Management of Citrus nematode, Tylenchulus semipenetrans through chemigation with liquid formulations of Purpureocillium lilacinum and neem in acid lime orchards

Abstract

Field experiments were conducted to study the individual and combined effect of neem seed kernel extract (NSKE) and liquid Purpureocillium lilacinum formulation delivered through drip irrigation system on acid lime trees naturally infested with citrus nematode, Tylenchulus semipenetrans. Both bio-products were applied at 4 L/ha, but NSKE alone delivered twice at 30 days interval and their effect was compared with carbofuran 3G at 100 g/tree as spot application. Results revealed that both NSKE and P. lilacinum tested significantly suppressed T. semipentrans density in soil and acid lime roots. However, T. semipenetrans suppression was significantly superior in acid lime trees when NSKE and P. lilacinum were concomitantly delivered. This combined treatment reduced T. semipenetrans density in soil by 78.0-88.8% and in roots by 73.5-79.2%. The density of T. semipenetrans was comparatively higher when inputs were applied alone. Root colonization and egg parasitization potential of P. lilacinum was improved 2-3 times more
when delivered along with NSKE. The integrated approach caused 26.3-33.6% more fruit yield with higher (1:3.2-1:4.2) cost benefit ratio. Hence, chemigation with NSKE + P. lilacinum in acid lime trees can be recommended for wide scale adoption to manage citrus nematodes.