Phoma black stem of sunflower (Phoma macodnaldii Boerema) occurrence in southwestern Slovakia

During 2012 - 2013 Phoma black stem on sunflower, caused by Phoma macdonaldii was studied at localities of the Southwest Slovakia (especially Nitra and Trnava region). Total 54 sunflower fields were evaluated during two years. The occurrence of Phoma black stem was higher in 2012 than 2013. Level of infection 80 - 100 % was recorded at all localities in Trnava region in 2012. Similar level of infection (80 - 100 %) in Nitra region was observed on more than 50 % localities. In 2013 were observed level of infection 1 - 30 % symptoms on most of the monitored localities in Nitra and Trnava region and only at one locality was number of infected plants by pathogen Phoma macdonaldii higher than 81 %. In 2012 was more suitable conditions for the development and widespread of pathogen Phoma macdonaldii. Lower occurrence of Phoma black stem of sunflower is probably resulting of low rainfall during the July in Nitra and Trnava region in 2013.