Effect of different pH and temperature levels on in vitro growth and sporulation of Phytophthora colocasiae, taro leaf blight pathogen

Taro leaf blight disease caused Phytophthora colocasiae Racib is the most destructive disease which can cause significant economic losses of taro. The research was aimed at examining the effect of temperature and pH on the in vitro growth and sporulation of the fungus. V8-agar medium was adjusted to various levels of pH by adding appropriate amount of sodium hydroxide or hydrochloric acid before autoclaving and incubation of the fungus took place at five different temperatures. Colony diameters of the fungus were measured every day for 7 days and the number of sporangia was assessed after 21 days. The results showed that a pH of 7 and a temperature of 27 °C were the optimum conditions for pathogen growth while those of sporulation were 6 and 18 °C respectively . It is suggested that these factors would play a role in disease development.