Controlled release formulations can reduce the losses of pesticides and prolong their effective duration. In this work, a novel pH responsive pesticide delivery system based on kasugamycin-conjugated ZnO quantum dots (KAS-ZnO QDs) was established via a cleavable benzoic-imine covalent bond. The as-prepared KAS-ZnO QDs could protect KAS against photodegradation effectively due to the UV shielding effect of KAS-ZnO QDs. The KAS and Zn2+ released from KAS-ZnO QDs in the acid condition could achieve a synergistic antimicrobial activity. The greenhouse experiment confirmed that application of KAS-ZnO QDs had a longer duration and a better antimicrobial activity against bacterial fruit blotch compared to KAS and NH2-ZnO QDs treatments, and showed no any toxicity to plants. Thus, pH-responsive KAS-ZnO QDs could achieve a synergistic antimicrobial effect and offer a new approach to manage plant diseases.