Witches’ Broom Disease of Lime (WBDL)in Iran

Abstract

Witches' broom disease of lime (WBDL) is a caused by " Candidatus Phytoplasma aurantifolia". The disease was first observed in the Sultanate of Oman in the 1980s and found to be present in the United Arab Emirates (UAE) in 1989. A putative leafhopper vector, Hishimonus phycitis , reproducing actively on lime trees, was identified in 1991 in Oman and found to be also present in the UAE in 1993. In July 1997, symptoms of the disease were observed in the southeastern region of Iran near Nikshar (Dapas Kur) and Qasr-e-Qand. Joint serological and molecular characterizations confirmed that the symptoms observed in Iran are those of WBDL and that, on the basis of ELISA and PCR, the WBDL phytoplasma in Iran is indistinguishable from that in Oman and the UAE. H. phycitis was easily recovered by D-Vac ® aspiration not only from lime trees in the affected region but also from lime trees in regions free of the disease. From the extent and severity of the symptoms observed and the presence of the vector, some trees must have become infected 10 yr ago. Eradication of the 500 or so affected trees is underway. A few individuals of Diaphorina citri , the psyllid vector of Huanglongbing, were also collected in the survey. This is the first report of D. citri and of H. phycitis in Iran. The origin of WBDL is discussed.

Discovery of Hishimonus diffractus Dai, Fletcher & Zhang, 2013 (Hemiptera: Auchenorrhyncha: Cicadellidae) in Europe, with remarks on previously recorded species of the genus

“…H. phycitis transmits 'Witches' broom disease of lime' (WBDL) (Bové & Garnier 2000), 'Sesame phyllody phytoplasma ' (un Nabi et al 2015), and 'Brinjal little-leaf phytoplasma' (eggplant) (Azadvar & Baranwal 2012). WBDL is associated with 'Candidatus Phytoplasma aurantifolia', considered one of the most lethal plant pathogens (EFSA 2021).…”

Pest categorisation of Witches' broom disease of lime (Citrus aurantifolia) phytoplasma

“…The phytoplasma was first detected in the Sultanate of Oman in the 1970s (Bové, ) and it was assigned to the ‘ Ca . Phytoplasma aurantifolia’ species (Zreik et al., ).…”

“…Small fruited acid lime ( C. aurantifolia ) is the most important citrus species naturally infected by the WBDL phytoplasma (Zreik et al., ). Sweet limes ( C. limetta and C. limettioides ; Bové, ), rough lemon ( C. jambhiri ) and trifoliate orange ( P. trifoliata ) can also be naturally infected by WBDL (EPPO, , Al‐Yahyai et al., ).…”

Pest categorisation of Hishimonus phycitis

“…Feeding can be persistent and last several hours. H. phycitis vectors plant pathogenic phytoplamas such as brinjal little‐leaf phytoplasma (Azadvar and Baranwal, ), sesame phyllody phytoplasma (Nabi et al., ) and lime Witches' broom phytoplasma (Bové and Garnier, ; Bagheri et al., ) (see Section 3.5 Impacts and EFSA PLH Panel ()). Following ingestion, the phytoplasma reproduces within the infected vector and the vector remains infected throughout its life.…”

“…As an organism extracting nutrients from the vascular tissue of its hosts H. phycitis is a direct plant pest. However, the most important impacts are caused by the pathogens transmitted by the pest, such as WBDL phytoplasma (Bové and Garnier, ), brinjal little‐leaf phytoplasma (Azadvar and Baranwal, ) and sesame phyllody phytoplasma (Un Nabi et al., ). Importantly, it is unknown whether any of these phytoplasmas would be carried within eggs of H. phycitis (assumed to be the most likely route of entry). RNQPs: Does the presence of the pest on plants for planting have an economic impact, as regards the intended use of those plants for planting?…”