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Poster: Diseases of Plants: Disease Detection & Diagnosis


Thielaviopsis punctulata Causes Black Scorch Disease on Date Palm in the United Arab Emirates
K. EL-TARABILY (1), S. AbuQamar (1), E. Saeed (1), A. Sham (1) (1) United Arab Emirates University, UAE

Date palm (Phoenix dactylifera L.) is one of the most important plants grown in the arid and semi-arid land that tolerates extreme environmental desert conditions. The main associated pathogens causing palm diseases are attributed to fungi and phytoplasma. In the United Arab Emirates (UAE), the causal agent of black scorch on date palm was found to be the fungal pathogen, Thielaviopsis punctulata. The pathogen was isolated from all tissues of diseased trees with virulent Thielaviopsis punctulata. Depending on the severity of the infection, symptoms included tissue necrosis, wilting, neck bending, death of terminal buds, and eventually plant mortality. This fungus, which was consistently isolated on potato dextrose agar from infected tissues, produced two types of conidia: the thick-walled aleuroconidia (chlamydospores) and phialoconidia (endoconidia). In addition, all target regions of 5.8S rRNA (ITS), 28S rDNA, β-tubulin and transcription elongation factor 1-α (TEF1-α) genes were amplified using polymerase chain reaction. We also found that the fungicide Score® inhibited the mycelial growth of Thielaviopsis punctulata both in vitro and in vivo. Altogether, the morphology of the fruiting structures, pathogenicity tests and molecular identification confirmed that the causal agent of symptomatic tissues is Thielaviopsis punctulata. This is the first report of the black scorch disease and the fungus Thielaviopsis punctulata on date palm in the UAE.