Interaction Studies between Meloidogyne javanica and Fusarium oxysporum f. sp. lycopersici (Fol) Race 3 on Different Isolines of Tomato cv. Tasti Lee

The Mi gene in tomato confers resistance to Meloidogyne javanica, M. incognita, and M. arenaria, the most common tropical root-knot nematode (RKN) species found in Florida. Fusarium wilt (Fol) is another major problem in Florida tomatoes which may interact with RKN and cause more plant damage. To study the interactions between RKN, Fusarium, and Mi in tomato, two greenhouse experiments were conducted. Both experiments used different isolines (with and without I-3 and Mi genes) of the tomato cultivar Tasti Lee^®. In the first experiment, all four isolines were subjected to two levels of RKN (~10,000 eggs/pot and no eggs) and two levels of Fol (1000 cc soil with 1,000 cfu/g at planting and no Fol), both applied at planting. In the second experiment, the two isolines without I-3 were exposed to the same two levels of RKN as described above and three levels of Fol (50 ml Fol with 1×10⁶ cfu/m at planting, at 10 DAT, and no Fol). Fol reduced root-knot infection and reproduction when both Fol and RKN were inoculated at planting but not when Fol was inoculated 10 days later. Plant damage from Fol was exacerbated in the presence of RKN, especially when both pathogens were present at planting. Isolines with I-3 grew better in Fol-inoculated soil but had no effect when Fol and RKN were both present. Isolines with Mi gene reduced RKN infection and reproduction but did not affect plant damage caused by Fol. In summary, while RKN reproduction was reduced in the presence of Fol, the overall plant damage was more severe when both pathogens were present.