There are two key differences between growers who manage the risk of crown rot well and those who don’t – soil moisture conservation and awareness of inoculum levels.
Those “differences” form an integral part of Mullaley grower Ross Durham’s crop management strategy and dictate paddock, crop and variety selection.
Mr Durham crops around 1500 hectares on the western side of the highly fertile Liverpool Plains under a rotation program that incorporates canola, faba beans, chickpeas, mungbeans, sorghum and durum wheat which is the main winter crop grown.
“Our rotation is based on several factors – soil moisture availability and retention, stubble load and disease risk and previous paddock history,” Mr Durham said.
As a durum wheat grower, Mr Durham takes a vigilant approach to soil moisture and disease management in order to maximise yield potential and grain quality.
“Conserving soil moisture is a critical consideration in all our crop management decisions. Much of our farming country is sloping basalt soils so maintaining ground cover and having a good root structure on plants is important to prevent erosion and maximise moisture availability,” he said.
“Disease management is similarly important – we always plant durum into paddocks with the best moisture levels and lowest crown rot inoculum levels.
“If that crop gets moisture stressed in any way, particularly in the flowering to grain fill period, there will be yield reduction and increased screenings and that’s the situation where appropriate agronomic management pays dividends.”
Given durum’s susceptibility to crown rot, Mr Durham regularly undertakes PreDicta B® DNA-based soil testing to assist in the identification of paddocks at risk from crown rot and other soil-borne diseases like root lesion nematodes prior to planting.
Crown rot is caused by the fungus Fusarium pseudograminearum and is one of the most serious disease threats to winter cereal crops in Australia costing northern growers around $80 million on average each year.
It is widespread in wheat, barley and durum paddocks in central and northern NSW and southern Queensland and can have a serious impact on yields. Symptoms include discolouration (honey brown) of the crown, lower leaf sheaths and tiller bases and formation of whiteheads during grain filling.
The Grains Research and Development Corporation (GRDC) is investing in a range of projects aimed at combatting the impacts of the disease including pre-breeding research to develop germplasm with improved crown rot tolerance and resistance, field-based trials aimed at improving agronomic management recommendations and PreDicta B® accreditation workshops.
Gunnedah-based senior agronomist Jim Hunt, Hunt Ag Solutions, said while seasonal conditions played a critical role in the incidence of crown rot, informed and proactive crop management could substantially alleviate the risk of major yield loss.
“There are some key messages for growers, particularly durum growers, when it comes to managing crown rot risk – don’t plant susceptible crops on marginal moisture or into paddocks with medium to high inoculum levels,” he said.
“We can’t control the seasonal factors but we can control our agronomic management in areas such as disease testing, rotations, sowing practices, stubble management, weed control and soil moisture capture and storage.
“While we didn’t experience high levels of crown rot incidence on the Liverpool Plains last year, this year might be a different story. Having a sound agronomic management strategy in place could mean the difference between a 25% or a 50% yield loss in a severe crown rot year.”
Mr Hunt recommends the use of PreDicta B® testing to assess the presence of crown rot inoculum and other soil-borne pathogens prior to planting but said it required a dedicated sampling strategy and was not a simple add-on to a soil nutrition test.
A PreDicta B® test can be arranged by contacting commercial testing service, Crown Analytical Services, which provides northern growers and advisors with bags, soil corers, protocols and procedures for sampling as well as an interpretation of results once tests are completed by the South Australian Research and Development Institute (SARDI) in Adelaide.
More information on the PreDicta B® tests is available on the SARDI website or by contacting Crown Analytical Services on 0437 996 678.
Jim Hunt, senior agronomist, Hunt Ag Solutions, Gunnedah
0429 721 367
Sarah Jeffrey, Senior Consultant Cox Inall Communications
0418 152 859