Development of New Methods for Diagnosing Yellow Leaf Syndrome

A disorder of sugarcane (Saccharum species hybrid) characterised by yellowing of the leaf midrib and lamina was first reported in East Africa in the 1960s. This disorder was termed yellow wilt (Ricaud, 1968). A similar disorder was reported as autumn decline in Brazil (Hughes, 1964). Some thirty years later similar symptoms were observed on sugarcane in Hawaii (Schenk et al., 1990) and Brazil (Comstock et al., 1994) and described as yellow leaf syndrome (YLS). Today YLS is prevalent in all sugarcane growing regions of the world (Lockhart and Cronje, 2000). YLS first became apparent in the South African sugar industry in 1995 when large areas of sugarcane suddenly began exhibiting yellowing symptoms (Bailey et al., 1996; Cronje et al., 1998). In some cases, YLS has been associated with significant yield losses, although this depends largely on varietal resistance/susceptibility and causal agent (Vega et al., 1997; Comstock et al., 1998).