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© 2006 Plant Management Network.
Accepted for publication 6 November 2006. Published 13 December 2006.


First Report of a Serenomyces sp. from Copernicia × burretiana, Latania loddigesii, and Phoenix canariensis in Florida and the United States


M. L. Elliott, Professor, and E. A. Des Jardin, Senior Biological Scientist, 3205 College Avenue, Fort Lauderdale Research and Education Center, University of Florida, Fort Lauderdale 33314


Corresponding author: Monica L. Elliott.  melliott@ufl.edu


Elliott, M. L., and Des Jardin, E. A. 2006. First report of a Serenomyces sp. from Copernicia × burretiana, Latania loddigesii, and Phoenix canariensis in Florida and the United States. Online. Plant Health Progress doi:10.1094/PHP-2006-1213-02-BR.


Fan palm leaves exhibiting a chlorosis and necrosis of some, but not all, leaflet segments within the blade were obtained from Latania loddigesii Mart. in Pinellas Co., FL in May 2005, and from Copernicia × burretiana Léon in Miami-Dade Co., FL in July 2005. The Copernicia leaf petiole also exhibited a reddish-brown stripe. In June 2006, leaves from a Phoenix canariensis Chabaud exhibiting necrotic leaflets on one side of the rachis and a reddish-brown petiole stripe were obtained from a second site in Miami-Dade Co. Petiole cross-sections from all three species exhibited internal discoloration. No lesions or fungal structures were evident on the petioles or blades.

Petiole sections were washed thoroughly with tap water, wiped clean with 95% ethyl alcohol, and placed in plastic containers lined with a wet paper towel. For each palm species, at least 2 weeks of incubation was required before stromata with multiple ostiolar dots and long (≥ 1500 µm), cylindrical, black necks (beaks) discharging a reddish-brown, cirrhus-like mass of ascospores were observed (Figs. 1 and 2). Ascospores were unicellular, ovoid with obtuse ends, and pale reddish-brown (Figs. 3 and 4). The average ascospore size (N = 50) was 13.4 ± 1.0 µm × 7.0 ± 0.5 µm, 13.4 ± 1.3 µm × 6.2 ± 0.6 µm, and 12.8 ± 1.0 µm × 7.3 ± 0.4 µm from L. loddigesii, Copernicia × burretiana, and P. canariensis, respectively. We identified the fungus from each palm as Serenomyces Petr.


     
 

Fig. 1. Cirrhus-like mass of discharged ascospores of Serenomyces sp. from infected petiole of Latania loddigesii. Note long necks (beaks) at top of photo.

 

Fig. 2. Long, black neck of Serenomyces sp.

 

 

Fig. 3. Ascospores of Serenomyces sp. from infected petiole of Phoenix canariensis.

 

Fig. 4. Ascospores of Serenomyces sp. from infected petiole of Copernicia × burretiana.


Four Serenomyces species are described by Hyde and Cannon (2). The two species with ascospores with < 8 µm width are S. mauritiae, which is lenticular with acute ends, and S. phoenicis, which is ovoid with obtuse ends. The stated ascospore size for S. phoenicis in the key is 8 to 12.5 µm × 5 to 7 µm. However, in the notes for this species, Hyde and Cannon (2) indicated specimens from Pakistan had slightly larger ascospores of 10 to 14 µm × 5 to 6.5 µm. While the Serenomyces sp. ascospores from the Florida palms most closely conform in size and shape to those of S. phoenicis, the neck length does not. S. phoenicis has a neck length of < 600 µm, whereas the neck length of the Florida palm Serenomyces sp. is at least 1500 µm. This Serenomyces sp. may represent a new species.

This is the first report of a Serenomyces sp. on Copernicia × burretiana, L. loddigesii, and P. canariensis in Florida and the United States. S. phoenicis has been reported from Miami-Dade Co. on P. dactylifera, but no information was provided regarding size and shape of the spores (3). If valid, that report would be the first report of S. phoenicis in the United States. S. mauritiae has been reported from Orange Co., FL on Serenoa repens (=S. serrulata) (2) and P. dactylifera (4). S. virginiae has been reported from California on P. dactylifera (1).

Serenomyces is a member of the "tar spot fungi," a group of fungi known only in association with members of the Arecaceae (=Palmae) family. Serenomyces spp. only invade leaf petioles or rachides, not leaf blades, causing a disease referred to as rachis (petiole) blight. In general, these fungi are biotrophic, and anamorphs are unknown. Although Barr et al. (1) reported that S. virginiae was culturable, our attempts to obtain cultures of the Serenomyces sp. were unsuccessful. Since the vast majority of tar spot fungi remain unculturable, including most Serenomyces spp., our unsuccessful attempts were not surprising. The speciation, host range, and epidemiology of this Serenomyces sp. remains to be elucidated.


Literature Cited

1. Barr, M. E., Ohr, H. D., Ferrin, D. M., and Mundo-Ocampo, M. 1997. A new species of Serenomyces from date palm in California. Mycotaxon 61:481-484.

2. Hyde, K. D., and Cannon, P. F. 1999. Fungi causing tar spots on palms. Mycol. Pap. 175.

3. Dixon, W. D., ed. 1995. Tri-ology, vol. 34, no. 5. Online. Div. of Plant Indust., Fla. Dept. of Agric. and Consumer Serv., Tallahassee, FL.

4. Dixon, W. D., ed. 1998. Tri-ology, vol. 37, no. 3. Online. Div. of Plant Indust., Fla. Dept. of Agric. and Consumer Serv., Tallahassee, FL.