Soil application of acibenzolar-s-methyl and thiamethoxam for the management of citrus canker under subtropical conditions

Abstract

Drench applications of systemic acquired resistance (SAR) inducing compounds acibenzolar-s-methyl (ASM) and thiamethoxam (THIA) may contribute for the control of citrus canker, caused by Xanthomonas citri subsp. citri. Here, we report the results of a 3-year field experiment on the effect of drench applications of two SAR-inducing compounds, applied alone or in combination with copper oxychloride (CuOX) foliar sprays, on citrus canker control, as well as tree growth and yield, of Natal sweet orange trees under Brazilian subtropical conditions. Leaf disease incidence, tree defoliation, and citrus leaf miner (Phyllocnistis citrella) attack were evaluated every 30 days for 16 months. Soil applications of ASM or THIA combined with foliar sprays of CuOX highly reduced citrus canker incidence on leaves. Effective control of the disease, comparable to regular foliar sprays of cupric bactericides, was obtained with two to four drench applications of SAR-inducing compounds. No differences among the treatments were observed in regard to tree height and canopy volume, and fruit yield of the young citrus trees. Soil applications of SAR-inducing compounds proved to be an important measure for the integrate management of citrus canker under the Brazilian subtropical conditions. Keywords Systemic acquired resistance. Xanthomonas citri subsp. citri. Citrus leaf miner. Copper in bacterial disease management. Neonicotinoid insecticide

Overexpression of CsSAMT in Citrus sinensis Induces Defense Response and Increases Resistance to Xanthomonas citri subsp. citri

“…Citrus plants pretreated with exogenous SA showed significantly enhanced endogenous SA levels that led to a reduction in the X. citri incidence rate ( Wang and Liu, 2012 ). Similarly, soil applications of the SA analog acibenzolar-S-methyl (ASM), a known SAR-inducing compound, have also contributed to the control of citrus canker disease ( Graham and Myers, 2011 ; de Mello et al, 2020 ).…”