Interaction between Meloidogyne incognita and Rhizoctonia solani on chile (Capsicum annuum)

Rhizoctonia solani and Meloidogyne incognita are two soil microorganisms associated with yield reduction in chile. Both pathogens can infect a single plant and kill chile. The hypothesis investigated whether R. solani and M. incognita have a synergistic effect on chile. Four greenhouse studies examined the interaction of R. solani and M. incognita on chile. In the first two experiments, soils were inoculated with each pathogen simultaneously, and in the second two experiments soils were inoculated with each pathogen sequentially. In the simultaneous experiments, soils were inoculated with R. solani, M. incognita, both pathogens, or not inoculated in the control treatments. Sequential experiments had additional treatments where soils were inoculated with R. solani two weeks prior to inoculation with M. incognita or soils were inoculated with M. incognita two weeks prior to inoculation with R. solani . In all experiments, M. incognita was inoculated at a rate of 5,000 eggs per plant and R. solani was inoculated at a rate of five agar pellets (1-cm in diameter) of R. solani per plant. The frequency of recovery of R. solani from root segments, M. incognita egg counts and reproduction factor, and plant growth parameters were measured for chile in simultaneous experiments at three different times after soil inoculation. Additional parameters were measured for chile in the sequential experiments. Neither reproduction rates of M. incognita in the presence of R. solani in chile roots, nor R. solani infection in the presence of M. incognita was affected in the simultaneous experiments. Meloidogyne incognita infection did not increase severity of chile infection by R. solani when both pathogens were inoculated simultaneously to soil. The simultaneous inoculation had no effect on plant dry biomass, while the sequential inoculation had a minor effect. In the sequential experiments, higher frequencies of R. solani were observed when R. solani preceded M. incognita than when M. incognita preceded R. solani and the effect of the sequential inoculation on several measured parameters was significant. Interaction of R. solani and M. incognita was more apparent when both pathogens were inoculated sequentially to soil rather than when inoculated simultaneously.