Crop disease surveillance activities

Page last updated: Thursday, 3 June 2021 - 2:27pm

Please note: This content may be out of date and is currently under review.

DPIRD staff are conducting an annual integrated surveillance and monitoring program for foliar diseases of cereal, oilseeds and pulses in WA cropping zones. The project, jointly funded by DPIRD and GRDC, aims to generate data that will minimise the impact of priority diseases and direct effective disease managemetn strategies. The program involves surveillance of commercial crops, NVT sites and trial sites. Results of recent disease surveys are presented here. 

Commencing in July 2019, this project is conducting an integrated surveillance and monitoring program across the WA grainbelt for endemic diseases of cereals and oilseeds. The project also involves surveillance for exotic pathogens.The project has staff allocated in five separate DPIRD offices (Geraldton, Northam, Perth, Albany and Esperance), conducting surveillance through all WA port zones. The official name of the project is 'Surveys and associated diagnostics of the incidence and severity of diseases of cereal, pulses and oilseeds' (DAW1907-002RTX).

The objective of the project is that Australian grain growers will have knowledge of and changes in the incidence and severity of established diseases and proof of absence from high priority exotic grain diseases updated annually. Surveys will be conducted during autumn if there has been summer rain, to determine distribution and extent of regrowth crop plants and weeds that present a risk of disease carryover (green bridge) for the upcoming growing season. Random stratified surveys will be conducted during the growing season across WA grain growing areas to record the incidence and severity of the established and emerging diseases of cereals, oilseeds, and pulses and provide proof of absence for high priority exotic diseases. 

2021 Green Bridge Surveillance Results

As a result of widespread summer and autumn rainfall, weed and crop regrowth occurred and are persisting in many areas across the wheatbelt. Vegetation can serve as a ‘green bridge’ for diseases and pests where regrowth persists to carry over diseases into the growing season. A webinar covering the main surveillance project findings and what diseases to look out for in the 2021 growing season is available on the DPIRD YouTube channel. During April, DPIRD staff in the surveillance project conducted a targeted green bridge survey in areas with advanced cereal volunteers on fencelines, in commercial cropping paddocks or experimental sites across the grain belt from Geraldton to Esperance. Any regrowth/weeds found were inspected for endemic and exotic foliar diseases as well as aphids and viruses. By end of April, rust had been found on wild oats near Esperance, powdery mildew on barley regrowth in the South Stirlings area and leaf spot diseases (yellow spot/nodorum blotch and net blotches) on wheat/barley in several areas. Monitoring and reporting any disease finds is the key to early and effective disease management.

A small number of turnip yellows virus (TuYV) carrying aphids have been detected at; Cranbrook, Mount Barker, Borden, Ongerup, Woogenellup and Kalgan. These aphids were caught by yellow sticky traps deployed by the DBM surveillance team from mid-March to mid-April and these are a part of a DPIRD Boosting Grains Science Partnership project. Cabbage aphids and GPA have been found in established wild radish on roadsides in the Albany port zone and both of these species can spread TuYV.The presence of volunteer canola and cruciferous weeds (particularly wild radish) in the grainbelt can give aphids a chance to build-up which can increase the risk of early incursion of TuYV if winged aphids transmit virus from infected weeds to vulnerable germinating canola crops. Growers in the Albany port zone are urged to monitor their germinating canola for aphids and signs of symptomatic plants.

In the Northam area, very low numbers of winged green peach aphid have been caught on sticky traps. There is established patches of wild radish in this region so there is potential for green peach aphid numbers to increase over the coming months and pose a risk to emerged canola crops.

For more information on this work see the TuYV early warning system page. For insecticide recommendations refer to DPIRD’s 2021 autumn winter insecticide guide.

Growers and agronomists are encouraged to monitor any persisting green bridge for aphids and disease, so that timely action can be taken to identify the pathogen, and limit the spread and build-up of inoculum that are a risk for this season's crops.

Please report green bridge aphid/disease to PestFax. This can be done online from the paddock to PestFax Reporter App, by emailing the PestFax editor PestFax@dpird.wa.gov.au or calling one of the DPIRD staff members below.

Should you find rust on volunteer cereals or grasses, you are encouraged to send samples for pathotype analysis in paper envelopes to the national rust survey, instructions and submission form available here.

Thank you for helping us with this important surveillance work that will be a helpful guide for what biotrophic diseases are around and posing a risk for 2021 crops.

Implications from Green Bridge survey results

Due to the presence of green bridge in many areas, monitoring of crops this season is very important. Where green bridge persists, there is an increased chance of development of rust or mildew. Presence of leaf spot diseases (yellow spot/nodorum blotch on wheat and net blotches on barley) and powdery mildew on barley demonstrates presence of inoculum and disease risk for this year's crops. A webinar covering the surveillance project findings and what diseases to look out for in the 2021 growing season is available on the DPIRD YouTube channel.

Recommended actions:

  • Destroy green bridge where possible at least three weeks prior to seeding.
  • In areas where green bridge is present –monitor persisting green bridge closely particularly volunteer cereal plans for rust or powdery mildew and also closely monitor susceptible crops regularly after emergence.
  • Use an integrated disease management approach - plan variety choices and crop rotations to minimise disease risks and avoid over reliance on fungicides, especially for stubble borne diseases as they persist even in dry seasons. The 2021 Crop Sowing guide includes variety disease ratings. Foliar fungicides are a finite tool, use them wisely. For example, DMI Fungicide resistance in barley net blotches continues to spread. For more information see the Australian Fungicide Resistance Extension Network webpage.
  • Use effective seed dressing or in-furrow fungicides for early disease management.
  • Field pea black spot and canola blackleg risk forecasts can be found on the Crop disease forecasts page. 

2020 Season Surveillance 

A webinar covering the 2020 surveillance project findings and what diseases to look out for in the 2021 growing season is available on the DPIRD YouTube channel.

2020 season overview

2020 was the second-warmest year on record for Western Australia, after the record warm year of 2019. Monthly rainfall was below average for most of the year apart from a wet February, August and November. Rainfall across the WA grain belt ranged from decile 1 to decile 7, but on average most locations had decile 2-3 rainfall for the year. Dry warm weather for much of the growing season and late sowing in many areas did not favour some diseases and aphids (vector of viruses), however the wet August conditions were favourable, so there were a wider range of diseases seen than in 2019, although often at lower severity. The diseases found at high incidence were endemic stubble-borne diseases, where disease from the 2019 season was carried into 2020 on stubble. There was significant green bridge (weeds/regrowth crops that harbour disease) in WA in autumn 2020, particularly in the central / Kwinana port zone after the widespread February rainfall and some follow up March/April rainfall. Barley net blotch was found on volunteer barley plants predominantly in the Albany or Esperance port zones, with the latter also having some observations of leaf rust on grass weeds (wild oats and veldt grass). There were no finds of rusts or powdery mildew on regrowth cereals so the season started with low risk of biotrophic disease carryover, but cautionary advice to growers to keep an eye on oat crops for rust. 

The break to the season was late and occurred in late May in most areas, so most crops were nearly a month behind in growth stage for much of the year, but this was not as noticeable as 2019. There was above average rainfall in August in some areas that promoted disease development and unseasonal heavy rain in November interrupted harvest and caused some sprouting and mouldy grain in some areas. 

Endemic disease surveillance during Spring

Methods

Standardised sampling and data recording protocols were developed to ensure uniformity of data collected across the Western region, across seasons and to be comparable with data being collected in other parts of Australia. The total sample numbers / crop were determined according to priorities and also considered area of each crop type in each port zone of the WA grainbelt. Major crops wheat, barley, canola, oat had greater sampling intensity than minor crops, such as pulses. Regional sampling was stratified by area of crops within designated regions (CBH port zones) and the size of the zone, from minimum five to maximum of 15 paddocks / port zone. On top of the stratified sampling strategy, a further number of barley and oat sites were visited as the surveillance work incorporated plant sampling for Ramularia testing as part of project DAW1909-003RTX 'Distribution of ramularia across the Australian grain belt' and results of oat sites visited for the National Hay Agronomy project were contributed to our survey ( PRJ-011029 National Hay Agronomy Project (Oats), funded by AgriFutures Australia). At each site multiple individual plants (>20) were assessed using a 0-9 scoring protocol depending on defined degrees of disease intensity on various leaf levels of cereals (0 =low on all levels, and 9 =severe disease on all levels). Sampling was conducted during the head emergence / flowering / grainfill stage of plants to maximise chance of disease incidence.

The number of crops surveyed in each port zone in 2020. Kwinana north and south were reported together as Kwinana port zone.
 

Wheat

Barley

Canola

Oat

Lupin

Pulse

Kwinana (north and south)

17

24

10

11

7

1

Albany

8

9

7

14

 

1

Esperance

12

21

8

 

 

6

Geraldton

10

5

11

 

10

1

2020 Surveillance Total

47

59

36

25

17

9

Results

Wheat

Across the grainbelt, 47 wheat paddocks were surveyed (10 in Geraldton, 17 in Kwinana, eight in Albany and 12 in Esperance Port Zone, Figure 4). The dominant disease across all port zones in these surveyed paddocks was yellow spot / Stagonospora nodorum blotch complex, average incidence within paddocks across all zones was 63% and out of all the paddocks surveyed 77% had this disease complex. Laboratory testing of a snap shot of samples across all port zones diagnosed the majority of the disease as Stagonospora nodorum blotch in 2020, whereas in 2019 yellow spot was more dominant. The dry late start to the growing season in 2020 in many areas would not have allowed for early yellow spot spore release from wheat stubble, and the heavy rains in August across the grainbelt favoured Stagonospora nodorum blotch.

Locations of wheat crops visited for spring disease surveillance in 2020 from Geraldton to Esperance in WA
Figure 4. Locations of wheat crops visited for spring disease surveillance in 2020 

All wheat paddocks surveyed in the Geraldton port zone had yellow spot/nodorum blotch complex, almost all those surveyed in the Esperance port zone, and about half those surveyed in the Kwinana and Albany port zones. Severity ranged from low to high (rating 0-9) but was on average low-moderate in all zones. Glume blotch (Stagonospora nodorum blotch infection in heads) was reported from Geraldton (30% of paddocks) and Esperance (8% of paddocks) port zones. There was low incidence of wheat powdery mildew reported from Albany and Esperance port zones. 25% of paddocks surveyed in Esperance port zone and 13% of paddocks in Albany port zone had wheat powdery mildew. Though severity in the canopy was generally low, powdery mildew head infection was observed in Esperance in 8% of paddocks with reports that growers struggled to manage the disease with fungicides on the SVS variety Scepter even after applying three foliar fungicides. Across all port zones, wheat flag smut was reported in 4% of paddocks, take-all in 2%, and crown rot in 11% of paddocks surveyed. Across all port zones, in the structured wheat survey there were no rust observations (stripe/leaf/stem), BYDV, WSMV, loose smut or septoria tritici blotch. It should be noted however, that there were some reports of BYDV and WSMV in the ad hoc wheat surveillance activities in the Esperance port zone. There were only a few reports of false black chaff but these were not tabulated as not consistently recorded between port zones.

Summary of wheat disease average incidence (%) between paddocks in each port zone (ie.percentage of paddocks surveyed that had disease). Blank indicates disease not found. Abbreviations: WSR is wheat stem rust, WLR is wheat leaf rust,WYR is wheat stripe (yellow) rust, and CR is crown rot. Of the YS/SNB complex Stagonospora nodorum blotch dominated.
Wheat YS / SNB Glume blotch (SNB head infection) WPM PM head infection WSR WLR WYR CR Loose smut Take all Flag smut
Geraldton

100%

30%                  
Kwinana

76%

            6%     6%
Albany 50%   12.5%                
Esperance

92%

8%

25%

8%       33%   8% 8%
All port zones 81% 9% 9% 2%       11%   2% 4%


Barley

Across all the port zones, 59 barley paddocks were surveyed (five in Geraldton, 24 in Kwinana, nine in Albany and 21 in Esperance Port Zone, Figure 5). The dominant disease in barley crops surveyed in the Geraldton, Kwinana and Esperance port zones was spot-type net blotch (STNB), with the average incidence within paddocks being high and severity ranging from low to high. As per 2019, severity and incidence of STNB was noticeably high in the Geraldton port zone where every plant at every site surveyed had the disease. Across all the port zones 83% of barley paddocks surveyed had STNB.

Locations of barley crops visited for spring disease surveillance in 2020 from Geraldton to Esperance in WA
Figure 5. Locations of barley crops visited for spring disease surveillance in 2020

Net-type net blotch (NTNB) was dominant in the Albany port zone with 78% of paddocks surveyed infected and high incidence of the disease within paddocks as well. NTNB was at low incidence in the Kwinana and Esperance port zones and on average severity was low and absent in the Geraldton port zone as was also the case in 2019. Barley powdery mildew was found at low incidence and severity in the Albany and Esperance port zones. Scald was not found in any port zones which was a noticeable difference from the 2019 structured survey, however it must be noted that a very low incidence of scald was found in the ad hoc survey in the Albany and Esperance port zones. Barley loose smut incidence was significantly higher in Kwinana and Esperance port zones than in 2019. There were few reports of crown rot, take-all, and none of Wirrega blotch. There were no reports of barley leaf rust, BYDV, or covered smut in any port zones during this structured survey (note: BYDV was found at very low incidence in the ad hoc survey in the Albany port zone). No Ramularia was identified visually on any of the 59 barley crops surveyed but out of all the barley leaf samples collected in WA as part of the ramularia project (DAW1909-003RTX), Ramularia collo-cygni was detected by LAMP testing in four paddocks (one in Kwinana west port zone, one in Albany port zone and two in Esperance port zone), three NVT sites (Kwinana and Albany port zones) and two trial sites. All of these sites are in the high rainfall zone.

Summary of barley disease average incidence between paddocks in each port zone (ie.percentage of paddocks surveyed that had disease). Blank indicates disease not found. Abbreviations: BPM is barley powdery mildew, and BLR is barley leaf rust.
Barley NTNB STNB Scald BPM BLR Takeall Crown rot Loose Smut Wirrega Blotch
Geraldton   100% 

 

           
Kwinana

12.5%

100%           25%  
Albany 78%) 22%   22%          
Esperance 19% 86%   5%   5% 5% 14%  
All port zones 24% 83%   5%   2% 2% 15%  

Oats

Across all the port zones, 25 oat paddocks were surveyed (11 in the Kwinana port zone, and 14 in the Albany port zone, Figure 6). Oat surveillance was conducted in conjunction with staff from the National Hay Agronomy Project (PRJ-011029 National Hay Agronomy Project - Oats, Funded by AgriFutures Australia) which resulted in nearly twice as many oat sites surveyed in 2020 than in 2019. Similar to 2019, the stubble borne disease Septoria avenae blotch was at high incidence within paddocks in both port zones and was found in 96% of total paddocks surveyed though generally at low severity. Bacterial blight was observed at significantly higher incidence in 2020 than 2019 which could be a seasonal difference and/or partly due to the larger sample size in higher rainfall areas in 2020 compared to 2019 (incidence between paddocks in Kwinana port zone in 2019 was 15% while in 2020 it was 64%). Though incidence in the two port zones surveyed in 2020 was high, severity was low. There are at least two bacterial diseases capable of infecting oats and these were combined for a single ‘bacterial blight’ score (stripe blight and halo blight). Both diseases are capable of reducing oaten hay quality through damage to leaves but may not necessarily cause significant yield loss. Surveys by the oaten hay project (PRJ-011029 National Hay Agronomy Project - Oats, Funded by AgriFutures Australia) suggest that stripe blight is more common than halo blight in WA. There are no chemical control measures registered for control so management recommendations for growers for the 2021 growing season should focus on reducing carry over from 2019 on seed and stubbles.

Locations of oat crops visited for spring disease surveillance in 2020 from Geraldton to Esperance in WA from central wheatbelt to southern region of WA
Figure 6. Locations of oat crops visited for spring disease surveillance in 2020 

Oat leaf and stem rust were detected at very low levels in both 2019 and 2020, including on roadside wild oats during and pre-season. This indicates the value of green bridge surveillance in determining risks for the upcoming season’s crops. Red leather leaf like symptoms were observed in a small number of paddocks in the Kwinana and Albany port zones. Samples are undergoing laboratory isolation and identification for confirmation of causal pathogen. Red leather leaf has not been confirmed in WA before. BYDV (barley yellow dwarf virus), crown rot and loose smut were observed in 2020 at low incidence and severity, these were not reported in 2019 oat surveys.

During ad hoc surveillance, oat stem rust and leaf rust were found in a few Esperance port zone oat sites and samples were sent to the ACRCP survey revealing a wide variety of pathotypes are present in WA. High incidence of cereal yellow dwarf virus (CYDV) was found in one oat crop in Kwinana port zone as part of ad hoc surveillance.

Summary of oat disease average incidence (%) between paddocks in each port zone(ie.percentage of paddocks surveyed that had disease). Blank indicates disease not found. Oats were only surveyed in Kwinana and Albany port zones. Abbreviations: OSR is oat stem rust, OLR is oat leaf (crown) rust, CR is crown rot and BYDV is barley yellow dwarf virus.
Oat Septoria avenae blotch Bacterial blight OSR OLR   CR Loose smut BYDV Takeall
Kwinana 91% 64%       9% 9% 9%  
Albany 100% 71% 14% 14%   7% 7% 21%  
All port zones 96% 68% 8% 8%   8% 8% 16%  

Canola

Across all the port zones, 36 canola paddocks were surveyed (11 in Geraldton, 10 in Kwinana, seven in Albany, and eight in Esperance Port Zone, Figure 7). Disease levels were higher than 2019 across all port zones. Sclerotinia stem rot was observed in all port zones in 2020, favoured by heavy and frequent August rainfall. It was at high incidence in the Geraldton port zone and moderate incidence in the Esperance and Kwinana port zones, low incidence and severity (mainly leaf symptoms) in the Albany port zone. It caused crop yield losses in heavily infected paddocks in the Geraldton and Esperance port zones. In 2019, sclerotinia incidence in canola was very low and only found in the Esperance port zone due to widespread extremely dry weather conditions. The disease has been present in almost all port zones every year from 2014-2018. Sclerotinia incidence is higher in seasons that have regular or above average rainfall especially during crop flowering and when rain persists until late in the season. The presence of sclerotinia in 2020 in all port zones increases the risk of the disease occurring in the 2021 season and future years as the disease is carried between seasons on fruiting bodies (sclerotes) left behind after harvest in the soil and canola stubble which can survive for up to six years.

Locations of canola crops visited for spring disease surveillance in 2020 from Geraldton to Esperance in WA
Figure 7. Locations of canola crops visited for spring disease surveillance in 2020 

There was moderate incidence of blackleg stem canker and pod symptoms (upper canopy infection) in Kwinana and Esperance port zones. Some powdery mildew was reported at low incidence in the Esperance port zone. There were no reports of downy mildew, white leaf spot, alternaria, Turnip yellows virus (TuYV) or Beet western yellows virus (BWYV) in any port zones during this structured survey. However, it should be noted that TuYV was found in ad hoc surveillance in Kwinana and Esperance port zones.

Implications for 2021: Risk of early blackleg infection is moderate for Kwinana and Esperance port zone canola crops as moderate levels of disease in 2020 mean potential for carryover on stubble. Inoculum of Sclerotinia can survive over many seasons and so canola and lupin growers who had sclerotinia in 2020 or previous years should be mindful of the disease risk in the 2021 season if weather favours disease development.

Summary of canola disease average incidence (%) between paddocks in each port zone (ie.percentage of paddocks surveyed that had disease). Blank indicates disease not found.
Canola Blackleg Foliar Sclerotinia stem Blackleg stem Blackleg pod Blackleg upper branch BWYV Downy mildew Powdery mildew
Geraldton 27% 73%            
Kwinana 40% 30% 40% 40%        
Esperance   50% 50% 50% 13%     13%
Albany   14%            
All port zones 21% 38% 19% 19% 2%     2%

Lupin

Across all the port zones, 17 lupin paddocks were surveyed (10 in Geraldton, and seven in Kwinana port zone, Figure 8).

Locations of lupin crops visited for spring disease surveillance in 2020 from Geraldton to central wheatbelt in WA
Figure 8. Locations of barley crops visited for spring disease surveillance in 2020 from Geraldton to Esperance in WA

In lupin crops, phomopsis was found at low incidence on stems in the Kwinana port zone while in the Geraldton port zone it was found on pods in 20% of paddocks. The dominant lupin disease found in the Geraldton port zone was sclerotinia on the stems and pods in 50% of paddocks, and ground level (basal) sclerotinia was found in 30% of paddocks surveyed. No sclerotinia or anthracnose was found in the Kwinana port zone. Anthracnose was reported on albus lupin stems in the Geraldton port zone but at very low severity and incidence. In the Kwinana port zone, brown spot in lupin was reported at very low severity, BYMV (bean yellow mosaic virus) and charcoal rot were also found at low incidence in the Kwinana port zone. BYMV incidence increased later in spring in some regions and may not be reflected in the results collected. Lupin sclerotinia is a growing issue in the Geraldton port zone in recent years, as all species of lupin are susceptible and grown in close rotation with canola which is infected by the same sclerotinia pathogen, Sclerotinia sclerotiorum. It was not found in 2019 due to the dry season.

Summary of lupin disease average incidence between paddocks in each port zone (ie.percentage of paddocks surveyed that had disease). Blank indicates disease not found.
Lupin Phomopsis Anthracnose stem Sclerotinia basal infection Sclerotinia stem or branch Sclerotinia pod infection Brown spot BWYV  Charcoal rot
Geraldton Pods 20% 10% 30% 50% 50%      
Kwinana Stem 14%         57% 14% 14%
All port zones 18% 6% 18% 29% 29% 24% 6% 6%

Pulses (other than lupin)

Across all the port zones, four chickpea paddocks (two in Esperance, one in Geraldton and one in Kwinana port zones), four lentil paddocks (Esperance port zone) and one Faba bean paddock (Albany port zone) were surveyed.

There were no diseases or viruses observed on lentils surveyed in the Esperance port zone.

A limited number of paddocks of chickpea were inspected but those that were had a high incidence of ascochyta in the Geraldton, Kwinana and Esperance port zones, with infected seed identified as the source of infection for all paddocks (a concern and focus for chickpeas growers in the 2021 season).

One paddock of faba bean was surveyed in the Albany port zone and found ascochyta blight and chocolate spot were present at low incidence and severity. No table presented.

In the Esperance port zone, Botyrtis grey mould was not an issue in pulses as growers applied fungicide ahead of winter rainfall which had been forecast.

In ad hoc surveillance section in the Esperance port zone cucumber mosaic virus was found in chickpea; chocolate spot and cercospora leaf spot in faba bean; downy mildew in field pea; ascochyta, luteovirus and Phasey bean mild yellow virus in lentil. In the Kwinana port zone, 1 faba bean (chocolate spot) and 1 field pea (downy mildew) crop were reported.

Summary of chickpea disease average incidence (%) between paddocks in each port zone. Blank indicates that disease was not found in the surveyed paddocks. Results are of 2 paddocks inspected in Esperance, 1 paddock in Kwinana, and 1 in Geraldton port zones.
Chickpea Ascochyta Botrytis Grey mould Sclerotinia
Geraldton 50%    
Kwinana 100%    
Esperance

100%

   

Roadside weeds adhoc surveillance

In the Esperance and Kwinana port zones the opportunity was taken to inspect roadside weeds comprising of wild oats, brome grass, and vetch during the growing season, particularly given the rust finds earlier in the year on roadside wild oats and veldt grass in the green bridge survey.

Of the 15 sites visited, samples of rust were taken from 12 of them. In the Esperance port zone, oat leaf rust was found on nine out of 11 wild oats inspected, oat stem rust on one out of 11 wild oats inspected, brome grass rust  on two out of two sites, and one vetch plant inspected was clean but sent for root disease survey. Despite staff in the Kwinana port zone stopping at many stands of wild oat on road sides they found very little rust. 

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