Appearance and Identification of the Causer of “White Mold” at Sunflower Plants in the Republic of Macedonia

Abstract

Sclerotinia spp. Is a very destructive fungus causing “white mold” and it has become one of the greatest problems in sunfl ower breeding in the Republic of Macedonia in 2010. Field monitoring in the region of Bitola showed very high infection of around 20 - 30%. Two types of symptoms where observed during the fi eld monitoring. First symptoms are observed on the leaves of the infected plants in form of wilting, prior to fl owering stage. The most characteristic symptoms are observed, at the lower part of the stem in form of a stem cancer. Big variable sclerotia in size and shape are observed inside the stem. Appearance of white mycelium on the infected lower parts of the plant was often observed during the humid climate. Other infected plants show different symptoms. The stem was longer and thinner than in uninfected plants, and the pit was very small of around 9 cm. Sclerotia observed inside the stem where not bigger than 2, 5 mm. In vitro investigations confi rm the presence of ascomycetes Sclerotinia sclerotiorum (Lib.) de Bary and Sclerotinia minor Jagger, for the fi rst time in the Republic of Macedonia.