Reducing poor root syndrome of sugarcane in Australia by minimum-tillage planting in previous inter-rows

Abstract

Poor root syndrome (PRS), a major disease of sugarcane in Australia was reduced by the use of minimum-tillage planting techniques involving planting into the inter-row of the previous crop. Populations of pathogens and yields were compared with planting into the previous row and with conventional cultivation and planting. The density of oospores of Pachymetra chaunorhiza was always lower in the inter-row at planting. At one site, planting in the previous inter-row gave 14% higher yields than planting into the previous row in the Pachymetra root rot susceptible cultivar Q90. The Pachymetra root rot resistant cultivar, 4138, yielded 6% more when planted in the interrow compared with planting in the previous row. The density of oospores of P. chaunorhiza in the row was ten times higher than in the inter-row at this site. At two other sites the oospore density was relatively low in both the row and inter-row and no difference in yield was found between the two planting positions. At a fourth site, high oospore densities were recorded in the row but the inter-row also had oospore densities above the threshold for maximum disease in susceptible cultivars. No yield difference was measured between the planting positions at this site. There was no advantage from conventional cultivation at the two sites where this treatment was included.