Copper and silver nanoparticles control coffee rust: decrease the quantity of sprayed active ingredients and is an alternative for sustainable coffee production

Abstract

Nanoparticles (NPs) have a high surface/volume ratio and small size (100 ≤ nm, these characteristics allow its use in the management of plant diseases in small quantities. The objective of this study was to evaluate the efficiency of silver (Ag) and copper oxide (CuO) NPs in the control of coffee rust (Hemileia vastatrix Berkeley & Broome). The effect of these NPs at doses of 0, 50, 100, 200 and 400 mg/L on the germination of spores of H. vastatrix and the control of rust in coffee seedlings in a greenhouse was evaluated. The CuO NPs 250 mg/L was also compared with other commercial copper fungicides: copper hydroxide, cuprous oxide and copper chelate (Ethylenediamine tetraacetic acid - EDTA). The incidence and severity of rust were evaluated every seven days, after the appearance the first pustules and the data obtained were transformed into area under disease progress curve for incidence (AUDPCI) and severity (AUDPCS). The 400 mg/L dose of Ag and CuO NPs inhibited 99.8 and 98.4% of H. vastatrix spore germination, respectively. In the greenhouse, in the experiments with Ag and CuO NPs, the lowest AUDPCS was also observed at the dose of 400 mg/L with 97.5 and 92%, respectively. The efficacy of NPs CuO 250 mg/L was equal (p < 0.05) to cuprous oxide, with a reduction of 84.2 and 83.1% of AUDPCS, respectively. Therefore, the potential of Ag and CuO NPs to inhibit the germination of H. vastatrix spores and to control rust in coffee seedlings was verified.