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

Abstract

RESUMONo primeiro experimento, plantas de cafeeiro com três pares de folhas foram pulverizadas com silicato de potássio (K 2 SiO 3 ), epoxiconazole, acibenzolar-S-metil (ASM) e água destilada de duas maneiras: pulverização do 3º par de folhas, a partir do ápice, protegendo o 2º par de folhas ou pulverização de um par de folhas da lateral esquerda da planta e protegendo o par de folhas da lateral direita. Após 24 h, a face abaxial dos pares de folhas protegidos foi inoculada com Hemileia vastatrix. No segundo experimento, o 3º par de folhas de plantas, a partir do ápice, foi pulverizado com K 2 SiO 3 , ASM e água destilada protegendo o 2º par de folhas. Aos 1, 5, 15, 25 e 35 dias após aplicação dos produtos, a face abaxial do 2º (proteção sistêmica) e do 3º par de folhas (proteção local) de oito plantas de cada tratamento foram inoculadas com H. vastatrix. O K 2 SiO 3 pulverizado no 3º par de folhas ou em um par de folhas da lateral esquerda foi ineficiente em aumentar a concentração de silício e reduzir a intensidade da esporulação (IE), o número total de pústulas (NTP) por folha e a severidade da ferrugem no 2º par de folhas ou no par de folhas da lateral direita, ao contrário do epoxiconazole e do ASM, os quais apresentaram sistemicidade na planta. A pulverização do K 2 SiO 3 no 3º par de folhas também não garantiu, devido a sua natureza não sistêmica, redução da IE, do NTP e da severidade da ferrugem comparado com a proteção local. Os resultados desse trabalho apontam para a possibilidade de se utilizar a pulverização com silicato de potássio para reduzir a intensidade da ferrugem do cafeeiro preventivamente. Palavras-chave: Coffea arabica, Hemileia vastatrix, nutrição mineral. ABSTRACT Local protection, not systemic, of potassium silicate to decrease coffee leaf rust symptomsIn the first experiment, coffee plants with three pairs of leaves were sprayed with potassium silicate (K 2 SiO 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 2 SiO 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 2 SiO 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...

Effect of foliar application of potassium silicate on the progress of coffee leaf rust

“…These results corroborate with the report of Carré-Missio et al (2012) showing that the foliar application of potassium silicate at a rate of 20 g/L did not increase Si concentration on coffee leaves. However, if there was polymerization of silicate in the leaf surface, it will not be enough to slow disease progress under field conditions.…”

“…Some plants when growing in soil with Si differ from those grown without it due to the mechanical resistance of the cells, leaf surface characteristics, and tolerance to abiotic stress (Epstein, 1999). The use of various Si sources has been reported as an alternative for management of various crop diseases of economic importance (Menzies et al, 1991, Bowen et al, 1992Chérif et al, 1994;Fauteux et al, 2005;Datnoff et al, 2007;Carré-Missio, 2012). Rice plants grown in soil with increasing Si rates presented reduced severity of sheath blight caused by Rhizoctonia solani Kühn (Rodrigues et al, 2002).…”

“…In the second experiment, rust incidence was lower in all treatments without difference between plants sprayed with copper hydroxide, potassium silicate or epoxiconazole + pyraclostrobin, but these treatments were different from the control plants (Table 1). Potassium silicate has showed promising results for coffee leaf rust control in a preventive way when rust germination is low (35%) (Carré-Missio et al, 2012). The local protection gained by potassium silicate spray to reduced coffee leaf rust was prolonged by up to 25 days (Carré-Missio et al, 2012).…”

“…Potassium silicate has showed promising results for coffee leaf rust control in a preventive way when rust germination is low (35%) (Carré-Missio et al, 2012). The local protection gained by potassium silicate spray to reduced coffee leaf rust was prolonged by up to 25 days (Carré-Missio et al, 2012). Foliar application of potassium silicate must have reduced the intensity of rust by created a physical barrier on the surface after its polymerization, which negatively affected the sporulation of H. vastatrix.…”

Potassium silicate and chitosan application for gray mold management in strawberry during storage

“…In previous research, Carr e-Missio et al (2012) suggests that, foliar application of potassium silicate must have reduced the intensity of rust by creating a physical barrier on the surface following polymerization, negatively affecting the sporulation of Hemileia vastatrix. Other mechanisms by which Si confers resistance to certain diseases are associated with the physical barrier formed by the deposition of this element under the cuticle and on the epidermal cell wall (Kim et al, 2002) or with the enhancement of defense mechanisms (Datnoff et al, 2007).…”