G. Beev, S. Denev, D. Pavlov

Abstract. Wheat fungal infections caused by Fusarium spp. is of great economic importance in cereal growing countries including Bulgaria. These infections greatly reduced crop yields and significantly decrease grain quality, because of mycotoxins production, that make grain unsuitable for human food and livestock diets. To establish the occurrence and distribution of Fusarium spp. were tested 21 samples of wheat from Stara Zagora area. To determine the internal contamination by microscopic fungi of grains, the agar plate method was applied. One hundred grains were tested for each sample. The grains were sterilized with 70 % ethanol, rinsed with sterile water, dried and placed on Petri dishes containing Chapeck-Dox`s agar medium. After incubation, the number of fungal genera detected in each sample was calculated. Conclusive identification of Fusarium spp. was made after transfer of selected isolates on SNA (Synthetischer nährstoffarmer agar) on the basis of their morphological and cultural characteristics. As a result of mycological investigation, fungi of 9 genera were obtained: Fusarium, Aspergillus, Penicillium, Alternaria, Mucor, Rhizopus, Cladosporium, Rhizoctonia and Nigrospora spp. From contaminated with Fusarium spp. wheat samples were identified 62 isolates attributed to the 8 sections. Most common isolated species were Fusarium verticillioides, followed by Fusarium poae and Fusarium solani. Particular interest is the species Fusarium equiseti, which is isolated for the first time from Bulgarian wheat.