EFFICIENCY OF BACILLUS SUBTILIS AND PSEUDOMONAS FLUORESCENCE AS BIOCONTROL AGENTS AGAINST RHIZOCTONIA SOLANI ON SPEARMINT PLANTS (MENTHA VIRIDIS L.)

The effect of Bacillus subtilis andPseudomonas fluorescence as biocontrol agent against Rhizoctonia solani on Menthaviridis L. plants was evaluated. The pot experiment was conducted during two successive seasons (2012 and 2013) in the Experimental Farm of Medicinal and Aromatic Plants Research Department in El Kanater El Khairia. Sex treatments were conducted , Control (without any treatments), R. solani (infested pathogenic fungi), R. solani + fungicide (Vitavax T. 0.15%), R. solani + Bacillus. subtilis (B.S), R. solani + Pseudomonas. fluorescence (Ps.f) and R. solani + B.s + Ps.f (combination of the two bioagents). The results showed that the highest decrease in percentage of infected plants, the increment of the survival plants percentage and the activity of dehydrogenase enzyme were recorded with the plants infested with B. subtilis,Ps. fluorescence individually and the combination treatment in comparison to the control and R. solani infested plants at both cuts in both seasons. Moreover, the highest values of growth parameters (plant height, number of branches, plant fresh and dry weight) as well as volatile oil percentage were recorded with the same treatments. The most effective treatment was the dual application treatment (B. s and Ps. f) which gave the highest volatile oil yield/plant in both cuts during the two seasons. While the volatile oil main component (Carvone) recorded maximum values 62.20 and 61.34% in case of R. solani + B. subtilis and the dual treatment.