Puccinia striiformis Westend. is an obligate biotrophic parasite that could infect wheat and barley to cause stripe rust. P. striiformis, a species of rust fungi, is divided into several formae speciales based on host specialization, such as P. striiformis f. sp. tritici (Pst) and P. striiformis f. sp. hordei (Psh). Stripe rust of wheat caused by P. striiformis f. sp. tritici (Pst) was first detected in Egypt in 1920. During the survey in 2021 in the hot spot of Sakha Agriculture Research Station in the 2022 season., stripe rust samples were collected from wheat and barley (Hordeum spp.). Observed on grass barleys were susceptible in infected wheat fields with Puccinia striiformis f. sp. tritici. Collected samples from barley were virulent to Chinese 166. This indicates the presence of a new race of Puccinia striiformis f.sp. tritici, that is virulent to Yr1, Yr10, Yr17, Yr24, Yr26, Yr27, Yr32, Yr54 and YrSp. Microscopic examination showed that, urediniospores and teliospores on wheat and barley are similar. The new races caused ‘break down’ of the resistance of major wheat cultivars possessing the specific Yr genes. (Shahin 2020).
