Study on Maize Lethal Necrosis Disease of Sweet Corn

Abstract

Maize Lethal Necrosis Disease (MLND) is a result of a combination of two virus infection, the Maize chlorotic mottle virus (MCMV) and any of the cereal viruses in the Potyviridae group. In this work, effect of co-infection by MCMV and Sugarcane mosaic virus strain MDB (SCMV-MDB) in 2 cultivars of sweet corn, Hybrix 3 and Insee 2 was studied. There are 7 treatments namely non-inoculation, inoculation by 0.1M Phosphate buffer pH7.2 (Mock), inoculation by sap of MCMV only, inoculation by sap of SCMV-MDB only, mixed-inoculation by sap of SCMV-MDB [1:10] and MCMV [1:10], mixed-inoculation by sap of SCMV-MDB [1:5] and MCMV [1:10] and mixed-inoculation by sap of SCMVMDB [1:10] and MCMV [1:5]. Then, symptoms and disease severity were observed at 7, 14, 21, 28 and 35 days post inoculation (dpi) and evaluated of the disease index (DI). The results showed that co-infection of the both viruses caused more disease severity and increased DI comparing to the single infection of MCMV. Base on this test, co-infection of both viruses in Hybrix 3 and Insee 2 produced a synergistic reaction causing MLND and infected plants were killed at 3 weeks after inoculation. Thus, control measures of both viruses should be concerned because both viruses have been found in the major areas of corn production in Thailand.