episkop konstantin preslavski” university of shumen ：episkop康斯坦丁preslavski”大学舒门....pdf

R esearch A rticle EVALUATION OF ISOLATES OF RHYZOCTONIA SOLANI AND FUSARIUM OXYSPORUM ON SUGAR BEET UNDER FIELD CONDITIONS *Krasimira Tanova and Svilen Raykov Episkop Konstantin Preslavski” University of Shumen –Shumen, Bulgaria ARTICLE INFO ABSTRACT The aim of this study is to test the aggressiveness of the isolates from Rhyzoctonia solani Kuhn and Fusarium oxysporum, obtained from sugar beet and establish their influence on the chemical composition and production of oxidase enzymes in a sick root. Th e study is conducted at the Laboratory of Phytopathology of Shumen University, the experiment field and beet technological laboratory of the Institute of Agriculture –the city of Shumen in 2014 -2015 г. Five isolates were used: 3 of Rhizoctonia solani Kuhn and 2 isolates of Fusarium oxysporum. Inoculation was made under field conditions in parallel by two methods: individually, by placing a block of agar culture pathogens at the head of root crop and by infected meal of beet seeds buried at about 4 -5 cm of root crop (150 -200 g/m 2). The infection was made in the middle of July in an area of 2m 2 of each isolate in 4 repetitions. The degree of attack was calculated on 5 grade scale. The aggressiveness of the pathogen was calculated as % diseased roots / m 2, du rin