Survey and Identification of Date Palm Pathogens and Indigenous Biocontrol Agents

Abstract

<jats:p> Fungal diseases are considered a major threat to plant growth and productivity. However, some beneficial fungi growing in the same environment protect plants from various pathogens, either by secreting antifungal metabolites or by stimulating the host immune defense mechanism. Date palms are susceptible to several fungal pathogens. Nevertheless, information on the pathogenic fungal distribution in date palm fields across different seasons is limited, especially that from Qatar. Therefore, the current study’s aim was to evaluate the pathogenic and beneficial fungal diversity and distribution, including the endophytic fungi from the date palm tissues and root-associated soil fungi, during different seasons, for the identification of indigenous biocontrol agents. Our results showed that the highest number of fungal species was isolated in fall and spring, and pathogenic fungi were isolated mainly in spring. This is the first report that in Qatar, Neodeightonia phoenicum and Thielaviopsis punctulata cause date palm root rot disease, Fusarium brachygibbosum and Fusarium equiseti cause date palm wilting, and N. phoenicum causes diplodia disease in date palm offshoots. The combinations of the fungi that did not frequently occur together in date palm rhizosphere soil were investigated to identify indigenous biocontrol agents. Based on the results, we determined that Trichoderma harzianum and Trichoderma longibrachiatum are effective antagonistic fungi against T. punctulata, N. phoenicum, F. brachygibbosum, and Fusarium solani, qualifying them as potential biocontrol agents. Antagonistic activity of endophytic fungi against the pathogens was tested; except for Ulocladium chartarum, no endophytic fungi showed antagonistic activity against the tested pathogens. </jats:p><jats:p> [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license . </jats:p>

Phylogeny and Mycotoxin Profile of Pathogenic Fusarium Species Isolated from Sudden Decline Syndrome and Leaf Wilt Symptoms on Date Palms (Phoenix dactylifera) in Tunisia

“…In both Saudi Arabia and Spain, several authors have isolated this species from symptomatic young plants, leaves, or roots [ 3 , 7 , 8 ], or rotten fruit, as in Israel and Iran [ 9 , 10 ]. Another Fusarium species that has been significantly reported as a serious pathogen of date palms is F. solani , isolated from date palm wilted leaves and roots, in several countries such as Iran, Egypt, Oman, Pakistan, Saudi Arabia, United Arab Emirates, and Qatar [ 3 , 11 , 12 , 13 , 14 , 15 , 16 ]. In addition, a single strain of F. brachygibbosum and F. verticillioides , isolated from symptomatic date palm roots, were reported by Saleh et al [ 3 ], while Abbas et al [ 17 ] reported the identification of F. equiseti isolated from date palm roots in Iraq.…”

“…In addition, a single strain of F. brachygibbosum and F. verticillioides , isolated from symptomatic date palm roots, were reported by Saleh et al [ 3 ], while Abbas et al [ 17 ] reported the identification of F. equiseti isolated from date palm roots in Iraq. Nishad and Ahmed [ 16 ] isolated the same species from wilted leaves in Qatar. Finally, the latter authors reported also a significant occurrence of F. brachygibbosum on wilted leaves and roots of date palms in Qatar [ 16 ].…”

“…Nishad and Ahmed [ 16 ] isolated the same species from wilted leaves in Qatar. Finally, the latter authors reported also a significant occurrence of F. brachygibbosum on wilted leaves and roots of date palms in Qatar [ 16 ].…”

Aspergillus niger, the causal agent of black mould disease in date fruits, infects and colonizes flowers and young fruitlets

“…Moreover, A . niger is not limited to the date fruits; it is detected on other date palm organs such as leaves, in the rhizosphere (Nishad & Ahmed, 2020), and can be easily isolated from the air in proximity to date orchards (authors’ unpublished results).…”

“…It is abundant mainly in the peel of the brown, ripened stage, suggesting that the colonization and proliferation of fruit tissues by A. niger occurs during fruit maturation (Piombo et al, 2020). Moreover, A. niger is not limited to the date fruits; it is detected on other date palm organs such as leaves, in the rhizosphere (Nishad & Ahmed, 2020), and can be easily isolated from the air in proximity to date orchards (authors' unpublished results).…”