Antifungal Activity of Copper, Zinc and Potassium Compounds on Mycelial Growth and Conidial Germination of Fusarium solani f. sp. piperis

Fusariosis is a disease that causes economic damage to black pepper (Piper nigrum L.) producers. Despite being a major disease, there is no record of efficient chemical control. Thus, the objective was to evaluate the antifungal activity of copper, zinc and potassium compounds in mycelial growth and conidial germination of Fusarium solani f. sp. piperis in vitro. For inoculation in PDA (Potato Dextrose Agar) medium, 7 mm discs from the pure culture were transferred to Petri dishes. The plates were incubated at 25ºC in a biochemical oxygen demand (BOD) chamber, with photoperiod of 12 h, for 15 days. Micronutrients were supplied as sulfates, CuSO4 (copper sulfate) and ZnSO4 (zinc sulfate), at concentrations of 1, 5, 10, 15 and 20 mmol/L. Potassium macronutrient (K) was supplied as KCl (potassium chloride) at concentrations of 30, 60, 90,120 and 150 mmol/L. The experiment was performed using a completely randomized design with 6 treatments and ten replications. CuSO4 showed fungicidal effect at concentrations of 10, 15 and 20 mmol/L. For ZnSO4 mycelial growth was completely inhibited at concentrations of 15 and 20 mmol/L. There was no inhibition or reduction of fungal growth in the presence of K. Copper and zinc at minimal concentrations were efficient in controlling mycelial growth and inhibition of spore germination of F. solani f. sp. piperis. In contrast, potassium did not exert fungicidal or fungistatic effect on the fungus.