Effect of foliar application of fungicides on incidence and severity of leaf spot disease of Roselle induced by Coniella musaiaensis B. Sutton var. hibisci
Three fungicides were evaluated for their efficacy in controlling leaf spot disease in Roselle induced by Coniella musaiaensis in a randomized compete block design experiment in 2003 at Abeokuta, (7015‘N, 3025‘E) a transition zone in South Western Nigeria. The experiment was replicated three times and repeated in 2004. The fungicides were Benlate, Bentex ‘T’ and Polygram combi applied at the rate of 0.6kgai/ha, 2.5kgai/ha and 3.5kgai/ha respectively. There were four field sprays of each of the three fungicides at 14 days interval starting from the time the disease was observed. Benlate was the most effective fungicide, leading to the least percentage disease incidence of 53% and severity of 2.8 in 2004. Benlate spray also led to highest dry calyx yield of 93.20 kg/ha in 2003 and 160.18 kg/ha in 2004 as against unsprayed (check) plot with average dry calyx yield of 16kg/ha and 26kg/ha in 2003 and 2004 respectively. The other fungicides also led to reduction in incidence and severity of Coniella leaf spot in 2003 and 2004. Polygram Combi was the least effective leading to the highest percentage incidence and severity of 52.7 and 5.70 respectively in 2003 and 64.3 and 3.73 respectively in 2004. It also had the lowest calyx yield of the three tested fungicides.
Keywords:- Coniella leaf spot, roselle, fungicides, Nigeria