, a fungal the center of the basal trunk area was already pathologist would like to have this confirmed. rotted from G. zonatum. We have also observed The term used for the process that confirms and been told on numerous occasions of pathogenicity is "Koch's Postulates."This requires Ganoderma butt rot occurring on Dypsls lutescens isolating the fungus from a host with typical (areca palm) after some of the mature canes had symptoms, obtaining a pure culture of the fungus, been removed. In all probability, the fungus moves using this culture to inoculate a healthy host, and in on the dead stumps of thesepalms and spreads then observing the development of typical from there to living canes. symptoms and re-isolating the samefungus. \Alhile Therefore, monitor your palms in Florida, and this may be a simple task when dealing with small other areasof the south-easternUSA where the annual plants, it is not simple when dealing with fungus has been documented, for the basidiocarps. mature palms. Furthermore, we would like to have Removethe basidiocarp (conk) and place in a trash a systern that would consistently provide us with receptacle that will be incinerated or delivered to a method for artificially inducing the diseasein a landfill. Do not place in trash that will be healthy palms in,:o4@erto conduct experiments recycled in the landscape. The earlier the relative to control tactics, fungal life cycle and basidiocarp is removed (i.e., before it becomesa diseasecycle. distinct shelf-like structure), the less likely that Researchersworking with the Ganodermadisease sporeswill be releasedinto the environment. If on oil palms in Southeast Asia have examined ;zou have never observed Ganoderma butt rot on pathogenicity of G. boninense using Elaeis the property, monitoring the palms once every guineensis(African oil palm) seedlings.Both natural six months will be adequate. Once you have inoculum (Navaratnam & Leong 1965) and observedthe basidiocarpson palms or have a palm artificial inoculum (Hashim et al. 1993; Sariahet cut or fall down for any reason,monitor the palms al..1994) were used and were successfulin at least once a month. inducing disease.Howeveq as Hashim et al. (1993) It has been observedrepeatedly that a replacement point out, reproducing these experiments has not palm planted into the same site where a palm died alwaysbeen possible.

69 PALMS Ganodermain Florida:Elliott & Broschat Volume 45(2) 2001

Fig.8. This map illustratesthose Floridacounties where Canoderma butt rot, caused by Gonoderma zonatum,has been reported on palms. Informationwas obtainedfrom the FloridaDepartment of PlantIndustry Universityof Florida'sPlant Disease rjll#+r".' Clinicsand CountyExtension Faculty.

Materials and Methods deep (until roots were contacted).The inoculum was divided among the holes and recoveredwith Field experiments with natural inoculum and soil. For inoculated non-transplanted palms, the mature palms inoculation procedurewas similar except that we A romanzofflana (queen palm) with avoided contacting or damaging any roots. The Ganoderma butt rot was obtained in Palm Beach non-inoculated palms were not disturbed. County, Florida,USA. This palm had basidiocarps Transplanted palms were maintained using present on the lower trunk that were confirmed standardprocedures. Once they were established, as G. zonatum.The lower portion of the trunk was no extra care (fertilizer or water) was provided rotted. This section (- 0.5 m) was cut into 10-15 these palms or the non-transplanted palms. cm cross-sectionswith a chainsaw, and then Shade-house experiments with natural and broken into different sizepieces (chunks, splinters, artificial inoculum and seedling palms etc.) by hand. Thesepieces were mixed with the sawdustin a large garbagecan and the lid replaced. Two experimentswere initiated to determine the This inoculum remained at air temperature in a best method for inducing diseaseby G. zonatum shade-housefor 14 days. A pure culture of the on seedlingpalms. The useof artificial and natural pathogen was obtained from the basidiocarpand inoculum was examined as well as size, amount the wood. and location of inoculum. Theseexperiments were initiatedin 1995. A block of 28 Syagrusromanzoffiana, 20-25 years June old, were used for the experiment. Half of the For Experiment I, three palm speciesin the palms were transplanted on 28 September7994, seedling phase, S. romanzoffiana (queen palm), on 6 m centers,to a site adjacent to the original Phoenix roebelenii(pygmy date palm), and Elaeis block. Half (7) of each palm group, transplanted guineenis(African oil palm), were inoculated with vs. non-transplanted,was inoculated with the either artificial or natural inoculum. Artificial infestedpalm trunk material on 10 October 1994. inoculum was made following the method of The inoculum was divided into 14 equal portions Sariah et al. (1994). Two isolates of G. zonatum (- 2 L volume per tree). For each inoculated were used, one from P. reclinata(GAN-9) and the transplanted palm, 3 equidistant holes were dug other from S. romanzoffiana(GAN-10). Bischofia 15 cm from the trunk base and about 8-10 cm iavanicawood was obtained and cut into 5 x 7.5

70 PALMS Ganodermain Florida:Elliott & Broschat Volume 45(2) 2001 cm pieces,with the bark removed. These pieces There were 13 treatments. Each size of inoculum were sterilized for 90 min. Individual pieces were was used as either a single piece per container or then placed separatelyin heat-sealablepouches as multiple pieces per container to obtain an and sterilized again for 90 min. Three days later, inoculum volume of 125 cm3. The remaining 3 25 ml of sterile, cooled, but not yet solidified, malt treatments were controls with either no inoculum, extract agar(1 .5o/o malt extract plus 2o/oBacto agar) 1 piece of uninfested palm wood (50 x 50 x 50 was added to.each pouch. Poucheswere rotated mm), or 8 piecesof uninfested palm wood (12.5 to evenly coat the wood pieces as the agar x 25 x 25 mm for a 125 cm3 volume). There were solidified. The next day half the pouches were 10 replicate containers for each inoculum volume inoculated with GAN-9 and the other half with LSize treatment. GAN-10. The G. zonatumisolates had been grown on potato dextrose agar in petri plates for 15 days. Palms were examined at 6-month intervals for Fungal growth in each plate was cut into 5 x 5 mm visible symptoms or signs of disease. After 24 present pieces,and one-quarter of the pieceswere added months, inoculum pieces that were still to each pouch. Poucheswere incubated at28-32 were removed, scrubbed clean, surface sterilized, C for 4 weeks. Natural inoculum was obtained blotted dry and placed on a semi-selectivemedium from a G. zonatum-infested Sabalpalmetto trunk. for G. zonatum. The wood was cut into 12.5 x 25 x 50 mm pieces. Shade-house experiment with natural and juvenile The E. guineenisand S. romanzoffianaseedlings artificial inoculum and mature or were transplanted from 1 L containers into 10 L palms plastic containers, while the P. roebelenii palms For Experiment III, nine palm species were were transplanted into 6 L plastic containers.The transplanted into 38 L plastic containers using the potting substrate was 500/opine bark, 40olosedge same potting substrate as described previously. peat and 10olosand. Roots were separatedand as Holes,0.5 cm diam. x 5 cm deep,were drilled into much potting mix as possible was removed prior the palm trunk or stem at the soil line (root-trunk to transplanting into containers with inoculum. interface) or 15 cm above the soil surface.The five All three palm species had the following G. zonatum inoculum treatments were: 1) no treatments: 1) artificial inoculum infested with inoculum; 2) 1 crfi of infested palm wood from 2) aftificial GAN-9, placed below the root ball; Sabalcausiarum; 3) I cm3 of oat kernel inoculum, with placed below the inoculum infested GAN-10, made by growing G. zonatum on sterilized oat root ball; 3) natural inoculum placed below the kernels for 4 weeks; 4) 1 cm: of basidiospores;and root ball; 4) natural inoculum placed on top of the 5) 1 cm3 of basidiocarptissue. The palms species root ball; 5) uninfested Bischofia wood placed on werc Phoenix roebelenii,Roystonea regia, Dypsis top of root ball; 6) uninfested palm piecesplaced Iutescens,Archontophoenix qlexandrae, Veitchia on top of the root ball; and 7) no wood pieces. arecina, Ptychospermaelegans, Thrinax radiata, Only one piece of artificial inoculum was placed Syagrus amaret and rivularis. The P. in the container. Twenty pieces of natural roebeleniipalms were mature (9-yr old) and had inoculum were placed in each container to obtain developed at least 90 cm of clear trunk. The A. a total inoculum volume of 15.5 cm3. There were alexandrae,V. arecina, and P. eleganshad begun to 10 replicate containers for each inoculum x palm form a woody trunk, but all other species were speciestreatment. without trunk tissue at the time of inoculation. Palms were examined at 6-month intervals for There were six replicatesof each palm speciesx visible symptoms or signs of the disease.After 19 hole location x inoculum type treatment. Palms months, roots and crowns of P. roebelenlland S. were examined at 6 month intervals for visible romanzoffiana ftom each treatment were symptoms or signs;oJdisease. examined, two replicates per treatment. After Results visual examination, roots were cut from the crown, washed, surface sterilized, blotted dry and Field experiments with natural inoculum placed on a semi-selectivemedium for G. zonatum. After 24 months, we observed that two of the For Experiment II, five different size pieces of seven inoculated, transplanted Syagrus natural inoculum were produced from a G. romanzoffiana had basidiocarps present on their zonatum-infested Sabalpalmetto trunk: a) 50 x 50 trunks. Until this point, all of the palms had a x 50 mm; b) 25 x25 x 50 mm; c) 12.5 x 25 x 50 similar appearance.Basidiocarps were removed mm; d) 72.5 x 25 x 25-mm; and e) 6.25 x 25 x 25 and confirmed as G. zonatum. Pure cultures of the mm. Only P. roebeleniipalms were used with the pathogen were obtained. These palms were same potting substrate as described previously. removed with as many roots as possible and

71 PALMS Ganodermain Florida:Elliott & Broschat Volume 45(2) 2001

replaced with S. romanzoffiana juveniles. To date, carp characters in several species of the no other palms in this experiment have died or Ganodermalucidum complex. Mycologia 80: produced basidiocarpsof G. zonatum. 493-507. Shade-houseexperiments An.a.sx.rvEc,J.E. nNn R.L. G[srRrsoN. 1989. Cultural No palm was killed by G. zonatumor ever exhibited studies of four North American species in the symptoms of the diseasein any of the three Ganodeftnalucidum complex with comparisons experiments. The fungus was not detectedin the to G. Iucidum and G. tsugae. Mycological roots examined in Experiment I, nor was it Research92: 182-797. detected in the inoculum examined in Experiment Ao.asxlvrc, J.E., R.A. BrlucHErrp, AND R.L. II. We observed that the center of the Bischofia GIrsERrsoN.1991. Decay of date palm wood by wood piecesused in Experiment I were completely white-rot and brown-rot fungi. Canadian degradedleaving a hollow core. Journal of Botany 69:615-629. Discussion Ar.rmRrJn.,S.A., K.R. LaNcooN,J.W. Krvnnoucu, N.E. The only time Ganoderma butt rot was induced Er-GHorr axo C. WnHr.sunc.1994. Diseasesand was when natural inoculum was used on mature disordersof plants in Florida. Bulletin No. 14, palms. Even then, only 2 of 14 inoculated palms Division of Plant Industry, Florida Department exhibited symptoms and signs (basidiocarps) of of Agriculture and Consumer Services, the fungus. Howeveq inoculation of field-grown Gainesville,Florida, USA. palms is not a good system for completing Koch's CHIrns,J.F.L. ml E. WEsr.1953. Butt rot of queen postulates. First, working with palms with tall palms in Florida associated with Ganoderma trunks is difficult and expensive. Second, there is sulcatum.Plant DiseaseReporter 37: 632-633. no way of definitely determining if these palms GrmEnrsox,R.L., .Lun L. RyvennpN.1986. North were already infected with G. zonatum. Our American Polypores. Volume l. Abortiporus- attempts to use seedling palms (i.e., palms without Lindtneria. Fungiflora, Oslo, Norway. woody trunk tissue) for pathogenicity assayswere HnsHrlr,K., L.T. KwpEaNu A.R.A. Razax.1993. not successful,whether we used artificial or natural Pathogenicity of Ganodermqboninense Pat. on inoculum. We also saw no evidence of root rot or oil palm seedlings.In Proceedings1991 PORIM root infection as has been observedwith oil nalm International Palm Oil Conference - Agriculture seedlings inoculated with G. boniiense (Module l), 478-423. Palm Oil ResearchInstitute (Navaratnam & Leong 1965; Hashim et al. 1993; of Malaysia,Selangor, Malaysia. Sariah et al. 1994). Even the experiments that inoculated mature Phoenix roebeleniiand various MIrrEn, R.N.G., M. Hor"oEnNESS,P.D. BnrncE,G.F. speciesof juvenile palms with different forms of CuuNc aNo M.H. Zarapra.1999. Genetic diversity inoculum placed directly into the trunks were of Ganoderma in o11palm plantings. Plant unsuccessfulin inducing the disease.However, Pathology 48: 595-603. the observed infection of clumping palms (e.g., Moucarvo,J.-M., H.-H. WaNcaNn R.-S. HsEu. 1995. Dypsis lutescens)that have mature canesremoved, Phylogenic relationships in Ganodermainferred the infection of two of the seven transDlanted from the internal transcribed spacersand 25S Syagrusromanzoffiana, and the pattern of disease ribosomal DNA sequences. Mycologia 87: development within the trunk suggeststhat G. 223-238. zonatum probably enters palm trunks via dead MuRRrLr,W.A. 1902. The polyporaceaeof North palm tissue (dead roots or palm stumps) as a America. I. The genus Ganodermq. Torrey saprophyte and spreadsfrom there into adjacent Botanical Club Bulletin 29: 599-608. living woody trunk tissue.Additional experiments Munnnl, W.A. 1908. Ganoderma.North American are planned to test this hypothesis. Flora9: 118-123. Acknowledgments N.qvlnarNevr,S.J. eNo C.K. LEoNc. 1965. Root We thank S. Thor and E. A. Des Jardin for field, inoculation of oil palm seedlings with shade-house and laboratory assistance.This Ganodermasp. Plant Disease Reporter 49: researchwas supported, in part, by grants from the 1011*1013. Palm Beach Gardens Mall and the Royal Palm SanraH,M., M.Z HussrN,R.N.G. MrrrsR ANDM. Chapter of the Florida Nursery Growers HoroEnNlss.1994. Pathogenicity of Ganoderma Association. Florida Agricultural Experiment boninensetested by inoculation of oil palm Station Seriesno. R-07860. Journal seedlings. 43: 507-5 10. Lirturunp Crrpn ScHuernl,T.S., W.N DrxoN, ANDR. Lntnv. 1997. AoRsxavrc, J.E. aNn R.L. GrrnrnrsoN. 1988. Florida's most wanted top 10 diseases. Basidiospores,pilocystidia, and other basidio- Ornamental Outlook 6(8): 10.

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