Control of endophytic fungi in the micropropagation of caari (Myrciaria dubia (Kunth) McVaugh)

The micropropagation of camu-camu (Myrciaria dubia) is frequently compromised by endogenous fungal contamination, requiring effective fungicides for explant disinfection. This study evaluated the efficiency of systemic fungicides (strobilurins, triazoles, benzimidazoles, phenylpyridinamines, and aromatic hydrocarbons) in controlling 20 endophytic fungal isolates associated with camu-camu, through two stages: (1) in vitro sensitivity tests and (2) application in micropropagation protocols. The experimental design followed a factorial scheme (3×4×20 for in vitro tests and 3×4×3 for micropropagation), analyzing mycelial growth inhibition (%MGI) and mycelial growth rate index (MGRI). The in vitro results demonstrated that the strobilurin + triazole + aromatic hydrocarbon combination inhibited 100% of the isolates at all tested concentrations (50 to 150 µg/mL). However, in the micropropagation phase, this fungicide was not effective in controlling the fungi, indicating that in vitro resistance does not guarantee success under actual cultivation conditions. The study highlights the need to optimize application strategies, such as dosage adjustments or combinations with other agents, to overcome the observed limitations. Key words: Systemic fungicides, endophytic manifestation, endogenous microorganisms and Strobilurin.