Severity of alternaria brown spot on Murcott tangor leaves with different levels of calcium and nitrogen

• Grant number: 17/10460-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2017
• End date: May 31, 2018
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Dirceu de Mattos Junior
• Grantee: Yuri Camatari
• Host Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil
• Associated research grant: 15/13572-8 - Nutritional status and strategic citrus diseases: integrating bases for the management of production, AP.TEM

Abstract

The alternaria brown spot (ABS) is the main fungal disease of tangerines. It has as causal agent the fungus Alternaria alternata, whose asexual spores (conidia) germinate on susceptible tissue: fruits, branches and new leaves, causing lesions of dark brown coloration. The penetration of the fungus on the leaf surface can be direct, in the epidermis or through the stomata and wounds. The two main varieties of the tangerines, most cultivated in Brazil, Ponkan mandarin and Murcott tangor, are susceptible to the fungus that causes ABS. The role of nutrients and other mineral elements on metabolism, growth, morphology and anatomy is related to the resistance/tolerance of plants to pathogens. This conceptual basis has been observed in long-term field experiments and others developed by the proponent team (Mattos Jr. et al., 2011, Zambrosi et al., 2013, Quaggio et al., 2014). In this context, the present proposal will test the hypothesis that the adequate supply of mineral nutrients for Murcott tangor plants, alter the structure and integrity of tissues, whose effects affect the pathosystem alternaria brown spot/tangerine. For that, Murcott tangor leaves with different concentrations of calcium and nitrogen will be inoculated with the fungus Alternaria alternata and later the severity of MMA symptoms will be evaluated. (AU)