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2008 Plant Management Network.
Accepted for publication 26 November 2007. Published 12 February 2008.


First Report of Stem Rot of Dracaena Caused by Aspergillus niger in Iran


Mehrdad Abbasi and Faezeh Aliabadi, Department of Botany, Iranian Research Institute of Plant Protection, Tehran 19395-1454, Iran


Corresponding author: Mehrdad Abbasi.  puccinia@gmail.com


Abbasi, M., and Aliabadi, F. 2008. First report of stem rot of Dracaena caused by Aspergillus niger in Iran. Online. Plant Health Progress doi:10.1094/PHP-2008-0212-01-BR.


Dracaena sanderiana Mast. has recently became a common ornamental plant in Tehran and other cities of Iran. In January of 2007 some D. sanderiana plants exhibiting stem rot symptoms were collected from a local market in Tehran. Leaves of infected plants were yellow. More importantly, there were rotted areas covered with black spots on the middle of the stem. In some cases, epidermis was ruptured and black masses of fungal spores covered the rotted area (Fig. 1A & B). We isolated Aspergillus from these D. sanderiana plants. The fungus grew rapidly and produced black colonies on PDA after 5 days at 24C (Fig. 1F). The conidial head was radiate, vesicles were nearly spherical and covered with metulae and phialides (biseriate). Conidia were globose (3 to 4.5 m in diameter) and usually very rough with irregular ridges, bars, and verrucae (Fig. 2). Morphology of the isolated fungus fit the description for A. niger provided by Klich and Pitt (1). Inoculation on four healthy plants was performed in the greenhouse. By means of a 1 ml insulin syringe approximately 0.1 ml of spore suspension (104 to 106 CFU/ml) was injected into the cortex region under epidermis in stem of healthy Dracaena plants between the nodes. Sterilized water was used as the control. Inoculated (0.1 ml of a 104 to 106 CFU/ml spore suspension injected into the cortex region under the epidermis) and control plants were grown at 25 to 27C. Water-soaked spots developed on inoculated plants in 5 days (Fig. 1C). Spots increased in size after 10 days and their color turned to pale-brown. Masses of spores covered the rotted area after 16 days. Inoculated plants wilted and often died within 25 days after inoculation (Fig. 1D & E). No symptoms developed on control plants. We were able to isolate A. niger from all inoculated plants. To our knowledge, the only report of A. niger on D. sanderiana was from Natour and Miller (2), who reported stem rot of Dracaena in the USA. They named it A. niger var. floridanus, based on cultural and morphological characteristics, cross-inoculation, and host-range studies but the name is a nomen nudum as it was not accompanied by a Latin description. More specimens and research is needed to verify that A. niger isolates on D. sanderana is a new taxon.


 
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Fig. 1. (A and B) Dracaena sanderiana naturally infected by Aspergillus niger; (C) Water-soaked spots on inoculated plant in 5 days after inoculation; (D and E) Masses of fungus spores covered the rotted area of inoculated plant after 25 days; (F) black colonies of A. niger on PDA.


 

Fig. 2. Aspergillus niger conidia. Bar in upper right = 10 m.

 

Literature Cited

1. Klich, M. A., and Pitt, J. I. 1988. A Laboratory Guide to the Common Aspergillus Species and Their Teleomorphs. CSIRO Div. of Food Processing, North Ryde, Australia.

2. Natour, R. M., and Miller, N. H. 1960. Stem rot of Dracaena sanderiana. Phytopathology 50:648.