Culture Medium, Light Regime and Temperature Affect the Development of Sirosporium diffusum

Sirosporium diffusum is the causal agent of the brown leaf spot disease on pecan trees that seriously damages the foliage of adult plants and seedlings. This fungal species is difficult to grow satisfactorily in a culture medium. Therefore, the aim of this study was to evaluate the effects of different physical conditions on the development of S. diffusum. In the first assay, eight culture media and five light regimes were combined, while in the second, the three treatments that promoted highest sporulation were combined with three temperatures. The trials were conducted in a two-factorial arrangement in a fully randomized design with six replicates. V8, V8CaCO3, and CA media under a 24-h photoperiod produced the highest respective sporulations: 29 × 104, 35 × 104, and 41 × 104 conidia ml-1. The best temperature for sporulation was 20±1 °C for all culture media, especially V8CaCO3 and CA. The best artificial conditions for obtaining good mycelial growth and sporulation consisted of a photoperiod of 24 h, temperature of 20±1 °C and V8CaCO3 or CA culture medium.