Rice False Smut Disease In Egypt

M.M.M. Atia
Agric. Bot. and Plant Pathology Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
E-mail: usamaatia@yahoo.com

Abstract

Rice is one of the most important cereal crop in Egypt and world-wide. Rice false smut (RFS) caused by Ustilaginoidea virens (Cooke.) Tak, the imperfect stage of Claviceps oryzae sativae is an important disease wherever rice is cultivated. RFS is a new disease in Egypt, it was reported for the first time in the Nile Delta in 1997, and since then it appeared annually and its incidence was high during 2000 and 2001 growing seasons. The disease usually affects few grains (1-20) in each panicle. RFS was surveyed in the major rice producing area of Egypt, mainly in El-Dakahlia, El-Sharkia and El-Ismailia governorates during two successive growing seasons. The FS fungus was found to attack Echinochoa crus-galli a common rice weed, and Imperata cylindrical, a common weed of the irrigation cannal. The fungal pathogen was isolated and identified on rice flour yeast extract dextrose agar medium (RYDA) and on PDA medium. Losses caused by the RFS disease ranged from 1.01 to 10.91% according to disease incidence and no. of smutted balls. The disease also reduced the 1000-grain weight. Rice cvs. Giza 171 and Riho were the most infected, whereas cvs. Sakha 102 and 101 showed the lowest disease incidence. High disease incidence and no. of smutted balls was correlated with high N fertilization. Early transplanting (at the first of June), cultivation using transplanting method and cultivation in clay soil reduced the disease incidence. Spraying rice plants with Ridomil, Topsin and Cupper-oxychloride at 2.5 g/l at the beginning of booting stage significantly reduced the disease severity. Further studies are needed to understand the viability of the fungus spores and sclerotia during winter, the variation between fungal isolates and its ability to produce mycotoxins and the effectiveness of using biocontrol agents