Nanoparticles of silver (AgNPs) were prepared by the green synthesis method using neem (Azadirachta indica) and lemon leaf extract. AgNPs were irradiated with several doses of gamma irradiation: 0, 1.5, 3, 6, 12, and 24 kGy. AgNPs were tested in the field against Alternaria solani, a tomato disease that causes early blight. There was a notable rise in various growth and physiological measurements. Every aspect of the plant's performance, including physiological traits and crop yield, showed improvement. FT-IR, TEM, UV-Vis, and DLS are used to characterize AgNPs. The results were computed as an average of two seasons. Application of neem AgNPs + 6 kGy and lemon AgNPs + 12 kGy was used as foliar spraying. A highly effective inhibitor of disease severity was obtained after mancozeb as compared with control (untreated). The improvement of all aspects of the plant was observed, including physiological characteristics as well as yield, compared with the control (untreated). The results also showed that there were significant differences in enzyme activity compared with the infected control (untreated). The highest value of peroxidase activity was with neem AgNPs + 3 kGy (39). The highest value of catalase was obtained by combining lemon AgNPs with 6 kGy (31). The highest value of polyphenol oxidase was achieved by Neem AgNPs + 1.5 kGy (35). All treatments were evaluated for total chlorophyll content in comparison to the control, with the healthy plant achieving the highest value (26), followed by the Neem AgNPs + 6 kGy, which recorded 23.1.