Pathogenicity and chemical control of Alternaria sp. on date palm (Phoenix dactylifera L.)

Abdulnabi Abbdul Ameer Matrood,Abdelhak Rhouma,Mohammad Imad Khrieba,Claudia Adriana Ramírez Valdespino,Muhannad Abdulridha Al-Waeli

doi:10.14719/pst.2021.8.2.1147

Abdulnabi Abbdul Ameer Matrood, Abdelhak Rhouma + Show 3 more

Open Access

https://doi.org/10.14719/pst.2021.8.2.1147

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Abstract

Recently, a wide range of symptoms including light yellow lesions gradually turning into brown stripes were noticed on date palm leaves in Iraq. In this context, the aim of this study were to isolate the phytopathogens associated with these symptoms, evaluate their pathogenicity and assess the efficacy of two fungicides (Score and Pentanol) under in vitro and in vivo conditions. Two fungal species (Alternaria sp. and Fusarium sp.) were isolated from the symptomatic leaves of date palm. The results of pathogenicity tested proved the ability of Alternaria sp. inoculated separately or in combination with Fusarium sp. to infect the leaves of date palm trees with disease severity index (DSI) values of 67.33% and 65.99%, respectively. The effect of Score (88.76%) and Pentanol (82.91%) against Alternaria sp. was examined by poisoned food technique, which leads a significant increase in mycelial growth inhibition (for 300% of commercial recommended dose of fungicide). Test results indicate that prophylactic spraying of date palm leaves with Score or Pentanol effectively controlled Alternaria sp. with DSI values of 22.65% and 17.87%, respectively. To control Alternaria sp. in field within integrated pest management strategies, chemical control using Score or Pentanol should be taken in consideration.

Highlights

Phoenix dactylifera L. (Arecaceae) is thought to be the oldest fruit tree grown in Iraq and is an important crop in term of the number of trees and their distribution
Phytopathogens isolation from date palm We successfully isolated two phytopathogens species (Alternaria sp. and Fusarium sp.) based on their visual morphological characterizations from the diseased leaves of date palm cultivated in Basra, Iraq (Fig. 1)
The isolation frequencies of these phytopathogens species were showed that the higher was registered for Alternaria sp. (89%), followed by Fusarium sp. (9%), Trichoderma spp. (1.7%), Aspergillus sp. (0.2%) and Penicillium sp. (0.1%)

Summary

Introduction

Phoenix dactylifera L. (Arecaceae) is thought to be the oldest fruit tree grown in Iraq and is an important crop in term of the number of trees and their distribution. Date palm is widely considered as a strategic source of food security and an essential crop in the Iraqi economy [1]. Date palm represents a source of income to many farmers in large parts of Iraq [2,3,4]. Date palm production in Iraq was reported to be around 250 thousand tons, with an average of 1666.67 kg/ha in 2017 (Iraqi ministry of agriculture). The date palm is being affected by several pathogenic fungi amongst them are Alternaria sp., Fusarium sp., Phytophthora sp., Diplodia sp., Mauginiella sp., Mycosphaerella sp., Thielaviopsis sp., Glomerella sp., Phoma sp., Graphiola sp., Nigrospora sp., Chalara sp., Chaetosphaeria sp., Phomopsis sp. These pathogens caused severe damages to different date palm parts such as stem, leaves, fruit and root leading to severe losses and reduction in total yield [5]. Worldwide annual economic yield lose due to these pathogens have been estimated more at 50% in 2002 [6, 7]

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