As expected, azadirachtin exhibited greater antimicrobial activity than the neem extract. Azadirachtin applied at a concentration of 0.3 mgmL-1 or more could
inhibit the growth of Rhizobium sp. and X. campestris pv. campestris. The growth of B. megaterium, P. aeruginosa, and P. carotovorum could be inhibited by azadirachtin applied at concentrations of at least 0.1, 0.4, and 0.5 mgmL-1, respectively. Neither azadirachtin nor neem extract could inhibit T. asperellum and F. oxysporum. Azadirachtin applied at concentrations of 0.4 mgmL-1 or more resulted in late sporulation only in T. asperellum (data not shown).