Etiology of raspberry leaf spots in Brazil and effect of temperature on disease development

• Grant number: 24/22042-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Lilian Amorim
• Grantee: Luís Henrique Aguilar Antunes
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The global demand for raspberry fruits has been increasing due to their organoleptic and nutritional characteristics, especially their richness in phenolic compounds with antioxidant and anti-inflammatory properties. The cultivation of these fruits in Brazil, although is expanding, faces challenges such as adverse climatic conditions and the occurrence of diseases that can compromise production. Recently, foliar lesions in Heritage cultivar raspberry plants were observed in a commercial raspberry orchard, in Piracicaba, SP, displaying characteristics different from the known local diseases. This project aims to investigate the etiology of these lesions, characterize the pathogens involved, and identify the environmental conditions that favor the disease occurrence. Potentially pathogenic fungi were isolated from symptomatic leaves, and their pathogenicity will be evaluated in Heritage cultivar seedlings through inoculations with conidia and mycelium discs. Those whose pathogenicity is confirmed will be identified at the species level based on morphological analyses and multilocus molecular phylogeny. In vitro experiments will be conducted to examine the effect of different temperatures on mycelial growth and to determine the conditions of temperature and foliar wetness that favor conidia germination and appressorium formation. In vivo experiments will also be conducted to evaluate the influence of temperature on the progress and severity of diseases in plants. This study will provide a deeper understanding of the etiology of leaf spots in raspberry plants in Brazil, as well as explore the interaction between pathogens, plants, and environmental conditions, offering insights for the development of effective management strategies.