FITONSIDHO (az yunoni rhuton— rastani va lotini saedo — mekusham), moddahoi az jihati biologi faolro guyand, ki rastaniho hosil karda, mikroorganizmho (bakteriyaho, zanburughoi mikrookopi, soddatarinho)-ro nobud yo sabzishu inkishofi onhoro sust mekunand. Onho yake az omilhoi immuniteti tabiii rastaniho buda, zimni aloqai mutaqobilai organizmho dar biogeosenoz ahamiyati kalon dorand.
Khosiyati ziddimikrobii fitonsidhoro ba nazar girifta, onhoro dar tib (davohoi az sir, piyoz, rosal va gayra tayyor kardashuda) istifoda mebarand.