Efficacy of Copper Oxide and Magnesium Oxide Nanoparticles on Controlling Black Scurf Disease on Potato

Black scurf disease caused by Rhizoctonia solani is common on potato crop worldwide. The current study aimed to evaluate the antifungal activity of CuONPs and MgONPs on R. solani in laboratory, greenhouse and fieldtrials. Field trials were conducted under naturally infected fields located in two Governorates, Behera and Menoufia. Potato tubers cv. Spunta were soaked in different concentrations (75, 150 and 200 mg/L) of the tested NPs for 2 hours pre-planting. Disease severity (DS) and disease incidence (DI) of black scurf symptoms on the harvested potato tubers were estimated. Ultrastructural changes in R. solani hyphae in response to the tested NPs were also detected using Transmission Electron Microscope (TEM). Physiological and biochemical activities were also determined in potato leaves after 20, 40 and 60 days of planting. In vitro results showed that MgONPs at 200 mg/L exhibited the greatest inhibitory effect on the mycelial growth of R. solani, with inhibition reached 73.47 %. Ultrastructural micrographs of TEM images of R. solani hyphae confirmed the damage induced by NPs. Greenhouse results exhibited that the great reduction in DI and DS% was achieved by MgONPs at concentration 200 mg/L, with efficacy reached 85.07 and 93.47 %, respectively. The same trend of greenhouse results was observed, of which MgONPs at concentration 200 mg/L, had significant (p < 0.05) effect in reducing both DI and DS% in both Menoufia and Behera field trials. Also, MgONPs had a significant (p < 0.05) effect in increasing the yield of potato tubers in both field trials. NPs had great impact in increasing enzyme activities, phenols and chlorophyll content when compared to untreated control plants. Energy Dispersive X-ray Spectrometry (EDX) analysis confirmed the presence of CuONPs in the tissues of treated harvested potato tubers compared with the control. The accumulation of CuONPs in edible plant tissues is a critical issue that could impact human health, and this should be taken in consideration when establishing control program for black scurf disease.