Characterization and Control of Thielaviopsis punctulata on Date Palm in Saudi Arabia

Abstract

Date palm (Phoenix dactylifera L.) is the most important edible fruit crop in Saudi Arabia. Date palm cultivation and productivity are severely affected by various fungal diseases in date palm-producing countries. In recent years, black scorch disease has emerged as a devastating disease affecting date palm cultivation in the Arabian Peninsula. In the current survey, leaves and root samples were collected from deteriorated date palm trees showing variable symptoms of neck bending, leaf drying, tissue necrosis, wilting, and mortality of the entire tree in the Al-Ahsa region of Saudi Arabia. During microscopic examination, the fungus isolates growing on potato dextrose agar (PDA) media produced thick-walled chlamydospores and endoconidia. The morphological characterization confirmed the presence of Thielaviopsis punctulata in the date palm plant samples as the potential agent of black scorch disease. The results were further confirmed by polymerase chain reaction (PCR), sequencing, and phylogenetic dendrograms of partial regions of the ITS, TEF1-α, and β-tubulin genes. The nucleotide sequence comparison showed that the T. punctulata isolates were 99.9–100% identical to each other and to the T. punctulata isolate identified from Iraq-infecting date palm trees. The pathogenicity of the three selected T. punctulata isolates was also confirmed on date palm plants of Khalas cultivar. The morphological, molecular, and pathogenicity results confirmed that T. punctulata causes black scorch disease in symptomatic date palm plants in Saudi Arabia. Furthermore, seven commercially available fungicides were also tested for their potential efficacy to control black scorch disease. The in vitro application of the three fungicides Aliette, Score, and Tachigazole reduced the fungal growth zone by 86–100%, respectively, whereas the in vivo studies determined that the fungicides Aliette and Score significantly impeded the mycelial progression of T. punctulata with 40% and 73% efficiency, respectively. These fungicides can be used in integrated disease management (IDM) strategies to curb black scorch disease.

In Silico Characterization of the Secretome of the Fungal Pathogen Thielaviopsis punctulata, the Causal Agent of Date Palm Black Scorch Disease

“…A phylogenetic tree was constructed using a concatenated alignment of 50 single copy orthologue proteins and revealed that T. cerberus was closely related to T. punctulata . The close genetic similarity between T. punctulata and T. cerberus was shown previously using internal transcribed spacer (ITS), β-tubulin, and transcription elongation factor 1-α DNA markers ( Figure 1 B) [ 25 ].…”

“…This disease has been reported on date palm in many date-growing areas in the world, including Saudi Arabia, Oman, Qatar, United Arab Emirates, Spain, etc. [ 22 , 23 , 24 , 25 , 26 , 27 ]. Once they have penetrated any vegetative part of the plant, this fungus causes severe rotting to occur in the buds, heart, inflorescence, leaves, and/or trunk of the plant.…”

Microbicidal effects of magnetic field and irradiation on plant pathogenic Thielaviopsis paradoxa and Pectobacterium cartovorum

“…Fig. 1 (A and B) shows that the thick-walled aleuroconidia were light to dark brown, oval-shaped, and borne singly on the top of short hyphae, while the phialoconidia were hyaline to pale brown, cylindrical-shaped, and formed lengthwise in chains (Alhudaib et al, 2022). Moreover, Th.…”

The 1-aminocyclopropane-1-carboxylic acid deaminase-producing Streptomyces violaceoruber UAE1 can provide protection from sudden decline syndrome on date palm

“…Several fungi have been recorded as causal pathogens of diseases on date palms. The fungal pathogens, Thielaviopsis punctulata, Thielaviopsis paradoxa, Omphalia pigmentata, Omphalia tralucida, Mycosphaerella tassiana, and Graphiola phoenicis can cause foliar diseases, root diseases, and false smut on date palm in Oman, Qatar, Saudi Arabia, and the UAE (Al-Sadi et al, 2012;Al-Naemi et al, 2014;Saeed et al, 2016;Alhudaib et al, 2022). Sudden decline syndrome (SDS), also known as Fusarium wilt disease, of date palm is also caused by different fungal species that belong to Fusarium (Al-Hammadi et al, 2019).…”