Biological control of Meloidogyne incognita and Rhizoctonia solani in eggplant
AbstractEggplant (Solanum melongena) is an important vegetable crop that is infected by root-knot (Meloidogyne incognita) and root-rot (Rhizoctonia solani) pathogens in Egypt. Bacillus subtilis, Pseudomonas fluorescens, Trichoderma harzianum and Trichoderma viride were tested for managing these two pathogens in vitro and in the greenhouse in comparison with the nematicide oxamyl. The efficacy of the commercial product Micronema was assessed in the field. In vitro, culture filtrates of B. subtilis, P. fluorescens, T. harzianum and T. viride at 10% concentration caused nematode mortalities of 100, 99, 98 and 96%, respectively, after 72 hours exposure to the filtrates. Also, T. harzianum greatly reduced mycelial growth of R. solani, followed by T. viride, B. subtilis and P. fluorescens. In the greenhouse, the most effective culture filtrate, applied as a soil drench, was that of B. subtilis at 10%, which reduced the number of juveniles in soil, galls and egg masses of M. incognita on the roots of eggplant cv. Pusa Purple Long by 91.9, 82 and 82.6%, respectively. Also, cultures filtrates of T. harzianum reduced damping-off and root-rot incidence in eggplants, followed by those of T. viride, P. fluorescens and B. subtilis. All bioagent treatments improved plant growth and their effectiveness was similar to that of oxamyl at 0.01% soil weight. In the field, Micronema protected eggplants from attack of M. incognita and R. solani, thus increasing yield, and affected populations of soil mycoflora differently.