The effect of yellow rust on grain yield of Sardari wheat cultivar in dryland areas of East Azarbaijan

Wheat is threatened by the devastating epidemics of yellow rust all over the world. A severe epidemic of yellow rust occurred on wheat in northwest and west of Iran during 2009-2010 cropping season. To study the effect of yellow rust on yield of Sardari, a wheat cultivar grown widely in dryland areas of Iran and to assess the effects of fungicides application on control of disease and yield reduction, an investigation was performed in 214 farmers field with 5150 hectares in a hot spot area of Mianeh, East, Azarbaijan. Two fungicides, Propiconazole and Tebuconazole at different growth stages of wheat were sprayed using three application methods. Disease severity was recorded at the end of growth period and grain yield and percentage of yield reduction were assessed after harvest. The results of analysis of variance for data showed significant differences for time of spry, method of sprying, grain yield and percentage of yield reduction. Average yields of Sardari cultivar in sprayed and non- sprayed fields were 2033 and 885 kgha-1, respectively, indicating 1148 kgha-1 yield reduction by the disease. Early spray of fungicides increased grain yield significantly compared to late sprying. Disease severity in early sprayed fields was 10-20% while in late sprayed or non- sprayed fields disease severity rised upto80-100%. Tebuconazole controlled disease better than propiconazole in many fields. Effects of yellow rust were different on yield of eight wheat advanced lines and two check cultivars Sardari and Azar2. The highest grain yield (3812 kgha-1) was produced by line CIMMYT 82-126 which was resistant to yellow rust. Mean grain yields of Sardari and Azar2 cultivars were 1490 and 2419 kgha-1 respectively. In general, the results of the present study showed that in epidemic years, yellow rust can reduce 55-65% grain yield of Sardari cultivar, but chemical control through on time application of fungicides can decrease disease severity and increase grain yield.