Crown rot in cereals
Crown Rot raises its ugly head
September 2014. Neroli Brennan, Senior Land Services Officer - Cropping
We are beginning to hear reports of 'white heads' appearing in wheat crops within the northern and central pasts of our region. This is more evident in soils where moisture is limiting. These 'white heads' are most likely the result of Crown Rot.
Crown rot is a fungal infection that attacks the base (crown) of the cereal (Durum, wheat, barley and oats) plant disrupting water and nutrient supply to the developing head.
This results in the droppy 'white head' appearance within the crop. Most of these heads will contain no grain or very pinched grain at harvest.
Water stress is the main reason for the visual expression of Crown Rot, so it is often seen first in paddocks along wheel tracks, surrounding trees and in paddocks with a high nitrogen content, where the crop has grown vigorously and then run out of moisture toward the end of the season.
It is important to note that Crown Rot can still be present in the crop even if the whiteheads are not visible. Yield losses can still occur in these crops.
Identification and diagnostics
Paddock identification of Crown rot can be made by looking at the base of the wheat plant, where a brown discolouration of the stem base is a key identifying feature. Pink/ red fungal growth may also be present.
Correct analytical diagnosis of Crown Rot and also the level of infection present can be done by sending stubble away for diagnosis. For further information and sampling protocols contact Crown Analytical Services at Moree...
Unfortunately, crown rot has a very good survival method within the stems and crown of the cereal plant and other host such as
- barley grass
- wild oats
- phalaris.
Management
If crown rot is left unmanaged it will remain in dead and living material within the paddock from season to season.
A common misconception is that stubble burning or cereal stubble grazing are both effective control methods for Crown Rot.
Burning stubble is not a reliable method as it only reduces the plant material on the soil surface and the crown rot fungus can still survive in the plants crown material that is unburnt or is beneath the soil surface. Grazing can have a similar result.
Additionally, grazing of stubble, cultivation and stubble mulching can result in fragmentation of the infected plant material into inter-row spaces and may spread the infected material across a larger area of the paddock.
- The most reliable methods for reducing fungal levels and controlling Crown Rot are:
Crop rotation with crops such as legumes (field peas, chickpeas, faba beans), canola, sunflower or sorghum. Potentially a break of more than 12 months between cereal crops is required to reduce inoculants levels. Importantly, the denser the break crop canopy the greater the breakdown of infected cereal residue. - A lucence pasture phase within a mixed farming enterprise is very effective in reducing and controlling Crown Rot as it allows for an extended break between cereal host crops. However control of grass weeds is essentially during the pasture phase.
- Good farm hygiene- controlling all grass weeds, within paddocks as well as along fencelines, roads etc.
- Interow sowing cereals between previous years cereal stubble. This can reduce Crown Rot infection by up to 50% in new plants by limitining the physical contact with infected residues of previous crops.
Additionally, you may reduce the impact of crown rot by:
- Planting wheat varieties with greater resistance to Crown Rot and Root Lesion Nematodes. Recent research has linked the two together. Consider varieties such as such as Longreach Spitfire, EGA Wylie and Sunguard.
- Reducing the potential moisture stress of a crop through good fallow management, in-crop weed control, matching nitrogen levels to plant requirements and avoiding very high plant populations.
Find out more
If you are seeing these symptoms is your crop and you would like more information please contact your local Central West Local Land Services Ag Advisory officers:
- Neroli Brennan (0428 692713 or neroli.brennan@lls.nsw.gov.au).
- Greg Paul (0428 258 540 or greg.paul@lls.nsw.gov.au).
Some helpful links for more information: