A survey of Downy Mildew Disease on Some Plant Hosts in Al- Hassakeh Governorate

Abstract

This study aimed to: A survey of  downy mildew disease on some plant hosts in Al-Malikiya, Ras al eyn and AL- Qamishly in Al- Hassakeh governorate in Syria. The study included 85 and 77 fields and with different plant species during 2017 and 2018 respectively. Ratio, severity and spread of infection was recorded. Infected plants samples were transferred to laboratory for further investigation and identification of fungal genera and species. Also the fungal pathogen was determine. Results of survey of  downy mildew disease on 12 plant species showed difference of ratio and severity of infection from region to other. The highest ratio and severity was recorded in Al-Malikiya region. Infection of plant hosts was recorded with fungus species: Pseudoperonospora cubenis, Bremia lactucae, Peronospora sparsa, Peronospora viciae, Peronospora pisi, Peronospora effuse, Plasmopara viticola. The highest spread was P. cubenis species with ratio 38.04% and 47.27% during 2017 and 2018 respectively. While P.pisi and P. effuse was the least spread with ratio 2.17 in 2017, both species did not appear in 2018. The highest ratio (70-80%) and the highest severity (3.8-4.5) was recorded on cucumber. While the least ratio (3%) and the least severity (1) was recorded on pea in 2017. No infection were recorded  in spinach, bean and pea in 2017.

Keywords: Downy mildew, Fungus species, Plant hosts, Syria.