Many plant pathogenic bacteria and fungi are known to infect olive trees, causing considerable crop losses. The present work deals with targeting some olive tree pathogens by ferrocene derivatives [1,1-bis-(4-hydroxyphenyl)-2 -ferrocenyl-but-1 -ene] (P1); (Z+E)-1-(p-aminophenyl)-1-phenyl-2-ferrocenyl-but-1-ene (P2); 2-ferrocenyl-1-(4-N-acetylaminophenyl)-1-phenyl-but-1-ene (P3); tamoxifen analogous hydroxyferrocifen (P4); 1,1-bis[4-(3 -dimethylaminopropoxy)phenyl] -2 -ferrocenyl-but-1-ene (P5); 1-[4-(3-dimethylamoniumpropoxy) phenyl]-1-(4-hydroxyphenyl)-2-ferrocenyl-but-1-ene citrate (P7) and 1,1-bis[4-(3-dimethylaminiumpropoxy) phenyl]-2-ferrocenyl-but-1-ene citrate (P8)] and an organic compound 1- [4-(3-dimethylamoniumpropoxy) phenyl]-1-(4-hydroxypheny1)-2-phenyl-but-1-ene (P6), whose antimicrobial activity was tested in vitro against Pseudomonas savastanoi pv. savatanoi (the agent of olive knot), Agrobacterium tumefaciens (responsible for crown gall) and the fungus Fusarium solani (agent in nature of occasional root rot). Young olive plantlets inoculated with the three pathogens, developed symptoms when not treated with the ferrocene derivatives. These compounds efficiently inhibited the growth of these microorganisms in culture media and in inoculated plantlets which did not contract the corresponding diseases, especially when treated with P8. These findings shed light on the potential utilisation of ferrocene derivatives, analogues of hydroxytamoxifen, in curing microbe-mediated plant diseases.