Relationship between occurrence of net blotch of barley and weather conditions in Fukuoka Prefecture

Abstract

We studied the effects of temperature on the growth and sporulation of six isolates of Pyrenophora teres Drechsler, which causes net bloch of barley. Temperatures for growth in culture ranged between 5 and 30°C; the optimum was 25°C. Sporulation in culture was abundant at 20-25°C, moderate at 15°C, and absent at 30°C over 10 days; and moderate at 10°C over 21 days. Net blotch appeared in fields of barley (cv. Asakagold) in 2000, 2001, and 2002 in Fukuoka prefecture. During the winter in early 2000 at normal cold temperatures, seedlings became infected through seed, but the infection did not develop systemically. During the warm winters in early 2001 and in early 2002, net blotch spread. These results suggest that a warm, wet winter promotes the spread of net blotch.