Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/20/2000
Publication Date: N/A
Technical Abstract: This chapter on mosaic is part of a guide to aid in the diagnosis and treatment of known sugarcane diseases. Mosaic is a major disease of sugarcane found in most sugarcane producing countries. The disease is caused by two closely related viruses, sugarcane mosaic potyvirus (SCMV) and sorghum mosaic potyvirus (SrMV). The general symptom of mosaic is a pattern of contrasting shades of green on the leaf blade. The primary means of plant to plant transmission of the viruses is by aphid vectors and the spread of the virus from field to field is by planting infected seed cane. Spread of mosaic is generally more rapid and the incidence higher in subtropical areas; probably because of high aphid populations moving from dying weeds in the autumn and spring to young, rapidly growing plants when they are the most susceptible. In addition to Saccharum, a number of wild and cultivated grasses have been reported as natural hosts of SCMV, but SrMV is limited to Saccharum and near relatives and Sorghum bicolor. In a 14-year study in Louisiana among released cultivars, mosaic caused yield losses ranging from 7 to 21% over a three-year crop cycle. Mosaic in combination with other diseases often reduces growth and yield more than each disease separately. The cultivation of resistant varieties is the most effective method of controlling mosaic. In susceptible cultivars, cultural practices such as planting mosaic-free seed cane and timing planting and harvest to avoid the exposing young, rapidly growing plant to transmission by virus-carrying aphids may help reduce the effects of mosaic.