Effect of water limitation on the intensity of rust (Austropuccinia psidii) in guava trees cv. Suprema

• Grant number: 25/10454-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Lilian Amorim
• Grantee: Juliana de Siqueira Barros
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 19/13191-5 - Epidemiological components, damage characterization and control of tropical and temperate rusts at a global climate change scenario, AP.TEM

Abstract

The guava tree (Psidium guajava L.), a member of the Myrtaceae family, is widely cultivated in Brazil and stands out as one of the most important tropical fruits due to its high nutritional value. However, the crop faces significant phytosanitary challenges, among which myrtle rust, caused by the fungus Austropuccinia psidii, represents one of the main threats to its productivity. The pathogen primarily infects young plant tissues and can lead to substantial yield losses, affecting both the qualitative and quantitative aspects of production. Management of guava rust relies on preventive strategies, including cultural practices and the application of protective and systemic fungicides. Nevertheless, the development and use of resistant cultivars have emerged as a promising alternative to mitigate disease impact. Among the cultivars available in Brazil, cv. Suprema has gained prominence due to its high yield potential, large fruit size, and good postharvest shelf life, as well as its moderate resistance to rust, which helps reduce disease severity under low inoculum pressure. Climate change may exacerbate the severity of rust outbreaks, as fluctuations in temperature, humidity, and precipitation directly influence the interaction among the pathogen, host, and environment. Previous studies with the rust susceptible cultivar Paluma have shown that disease severity increases under water deficit conditions. However, the effects of such stress on rust development in cv. Suprema remain uninvestigated. Given this context, the objective of this proposal is to assess the interaction between guava rust and water limitation in the cultivar Suprema. (AU)