Brazilian isolates of Clonostachys rosea: colonization under different temperature and moisture conditions and temporal dynamics on strawberry leaves

Abstract

In a research programme for managing diseases caused by Botryis cinerea, four isolates of the antagonistic fungus Clonostachys rosea (Cr) were obtained from different ecosystems in Brazil. We studied ecological requirements for the colonization of strawberry leaves by these isolates. Temperature effects on both mycelial growth in vitro and leaf colonization by Cr were studied. At 10°C, growth on potato dextrose agar and colonization of leaf discs were poor. Optimum temperature for mycelial growth and leaf colonization was around 25°C. The isolates were applied to leaves which were exposed to 0–48 h intervals of moisture. They were also applied to leaves which remained from 0 to 36 h without wetness. All isolates efficiently colonized leaves, regardless of moisture interval or the delay to begin wetness. Although all isolates survived in green leaves of whole plants, colonization decreased throughout a 49-day period. Brazilian isolates of Cr can establish and colonize strawberry leaves under a wide range of temperature and moisture conditions. It is expected that the Brazilian isolates of Cr will establish efficiently in strawberry leaves where they can compete with B. cinerea.