Chemical control of rice brown spot (Bipolaris oryzae) in Paraguay

Rice brown spot produced by Bipolaris oryzae is one of the most prevalent fungal diseases in Paraguay and it is associated with rice brown spot, which can decrease yield and seed quality. The research work was carried out in the 2016 crop season in the experimental plot of a private rice producer, located on the district of San Juan Bautista, department of Misiones, Paraguay with the aim of evaluating fungicides for the control of rice brown spot and its effect on yield crop. The treatments consisted on the application of a mixture of fungicides, Azoxystrobin 20% + Difenoconazole 12.5% (400 cc ha) at different rice growth stages. All treatments with fungicides decreased rice brown spot incidence significantly and increased yield compared with non-sprayed control. Fungicides applied at R2+R4 and at R2+R3a+R4 resulted in a lower average incidence of rice brown spot (17–15%).