Mycelial growth, sporulation, and survival of Monilinia fructicola in relation to osmotic potential and temperature

The effects of osmotic potential (Psi) and temperature on mycelial growth, sporulation, and survival of Monilinia fructicola were determined using potato-dextrose agar (PDA) amended with KCI and sucrose. Comparatively, KCl facilitated the sporulation and sucrose facilitated the mycelial growth and survival of the fungus. Optimal mycelial growth occurred at -1 MPa and 25 C and sporulation at -3 MPa and 20 C. Sporulation decreased more rapidly than mycelial growth as osmotic potential and temperature became less conducive. Significant interactions between osmotic potential and temperature were observed on affecting the mycelial growth and sporulation. Monilinia fructicola did not grow in PDA amended with KCl at Psi < -11 MPa (20 and 25 C), -9 MPa (15 and 30 C), or -7 MPa (10 C) after 6-d incubation; it also did not grow in PDA amended with KCl at Psi < -11 MPa nor in PDA amended with sucrose at Psi < -13 MPa even after 60-d incubation at any temperatures tested. Monilinia fructicola survived water stress better at low temperatures than at high temperatures. These results could help in understanding the ecology and epidemiology of brown rot of stone fruit and in development of integrated disease management strategies.