Assessment of nematicidal efficacy of chitosan in combination with botanicals against Meloidogyne incognita on carrot

Root-knot nematode, Meloidogyne incognita (Kofoid and White) is one of most damaging pathogen of vegetables, including carrot (Daucus carota L.). We evaluated nematicidal potential of chitosan in combination with chopped leaves of Argemone mexicana L., Achyranthes aspera L., and Ricinus communis L. against infestation caused by M. incognita on carrot under both in vitro and in vivo. Infectious stage (J2s) and egg masses of M. incognita were exposed to different concentrations (2500, 2000, 1500, 1000, and 500 ppm) of chitosan and botanical extracts separately. Maximum mortality of J2s and the highest inhibition in egg hatching was observed at 2500 ppm of chitosan after 36 h and days incubation period, respectively and minimum found in 500 ppm of A. aspera after 12 h of incubation period. Furthermore, pots treated with 1 g chitosan and 30 g of freshly chopped leaves of all three tested botanicals significantly reduced pathological parameters and improved growth and photosynthetic attributes of carrot. In combination with botanicals, chitosan showed a synergistic effect against M. incognita on carrot as compared to chitosan alone. This study proves that chitosan's bio-efficacy, combined with selected three botanicals, could be utilised to manage M. incognita on the carrot as a potential sustainable treatment.