Powdery mildew of wheat caused by the pathogen Blumeria graminis f.sp. tritici is one of the most common diseases of wheat which occurs on temperate area. Previous findings emphasized that according with severity and time of attack Blumeria graminis f.sp. tritici reduces supply of photosynthesis on leaves, decreases leaf assimilation index, negatively affects yield components and finally the grain yield. The pathogen attack was evaluated on twenty-five winter wheat varieties under natural field conditions during the year 2010-2011. The experimental design was a randomized block design with three replications. Disease rating was visually recorded using the double-digit scale (00-99) on the growth stage 9-ligule of flag leaf just visible (Freekes scale).There were also calculated for each wheat genotype the attack frequency (F%), the attack severity (I%) and attack degree (AD%).The attack degree value ranged between 2,8% for Dor variety and 12,4% for Gruia variety. Among the most affected varieties were also Simnic 30, Delabrad, Noroc, Magistral, while a better assessment to the pathogen attack was recorded by Crina, Romulus and Dor varieties. According with crop stage and pathogen attack severity, the extend of yield losses can be predicted mathematically and it was observed that during 2010-2011 conditions the occurrence of the attack on the stage ligule of flag leaf just visible didn’t influence significantly the yields, aspect emphasized also by the negative correlation coefficient between attack degree and yield level (r=-0,3258).The highest yields were recorded by the varieties Trivale (6277 kg/ha) and Europa (6230 kg/ha), while the lowest yields were recorded by Noroc (4187 kg/ha) and Briana (4029 kg/ha). Despite Gruia variety recorded the highest attack degree on the conditions of 2010-2011 year, its yield was 6027 kg/ha leading to the conclusion that it could has tolerance to that attack of Blumeria graminis f.sp. tritici, but this needs further investigation on the higher infection pressure levels on the years more favorable for this pathogen development.

pathogen attack, Blumeria graminis f.sp. tritici, powdery mildew, yield, winter wheat

Presentation: oral