Sugarcane streak mosaic virus in Indonesia: Distribution, Characterisation, Yield Losses and Management Approaches

Streak mosaic is a new disease of sugarcane in Indonesia caused by Sugarcane streak mosaic virus (SCSMV). An extensive survey conducted during milling season 2008/2009 at 30 sugar factories (SF) across the Java revealed that about 30 % of observed sugarcane fields of 28 SF were affected by the streak mosaic disease. Most commercial cane cultivars were infected by the virus but the cultivar PS 864 was found most susceptible. RT-PCR detection, using SCSMV coat protein specific gene primers SCSMV-cpF and SCSMV AP3, successfully amplified a 500 bp DNA fragment, suggesting the positive identity of the SCSMV with all the tested symptomatic samples. Protein analysis of the virus confirmed that SCSMV has a coat protein of size approximately 40 kDa and flexuous, filamentous particles about 890 nm in length was observed under an electron microscope. The virus was easily transmitted by infected cane cuttings and mechanically by sap inoculation and cutting knife. Host range test on 23 plant species revealed that maize, sorghum and Dactyloctenium aegyptium were alternative hosts of SCSMV. A preliminary yield loss assessment on PS 864 cultivar revealed that the disease incidence at >= 50 % reduced sugar yield by about 20 %. Hot water treatment of cane cuttings was not able to eliminate the virus in cane stalks but only postponed the appearance of the symptom. Response of 16 commercial cane cultivars to artificially inoculation of SCSMV using an abrasive pad rubbing technique showed that only five cultivars were resistant to the disease.