First Report of White Leaf Streak of Rice Caused by Mycovellosiella oryzae in Texas

Rice (Oryza sativa L.) plants in experimental plots in Beaumont, TX developed symptoms on leaf blades similar to white leaf streak caused by Mycovellosiela oryzae (Deighton & Shaw) Deighton (synonym Ramularia oryzae Deighton & Shaw) (1,3,4) during the late summer of 2009. Symptoms were observed on several rice cultivars and breeding lines including Cocodrie, Cypress, and Lemont. Lesions usually appeared on lower leaves and were approximately 2 to 7 mm long and linear with whitish or grayish centers surrounded by a narrow brown-or-dark brown margin. Symptoms were similar to narrow brown leaf spot caused by Cercospora janseana (Racib.) O. Const. (synonym C. oryzae Miyake) (3,4), but the centers of lesions were slightly wider (up to 2 mm). Symptoms were visible on the upper and lower leaf surfaces. Some lesions on heavily infected leaves were long (10 to 15 × 0.5 to 2 mm) whitish streaks parallel to the midrib. Leaves with typical symptoms were collected and incubated in a petri dish lined with moistened fil...