The toxicity of azadirachtin, plant extract of Azadirachta indica and captan, active ingredient of fungicide for seed treatment (Bralin 48 SC), to Fusarium graminearum Schwabe, isolated from maize root, was researched. The experiments were carried out in vitro, on potato dextrose agar (PDA) with incorporated different concentrations of azadirachtin or captan. The experiment was carried out in two series, with 5 concentrations, in 5 repetitions.
The obtained data were processed by linear functional model of probity regression, method of maximal probability, and obtained experimental data were evaluated by c2-test.
It was proved that the extract of Azadirachta indica manifested higher toxic effect (over 6000 times) to the mycelium F. graminearum (EC50 = 40.76 mg/l), then captan (EC50 = 261140.57 mg/l). These results are good basis for further investigations and eventually introducing azadirachtin for the control of F. graminearum on maize by seed treatment.
The coefficients for captan were 0.74 and for azadirachtin 0.76, which means that F. graminearum is relatively equally susceptible to both compounds. This was also confirmed on the basis of the parallel relationship between their regression lines (ec-p lines).
Key words: azadirachtin, captan, toxicity, F. graminearum, maize, seed treatment.