False smut on upland rice in eight rice producing locations of Edo State, Nigeria

Incidence and severity of false smut caused by Ustilaginoidea virens (Cook) Tak. on upland rice in eight rice producing locations in Edo State of Nigeria were assessed in 1992 through survey. The eight locations are Agbede, Agenebode, Idoa, Ihievbe, Ilushi, Ovbiowun, Ukhun, Uokha, all within longitude 6-7degrees E and latitude 6-7degrees N. The survey for disease assessment was conducted three times-21 st to 27th July, 2nd to 16th September, and 3rd to 13th October, 1992. Incidence and severity of false smut differed significantly by time of survey and location, as well as farm site within location. Incidence and severity of the disease on upland rice were highest during the survey conducted in the month of September in all the locations, but with Ovbiowun most affected (53.8% mean incidence and 29% mean severity), followed by Uokha, both in eastern Owan of the state. During the survey conducted in July, the disease incidence was zero throughout the eight locations. Higher incidence of the disease in Ovbiowun and Uokha may be due to the most commonly grown variety (FARO 3), which is susceptible to the disease and may have led to a build-up of inoculum. Difference in false smut incidence and severity according to time of survey may be attributed to frequency of rainfall and cloud cover during the time of flowering and indicate that planting time could be manipulated to control the disease in this area. Planting an early maturing variety at the start of rains may be a good method of escaping the disease. (C) 2002 by The Haworth Press, Inc. All rights reserved.