The Collaborative International Dictionary of English v.0.48:

nematocide \nem"a*to*cide\ (n[e^]m"[.a]*t[-o]*s[imac]d or
   n[i^]*m[a^]t"[-o]*s[imac]d), n.
   A substance that kills nematodes, especially one used in
   medicine or to kill plant pathogens. [Also spelled
   nematicide.]
   [PJC]