Spreading of wheat yellow rust pathogen (Puccinia striiformis West.) in the south of Russia in 2017
Yellow rust caused by Puccinia striiformis West. is a harmful and dangerous disease in the south of Russia. Yield losses under optimum conditions on highly susceptible varieties can vary from 10 to 100%. During the growing season of 2017, cool weather with constant precipitation from the third decade of April to the first decade of June contributed to the intensive development of the pathogen. Surveys of the main winter wheat production areas in five agroclimatic zones of the region revealed that yellow rust was prevalent in all areas. The maximum development of P.striiformis was observed in southern submontane and western Priazovsky agroclimatic zones. Some varieties such as Grom, Yuka, Tanya, Anka had losses to yellow rust of up to 30-40 %. In the central and northern agroclimatic zones, the losses averaged 5%, whereas in the dry eastern steppe zone losses were only up to 1%. The build up of yellow rust inoculum in the region raises concerns that in 2018, under favorable weather conditions in spring, winter wheat crops could be infected with the disease, especially in the wetter agroclimatic zones.