Molecular identification of fungal pathogens associated with leaf spot disease of date palms (Phoenix dactylifera)

Abstract

Date palm is the most important crop in Oman, occupying approximately 50% of the area devoted to agriculture. Little information is available on leaf spot diseases of date palm in Oman and in the world. This study was conducted to identify the most common fungal pathogens associated with leaf spot diseases of date palm. A total of 198 symptomatic leaf samples were collected from seven districts in Oman. Isolations revealed that most isolates belonged to the genus Alternaria. Molecular-based identification using multigene sequences revealed that the isolates belonged to Alternaria alternata, A. burnsii, A. tomato, Curvularia subpapendorfii, Didymella microchlamydospora, Fusarium brachygibbosum, F. incarnatum-equiseti and Nigrospora lacticolonia. In pathogenicity tests, A. alternata was found to be the most aggressive. F. incarnatum-equiseti was the least aggressive, only inducing symptoms in leaves injured prior to inoculation. The other species caused moderate leaf spot symptoms on the leaves. This study shows that several fungal species belonging to different genera can be found associated with leaf spot symptoms of date palms, and they vary in their aggressiveness on date palm leaves. It is the first study to report C. verruculosa, D. microchlamydospora, and N. lacticolonia as leaf spot pathogens of date palm in the world.

KEYWORDS:

• Palm diseases
• ascomycota
• necrosis
• chlorosis
• blight

Acknowledgements

Thanks to Sultan Qaboos University, OAPGRC and VALE Oman for financial support of the study.

AMA designed the study, HA, ZA and AA conducted lab experiments, AMA and RV supervised the research project, AMA, HA, SM and RV wrote the manuscript, all authors approved the final version.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.

Compliance with ethical standards

Ethical approval

This article is original and not published elsewhere. The authors confirm that there are no ethical issues in the publication of the manuscript.

Additional information

Funding

This work was supported by grants from Sultan Qaboos University [OAPGR and VALE].