The health report - 2019 pulse disease seasonal update and NVT disease ratings

Take home messages

  • Consult a current pulse disease guide for the latest pulse disease ratings and up to date disease management information.
  • A new national pulse disease rating system has been implemented, which will ensure a consistent and independent disease rating system for pulses.
  • In lentils, there are now two pathotypes of Ascochyta blight (AB) present in the southern region. In Victoria, the AB rating for PBA Hurricane XT has not been downgraded, as it has in South Australia (SA). Growers are advised to closely monitor both PBA Hurricane XT and PBA Hallmark XT varieties for infection, and manage as a potentially higher risk of AB.
  • In faba beans, there are currently two pathotypes of AB which are widespread across the southern region. It is assumed reports of higher incidences of AB on PBA Samira is due to on-farm retained seed which had outcrossed with more susceptible varieties. Ensure seed is isolated from other varieties by a minimum of 200m to minimise the risk of cross-pollination.
  • Following the first signs of AB infection in chickpea, a fungicide application of a premium product has resulted in grain yield and AB infection comparable to the multiple preventative application of fungicides. Research is continuing to ensure a similar result is observed across seasons.

2019 pulse disease seasonal review

Widespread disease development occurred in pulse crops, in Victoria, during winter 2019. The dry conditions during spring slowed further disease development, however Agriculture Victoria field experiments measured yield losses up to 95% when susceptible chickpea varieties were not protected with fungicides. This highlighted the benefits of proactive disease control, even in a season with a dry finish. Bacterial blight was a significant issue in field peas during 2019, with several reports of total crop loss. Unfortunately, there are no in-crop management options available for bacterial blight.

New varieties and their disease resistance

The recent release of several new pulse varieties is, in many cases, providing improvements in resistance to diseases of importance in Victoria. Implementation of a nationally standardised approach to pulse disease resistance ratings may have resulted in some minor changes to resistance classifications. With the changes in diseases over time, it is always recommended to consult a current disease guide.

Chickpea

PBA Royal is a new kabuli chickpea variety with comparable Ascochyta blight (AB) resistance to GenesisTM090.

Experiments conducted during 2018 and 2019 compared AB severity and grain yield across varieties, in the presence of AB, at both Curyo and Horsham. These experiments had three treatments:

  • Full control/minimal disease – multiple fungicides applied to achieve no disease. No infested stubble applied.
  • Bixafen (45gai/ha) and prothioconazole (90gai/ha), applied at 4-node and flowering growth stages. Plots were inoculated with AB infested stubble at the 4-node growth stage.
  • Diseased plots where no fungicides were applied. Plots were inoculated with AB infested stubble at the 4-node growth stage.

During 2019, high levels of disease was observed in the experiments at both sites, particularly where no fungicide was applied. At Curyo, GenesisTM090 and PBA Royal showed equivalent yield loss due to AB. This was less than in most other lines evaluated in the experiment, showing the benefit of partial resistance in newer varieties (Table 1). At Horsham, PBA Royal had less disease than GenesisTM090. At both sites both PBA Royal and GenesisTM090 had similar grain yields in the reduced fungicide treatment (Bixafen + Prothioconazole), compared with the ‘full control’ treatment.

Table 1. Grain yield (t/ha) of 15 chickpea varieties in the presence and absence of Ascochyta blight (AB), with three different treatments applied at Curyo during 2019.

Variety

Treatment*

Full control

Bixafen (45gai/ha) + Prothioconazole (90gai/ha)

4-node and flowering

Nil

PBA Striker

1.97

0.93

0.37

Howzat

1.87

1.09

0.53

CICA1521

1.89

1.18

0.61

PBA Monarch

1.94

1.26

0.73

Sonali

2.01

1.42

0.79

CICA1841

1.63

1.27

0.84

CICA1352

1.81

1.71

1.06

PBA Slasher

1.79

1.49

1.10

Almaz

1.83

1.66

1.12

Kalkee

1.41

1.57

1.13

CICA1551

1.88

1.46

1.35

CICA1552

1.69

1.78

1.39

GenesisTM090

1.76

1.72

1.39

PBA Royal

1.67

1.60

1.56

CICA1454

1.94

1.75

1.59

 

P value

Lsd

 

Variety

<.001

0.09

 

Treatment

<.001

0.21

 

Variety x Treatment

<.001

0.36

 

*The three treatments were; full control — no AB stubble was applied and fungicides were applied to ensure no disease; Bixafen + Prothioconazole — applied at 4-node and flowering growth stages and inoculated with AB infested stubble at the 4-node stage; and Nil — where there was no disease control and the plots were inoculated with AB infested stubble.

Faba bean

PBA Amberley has improved chocolate spot resistance compared to the other commercial varieties. Preliminary field data is showing minimal yield losses due to chocolate spot, although currently there are few experiments with good levels of infection. Glasshouse results are also showing good resistance to AB pathotypes 1 and 2.

Lentil

PBA Highland XT has improved resistance to AB, including the isolates in SA that are now compromising the resistance in PBA Hurricane XT and PBA Hallmark XT.

Pulse disease National Variety Trials (NVT)

Through an expansion of the GRDC’s National Variety Trials (NVT) program, independent disease ratings of pulses are now available. This provides robust disease ratings using processes adapted from those established for wheat and barley. Table 2 lists included crops and diseases.

Definitions for each disease rating category were updated as part of this new project (Table 3). The update changes some pulse disease ratings, with better alignment between crops and diseases nationally.

A total of 49 disease screens are conducted annually, drawing on the extensive plant pathology expertise available across Australia. Disease screens are conducted in field, and/or glasshouse conditions designed to maximise disease expression.

At the end of the season, data collected nationally are collated and disease ratings are assigned by experts. Disease ratings are updated annually and made available in State-based disease guides and on the NVT web site

Table 2. Crops and diseases included in the new National Variety Trials (NVT) 2019 screening and States where they will be screened.

Crop

Disease

Screening State

Chickpea

Ascochyta blight

SA, VIC, NSW

Botrytis grey mould

NSW

Pratylenchus neglectus - tolerance

QLD

Pratylenchus neglectus - resistance

VIC, QLD

Pratylenchus thornei - resistance

VIC, NSW, QLD

Pratylenchus thornei - tolerance

QLD

Faba bean

Ascochyta blight

SA, VIC

Cercospora leaf spot

SA

Chocolate spot

SA

Pratylenchus neglectus

VIC, QLD

Pratylenchus thornei

VIC, NSW, QLD

Field Pea

Ascochyta blight (synonym: blackspot)

WA, SA, VIC

Bacterial blight

NSW

Downy mildew

SA

Powdery mildew

SA

Pratylenchus neglectus

VIC, QLD

Pratylenchus thornei

VIC, QLD

Lentil

Ascochyta blight

SA, VIC

Botrytis grey mould

SA, NSW

Pratylenchus neglectus

VIC

Pratylenchus thornei

VIC

Lupin

Anthracnose

WA

Brown spot

WA

Cucumber mosaic virus

WA

Phomopsis

WA

Pleiochaeta root rot

WA

Sclerotinia

WA

Table 3. Updated pulse disease ratings used in the National Variety Trials (NVT), to be implemented in pulse ratings released during 2020 and onwards.

Rating category

Definition

R

Resistant

No symptoms visible. No fungicides are required.

RMR

Resistant to

Moderately Resistant

The disease may be visible but will not cause significant plant damage or loss. However, under extreme disease pressure or highly favourable environments conditions fungicide applications may be required e.g. to prevent seed staining.

MR

Moderately Resistant

The disease may be visible but will not cause significant plant damage or loss. However, under high disease pressure or highly favourable environments conditions fungicide applications may be required e.g. to prevent seed staining.

MRMS

Moderately Resistant to Moderately Susceptible

The disease symptoms are moderate and may cause some yield and/or seed quality losses in conducive conditions. Fungicide applications, if applicable, may be required to prevent yield loss and seed staining.

MS

Moderately Susceptible

Disease symptoms are moderate to severe and will cause significant yield and seed quality loss in the absence of fungicides in conducive seasons, but not complete crop loss.

S

Susceptible

The disease is severe and will cause significant yield and seed quality loss, including complete crop loss in the absence of fungicides, in conducive conditions.

VS

Very Susceptible

Growing this variety in areas where a disease is likely to be present is very high risk. Significant yield and seed quality losses, including complete crop loss can be expected without control and the increase in inoculum may create problems for other growers.

Monitoring Ascochyta blight pathogen populations of lentil and faba bean

To monitor shifts in the AB pathogen population of both lentil and faba bean, annual monitoring and pathogenicity testing has been conducted at SARDI since 2015. Each year, in controlled environment conditions, 40 isolates (single disease sample) of Ascochyta lentis and Ascochyta fabae are tested on a differential host set of lentil and faba bean, respectively. Results from isolates collected from commercial crops and field trials in SA and Victoria during the previous season, are reported in Tables 4 and 5.

Ascochyta blight in lentil

Early and severe Ascochyta lentis infection in PBA Hurricane XT crops and volunteer plants were reported during 2019 on the Yorke Peninsula (YP) and in the Mid-North region of South Australia (SA). Indicating that the variety’s MRMS rating is under threat. PBA Hurricane XTA remains rated MR in Victoria but may change when additional data becomes available.

Annual testing has confirmed two pathotypes of A. lentis present in SA; a Nipper-virulent type, and a Hurricane-virulent type. Controlled environment testing was conducted in 2019, of A. lentis isolates collected in 2018 (35 from SA, five from Victoria) on a differential host set that includes NipperA and PBA Hurricane XT (Table 4). Of the isolates tested in 2019; 27 out of 40 (67.5%) were capable of infecting PBA Hurricane XT, an increase from 50% in 2018 and 28% in 2016 (Blake et al. 2019a; Blake et al. 2019b; Blake et al. 2017). Indianhead is a source of resistance for the breeding program and the presumed source of resistance in PBA Hurricane XT, however it was infected by 25 of the 40 isolates (62.5%), an increase from 33% in 2018 and 5% in 2016 (Blake et al. 2019a; Blake et al. 2019b; Blake et al. 2017). Hence this source of resistance is now compromised across SA lentil growing regions. The A. lentis pathogen population is naturally variable and these aggressive forms have been selected for, over time, in intensive cropping systems. Although high levels of AB are not commonly observed in Victoria, the SA isolates may spread, so growers and agronomists are advised to monitor lentil crops for this potential new pathotype.

Table 4. Forty (40) Ascochyta lentis isolates collected in 2018 were inoculated onto a lentil host differential set, in controlled environment conditions during 2019 at SARDI. Entries in the table are the number of isolates per category.

Test reaction*

Cumra

(susceptible check)

Nipper

PBA

Hurricane XT

Indianhead

(resistant line)

ILL7537

(resistant line)

R

2

22

13

15

40

MR

3

10

8

14

0

MRMS

11

8

15

10

0

MS

10

0

4

0

0

S

14

0

0

1

0

*R = resistant, MR = moderately resistant, MRMS = moderately resistant-moderately susceptible, MS = moderately susceptible, and S = susceptible.

In light of the observed reactions on PBA Hurricane XT in SA coupled with the results of the annual pathogenicity testing, growers should regularly inspect both PBA Hurricane XT and PBA Hallmark XT lentil crops to determine if AB infection is severe enough to directly affect yield. PBA Hallmark XTA is presumed to have the same source of resistance to AB as PBA Hurricane XT. Tests at SARDI have found that PBA Hallmark XT is able to be infected by recently collected Hurricane-virulent isolates at a moderate level.

The newly released lentil variety, PBA Highland XT, has a provisional rating of MR to foliar AB in SA, with resistance to both the Nipper-virulent and Hurricane-virulent AB pathotypes. However, this rating may be subject to change when more data becomes available. Growers should monitor for AB and if infection is present, plan to spray ahead of rain fronts at podding to protect the developing seed.

Ascochyta blight in faba bean

There were a number of reports of mild AB leaf infection in SA and Victorian faba bean crops in 2019. This did not cause major problems as the cool (5-15°C) and wet conditions did not persist in most growing regions. However, two pathotypes of A. fabae are found in all faba bean growing regions in the southern region, with the more aggressive pathotype 2 also present across Victoria. Farah is currently rated S to pathotype 2, while PBA Rana, PBA Zahra and PBA Marne are MRMS to this pathotype. PBA Samira, Nura, the Group B herbicide tolerant PBA Bendoc and the new release PBA Amberley (tested as AF11023), are all RMR to both pathotypes. Check updated pulse disease guides as ratings may change between years.

During the 2019 season, reports were received of higher than expected levels of AB on PBA Samira in commercial crops in SA and Victoria. In most of these reports, crops were sown with on-farm retained seed and in many cases the seed crop had been grown next to a faba bean variety which is susceptible to pathotype 2 of A. fabae, such as PBA Rana or Farah. Faba beans are open pollinated which can lead to mixing of genetic material from grower retained seed. These genetic mixtures can lead to perceived changes in the resistance of a variety. Growers should ensure seed kept for future plantings are isolated from other varieties by a minimum of 200m to minimise the risk of cross-pollination.

The annual testing of A. fabae 2018 isolates (23 from SA, 17 from VIC) were conducted on a differential faba bean host set, including the commercial varieties PBA Rana and PBA Zahra, as well as three Ascochyta resistant (AR) selections; viz. Farah AR, Samira AR and Nura AR. The AR selections are fixed for AB resistance within the breeding program and known not to be outcrossed. For the first time, results suggest the presence of a possible third pathotype emerging in the A. fabae population which is aggressive on PBA Samira. This is demonstrated by four out of 40 (10%) isolates causing a MRMS reaction on Samira AR (Table 5). Continued monitoring will be critical to confirm these shifts in the pathogen population.

Table 5. Forty (40) Ascochyta fabae isolates collected in 2018 were inoculated in 2019 onto a faba bean host differential set, in controlled environment conditions at SARDI. Entries in the table are the number of isolates per category. AR lines are Ascochyta resistant selections fixed within the breeding program.

Test reaction*

Icarus
(susceptible check)

Farah

AR

PBA Zahra

PBA Rana

Samira

AR

Nura
AR

R

0

2

2

2

32

36

MR

1

1

11

7

4

4

MRMS

0

7

12

16

4

0

MS

9

15

13

13

0

0

S

30

15

2

2

0

0

*R = resistant, MR = moderately resistant, MRMS = moderately resistant-moderately susceptible, MS = moderately susceptible, and S = susceptible.

A helpful guide for growers and agronomists to identify common faba bean diseases can be found at Spot the difference - Identifying faba bean diseases - GRDC Communities

Correct identification is important as different fungicides are used to manage different fungal disease.

Chickpea Ascochyta blight management

Research to reduce fungicide use in chickpeas is an Agriculture Victoria priority. Experiments continue to investigate the use of post infection sprays of premium fungicides, as opposed to the current practice of multiple preventative fungicide applications. These experiments compared two varieties with different resistance; GenesisTM090 and PBA Striker, across 10 fungicide treatments (Table 6). During the 2019 experiments at Curyo and Horsham, there was no significant difference in grain yields between the single application of a premium fungicide, once the first signs of AB infection were observed, compared to multiple preventative fungicide applications (Table 7). These results are similar to 2018, however, only two applications of strategic chlorothalonil (1080 gai/ha) were required during 2019 compared to three during 2018 (Brand and Fanning 2019). This indicates a fungicide application of a premium product, following the first signs of AB infection, results in comparable grain yield and AB infection compared to the preventative application of fungicides during 2019.

The application of fungicides following disease infection remains a higher-risk scenario. These field experiments were inoculated with infested stubble however, so it would be expected that results on a paddock scale may vary. This work will continue so we can develop solid messaging around fungicide usage as a curative approach for disease control.

Table 6. Fungicide treatments and the number of sprays applied for each treatment to assess control of ascochyta blight (AB) in chickpea at Curyo during 2019.

Seed Treatment

Rate

(gai/kg of seed)

In-season Fungicide

Rate

(gai/ha)

TimingB

Number of Sprays

Thiram

Thiabendazole

0.72

0.4

CaptanTM

1000

Strategically

2

Thiram

Thiabendazole

0.72

0.4

PropiconazoleA

125

Strategically

2

Thiram

Thiabendazole

0.72

0.4

Chlorothalonil

1080

Strategically

2

Thiram

Thiabendazole

0.72

0.4

Tebuconazole

Azoxystrobin

200

120

Strategically

2

Thiram

Thiabendazole

0.72

0.4

Bixafen

Prothioconazole

45

90

Strategically

2

Thiram

Thiabendazole

0.72

0.4

Tebuconazole +

Azoxystrobin

200

120

Post Infection

1

Thiram

Thiabendazole

0.72

0.4

Bixafen

Prothioconazole

45

90

Post Infection

1

FluxapyroxadA

0.5

Bixafen

Prothioconazole

45

90

Post Infection

1

Thiram

Thiabendazole

0.72

0.4

Full controlC

A Some of the fungicides used in this trial have been used in an off-label manner. The ‘Off-label’ treatments used in these trials are allowable in the state of Victoria ONLY having met the requirements of the state legislation. Their use remains a high risk activity so before using a chemical off-label please consult your agronomist or go to Agriculture Victoria - Farm-management_ chemicals

B Strategic sprays were applied before rainfall events, at key growth stages to maximise foliage protection (4th node and late vegetative / early flowering stage). Post infection sprays were applied when the first AB lesions were observed and at flowering. Trials were inspected at least weekly.

C The full control treatment is a rotation of fungicides applied to ensure minimal to no disease as a control in the experiment.

Table 7. Grain yield, percentage plot affected with ascochyta blight (AB) and percentage of pods affected with AB in plots treated with 10 fungicide treatments at Curyo during 2019. Different letters indicate pairwise significance where the variety, treatment or interaction were significant (P<0.05).

Treatment

TimingB

Plot affected (%)

Yield (t/ha)

 

Genesis™090

PBA Striker

Genesis™090

PBA Striker

Mean

Nil

Nil

21 cde

88 h

1.35

0.56

0.95 a

Thiram + Thiabendazole on seed
Captan

Strategically

14 abcd

79 gh

1.36

0.88

1.12 ab

Thiram + Thiabendazole on seed
Propiconozole A

Strategically

9 abc

69 fg

1.60

0.94

1.27 bcd

Thiram + Thiabendazole on seed
Tebuconazole + Azoxystrobin

Strategically

18 bcde

57 f

1.63

1.07

1.35 bcd

Thiram + Thiabendazole on seed
Chlorothalonil

Strategically

8 abc

58 f

1.57

1.16

1.37 bcd

Thiram + Thiabendazole on seed
Bixafen + Prothioconazole

Strategically

2 ab

26 de

1.65

1.30

1.48 cd

Thiram + Thiabendazole on seed
Tebuconazole + Azoxystrobin

Post Infection

5 abc

33 e

1.56

0.94

1.25 bc

Thiram + Thiabendazole on seed
Bixafen + Prothioconazole

Post Infection

3 ab

16 abcde

1.76

1.20

1.48 cd

Fluxapyroxad A on seed
Bixafen + Prothioconazole

Post Infection

2 ab

14 abcd

1.88

1.21

1.54 d

Thiram + Thiabendazole on seed
Full Control C

 

0 a

0 a

1.94

1.87

1.9 e

Mean

   

1.63

1.11

 
  

P value

Lsd

P value

Lsd

 

Variety

 

<.001

6

<.001

0.06

 

Treatment

 

<.001

12

<.001

0.14

 

Variety x Treatment

 

<.001

17

0.412

ns

 
        

A Some of the fungicides used in this trial have been used in an off-label manner.  The ‘Off-label’ treatments used in these trials are allowable in the state of Victoria ONLY having met the requirements of the state legislation. Their use remains a high risk activity so before using a chemical off-label please consult your agronomist or go to Agriculture Victoria - Farm-management_ chemicals

B Strategic sprays were applied before rainfall events, at key growth stages to maximise foliage protection (4th node and late vegetative / early flowering stage). Post infection sprays were applied when the first AB lesions were observed and at flowering. Trials were inspected at least weekly.

C The full control treatment is a rotation of fungicides applied to ensure minimal to no disease as a control in the experiment.

Disease survey of chickpea, faba bean and lentil in Victoria

A survey of 19 chickpea, nine faba bean and 26 lentil crops for the incidence and severity of foliar and soil-borne diseases was conducted between September and October 2019. The results showed that both soilborne and foliar diseases posed important threats to Victorian crops (Figure 1). Among the foliar diseases in pulses, AB was most commonly observed. The soil-borne disease analysis is still ongoing.

Figure 1. Proportion of pulse diseases in Victoria.

How can you help pulse pathology research?

Samples of pulse crops with the following diseases are being sought:

  • Ascochyta blight,
  • Botrytis (Botrytis grey mould (BGM) or chocolate spot),
  • Sclerotinia; and,
  • soil-borne disease.

The latest disease samples ensure researchers are monitoring changes in both the pathogen populations and variety resistance. If you can help, please contact Joshua Fanning (Victoria) for a collection kit, which includes sample envelopes and a return post envelope.

Crop protection products

There are often changes to permits for the use of fungicides in pulse crops. Pulse Australia’s website has current information on Crop Protection Products including Minor Use Permits, as does the Australian Pesticides and Veterinary Medicines Authority (APVMA) website

Off-label chemical use (Victoria ONLY)

The ‘Off-label’ treatments used in these trials are allowable in the state of Victoria ONLY having met the requirements of the state legislation. Their use remains a high-risk activity.

Any person that uses a chemical off label must accept and manage all risks associated with that use, such as the risk of residues in produce or the environment, occupational health and safety concerns and the efficacy of the chemical. This is particularly important for export commodities. In the past, access to export markets have been disrupted due to unacceptable residues caused by off-label use.

It is critical that people using chemicals off-label under the Victorian legalisation:

*             DO NOT use a Schedule 7 Dangerous Poison (e.g. Carbendazim) in an off-label manner without a permit from the                            Australian Pesticides and Veterinary Medicines Authority (APVMA)

*             DO NOT use the chemical at an above label rate

*             DO NOT use the chemical more frequently than the label states

*             DO NOT use the chemical contrary to any prohibitive label statements e.g. DO NOT statements

For more information on the off-label use of chemical in Victoria; Agriculture Victoria _farm-management_off-label-chemical-use

Acknowledgements

This research is a collaborative project between the GRDC, and the Victorian Government. The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the author would like to thank them for their continued support.

Significant contributions have been made by of growers and agronomists through provision of diseased plant materials for the isolate collection, the authors would like to thank them for their continued support. We would also like to thank the large research teams supporting this research at Agriculture Victoria and the South Australian Research and Development Institute (SARDI).

Useful resources

Pulse disease guide

ExtensionAus website - communities.grdc- field-crop-diseases

National Variety Trial (NVT) website

Victorian crop sowing guide

New pulse variety releases:

PBA Royal chickpea

PBA Highland XT lentil

PBA Amberley faba bean

References

Blake, S., Kimber, R., Day, S., McMurray, L., Brand, J., Paull, J. and Davidson, J. (2017) Pulse diseases 2016. In ‘GRDC Update proceedings, Adelaide, 7-8 February 2017’. pp. 89-95. https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2017/02/pulse-diseases-2016

Blake, S., Farqharson, L., Walela, C., Hobson, K., Kimber, R. and Davidson, J. (2019a) Ascochyta blight in intensive cropping of pulses. In ‘GRDC Update proceedings, Adelaide, 12-13 February 2019’. https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2019/02/ascochyta-blight-in-intensive-cropping-of-pulses

Blake, S., Rose, J., Roberts, P., Day, S., Hobson, K. and Davidson, J. (2019b) In-Season Pulse Disease Update. In ‘Hart Field Day Guide, 17 September 2019’. Pp. 70-78.

Brand, J. and Fanning, J. (2019) Southern Region pulse performance and agronomy update 2018 — Victoria. In ‘GRDC Update proceedings, Bendigo, 26-27 February 2019’. https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2019/02/southern-region-pulse-performance-and-agronomy-update-2018-victoria

Contact details

Joshua Fanning
110 Natimuk Road, Horsham VIC 3400
03 5362 2111
Joshua.fanning@agriculture.vic.gov.au
@FanningJosh_

Sara Blake
GPO Box 397, Adelaide SA 5001
08 8429 2248
sara.blake@sa.gov.au
@Sara_N_Blake

GRDC Project Code: DJP1097-001RTX, CUR00023, DAV1706-003RMX, UA00163, DAS1905-013SAX, DJP1907-004RTX, DJP1905-002SAX,