Effect of culture medium, light and air circulation on sporulation of Neonectria ditissima

Abstract

In culture, most isolates of Neonectria ditissima, the causal organism of European canker, do not produce conidia. Those that do, often produce single-celled conidia rather than the typical multi-celled conidia that are found in nature. A series of experiments was conducted to determine the conditions needed for conidium production. Four culture media (malt extract agar, modified Matsushima's medium (MM), apple sap amended water agar (ASAWA) and water agar), five light regimes, including darkness, near ultra violet (NUV) light and white fluorescent light, and three plate sealing patterns were tested. Subculturing onto MM in sealed plates, exposed to NUV light at 20°C for 3 weeks, resulted in 100% of isolates producing large numbers of viable conidia, of which 71% produced multi-celled conidia. Similarly, under a white fluorescent light/darkness regime, all isolates produced viable conidia on MM and ASAWA, and 100% and 97% of the isolates produced multicelled conidia, respectively.