REACTION OF TOMATO (SOLANUM LYCOPERSICUM) CULTIVARS TOWARDS ROOT-KNOT NEMATODE (MELOIDOGYNE INCOGNITA) AND BACTERIAL WILT (RALSTONIA SOLANACEARUM)
Tomato (Solanum lycopersicum) is one of the most popular vegetable crops grown worldwide. However, tomato production is constrained by root-knot nematode (Meloidogyne incognita) and bacterial wilt (Ralstonia solanacearum) either singly or as a disease complex. Thus, the reaction of tomato cultivars Assila, Cochoro, Marmande, and Moneymaker was evaluated in a glasshouse experiment. Disease resistance against a single isolate of M. incognita and R. solanacearum alone or as a co-infestation was tested. Six inoculation sequences (simultaneous, M. incognita inoculation 10 days prior to R. solanacearum, and R. solanacearum inoculation 10 days prior to M. incognita) were considered in the study. The experiment was factorially arranged in a completely randomized design with four replications. Responses of tomato genotypes to inoculation sequences were made based on tomato biomass and growth and disease development parameters. Inoculation sequence significantly (P<0.05) influenced plant and disease parameters. Inoculation of M. incognita 10 days prior to R. solanacearum led to maximum (3.75) wilt severity at the final wilt assessment. This same sequence reduced plant height, fresh root weight, and shoot dry weight by 24.99, 55.93, and 51.88%, respectively. Inoculation with M. incognita alone increased all nematode-associated parameters. Severe nematode and bacterial diseases were recorded on Marmande. Conversely, Assila performed well against the nematode and bacteria compared to the other cultivars tested. The overall results of this study demonstrated that inoculation sequence greatly influenced the response of tomato genotypes to M. incognita and R. solanacearum and their complex. However, studies of this kind should be further executed with many isolates of pathogens, inoculum levels, and tomato genotypes under actual farmer’s conditions to verify the validity of the results.