Evaluation of fungicides for the control of false smut of rice caused by <I>Ustilaginoidea virens</I> (Cooke) Tak.

Abstract

Benomyl, Copper Oxychloride, Iprodione, Thiabendazole (TBZ) and Mancozeb were evaluated both in the laboratory and field study in 1994, for the control of false smut of rice caused by Ustilaginoidea virens (Cooke) Tak. in upland rice in Edo State, Nigeria. In the laboratory the fungicides were evaluated at three concentration levels, X, 2X, and 0.5X, where X is the recommended field rate. Copper Oxychloride, Benomyl, and Thiabendazole were most effective in – vitro, completely inhibiting the mycelial growth of U. virens even at 0.5X c(5 g/l,1.5g/l, and 0.3 ml/l, respectively). Four sprays of any of the five fungicides at an interval of 7-days, starting at the sighting of the first ‘boot', reduced incidence and severity of the diseases in the field, with the best result obtained with the Copper Oxychloride. Spraying rice with Copper Oxychloride (at 4kg i.e./ha) resulted in 72% reduction in false smut severity resulting in significant increase of 39% in grain yield compared with the control treatment (no fungicide spray). Disease control in rice spray with Mancozeb, Thiabendazole and Benomyl was 47, 27, and 24% respectively, but increases in rice grain yield due to sprays were not significant. Spraying rice with Iprodione did not result in any significant disease control.


Key Words: False smut; ustilaginoidea virens; upland rice; fungicide


Moor J. Agric. Res. Vol.4(1) 2003: 118-122