Intraction between root knot nematode with root rot and wilt fungi its effect on disease severity and soil population of fungus and nematode on tomato

A pot trial was conducted to determine the effect of single, sequential and concomitant inoculation with root-knot nematode (Meloidogyne incognita), root-rot fungus (Rhizoctonia solani and Pythium aphanidermatum) and wilt fungus (Fusarium oxysporum f sp. lycopersici) on gall, egg mass, wilt, root rot index and soil population of fungus and nematode on tomato cv. Local. The sequential inoculations comprised of nematode prior to fungus (N→F) and fungus prior to nematode (F→N). inoculation with M. incognita, R. solani, F. oxysporum f. sp. lycopersici and P. aphanidermatum singly caused severe galling, rotting and wilting on tomato root with 1.3, 2.3 and 3.3 indices on 0-5 scale, respectively. The severity of rotting (20-42%) and wilting (12-30%) significantly increased (P ≤ 0.05) in the presence of root-knot nematode in both sequential and concomitant inoculations due to synergistic interaction between two pathogens. However, the galling in all combined treatments significantly decreased (31-46%) in comparisons to nematode alone. Among all the combinations, N→F was recorded most destructive, followed by F+N, F →N and fungus and nematode alone. Final soil population of nematode in alone treatment increased four times of their initial population while substantial variability in population of fungal pathogens were recorded with highest in P. aphanidermatum followed by F. oxysporum f. sp. lycopersici and lowest in R. solani. In combined treatments, the soil population of nematode significantly decreased (60-90%) in the presence of root-rotting and wilt inducing fungus while the population of fungal pathogens also influenced by the presence of nematode and significantly increased by 80-110%. Highest soil population of fungal pathogen was recorded with N→F, followed by (F+N), (F→N) and fungus and nematode alone.