Oligochitosan (OC) with molecular weight Mw of 5000 g/mol was prepared by gamma Co-60 ray irradiation of chitosan solution. Nanosilica (nSiO₂) with the size of 10 - 30 nm was synthesized by calcination of acid treated rice husk. The mixture of 1% OC - 1% nSiO₂ was prepared by dispersion of nSiO₂ in OC solution. The morphology of nSiO₂ in the mixture of OC-nSiO₂ was measured from images of transmission electron microscopy (TEM). The effect of foliar application of the mixture of OC-nSiO₂ on the induction of resistance against anthracnose disease caused by Colletotrichum gloeosporioides fungus on chili fruits was investigated. Results indicated that foliar application of OC-nSiO₂ with the concentration of 60 mg/l - 60 mg/l was found to be as the optimal treatment that reduced the disease severity on chili fruits to 22.2% compared with 90.0% of the control. Thus, OC-nSiO₂ hybrid material could be considered as an effective biotic elicitor to prevent anthracnose disease infection for chili fruits. Furthermore, the prepared OC-nSiO₂ hybrid material can also be used as an environmentally friendly agrochemical product for sustainable development of agriculture.