Study on effect of temperature on growth, spore and Cerato-ulmin production of Ophiostoma ulmi and O. novo-ulmi

Temperature is one of the most important environmental factors affecting physiological characteristics of fungi. Effect of temperature on growth, spore and Cerato-ulmin production of Ophiostoma ulmi (4 isolates) and O. novo-ulmi (6 isolates), causal agents of Dutch elm disease, was studied. MEA 2% was used to estimate rate of daily growth and Zentmyer`s liquid medium was used to estimate spore and Cerato-ulmin production rates. Each experiment was carried out in 3 treatments of temperature including 22±1, 27±1 and 33±1 °C. The results showed that effect of temperature on growth and Cerato-ulmin production was more perceptible than spore production. The O. novo-ulmi isolates had the most daily growth and Cerato-ulmin production in 22±1 °C. For the O. ulmi isolates, the most daily growth and Cerato-ulmin production were recorded in 27±1 and 33±1 °C, respectively. However, the most spore production for each of the isolates of two species occurred in different temperatures. Spore-production ability of causal agent, with regard to importance of its spread by spore within xylem vessels of elm trees, could be considerable and discussable.