Occurrence and Yield Loss Assessment of Root-Knot Nematode (Meloidogyne incognita and M. javanica) infesting Green Gram in Western Uttar Pradesh, India

Field surveys conducted across six districts in Western Uttar Pradesh, India (Aligarh, Bulandshahr, Etah, Ghaziabad, Hathras, and Mathura), revealed occurrence of 22-43% (Meloidogyne incognita), 13-30% (M. javanica) and 18-38% (M. incognita + M. javanica). The maximum frequency of occurrence (19-28%) and incidence (22-34%) of root-knot disease in green gram was recorded in Bulandshahr district, with M. incognita being highest in Debai tehsil (34% and 44%, respectively), whereas M. javanica was highest in the Khurja tehsil (24% and 29%). The lowest occurrence and incidence were observed in Anupshahr tehsil for M. incognita (22% and 26%, respectively), and in Shikarpur tehsil for M. javanica (13% and 16%). The Aligarh and Hathras districts showed relatively higher disease incidence, whereas the lowest was in the Mathura district (5-12% and 7-15%, respectively). The highest occurrence of mixed infection (M. incognita + M. javanica) was recorded in Bulandshahr district (14%). The disease severity (number of galls) and reproduction (egg masses per root system) were also highest in Bulandshahr district (57-104 and 40-88 per root system, respectively). Relative yield (RY) losses ranged from 11-32% (M. incognita) and 5-22% (M. javanica) and 4-16% (M. incognita + M. javanica), and the maximum loss was recorded in Bulandshahr (32% and 22%) and the minimum in Mathura (11% and 5%). The RYL was found to be directly correlated with the nematode soil population, which ranged from 635 to 2642 J₂/kg soil in green gram fields in Mathura and Bulandshahr districts, respectively.