Abstract
Date palm phytoplasma disease (Wijam) is an emerging economical threat to the production of dates in the western provenance of Saudi Arabia. Disease symptoms were first observed in Al-Madinah region in 2014; a total of 525 healthy and symptomatic samples were collected from 34 date palm cultivars, were analysed by PCR and dot-blot hybridization. Nested PCR (nPCR) and sequencing results confirmed the presence of 16S rDNA phytoplasma, scoring 98% similarity to the 16SrI phytoplasma. Hybridization results showed that 17.4% of the collected samples were positively infected, the highest percentage of infection was found in city farms, reaching up to 13.4%. Furthermore, 16 date palm cultivars did not show any infection, while the other 18 cultivars had different percentages of infectivity. This finding may partially explain the sudden decline of date production in Al-Madinah region and suggests an alert to investigate disease control management procedures.