Appraisal of the invasive species of root knot nematode Meloidogyne enterolobii on guava and its management using microbial agents

Abstract

newline Root knot nematodes, particularly Meloidogyne enterolobii, can pose a significant newlinethreat to guava (Psidium guajava L.) crop, leading to reduced yields and economic losses. newlineHere is an appraisal of the invasive species and its potential management strategies using newlinemicrobial agents. Firstly, a random survey was conducted in major guava growing districts newlineof Tamil Nadu viz., Coimbatore, Theni, Dindigul, Tiruchirapalli, Karur, Madurai, newlineDharmapuri, Krishnagiri, Erode, Villupuram and Tiruvannamalai. A higher percentage of newlinewilt incidence was recorded in Malumichampatti (85%) and Thirthipalayam (60%) in newlineCoimbatore, Avoor (42 45%) in Thiruvannamalai and Seethapatti (40%) in Tiruchirapalli newlinewhen compared to that of the other surveyed districts. newlineMorphological and molecular characterization of nematode and fungus were newlineperformed and M. enterolobii, Fusarium oxysporum and specifically Fusarium oxysporum newlinef. sp. psidii were confirmed as the causal organisms for causing wilt disease in Guava. newlineAmong different isolates of F. oxysporum, F. oxysporum f. sp. psidii was identified as the newlinevirulent isolate and the plants inoculated with M. enterolobii followed by Fusarium newlineoxysporum f. sp. psidii (15DPI) expressed the symptoms earlier and showed highest newlinepercentage of wilt incidence. newlineThe plants belonging to the family Poaceae such as maize, ragi, cumbu and fruit crops newlinelike citrus, mango serve as a non-host against M. enterolobii and M. incognita. The crops newlineincluding rice and groundnut were determined as poor hosts for M. enterolobii. Histopathology newlineof M. enterolobii inoculated plants revealed that lesser number of females was present in simple newlinegalls and many in compound galls, with the presence of large number of giant cells. newlineThis immense crowding appears to restrict the stellar region, resulting in disturbance of the newlinevascular bundles and their function. M. incognita infested guava roots showed minimum newlinenumber of giant cells with the presence of 2-3 mature females. It was evident that the cortical newlineregion inhabited more adults t