First Report of Nematicidal Activity of Planococcus plakortidis Against the Citrus Nematode Tylenchulus semipenetrans.

This study reports, for the first time, the nematicidal potential of the cell-free culture filtrate of Planococcus plakortidis against the citrus nematode Tylenchulus semipenetrans. In vitro bioassays revealed a strong nematicidal activity, reaching 83.06% mortality after five days of incubation. The highest nematicidal effect coincided with the maximum bacterial population density (5.6 × 106 cells ml-1), suggesting a close association between the exponential growth phase of the bacterium and the production of bioactive metabolites. Under greenhouse conditions, application of the culture filtrate through irrigation significantly reduced nematode populations and enhanced the growth performance of Citrus aurantium and Citrange Carrizo plants infested with T. semipenetrans. These findings highlight the potential of P. plakortidis-derived metabolites as an environmentally friendly and sustainable biological alternative for the management of citrus plant-parasitic nematodes.