Crown rot

TAKE HOME MESSAGES

  • Yield loss due to crown rot was greatest in durum wheat and least in barley.
  • A PreDicta B soil test can be used to identify crown rot levels prior to sowing and inform crop choices to minimise loss.

BACKGROUND

Prior to the 1990s, crown rot was regarded as a relatively minor disease in Victoria. Since then, intensification of cereals and adoption of stubble retention practices in the cropping system has favoured the carry-over of this stubble borne disease ( Hollaway and Exell 2010 ). Crown rot is more severe in seasons with a dry finish. It cannot be controlled using fungicides and adapted resistant wheat cultivars are not available.

Paddocks at risk of crown rot can be identified pre-sowing using a PreDicta B soil test ( Hollaway et al. 2013 ). If a paddock has a high test result, planting a non-cereal break crop will reduce crown rot inoculum ( Evans et al. 2010 ). In paddocks with a low to medium test result, selection of partially resistant cereals may reduce yield loss. The studies currently undertaken in Victoria are part of a national GRDC funded project to develop improved strategies for the management of crown rot.

AIM

To evaluate a range of cereals (wheat, barley, triticale and durum) for their performance in the presence of crown rot inoculum.

Table 1: Trial details.

Hollaway_1_2014

Herbicides were applied to best management practice. 

METHOD

Six cereal cultivars (Table 1) were sown with and without crown rot inoculum in a randomised split plot design, with six replicates at Quambatook and Horsham. The crown rot inoculum (Fusarium pseudograminearum) was applied to seed prior to sowing. Plots were harvested for grain yield.

Table 1. Cereal cultivars and their crown rot resistance rating grown at Quambatook and Horsham during 2014 to measure relative yield loss due to crown rot.

Hollaway_2_2014

A Ratings taken from the Victorian Cereal Disease Guide (Hollaway and McLean 2014). R = Resistant RMR = Resistant to moderately resistant MR = Moderately resistant MRMS = Moderately resistant to moderately susceptible MS = Moderately susceptible MSS = Moderately susceptible to susceptible S = Susceptible SVS = Susceptible to very susceptible VS = Very susceptible.

RESULTS AND INTERPRETATION

The effect of crown rot on the grain yield of barley, triticale, three bread wheat cultivars and durum wheat is shown in Table 2. Yield losses ranged from two to over 40%. Overall, barley and triticale suffered less yield loss than durum wheat, while the yield loss in the three bread wheat varieties was similar. The yield loss due to crown rot in the partially resistant wheat cultivars LRPB Phantom and Suntop was similar to that in the susceptible wheat cultivar Yitpi.

Table 2. The effect of crown rot (+) on the grain yield of barley, triticale and bread and durum wheat compared with untreated plots (-) at Quambatook and Horsham during 2014 with a mean yield loss (%) for individual and across the two sites also shown.

Hollaway_3_2014

A Numbers followed by the same letter are not significantly different for that site (P<0.05). * Significant difference between the crown rot infected and untreated plots for that variety at that site (P<0.05).

COMMERCIAL PRACTICE

In paddocks with a medium risk of crown rot, yield loss can be reduced by growing either barley or triticale. In paddocks where crown rot is detected, durum wheat should not be grown due to the potential for much greater yield loss. If bread wheat is to be grown, these trials did not show an advantage in selecting partially resistant wheats (MS and MSS to crown rot) in preference to the susceptible wheat (S).

ON-FARM PROFITABILITY

Crown rot is a potentially damaging disease in Victoria’s Wimmera and Mallee. In paddocks with medium to high levels of crown rot, losses can be reduced by growing barley in preference to wheat, noting that barley will still increase inoculum levels.

REFERENCES

Evans ML, Hollaway GJ, Dennis JI, Correll R, Wallwork H (2010). Crop sequence as a tool for managing populations of Fusarium pseudograminearum and F. culmorum in south-eastern Australia. Australasian Plant Pathology 39: 376-382.

Hollaway GJ, Exell GK (2010). Survey of wheat crops for white heads caused by crown rot in Victoria, 1997-2009. Australasian Plant Pathology 39: 363-367.

Hollaway GJ, Evans ML, Wallwork H, Dyson CB, McKay AC (2013) Yield loss in cereals, caused by Fusarium culmorum and F. pseudograminearum, is related to fungal DNA in soil prior to planting, rainfall and cereal type. Plant Disease 97, 977-982.

ACKNOWLEDGEMENTS

These studies were funded by GRDC through the ‘National crown rot epidemiology and management program’ (DAN00175) and the Victorian Government. Thanks for the Horsham cereal pathology and BCG technical staff for assistance with the two field trials.

ADDITIONAL INFORMATION

2014 CHAIRMANS WELCOME | 2014 THE BIG 10 | THE YEAR THAT WAS | 2014 RESEARCH SITES | 2014 SITE DESCRIPTIONS | 2014 RESEARCH METHODOLOGY | 2014 GUIDELINE TO INTERPRETING SOIL TESTS | 2014 GRAIN PRICES | 2014 BOARD STAFF AND COMMITTEE | 2014 ACRONYMS AND ABBREVIATIONS | 2014 CEREAL GROWTH STAGE CHART

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