Take Home Message
- Crown rot does not disappear in wet seasons.
- PREDICTA®B test mid to high-risk paddocks to help plan crop rotations and minimise yield losses from crown rot.
- Fungicide seed treatments, including Vibrance®, Rancona® Dimension and EverGol® Energy as well as the soon to be commercially available product Victrato®, should be used as part of an integrated disease management strategy.
Background
Crown rot is a major constraint to cereal production, with survey results from 2009 indicating $79 million is lost annually because of the disease, with the potential for even greater losses, up to $434 million (Murray & Brennan, 2009) in conducive seasons. It is predominantly caused by the stubble-borne fungus Fusarium pseudograminearum. Infected plants are characterised by the premature death of tillers and the presence of white dead heads. All winter cereals, as well as many grass weeds, are hosts and the pathogen can survive for many years in infected plant residues.
Yield losses are most severe when disease levels are high and there is moisture stress in the crop at the grain fill stage. A soft finish to the season can reduce crown rot damagebut may not entirely prevent yield losses. Durum wheat is more susceptible to crown rot than many wheat and barley varieties.
In 2021, BCG undertook a trial at Birchip investigating the effectiveness of Victrato® — a soon to be commercially available seed treatment product from Syngenta, containing the active ingredient cyclobutrifluram — at limiting yield losses from crown rot. The seasonal conditions were not conducive for crown rot expression and no yield differences between seed treatments were observed. The trial was repeated in 2022 at Kaniva and the results are discussed here.
Aim
To determine the efficacy of Syngenta’s Victrato® seed treatment at limiting yield losses from crown rot in durum wheat.
Paddock Details
Location: Kaniva
Crop year rainfall (Nov–Oct): 555mm
GSR (Apr–Oct): 448mm
Soil type: Clay
Paddock history: Lentil
Predicta B Result: 2.85 log(pg DNA/g soil) (high crown rot disease risk)
Trial Details
Crop types: Durum wheat: DBA Aurora, Bitalli, Patron Bread wheat: Scepter
Seed Treatments:
1. Control (no seed treatment for disease)
2. Vibrance® @ 360mL/kg
3. Vibrance® @ 180mL/100kg & Victrato® @ 200mL/100kg
4. Vibrance® @ 180mL/100kg & Victrato® @ 400mL/100kg
Target plant density: 140 plants/m²
Seeding equipment: Knife points, press wheels, 30cm row spacing
Sowing date: 3 June 2022
Replicates: Four
Harvest date: 29 December 2022
Trial average yield: 6.7t/ha
Trial Inputs
Fertiliser: Granulock® SZ Blend + Flutriafol (400mL/100kg) @ 60kg/ha at sowing and 200kg/ha of urea applied as a split application (GS13, GS32).
Weeds, insects, and diseases were managed as per best practice.
Method
A replicated field trial was sown using a complete randomised block trial design. Assessments included establishment counts, basal browning scores, grain yield and grain quality parameters.
Results & Interpretation
Given the expression of crown rot is somewhat dependent on seasonal conditions, the very wet spring of 2022 was not ideal for effectively evaluating the ability of Victrato® seed treatment to limit yield losses from crown rot.
Basal browning scores undertaken at the grain filling stage (7 November) indicated no expression of crown rot and the yield and grain quality results showed no significant differences between seed treatments (data not presented). There was, however, varietal differences with the new durum variety, Patron marketed by AGT, out yielding all other varieties (Table 1). Patron also had significantly lower grain protein than other varieties, with DBA Aurora and Bitalli making DR3 and Patron not meeting grain protein standards for durum wheat (Table 1).
Some caution should be taken with interpreting these varietal results however, as the seasonal conditions made it challenging for timely application of fungicides and Stripe Rust was present in the trial. Diseasing scoring at grain fill revealed Scepter was by far the worst affected. Even the durum wheats showed some evidence of infection, with Patron scoring slightly lower for disease incidence than DBA Aurora and Bitalli (data not presented).

Commercial Practice and On Farm Profitability
Whilst the soft springs of 2021 and 2022 around Birchip and Kaniva have not enabled us to sufficiently evaluate the effectiveness of Victrato® to limit yield losses from crown rot, other independent trial work has.
Led by NSW DPI, trials across 18 different sites over three seasons (2018–2021) have been able to demonstrate Victrato® has the potential to limit yield losses from crown rot (Simpfendorfer, 2022a). The trials used an inoculated versus. uninoculated randomised complete block design and compared a control to six fungicide seed treatments, including Vibrance®, Rancona® Dimension, EverGol® Energy and Victrato® (40 and 80 grams of active ingredient). The yield results indicated that, in the absence of a fungicide seed treatment, average yield losses from crown rot were 21.5 per cent. The addition of Victrato® at 80 gai significantly reduced losses to an average of 4.9 per cent, across the 18 sites (Simpfendorfer, 2022a). The other seed treatment products examined in these trials also reduced the level of yield loss from crown rot, but not across all sites and not to the same extent as Victrato® (Simpfendorfer, 2022a).
There is therefore a potential role for Victrato® to become part of growers’ integrated disease management strategies for crown rot management, alongside well-established practices such as crop rotation and inter-row sowing. Adoption will also come down to product cost and whether it is reasonable to use it as an insurance policy or reserve it for a high-risk situation or when pushing boundaries ie. with cereal on cereal.
Assessing your risk
Two ways to determine if a paddock is at high risk of yield losses from crown rot infection include:
- A visual assessment
During grain development or near harvest, assess the standing cereal crop for basal browning. This can be achieved by randomly pulling out 10 plants from 10 different locations within a paddock and rubbing the leaf sheaths back up to the first node. Low disease risk <11 per cent, medium = 11–24 per cent and high >24 per cent of plants affected. NOTE: the expression of white heads can indicate crown rot, but this can also be due several other factors (ie. frost, take-all, copper and molybdenum deficiencies) (Simpfendorfer, 2022a). - PREDICTA B Test
Undertake a PREDICTA B soil test pre-sowing to determine levels of crown rot. Sampling technique is important and needs to be completed by an accredited agronomist. The report will indicate if the paddock has a high, medium or low risk of crown rot by measuring the amount of the fungus’s DNA.
Fusarium Head Blight (FHB)
Another consideration, particularly heading into 2023, is having retained grain tested for Fusarium head blight (FHB). FHB was detected across eastern Australia in 2022, when conditions during flowering, ie. high humidity (>80 per cent) were extremely conducive to FHB infection and development (Simpfendorfer, 2022b).
Several different pathogens can cause FHB, including the crown rot pathogen, Fusarium pseudograminearum. Fusarium infected grain (white or pink in colour) can reduce germination, cause early seedling death, and introduce Fusarium crown rot into clean paddocks through seed infection (Simpfendorfer, 2017). There are registered fungicide seed treatments to reduce the extent of seedling blight when sowing Fusarium infected grain. Once infection levels get over 5 per cent however, finding a cleaner source is recommended as higher infection levels are also often linked to poor seedling vigour (Simpfendorfer, 2022b). Grading out lighter seed prior to sowing can help, as this will remove obvious severely infected grains.
References
Murray, G. and Brennan, J., 2009, Estimating disease losses to the Australia wheat industry. Australian Plant Pathology, vol 38, pp. 558–570.
Simpfendorfer, S., 2022a, Fusarium crown rot seed fungicides – independent field evaluation 2018–2021. GRDC Research Update Paper, <https://grdc.com.au/resources-and-publications/grdc- update-papers/tab-content/grdc-update-papers/2022/02/fusarium-crown-rot-seed-fungicides- independent-field-evaluation-2018-2021>.
Simpfendorfer, S., 2022b, Fusarium head blight – the basics factsheet.
Simpfendorfer, S., Giblot-Ducray, D., Hartley D. and McKay A., 2017, Where did the low levels of Fusarium head blight come from in 2016 and what does it mean. GRDC Research Update Paper, <https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update- papers/2017/02/where-did-the-low-levels-of-fusarium-head-blight-come-from-in-2016-and-what- does-it-mean>.
Acknowledgements
This research was funded by the Southern Australia Durum Growers Association (SADGA) and BCG members through their membership.
We thank the Dyer Family for hosting this trial.