Temperature effect on C halara fraxinea: heat treatment of saplings as a possible disease control method

Summary Ash dieback is an emerging disease caused by the fungusChalara fraxineathat severely affectsFraxinus excelsiorandF. angustifoliastands inEurope. Previous studies have shown that this pathogen prefers temperatures around 20°C, while its growth in pure cultures at 30°C proved to be very limited. The purpose of this study was to determine the effects of temperature on the development and growth ofC. fraxineain pure cultures and in plant tissues, as well as to test the heat tolerance ofF. excelsiorsaplings. The sensitivity of fungus to heat in ash tissues was higher than in pure cultures. Low isolation success rate from diseased ash tissue after a five‐hour hot water treatment at 36°C and the relatively high survival rate of ash saplings after hot water treatments at 36°C and 40°C indicate possibilities for the development of aC. fraxineaeradication method in ash saplings. Field monitoring showed that in hot weather periods, thermal conditions inside the ash tissues can be extreme enough to markedly decrease the viability ofC. fraxineain infected plant tissues.