Bài báo khoa học

Anthracnose in citrus is a severe disease caused by Colletotrichum species. Synthetic fungicides have been used to combat this citrus disease; however, they may have adverse health effects on humans and cause harmful environmental impacts. During a search for environmentally friendly fungicides, we successfully prepared organic copper (copper (II) oleate) nanoparticles by using natural chitosan polymer as a coating agent and stabilizer and by combining an exchange reaction and in situ coating method. Organic copper nanoparticles coated with chitosan polymer (Cu-oleate@CS NPs) with Cu contents ranged from 5.0 to 6.0 % by weight. The nanoparticles have an average particle size ranging from 50 nm to 60 nm (TEM), covered by a layer of polymer with a thickness of about 10 to 2 nm. The analytical results of zeta potential and dynamic solution size showed that the nanoparticles are uniformly dispersed (90–120 nm by DLS), with high stability (zeta potential= 61.7 mV) and low cytoxicity to Vero healthy cell line. Cu-oleate@CS NPs significantly inhibited the mycelial growth of C. gloeosporioides in vitro at 500 and 1000 μg/mL. In field trials, the best antifungal efficacy of Cu-oleate@CS NPs against citrus anthracnose on orange plants was found at a spray concentration of 0.33% with a disease control efficacy of 54.18% at 14 days after the second spraying. Our study results demonstrated a novel preparation of Cu-oleate@CS NPs and suggested that it could be used as a promising nanoformulation to control citrus anthracnose in vitro and in vivo.