Southern Ethiopia is potential area for taro production and because of drought tolerance of the crop; it is used to fill seasonal food gaps when other crops are not in the field. However, this important crop has been severely affected by leaf blight disease. Therefore, the current study was designed with the objectives of assessing the intensity and severity of the disease in Southern Ethiopia and to identify the causative agent of taro leaf blight. For this purpose, total of 27 farm fields were surveyed across 9 Woredas of two zones, Wolaita and Kembata Tembaro, during 2017 cropping season. Among fields surveyed 15 representative taro leaf bight samples were collected for the identification of causative agent. All the 15 isolates had fluffy or slightly fluffy colony texture and whitish or dull white colony. Mycelium was aseptate and Sporangium types ranged from semipapillate to papillate, Sporangium shapes were ovoid or lemon shaped. Based on microscopic observation of colony character, sporangial nature and by comparing with key for the identification of species of the genus Phytophthora, the pathogen isolated was identified as Phytophthora colocasiae. The mean P. colocasiae leaf blight incidence varied from 10 to 100% while mean disease severity ranged from 16.67 to 50% which indicate that the disease occurred in moderate to severe form in all taro surveyed fields. The present study revealed the importance of Phytophthora leaf blight of taro in Southern Ethiopia and the need of developing resistant varieties for the area.
Keywords: Disease intensity; Phytophthora colocasiae; Disease severity; Taro leaf blight; Taro