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Disease Note.

First Record of Alternaria eichhorniae and Allernaria alternata on Waterhyacinth (Eichhornia crassipes) in Egypt. Y. M. Shabana, Departments of Plant Pathology, University of Florida, Gainesville 32611. R Charudattan, and M. A. Elwakil, Departments of Plant Pathology, University of Florida, Gainesville 32611, and University of Mansoura, El-Mansoura, Egypt. Florida Agric. Exp. Stn. Jour. Ser. Paper R-04067. Plant Dis. 79:319. Accepted for publication 19 January 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0319B.

Two hundred fungal isolates were collected from diseased waterhyacinth plants in the Nile Delta, Egypt and tested on this host by spraying mycelial pieces and conidia on the foliage and incubating the plants in high humidity at 28 C. Suspected pathogens were tested further to fulfil Koch's postulates, and three isolates of Allernaria spp. were confirmed to be pathogenic. Based on pathogenicity, conidial measurements, and pigmentation in culture, two of the isolates were identified as Allernaria eichhorniae Nag Raj & Ponnappa and the third as A. alternata (Fr.:Fr.) Keissl. The symptoms from artificial inoculations were identical to those seen in the field: chlorotic flecks that turned to discrete necrotic lesions with yellow margins. The symptoms of all three isolates were initially alike, but based on disease severity the two A. eichhorniae isolates were more virulent than the A. alternata isolate. Of the former, isolate Ae5 was more virulent; it caused severe leaf blight, and the laminar lesions enlarged and coalesced, spread to the bulbous petioles, and caused leaf death. Nag Raj and Ponnappa (2) described A. eichhorniae as a new species from India and a potential biocontrol agent of waterhyacinth. Aneja and Singh (1) reported A. alternata as a pathogen of waterhyacinth, also in India. Ours is the first report of occurrence of these pathogens on this host in Egypt.

References: (1) K. R. Aneja and K. Singh. Trop. Pest Manage. 35:354, 1989. (2) T. R. Nag Raj and K. M. Ponnappa. Trans. Br. Mycol Soc. 55:123, 1970.