Trichoderma harzianum as a potential biological agent in control of the charcoal root rot of sugar beet

Sugar beet is one of the most profitable crops in Serbia. The charcoal root rot is an emerging disease of sugar beet that significantly reduces yield and affects the economic viability of production. The objectives of this research were to determine the antagonist activity of selected Trichoderma harzianum isolates (T1 to T13) on two Macrophomina phaseolina isolates in vitro using a dual culture test and a volatile compounds test, as well as in vivo. The efficacy of these treatments was compared to two commercial biopesticides (Bacillomix® Original and Trifender Pro®) and one synthetic fungicide (Funomil 700 WG®). The strongest inhibition in the dual culture test was observed in the treatment with T. harzianum T2 against both tested M. phaseolina isolates. Also, the volatile compounds produced by isolates T2 and T12 exhibited the strongest inhibitory effect on M. phaseolina isolates (from 48.22 to 62.75%). Differences in efficacy were found not only between tested Trichoderma isolates, but also between M. phaseolina isolates used for inoculation which indicates different susceptibility of pathogen population to bioagent. The in vivo test confirmed the strong antagonistic effect of the T. harzianum T2 and T12 isolates. Bacillomix® Original, Trifender Pro® and Funomil® 700 WG did not express satisfactory effects in pathogen control.