The Status of Wheat Stem Rust in Syria During the Period 2018-2021

Abstract

Kassem, M. 2023. The Status of Wheat Stem Rust in Syria During the Period 2018-2021. Arab Journal of Plant Protection, 41(4): 339-347. https://doi.org/10.22268/AJPP-41.4.339347 Wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is an important disease of wheat in the world. This disease is also observed in Syria and repeatedly increased from one year to another during the last decade. This study aimed to investigate the status of the distribution of the disease in the Syrian wheat fields, in addition to its virulence by evaluating the reaction type of differential lines and local varieties. The results of the field survey showed that the spread of wheat stem rust disease in all studied regions in Syria (northern, central and coastal regions) during the period 2018-2021. The prevalence of infected fields reached 59, 75, 67, 59%, respectively, with some variability among regions based on the moisture level (rainfall/irrigation) and average temperature. In general, the infection with Pgt appeared in wheat fields earlier than usual in Syria (mid-May), with costal wheat field infection observed at the beginning of April, whereas from mid to late April in the central and northern regions. The dominant bulk of Pgt characterized by increased virulence, year after year in Syria. The percentage of susceptible genes reached 77% in 2021, whereas it was 47.7% in 2018. One major gene Sr13 was still effective against Pgt population. Reaction type of resistance genes varied, some of them maintained the reaction type during the study period, but most of them was susceptible and moderately susceptible, and the others lost its resistant. For example, genes 9e, 24 and 31 that were resistant in 2018 began to lose resistance in 2019. The reaction type of Syrian local cultivars was affected by the virulence of the Pgt bulk. The percentage of susceptible cultivars was 66.6%, the moderately susceptible was 20.8%, and the moderately resistant was 12.5% and restricted to three varieties (Doma 6, cham 9 and Bohouth9), whereas resistant varieties were absent. Keywords: Differential lines, Cham 9, Bohouth 9, wheat stem rust, Sr2, Sr13, Syria