Source: UNIVERSITY OF FLORIDA submitted to NRP
FUNGAL DISEASES OF ORNAMENTAL PALMS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
0228670
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Apr 1, 2012
Project End Date
Sep 30, 2017
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
Ft. Lauderdale Research and Education Center
Non Technical Summary
Palms define Florida, whether in a landscape or natural setting. Due to its climate, Florida has more native palm species than any other state in the continental U.S. While diseases do affect palms in native habitats, diseases are of greatest concern in the landscape where palms have not only an aesthetic value but also a definite monetary value. This monetary value extends from the seed to transplantation of mature palms into residential and commercial landscapes. For the Florida nursery industry alone, the monetary value of palms has almost doubled every 5 years for the past 10 years. The estimated total sales value for palm trees by Florida producers in 2010 was $404 million, representing 9.5% of nursery growers' sales. While this only represents a 2.5% increase in percentage of nursery sales from 2005, it is a near doubling of the monetary value ($220 million) from 2005, and the 2005 monetary value was a near doubling of the 2000 palm sales, which were $123 million. In 2010, palms as a percentage of sales (9.5%) were equal to the combination of deciduous shade trees, flowering and fruiting trees and evergreen trees (9.8%). One characteristic that drives the use of palms in the landscape is the fact palms do not have secondary growth of their roots or canopy. Unfortunately, there are a number of communities where the homeowner association documents or the covenant tied to the land requires certain species, specific sizes and numbers of palms that must be planted at each home site. Thus, when a palm dies in the landscape, the dollar value loss can be significant, as the homeowner must pay to remove the palm, buy a new palm of the same species and size and have it installed. If the palm died due to a disease for which we have no controls (e.g., Fusarium wilt), in all probability, they will replace a palm multiple times until the rules or covenant documents are changed. While palms will remain an integral part of the Florida landscape, the increasing pressure from diseases may decrease the number of palms used in the landscape, which will impact nursery growers, landscape professionals and associated businesses (e.g. fertilizer manufacturers). New knowledge will be gained regarding host range of the fungal pathogen Fusarium oxysporum f. sp. palmarum, as well as a determination if there are differences in the pathogen populations from different hosts and/or geographic locations in Florida. Knowledge will be gained regarding uptake and distribution of xylem-limited fungicides in mature palms, which can then be used to decide whether it is efficient and effective to use these fungicides for control of systemic palm diseases. An examination of Serenomyces species associated with palms will determine if the host is a driving force in the morphological and molecular characteristics observed in vivo and in vitro. Determining the pathogen causing a lethal disease of Pseudophoenix species in Florida will then allow the landscape and conservation biology community to consider methods for managing this disease on palm species which are near extinction in other parts of the Caribbean Basin.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2122110110225%
2122110116025%
2122110117020%
2125220110210%
2125220116010%
2125220117010%
Goals / Objectives
1. Determine diversity of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum. 2. Assess potential fungicides and methodology for control of Fusarium wilts of palms. 3. Determine diversity of Serenomyces isolates from multiple palm hosts in Florida. 4. Determine etiological agent causing death of Pseudophoenix and Ravenea species. Refereed manuscripts will be developed to disseminate information to colleagues. Extension publications will be developed and disseminated to the public (homeowners, nursery growers, professional landscapers, etc.)via the Florida Cooperative Extension Service web site, county agents and popular journals. Extension presentations will be made to the general public and professionals at Master Gardener events, ISA events, Professional Horticulture events and training programs at the FLREC.
Project Methods
Determine diversity of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum: The potential host range of these two pathogens will be examined using container-grown palms with 3-5 juvenile leaves inoculated using a conidia suspension applied to and between the leaf bases. Palm species to be evaluated initially include Phoenix canariensis, P. dactylifera, P. reclinata, P. sylvestris, P. roebelenii, Syagrus romanzoffiana, Washingtonia robusta and W. filifera. A comparison of genetic profiles of isolates and populations will be conducted using inter-simple sequence repeat (ISSR) analysis. Isolates of F. oxysporum f. sp. palmarum from three general locations (=populations) in Florida will be compared, southeast coastal Florida, west-central coastal Florida and inland-central Florida. 2. Assess potential chemicals and methodology for control of Fusarium wilts of palms: Cocos nucifera with at least 2 m of clear trunk located will be used for these experiments. Fungicides to be tested with this application methodology include thiabendazole, propiconazole and tebuconazole. A bioassay method using a Penicillium sp. will be used to detect these fungicides in the leaf. For sampling leaflet tissue, 4 basal leaflets and 4 distal leaflets (2 from each side of the rachis) will be cut from the rachis, washed and blotted thoroughly dry. For sampling petiole and rachis tissue, three 10-cm segments will be obtained from each leaf: a) petiole section (P), located half way between the trunk and rachis, b) basal section of the rachis, located about 45 cm from beginning of the rachis (B), and c) distal section of the rachis, located about 45 cm from leaf tip (D). Palms will be sampled every 30 days until the fungicides are no longer detected with the assay. 3. Determine diversity of Serenomyces isolates from multiple palm hosts in Florida: A collection of Serenomyces isolates will be assembled from as many palm hosts as possible. Material will be dried and stored in a Riker mount. Ascospores will be collected for either direct PCR or to extract DNA for use in PCR at a later date, using primers ITS1 and ITS4 to amplify the internally transcribed space region (ITS) of nuclear rRNA. Ascospores will be also collected in order to obtain single-spore isolates. Mycelial growth will be stored as agar plugs in sterile deionized water in cryogenic vials stored at room temperature. If perithecia and ascospores form in culture, a small section of the agar plate will be dried down and placed in a small box for storage in a desiccator. Dried cultures will be sent to the USDA Mycology collection. Resulting amplification products will be sequenced and the sequences submitted to GenBank. 4. Determine etiological agent causing death of Pseudophoenix and Ravenea species: Isolation attempts will be continued using direction isolation with various general and selective media and indirect isolation with various baiting techniques. Isolates will be identified morphologically and genetically using standard protocols. Pathogenicity studies will be conducted when likely pathogen candidates are obtained.

Progress 04/01/12 to 09/30/17

Outputs
Target Audience:Target audiences included the scientific community, landscape professionals, arborists, landscape architects, nursery stock growers, extension personnel, and the general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student obtained her Ph.D. under this project, which included sequencing the gemones of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum. Seven undergraduate students worked on various aspects of the project to gain knowledge on molecular techniques useful for identification of plant pathogenic fungi associated with palms. How have the results been disseminated to communities of interest?Results from the research have been disseminated to the scientific community via refereed journal publications, abstracts and posters. Extension outreach programs have disseminated research information to landscape professionals, landscape architects, arborists and the general public via presentations, Extension fact sheets, websites and personal contacts. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Palms in the landscape have not only an aesthic value but also a definite monetary value. For the Florida nursery industry alone, monetary value of the sale of palms has almost doubled every 5 years since 2000. The Florida Department of Transportation has made palms the focal point of their multi-million dollar landscaping plan along all major highways in the state to emphasize to Floridians and tourists that Florida is unique compared to all other states in the continental U.S.A. While palms remain an integral part of the Florida landscape, the increasing pressure from diseases may ultimately decrease the number of palms in the landscape, which will impact nursery growers, landscape professionals and associated businesses (e.g., fertilizer manufacturers). The genomes of a Fusarium oxysporum f. sp. canariensis (FOC)isolate and f. sp. palmarum (FOP)isolate have been sequenced and a de-novo draft assembled for each. A comparative analysis of the two genomes indicates that the genome size of FOP is slightly larger than FOC. FOP is distinct from FOC due to the presence of four novel secondary metabolites, the presence of SIX8 and SIX9 genes, higher copy number of detoxifying enzymes, and expansion of transposons.Even though it has been determined that at least two trunk injectable fungicides (propiconazole and thiabendazole) are moved into the canopy after trunk injection, their persistence is short-lived. Propiconazole has potential phytotoxicity and growth regulating issues that are not conducive to its use. While thiabendazole appears safe for use, studies at a site where Fusarium wilt is active in Syagrus romanzoffiana (queen palm) indicate it is not effective in preventing the disease. Members of the Phaeochoraceae (Cocoicola and Serenomyces) form a monophyletic group within the order Phyllachorales. Based on ascospore size and ITS sequencing of Serenomyces isolates obtained in Florida, isolatesfrom Phoenix canariensis (Canary Island date palm) and P. dactylifera (edible date palm) form one group, isolates from Thrinax radiata (thatch palm) form a second group, and isolates from Sabal palmetto (cabbage palm) form a third group. Since this fungus is not stable in culture, representative isolates have been deposited with the U.S. National Fungus Collections and the University of Florida Mycological Herbarium. The etiological agent causing the death of mature Pseudophoenix species in Florida may be a Lasiodiplodia species complex, but pathogenicity studies need to be completed to confirm.

Publications

  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Elliott, M.L., and Des Jardin, E.A. 2014. Serenomyces associated with palms in the southeastern USA: isolation, culture, storage and genetic variation. Mycologia 106:698-707
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Broschat, T.K., Hodel, D.R., and Elliott, M.L. 2014. Ornamental palms: biology and horticulture. Horticultural Reviews 42:1-120
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Elliott, M.L. 2015. First report of Fusarium wilt caused by Fusarium oxysporum f. sp. canariensis on Phoenix reclinata in Florida. Plant Disease 99:887
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Elliott, M.L., Broschat, T.K., and Gocke, L. 2016. Preliminary evaluation of electrical resistance tomography for imaging palm trunks. Arboriculture & Urban Forestry 42:111-119
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Elliott, M.L., Des Jardin, E.A., Harmon, C.L., and Bec, S. 2017. Confirmation of Fusarium wilt caused by Fusarium oxysporum f. sp. palmarum on xButyagrus nabonnandii (mule palm) in Florida. Palm Disease 101:381
  • Type: Books Status: Published Year Published: 2017 Citation: Broschat, T.K., Meerow, A.W., and Elliott, M.L. 2017. Ornamental Palm Horticulture, 2nd edition. University Press of Florida, Gainesville
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Elliott, M.L., and Broschat, T.K. 2017. Uptake, movement, and persistence of fungicides in mature coconut palms in Florida, U.S. Arboriculture & Urban Forestry 43:133-143
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Mardones, M., Trampe-Jaschik, T., Oster, S., Elliott, M., Urbina, H., Schmitt, I., and Piepenbring, M. 2017. Phylogeny of the order Phyllachorales (Ascomycota, Sordariomycetes): among and within order relationships based on five molecular loci. Persooni 39:74-90
  • Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Ponukumati, S.V. 2017. Diagnostics, Genomics and Population Studies on Fusarium oxysporum of Palms. University of Florida, Gainesville


Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Target audiences included the scientific community, landscape professionals, arborists, nursery stock growers and the general public Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student is conducting research on the genomes of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum. How have the results been disseminated to communities of interest?Results from the research have been disseminated to the scientific community via refereed journal publications, abstracts and posters. Extension outreach programs have disseminated research information to landscape professionals, landscape architects, arborists and the general public. What do you plan to do during the next reporting period to accomplish the goals?This project terminated on September 30, 2017, and I retire on January 31, 2018.

Impacts
What was accomplished under these goals? Palms in the landscape have not only an aesthic values but also a definite monetary value. For the Florida nursery industry alone, monetary value of the sale of palms has almost doubled every 5 years since 2000. The Florida Department of Transportation embarked on a multi-million dollar landscaping plan along on all major highways in the state that includes palms as the primary landscape architectural feature to emphasize that Florida is unique compared to all other states in the continental U.S.A. The genomes of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum have been successfuly sequenced, with annotation accomplished for most of the genomes. Presence or absence of known effector genes of pathogenic Fusarium oxysporum have been determined in both formae speciales. The effector genes for each formae species are distinctly different. It has been determined that palm inhabiting species in the order Phyllachorales have evolved independently at least three times. However, members of the family Phaeochoraceae (Cocoicola and Serenomyces) form a monophyletic group, which is distinct from members of the Phyllachoraceae and a newly described family Telimenaceae. Only members of the Phaeochoraceae are exclusively found in association with palms (Arecaceae). Fungicide uptake studies determined that propiconazole and thiabendazole do move into leaves that emerge after the fungicides are injected into the trunk. However, the fungicides appear to be persistent for no longer than 28 weeks after injection.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Elliott, M. L., and Broschat, T. K. 2017. Uptake, movement, and persistence of fungicides in mature coconut palms in Florida, U.S. Arboriculture & Urban Forestry 43:133-143
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Mardones, M., Trampe-Jaschik, T., Oster, S., Elliott, M., Urbina, H., Schmitt, I., and Piepenbring, M. 2017. Phylogeny of the order Phyllachorales (Ascomycota, Sordariomycetes): among and within order relationships based on five molecular loci. Persoonia 39:74-90


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Target audiences included the scientific community, landscape professionals, arborists, nursery stock growers and the general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student is conducting research on the genomes of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum. Three undergraduate students worked in the laboratory during Summer 2016 gaining knowledge about these two pathogens and molecular techniques useful for the genome project. How have the results been disseminated to communities of interest?Results from the research have been disseminated to the scientific community via refereed journal publications, abstracts and posters. Extension outreach programs have disseminated research information to landscape professionals, landscape architects, arborists and the general public. What do you plan to do during the next reporting period to accomplish the goals?Research will continue on: i) the molecular characterization of fungi in the Botryosphaeraceae fungal family that have been isolated from palms; ii) complete the journal manuscript on molecular characterization of Ganoderma zonatum from palms in Florida; and iii) complete thecharacterization of Fusarium oxysporum f. sp. cananriensis and f. sp. palmarum genomes.

Impacts
What was accomplished under these goals? Palms in the landcape have not only an aesthetic value but also a definite monetary value. For the Florida nursery industry alone, monetary value of the sale of palms has alsmost doubled every 5 years for the past 15 years. The Florida Department of Transportationcontinues to include palms as a major part of its bold landscaping plan along all major highways, including interstates,to emphasize the unique difference of the flora in Florida and because palms have the same landscape architecural footprint at 10 years that they do when they are planted (single-stem palms do not branch). With the squencing of the Fusarium oxysporum pathogens that affect palms in Florida, it has become apparent that one of the reasons F. oxysporum f. sp. palmarum (Fop) is more virulent is due to the greater number of secondary metabolite genes it contains. This pathogen can kill certain maturepalm species within a matter of months, sometimes weeks. The other importance of Fop is it illustrates that not all new pathogens invade from outside the U.S. This pathogen has evolved here in Florida. Likewise, the research on molecular characterization of Ganoderma zonatum, a fungal pathogen that probably evolved with the native Sabal palmetto, indicates that spores are the primary means of dispersal. While isolates of this fungus are rarely compatible in culture, overall, their molecular similarity is remarkably high, no matter what palm species the fungus infected or from what part of the state the fungus was found.

Publications

  • Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Elliott, M.L., Broschat, T.K., and G�cke, L. 2016. Preliminary evaluation of electrical resistance tomography for imaging palm trunks. Arboriculture and Urban Forestry 42:111-119.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Harrison, N.A., and Elliott, M.L. 2016. Phytoplasmas associated with date palm in the continental USA: three 16SrIV subgroups. Emirates Journal of Food and Agriculture 28:17-23
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2017 Citation: Elliott, M. L., DesJardin, E.A., Harmon, C.L., and Bec, S. 2017. Confirmation of Fusarium wilt caused by Fusarium oxysporum f. sp. palmarum on x Butyagrus nabonnandii (mule palm) in Florida. Plant Disease In Press
  • Type: Books Status: Awaiting Publication Year Published: 2017 Citation: Broschat, T. K., A. W. Meerow, and M. L. Elliott. 2017. Ornamental Palm Horticulture, 2nd edition. University Press of Florida, Gainesville.


Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Target audiences included the scientific community, landscape professionals, arborists, nursery stock growers and the general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student is conducting research on the genomes of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum. One undergraduate student worked in the laboratory during Summer 2015 to gain knowledge on molecular techniques that are useful for identification of plant pathogenic fungi. How have the results been disseminated to communities of interest?Results from the research has been disseminated via Extension outreach events to landscape architects, landscape professionals, arborists and the general public. What do you plan to do during the next reporting period to accomplish the goals?Research will continue on:i) the molecular characterization of fungi isolated from palms in the Botryosphaeraceae family,; ii) molecular characterization of Ganoderma zonatum isolates from palms in Florida; and iii) examinmation of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum genomes for clues regarding pathogenicity and host range.

Impacts
What was accomplished under these goals? Palms in the landscape have not only an aesthetic value but also a definite monetary value. For the Florida nursery industry alone, the monetary value of palms has almost doubled every 5 years for the past 15 years. The Florida Department of Transportation has and continues to include palms as a major part of its bold landscaping along all major highways to emphasize that Florida is different from virtually all states except Hawaii. While palms remain an integral part of the Florida landscape, the increasing pressure from diseases may ultimately decrease the number of palms in the landscape, which will impact nursery growers, landscape professionals and associated businesses (e.g., fertilizer manufacturers). The genomes of a Fusarium oxysporum f. sp. canariensis isolate and f. sp. palmarum isolate have been obtained. The sequences obtained are now being examined for information that will explain pathogenicity, virulenceand host range. It has been determined thatNeodeightonia is the primary genus from theBotryosphaeraceae fungal family associated with petiole/rachis blight symptoms in Florida. This is the first time this fungus has been identified from Florida. Three gene regionshave been amplified from Ganoderma zonatum isolates obtained from various palm species throughout Florida. The information obtained thus far indicates there is significant genetic variation, which indicates that sexual spores are the primary means of spread of this pathogen within the state.

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Elliott, M. L. 2015. First report of Fusarium wilt caused by Fusarium oxysporum f. sp. canariensis on Phoenix reclinata in Florida. Plant Disease 99:887


Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Target audiences included the scientific community, landscape professionals, arborists and the general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Three undergraduate students worked in the laboratory during Summer 2014 to gain knowledge on molecular techniques that are useful for identification of plant pathogenic fungi. How have the results been disseminated to communities of interest? Results from the research has been disseminated via Extension outreach events to landscape architects, landscape professionals and arborists. What do you plan to do during the next reporting period to accomplish the goals? Research will continue on molecular characterization of fungi belonging to the Botryosphaeraceae, which are likely the cause of diseaes associated with Ravenea, Pseudophoenix and other palm genera.

Impacts
What was accomplished under these goals? Palms in the landscape have not only an aesthetic value but also a definite monetary value. For the Florida nursery industry alone, the monetary value of palms has almost doubled every 5 years for the past 10 years.The estimated total sales value for palm trees by Florida producers in 2010 was $404 million, representing 9.5% of nursery growers' sales, whichas a percentage of sales was almostequal to the combination of deciduous shade trees, flowering and fruiting trees and evergreen trees (9.8%). While palms will remain an integral part of the Florida landscape, the increasing pressure from diseases may decrease the number of palms used in the landscape, which will impact nursery growers, landscape professionals and associated businesses (e.g. fertilizer manufacturers). New primers to use in the polymerase chain reaction technique have been developed that will allow detection of both Fusarium oxysporum f. sp. canariensis and f. sp. palmarum from palm tissue. Using different types of taq polymerase, we can, if necessary, separate the two ff. spp.. This has become an important issue as we are now detecting F.o. palmarum from palms other than Syagrus romanzoffiana and Washingtonia robusta. This is an increase in our scientific knowledge and may change the analytical technique used to detect and identify these pathogens. An experiment was initiated to assess the value of using fungicides as trunk injections to prevent Fusarium Wilt in Syagrus romanzoffiana. The practical aspects of injecting fungicides, which amounts to 100 ml or more per palm trunk, will likely not be feasible for commercial purposes, except under tightly controlled situations. Phytoxicity of propiconazole is being observed, but the effects are very random and not consistent. A serenomyces species was identified in Texas in association with Pheonix canariensis, and at the molecular level, it matched isolates obtained from this palm species in Florida.

Publications

  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Broschat, T.K., Hodel, D.R., and Elliott, M.L. 2014. Ornamental Palms: Biology and Horticulture. Horticultural Reviews 42:1-120.


Progress 10/01/12 to 09/30/13

Outputs
Target Audience: Scientists interested in palm diseases; Extension professionals; professional landscapers and arborists; nursery growers; homeowners Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Information regarding palm diseases was disseminated via three 2-day workshops (two in Florida and one in Puerto Rico), county-sponsored training programs for nursery personnel, landscape personnel, Master Gardeners and homeowners. Palm disease fact sheets are freely accessible via the UF-IFAS Extension website. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Palms define Florida, whether in a landscape or natural setting. This is illustrated by the prominent display of palms (stylized and real) in logos for cities, tourism councils, and, of course, the seal for the State of Florida. The latter is the native Sabal palmetto (cabbage or sabal palm). The Department of Transportation roadside sign indicating a Florida Heritage site illustrates a building roof held up with two palm trees. Due to its climate, Florida has more native palm species than any other state in the continental U.S. While diseases do affect palms in native habitats, diseases are of greatest concern in the landscape where palms have not only an aesthetic value but also a definite monetary value. This monetary value extends from the seed to transplantation of mature palms into residential and commercial landscapes. For the Florida nursery industry alone, the monetary value of palms has almost doubled every 5 years for the past 10 years. The estimated total sales value for palm trees by Florida producers in 2010 was $404 million, representing 9.5% of nursery growers’ sales (Hodges et al., 2011). While this only represents a 2.5% increase in percentage of nursery sales from 2005, it is a near doubling of the monetary value ($220 million) from 2005 (Hodges and Haydu, 2006), and the 2005 monetary value was a near doubling of the 2000 palm sales, which were $123 million (Hodges and Haydu, 2002). In 2010, palms as a percentage of sales (9.5%) were equal to the combination of deciduous shade trees, flowering and fruiting trees and evergreen trees (9.8%). While palms will remain an integral part of the Florida landscape, the increasing pressure from diseases may decrease the number of palms used in the landscape, which will impact nursery growers, landscape professionals and associated businesses (e.g. fertilizer manufacturers). 1. Determine diversity of Fusarium oxysporum f. sp. canariensis and f. sp. palmarum. Potting mix naturally infested with Fusarium oxysporum f. sp. palmarum did not result in Fusarium wilt of Washingtonia robusta, even when 100% of the potting mix used was the naturally infested material. The disease did develop if fresh inoculum of the pathogen was added to the potting mix. A spore suspension containing 1 million conidia (primarily microconidia) per ml was used for the inoculation amount x technique experiment. As little as 3 ml of this suspension caused disease (4 of 5 replicate plants died) if the palm roots were disturbed and the lower 25% of the roots cut off before transplanting into 1 quart containers and inoculating by pipetting the spore suspension around the base of the palm seedling. If the roots were only disturbed, disease was not observed until 5 ml of inoculum was added (3 of 5 replicate plants died). If the roots were not disturbed at all, disease development was observed at 25 ml inoculum (2 of 5 replicate plants died). 2. Assess potential fungicides and methodology for control of Fusarium wilts of palms. No accomplishments this reporting period. 3. Determine diversity of Serenomyces isolates from multiple palm hosts in Florida. Over an 8-year period, leaves symptomatic for rachis or petiole blight were obtained from Florida and South Carolina, USA. The fungus Serenomyces was induced to produce ascospores, and single-spore isolates were obtained in culture and, in some instances, induced to produce ascospores in culture. Based on ascospores size and ITS sequencing, Serenomyces from Phoenix canariensis and P. dactylifera form one group, Serenomyces from Thrinax radiata form a second group, and Serenomyces from Sabal palmetto form a third group. All three groups are most similar morphologically to Serenomyces phoenicis. 4. Determine etiological agent causing death of Pseudophoenix and Ravenea species. No accomplishments this reporting period.

Publications

  • Type: Journal Articles Status: Awaiting Publication Year Published: 2014 Citation: Elliott, M.L. and Des Jardin, E. A. 2014. Serenomyces associated with palms in the southeastern USA: isolation, culture storage, and genetic variation. Mycologia.


Progress 04/01/12 to 09/30/12

Outputs
OUTPUTS: Experiments were conducted evaluating host range of Fusarium oxysporum f. sp. canariensis and F.o. palmarum. Palm species evaluated, as seedlings, were Phoenix canariensis, P. dactylifera, P. reclinata, P. sylvestris, Syagrus romanzoffiana, and Washingtonia robusta. Three isolates of each pathogen were used as inoculum and applied individually as spore suspensions to the leaf bases. Propiconazole and thiabendazole fungicides were applied to mature Cocos nucifera at the highest labeled rates using two different application methods - injection directly into the trunk or as a soil/root drench. The same amount used for injections was used for the soil/root drench. Bioassays of rachis and petiole tissue were completed every 5 weeks after application to determine presence and distribution of fungicides within the palm canopy. Additional isolations of potential pathogens were made from diseased Pseudophoenix sargentii located in south Florida. Consultations and diagnostic services were provided to clientele in Florida. Information regarding palm diseases was disseminated via four 2-day workshops (three in Florida and one in Puerto Rico), county-sponsored training programs for nursery personnel, landscape personnel, Master Gardeners and homeowners. Palm disease fact sheets are freely accessible via the UF-IFAS Extension website. Five of the fact sheets were updated this year. PARTICIPANTS: Monica L. Elliott, PI TARGET AUDIENCES: Three 2-day workshops (two in Florida and one in Puerto Rico) were conducated to provide professional landscapers, arborists, landscape architects and nurser professionals with up to date information on palm management, including palm diseases. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Phoenix canariensis, P. dactylifera, P. reclinata, P. sylvestris, Syagrus romanzoffiana, and Washingtonia robusta seedlings were all susceptible to all 3 isolates of Fusarium oxysporum f. sp. palmarum. While all six species were susceptible, P. sylvestris appeared to be less susceptible. Only P. canariensis, P. reclinata and P. sylvestris seedlings were susceptible to F. o. canariensis, with P. canariensis the most susceptible to all 3 isolates. Propiconazole and thiabendazole fungicides were detected throughout the canopy of Cocos nucifera, but only if the fungicides were injected. The fungicides were not detected if applied as a soil/root drench. The fungicides were detected up to 15 weeks after the injections. Workshop participants were asked if they would be changing their palm disease management practices based on the information provided; 95 of 103 participants responding indicated yes.

Publications

  • Elliott, M.L. and Broschat, T.K. (2012) Detection of thiabendazole fungicide in coconut palms using a bioassay. PALMS 56(1):21-27.
  • Yu, J., Elliott, M.L., and Broschat, T.K. (2012) Effects of phosphite on Fusarium oxysporum in Washingtonia robusta. 2012 ASHS Annual Conference, Miami, Florida. Poster Session Abstracts. No. 124, Page 97.