Preliminary studies by the Victorian Institute for Dryland Agriculture suggest that both climatic conditions and cultivation can affect levels of Rhizoctonia in the soil and that low levels of the disease prior to sowing could increase rapidly under favourable conditions.
Field trials at Cooke Plains and Pinnaroo in South Australia showed that a modified direct-drill system consistently reduced Rhizoctonia better than direct-drill without the deep cultivation. Specifically:
- modified direct-drill with urea banded 5 cm below the seed, in the sowing pass, reduced Rhizoctonia bare patch and increased yield more often than did modified direct-drill with urea broadcast at tillering (a modified direct-drilling system is where the weeds are sprayed early after the break, and the soil is disturbed to a depth of 5 cm directly below where the seed is placed, in the sowing pass, using narrow points and press-wheels)
- a cultivation 6-11 days after the break may be the most effective time to reduce Rhizoctonia bare patch in a reduced tillage system (one cultivation prior to sowing).
A modified direct-drill system consistently reduced Rhizoctonia better than direct-drill without the deep cultivation.
Boost to conservation farming in marginal areas
The South Australian Research and Development Institute researchers who conducted the trials say the results can boost conservation farming in marginal areas vulnerable to erosion, by helping conservation farmers manage the disease and increase their returns from nitrogen by using urea more efficiently.
The Victorian researchers also reported some success in controlling the disease through tillage and modified sowing systems.
Contact: Dr Stephen Neate 08 8303 8400 (CSIRO), Dr Alan Dube 08 8303 9370 (SARDI), Dr Grant Hollaway 03 5362 2111 (VIDA)