Managing crown rot in WA
Despite a dry summer, the incidence of crown rot is expected to be high in parts of WA this year following a prolific year for the disease in 2013. Caused by Fusarium pseudograminearum and F. culmorum, the fungal disease can reduce grain yield and quality, and increase screenings.
Crown rot is hosted by all winter cereals and many grassy weeds. It affects roots and lower stems and is usually not detected until after heading. Significant yield losses can occur when high disease levels coincide with moisture stress during grain fill.
The disease can persist in infected crop residues for at least two years and be carried over in infected grass weeds. Crown rot is more common when susceptible crops (cereals) are grown sequentially or after long-term grass pastures. Its symptom of white heads can be confused with symptoms for take all disease, frost or copper and molybdenum deficiency. However, crown rot also causes a distinct golden brown coloured symptom on the stem base, and the white heads are scattered throughout the crop, but not in distinct patches (as with take-all).
A joint Department of Agriculture and Food WA (DAFWA) and Grains Research and Development Corporation (GRDC) study has in recent years found that there is an increased incidence of soilborne diseases, such as crown rot, when wheat is grown without a break crop.
Soil samples from 184 ‘Farm Focus Paddocks’ across WA regions, but mainly from the medium rainfall areas, collected in 2013 showed a general increase in soilborne diseases, compared with 2010. According to DAFWA plant pathologist Daniel Huberli the findings highlight that growers and agronomists should be on the lookout for crown rot and other soilborne diseases.
Root diseases can go unnoticed in a paddock until they build up over time and cause problems with the crop. With an increase in continuous wheat crops and reduced tillage systems, it is important for growers to keep an eye out as the growing season progresses. When checking a paddock, observe your crop closely, look for a lack of vigour or crown discolouration under leaf sheaths, and later in the season watch out for white-heads in the crop with associated crown discolouration.
For an overview of identification and control of crown rot in WA see: https://www.agric.wa.gov.au/mycrop/crown-rot-cereals
- White heads scattered throughout crop but not in distinct patches (as with take-all)
- Scattered single tillers and white heads
- In severe cases whole plants develop white heads after flowering
- Tiller bases honey-brown colour especially under leaf sheaths
- Pink discolouration often forms around or in the crown or under leaf sheaths - with pink colour becoming very evident on infected plants left in a damp plastic bag for several days
- Affected heads have shrivelled or no grain
For additional information on crown rot see the GRDC Crown Rot in Cereals fact sheet.
For crown rot management strategies read more…