Interaction between root-knot nematode,  Meloidogyne incognita alone and in combination with the bacterium,  Ralstonia solanacearum   were evaluated on the growth of potato plants cvs. Diamant and Spunta,nematode reproduction and bacteria as well under greenhouse conditions.
Results showed that potato cv. Spunta was highly susceptible to bacterial wilt disease than cv. Diamant. The possible combinations of M. incognita and R. solanacearum revealed that potato plants inoculated with M. incognita 10 days prior to bacterial pathogen's inoculation showed higher bacterial wilt disease rating than those inoculated with both pathogens simultaneously with values of 3.95 and 3.45, respectively. The higher nematode galling index was noted on potato plants cv. Diamant than cv. Spunta with values of 2.32 and 1.92, respectively.  
Results also showed that plants receiving  nematodes with bacteria added at the same time, the highest injury of nematode accompanied by  the highest rate of build-up  that recorded to be   30.83   and 22.15 for potato cvs,Diamant and Spunta, followed by the combination with R. solanacearum 10 days after nematode inoculation that  was recorded to be  26.78 and 20.35 for the same potato cultivars,  respectively.  Moreover, there was a significant reduction in both shoot and root fresh weights of the two tested cultivars infected with either  pathogen alone or  together.