August 2015 – Daniel Huberli from DPIRD discusses how to identify what is causing a patch in your cereal crop and the options available to help you manage Rhizoctonia in your paddocks.
Rhizoctonia is found across the growing regions of WA. The SARDI Predicta B Soilborne Disease Tests show a third of WA paddocks sampled in Autumn 2015 have a medium-high risk of Rhizoctonia.
How to identify if you have Rhizoctonia in your paddock?
Bare patches of crop may have soil borne diseases in that area. To check if your bare patch is affected by Rhizoctonia, dig up plants in the affected area taking care to dig up intact roots. After washing the roots it may be easy to see spear tipping of the roots and the lack of the crown roots on the plant. Rhizoctonia causes this spear tipping and brown lesions on the roots.
For full diagnosis, samples can be sent to Agwest Plant Laboratory (APL) by following the sampling techniques shown on this video.
Management of Rhizoctonia
As with most other soil borne diseases, there is no in-season control available for Rhizoctonia. The main control option available is crop rotation next season.
It is important to identify what the issue is now and respond to it before sowing in 2016.
An integrated management approach is required in order to actively manage Rhizoctonia in your paddocks. This includes:
- Crop selection – preferably rotated to grass-free crops such as Canola, pulses and grass-free pastures;
- Weed control early (4-6 weeks prior to sowing) to remove the green bridge;
- Sowing early to ensure roots are developed prior to the active disease period in cooler weather;
- Cultivating the soil to at least 10cm below seed to assist root development;
- Using seed dressings and/or in-furrow fungicides to control Rhizoctonia and
- Ensuring your crop has adequate nutrition at seeding and tillering including Nitrogen, Phosphorus, Zinc and other micronutrients.