Occurrence of a novel disease on cereals in Hungary

Winter barley fields were surveyed for leaf spot diseases in the vegetation periods from 2005 to 2007 in Hungary. There was a dynamic increase in occurrence and spread of leaf spot pathogens in vegetation period 2005/2006. Based on microscopic examination we determined that Pyrenophora species were the dominant pathogens on winter barley. However, a new infection picture was observed in the vegetation period 2006/2007. Well-known pathogens infected the winter barley, but the development of the diseases was much slower and weaker than in previous year. There were no leaf spots on the upper leaf of winter barley until flowering (middle of May) in several experimental plots. During and after the florescence of winter barley there were little spotty marks on the upper leaves, which we determined as physiological leaf spots. A week later the infection increased, the spotty marks become larger and darker. The same symptoms were found on winter wheat and triticale, too. This time we collected the infected cereal leaves to determine what might have caused the leaf spots. The microscopic test of leaves proved the leaf spots were caused by Ramularia collo-cygni (Sutton et Waller). The shape and size of conidiophores and conidia demonstrate the presence of this pathogen. The new Ramularia leaf spot was recorded for the first time on winter cereals (barley, wheat, triticale) in Hungary.