Yield Losses in Wheat Caused by Stripe Rust ( Puccinia striiformis ) in Egypt

The production loss in eight local wheat cultivars was estimated under yellow rust disease pressure at four locations of northern Egypt during 2017/2018 and 2018/19 growing seasons. Considerable disease pressure, as revealed by final rust severity (%), was observed at all locations with a maximum value (100%) in northern Egypt. The tested wheat cultivars were evaluated at the adult plant stage under field conditions using two epidemiological parameters final rust severity (FRS%) and area under disease progression curve (AUDPC). Final rust severity ranged from 5% to 100% for the tested cultivars. AUDPC ranged from 260 to 2800 at Sakha, 115 to 2800 at El- Gemmeiza, 115 to 2600 at Itay El-Baroud, and 115 to 2600 at Shebin El-Koum during the two growing seasons. The values of FRS (%) and AUDPC during the first season were less than those in the second season. Losses in grain yield per plot ranged from 2.72% to 37.72% during the first season and 6.18% to 69.33% in the second season at the Delta region. The highest grain yield losses were recorded with wheat cvs.; Gemmeiza 11 (64.20%), followed by Misr 1 (62.38%), as well as for Misr 2 (57.66%) and Sids 12 (50.89%). While, the lowest loss cvs.; was recorded in Misr 3 and Giza 171, as it was 7.65% and 9.44%, respectively. Regarding yield losses in the 1000 kernel weight, wheat cvs.; Misr 3 showed the lowest value of loss i.e. 1.71%, while Gemmeiza 11 showed the highest loss i.e. 39.67% during 2018/2019 growing season. A significal positive correlation was found between yield losses and each of final rust severity (%) and area under disease progression curve (AUDPC). These results would serve as a fruitful tool in the national wheat breeding program for yellow rust resistance, in Egypt.