Application of silver nanoparticles for the control of colletotrichum species in vitro and pepper anthracnose disease in field

Abstract

Pepper anthracnose caused by Colletotrichum species is one of the most important limiting factors for pepper production in Korea, its management being strongly dependent on chemicals. The aim of this work was to evaluate the possibilities of using silver nanoparticles instead of commercial fungicides. In this study, we evaluated the effect of silver nanoparticles against pepper anthracnose under different culture conditions. Silver nanoparticles (WA-PR-WB13R) were applied at various concentrations to determine antifungal activities in vitro and in the field. The application of 100 ppm concentration of silver nanoparticles produced maximum inhibition of the growth of fungal hyphae as well as conidial germination in comparison to the control in vitro. In field trials, the inhibition of fungi was significantly high when silver nanoparticles were applied before disease outbreak on the plants. Scanning electron microscopy results indicated that the silver nanoparticles caused a detrimental effect on mycelial growth of Colletotrichum species.

Keywords: Colletotrichum species; Fungicide; Inhibition effect; Silver nanoparticle.

Fig. 1

Effect of silver nanoparticles WA-PR-WA13B against pepper anthracnose in the field. Results were obtained one wk after the last treatment for after-the-disease outbreak treatment (treated three times for three wk at one-wk interval) and the other results were obtained 4 wk after the last treatment for before-the-disease outbreak treatment (treated three times for 3 wk at one-wk interval). Commercial fungicides NSS-F and Fenari were used as positive controls. Distilled water was used as a negative control. Data were obtained from triplicate assays and are presented as mean ± SD.

Fig. 2

Scanning electron microscopy of hyphae of Colletotrichum gloeosporioides treated with silver nanoparticles. Fungal hyphae grown on potato dextrose agar plates were sprayed with either water as a control (A) or equal volume of 30, 50, and 100 ppm silver nanoparticle solution (B~D, respectively). Photos were taken three days after the treatment (scale bars = 5 µm).