Evaluation of silver nanoparticles for controlling Lipaphis erysimi and Alternaria brassicicola and assessing their effects on Chinese kale growth and soil properties

IntroductionChinese kale (Brassica oleracea var. alboglabra) is an important leafy vegetable that is highly susceptible to the mustard aphid, Lipaphis erysimi, and the fungal pathogen Alternaria brassicicola, which can reduce crop yield and quality. This study evaluated the efficacy of silver nanoparticles (AgNPs) against L. erysimi and A. brassicicola and assessed their effects on plant physiological characteristics and soil nutrient status.MethodsAgNPs at different concentrations were evaluated for their toxicity against L. erysimi and their inhibitory effects on the mycelial growth and spore germination of A. brassicicola. The effects of AgNPs on Chinese kale growth, chlorophyll content, and selected soil chemical properties were also assessed.ResultsAgNPs exhibited significant dose- and time-dependent toxicity against L. erysimi, with LC₅₀ values decreasing from 43.109 ppm at 24 h to 19.343 ppm at 48 h. Aphid populations were reduced by 88.33% following treatment with 100 ppm AgNPs for 48 h. AgNPs at 80–100 ppm also significantly inhibited the mycelial growth and spore germination of A. brassicicola. However, higher AgNP concentrations reduced chlorophyll content and adversely affected fresh weight and leaf development. Soil analysis showed slight increases in pH and organic matter, whereas available phosphorus and exchangeable potassium decreased following AgNP application.DiscussionThese findings indicate that AgNPs have potential as a component of integrated pest and disease management for Chinese kale. However, optimization of application rates is necessary to balance pest and disease suppression with potential adverse effects on plant growth and soil properties. Further studies under field conditions are needed to determine appropriate application rates and evaluate their long-term environmental effects.