Timing and intensity of surface cultivation and depth of cultivation affect Rhizoctonia patch and wheat yield

Abstract

The incidence of rhizoctonia patch was reduced by both intensity and depth of cultivation on a fine white sand near Gibson, W.A. When seed was direct drilled with a triple disc drill, 13.3% of the plot area was covered with patches compared with 16.1% following a tined combine seeder. Direct drilling with a modified tined combine seeder which cultivated 10-cm deep while seeding at 3-cm depth had 6.2% patch and was as effective, in reducing patch area, as the best pre-seeding cultivation treatment of 2 scarifying (6.6%). Deep ripping to a depth of 27 cm with an Agrowplow before scarifying and seeding reduced the incidence of patch to only 2.1%. The area of patch and wheat grain yield were inversely correlated (P< 0.001) and accounted for 32% of the variation. Effects (other than rhizoctonia) on grain yield due to the cultivation treatments are suggested. Cultivation directly below the seed placement with the modified combine increased wheat plant growth and grain yield. Deep ripping further increased above-ground dry matter, and grain yield was 58% greater than the yield from direct drilling with the triple disc drill.