This study was carried out to test the antimicrobial activities of nano metal hybrid materials produced by plasma technologies (radio frequency–thermal plasma system and direct current sputtering system) against microbes isolated from cucurbit (watermelon, pumpkin, and gourd) seeds. Eight different nano metal hybrid materials and four carriers were tested against five different fungal and ten different bacterial isolates in vitro. Among the tested nano metal hybrid material, Brass/CaCO3 (1,000 ppm) exhibited 100% antimicrobial effect against all the five tested fungi. However, nano metal hybrid material Brass/CaCO3 (1,000 ppm) inhibited only four bacterial isolates, Weissella sp., Rhodotorula mucilaginosa, Burkholderia sp., and Enterococcus sp. at 100% level, and did not inhibited other six bacterial isolates. Nano metal hybrid material graphite-nickel (GNi) showed 100% inhibition rate against Rhizopus stolonifer and 52.94–71.76% inhibition rate against four different fungal isolates. Nano metal hybrid material G-Ni did not show any inhibition effects against tested ten bacterial isolates. In summary, among the tested eight different nano metal hybrid materials and four carriers, Brass/CaCO3 showed inhibition effects against five fungal isolates and four bacterial isolates, and G-Ni showed variable inhibition effects (52.94–100%) against five fungal isolates and did not show any inhibition effects against all the bacterial isolates.