Mycelial growth, sporulation, conidial germination, and secondary conidiation in vitro of Colletotrichum abscissum using beach-cast seaweed extract.

• Grant number: 21/10182-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2021
• End date: October 31, 2022
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Maria Candida de Godoy Gasparoto
• Grantee: Caio Gomes
• Host Institution: Faculdade de Ciências Agrárias. Universidade Estadual Paulista (UNESP). Campus do Vale do Ribeira. Registro , SP, Brazil

Abstract

Brazil is the largest producer and exporter of orange juice in the world. São Paulo State is the major commercial citrus-producing area in Brazil. Phytosanitary problems are responsible for losses in citrus production. In this context, an important citrus disease is the postbloom fruit drop (PFD), which it is mainly caused by the fungus Colletotrichum abscissum. High intensity of this disease in the orchard can cause losses, which can compromise up to 80% of the production of a citrus farm. Severe epidemics can occur when plant flowering coincides with high rainfall frequency. Although it is a sporadic disease, in citrus-growing areas where the disease is frequent, preventive fungicide application during the flowering period is the main control recommendation, even when there are no favorable weather conditions for PFD development. The problem of unnecessary applications of single-site fungicides is, in addition to possible environmental contamination, the selection of resistant isolates of the pathogen. In addition to low active ingredients registered for PFD control in Brazil, there is no record about alternative products to control the disease. Thus, studies with algae extracts should be conducted since some of these products have already confirmed their antifungal potential. Among seaweeds that can be used in these studies, a group draws attention due to its abundant source and easy collection, besides collaborating to maintain "cleaner" beaches and serve as an alternative income to the coastal community: the beach-cast seaweeds. Beach-cast seaweeds are those detached from the rocks due to the dynamics of tides and winds, and they accumulate on the coast. In this study, the potential in vitro control of the fungus C. abscissum by beach-cast seaweed extracts (dimethylsulxide and n-hexane) will be evaluated. (AU)