Proteção local, não sistêmica, do silicato de potássio reduz os sintomas da ferrugem do cafeeiro

Abstract

In the first experiment, coffee plants with three pairs of leaves were sprayed with potassium silicate (K 2SiO 3), epoxiconazole, acibenzolar-S-methyl (ASM), and distilled water in two different ways: spraying the 3 rd pair of leaves from the apex and protecting the 2 nd pair of leaves or spraying the two pair of leaves on the left side of the plant and protecting the pair of leaves on the right side. After 24 h, the abaxial surface of the protected pair of leaves was inoculated with Hemileia vastatrix. In the second experiment, the 3 rd pair of leaves from the apex was sprayed with K 2SiO 3, ASM, and distilled water and the 2 nd pair of leaves was protected. At 1, 5, 15, 25, and 35 days after products application, the abaxial surface of 2 nd (systemic protection) and the 3 rd pair of leaves (local protection) of eight plants per treatment were inoculated with H. vastatrix. The K 2SiO 3 spray on the 3 rd pair of leaves or on the pair of leaves on the left side was ineffective in increasing silicon concentration and also decreasing the intensity of sporulation (IE), the total number of pustules (TNP) per leaf, and rust severity on the 2 nd pair of leaves or in the pair of leaves on the right side, unlike the epoxiconazole and the ASM, which exhibited systemicity in the plant. The K 2SiO 3 sprayed in the 3 rd pair of leaves also did not guarantee, due to its non-systemic action, reduction in the IE, TNP, and rust severity compared to its local protection. The findings of this study show the possibility of using potassium silicate spray to reduce the intensity of coffee leaf rust preventively.