author(s)
Sirisha Tadigiri, Kesava Kumar H and Veena SS

abstract
The present study was conducted to evaluate the efficacy of indigenous bacterial [Bacillus amyloliquefaciens (Ba-14.5), Bacillus subtilis (Bs-13.9 and Bs-13.19)] and fungal bioagents [Trichoderma asperellum (Tr- 9 and Tr-15)] on root-knot nematode, Meloidogyne incognita under in vitro conditions. Cell free culture filtrate of these isolates significantly inhibited the egg hatching and caused juvenile (J2) mortality of root knot nematode at 25, 50, 75 and 100% culture filtrate concentrations. In this study, bacterial bioagents were more virulent to second stage juveniles (J2) compared to fungal bioagents. At 24h exposure period, cent percent mortality was recorded in the culture filtrate prepared from B. subtilis (Bs-13.9) and B. amyloliquefaciens (Ba-14.5) and 74.66 % mortality of J2 was recorded from B. subtilis (Bs-13.19). Whereas, in case of fungal bioagents 88.66% and 85% mortality of J2 was recorded at 72 hours after exposure (HAE) period in T. asperellum (Tr-9) and T. asperellum (Tr-15) respectively. All bioagents significantly suppressed the egg hatching and was maximum in B. amyloliquefaciens, Ba-14.5 (86.00%) followed by B. subtilis, Bs-13.9 (82.33%) and B. subtilis, Bs-13.19 (80.33%). Similarly, the maximum suppression by fungal bioagents in egg hatching of nematodes was observed in T. asperellum, Tr-9 (84.66%) followed by T. asperellum, Tr-15 (78.66%). The culture filtrate studies revealed that all the five biocontrol agents were effective in suppressing the egg hatching of M. incognita and percentage mortality of second stage juveniles (J2) increased with increase in time of exposure to cell free culture filtrate as well with increase in concentration. Further studies to be conducted in pot and field conditions to evaluate the efficacy of these bioagents against root knot nematode, M. incognita.