Effect of chickpea ascochyta on yield of current varieties and advanced breeding lines – the 2015 Tamworth trial VMP15

Author: Kevin Moore, Kristy Hobson, Steve Harden, Paul Nash, Gail Chiplin and Sean Bithell, Department of Primary Industries, Tamworth, NSW | Date: 01 Mar 2016

Take home message

  • Under extreme disease pressure, Ascochyta can be successfully and economically managed on susceptible varieties such as Kyabraand Jimbour.
  • However, Ascochyta management is easier and more cost effective on varieties with improved resistance eg PBA HatTrick and PBA Boundary.
  • The 2015 Ascochyta trial, VMP15, confirmed the next variety planned for release (CICA0912) has excellent resistance to Ascochyta.

2015 Tamworth Ascochyta management trial, VMP15

VMP15 sought to evaluate Ascochyta blight (AB) management using ten varieties/advanced breeding lines with a range of Ascochyta resistance ratings: seven desis Kyabra (S, susceptible), PBA HatTrick (MR, moderately resistant), PBA Boundary (MR), CICA0912 (putatively R, resistant), CICA1007 (putatively MR), CICA1302 (for CQ, putatively MR) and CICA1303 (for CQ, putatively MR) plus the kabulis Genesis Kalkee TM (rated MS), PBA Monarch (MS, moderately susceptible) and Genesis 425 TM (rated R).

There were three treatments: a regular fungicide application with regular applications of 1.0L/ha chlorothalonil (720g/L active), an alternative application variety management package (VMP) treatment with a low and off label rate of chlorothalonil; and a nil application; irrespective of treatment, all fungicides were applied before rain. Data for full rate and nil fungicide treatments only, are reported here because of restrictions on publishing off label results.

The trial was sown into standing cereal stubble on 18-19 May 2015 using tyne openers on 50cmrow spacing in plots 4m wide by 10m long.  VMP15 was split across two experiments, one on red soil, one on heavy black soil, the later had waterlogging problems which affected AB resistance (data not presented), here we present results for the trial on the red soil.  We have seen examples of this in commercial crops of PBA HatTrick, e.g. at Yallaroi in 2014 and Gulargambone in 2015 where waterlogging stress lead to a decline in AB resistance. On 16 Jun, when plants were at the 3 leaf stage, the trial was inoculated during a rainfall event with a cocktail of 20 isolates of Ascochyta collected from commercial chickpea crops (1999-2014) at a rate of 1,066,666 spores per mL in 200L/ha water.  This early and heavy rate of inoculation combined with extremely favourable conditions resulted in high levels of Ascochyta disease, so much so that the unprotected susceptible varieties were dead by the end of July and even unprotected PBA HatTrick had severe damage (stem breakage). From inoculation to desiccation (1 Dec), the trial received 341mm in 46 days (32 days >1.0mm).

The first Group S VMP spray for Kyabra was applied before inoculation.  The first Group MS VMP spray for Genesis Kalkee TM, PBA Monarch, CICA1302 and CICA1303 was applied after three infection events (6 rain days, 67 mm rain since inoculation), for Group MR VMP spray (PBA HatTrick and PBA Boundary, CICA1007) and R (CICA0912, Genesis 425 TM) the first spray occurred after four infection events (14 rain days, 79 mm rain since inoculation).  The number of rain days, rainfall and spray applications are summarised in Table 1.

Key findings of VMP15 (see Table 2) were:

  • Under extreme disease pressure, Ascochyta can be successfully managed on susceptible varieties with frequent applications of registered rates of chlorothalonil.
  • Well managed Kyabra yielded 1862 kg/ha with a GM of $954/ha.
  • Under extreme disease pressure, unsprayed PBA HatTrick yielded only 417 kg/ha (GM -$4/ha).
  • The new line CICA0912 performed well, yielding 1568 kg/ha (GM $844/ha) with no foliar fungicide.

The performance of PBA HatTrick in VMP15 was both a surprise and a disappointment.  In all previous VMP trials at Tamworth, unsprayed (Nil treatment) PBA HatTrick has produced substantial and profitable yields. For example in the 2010 trial, VMP10, it produced 1707 kg/ha (Table 3).  2010 also had above average rain in Jun/Jul that persisted throughout the season, so was in fact more conducive to Ascochyta than 2015 (although 2015 had more rain days in Jun/Jul than 2010).

VMP10 was sown 19 May 2010 using disc openers on 38cm row spacing in plots 4m wide by 10m long.  There were four replicates (Table 3).  On 17 Jun, when plants were at the 3 leaf stage, the trial was inoculated during a rainfall event with a cocktail of nine isolates of Ascochyta collected from commercial chickpea crops in 2008 and 2009 at a rate of 1 million spores per mL in 200L/ha water. From inoculation to desiccation (28 Nov), the trial received 430mm rain in 67 rain days (46 days >1.0mm), i.e. wetter than VMP15 both in total mm and number of rain days. Both VMP15 and VMP10 were in seasons that had regular rainfall and so supported the Ascochyta development consistently over the season and so provide a strong evaluation of current varieties and advanced breeding lines.  A number of the key findings of VMP10 were similar to VMP15:

  • Under extreme disease pressure, Ascochyta can be successfully managed on susceptible varieties with registered rates of chlorothalonil.
  • Well managed Jimbour yielded nearly 3t/ha with a GM of $750/ha.
  • The performance of varieties and advanced breeding lines with improved resistance to Ascochyta provided the best gross margins.

The findings below contrasted between the two VMP experiments:

  • In 2010 PBA Boundary performed exceptionally well, yielding over 2t/ha without any foliar fungicide, a minimal yield loss (4%), compared with 53 % in 2015.
  • Under extreme disease pressure in 2010 unsprayed HatTrick still gave a profitable yield, but unsprayed HatTrick yields were lower in 2015 and was not profitable

Table 1.  VMP15 2015 dates, number of rain days (>1 mm rain), mm of rain and dates and number of 1 L/ha chlorothalonil applications, trial sown 18-19 May. *trial was AB inoculated on 16 June

Date

No. days

mm Rain

1L spray

28-31 May

4

31

12 Jun

1st All genotypes

16*-19 Jun

4

61

22 Jun

1

1

30 Jun-01 Jul

2

4

9 Jul

2nd All genotypes

10-17 Jul

8

12

21 Jul

3rd All genotypes

24-27 Jul

4

13

21 Aug

4th All genotypes

23-24 Aug

2

40

1 Sep

5th All genotypes

3 Sep

1

11

4 Sep

1

6

16 Sep

1

4

11 Oct

6th All genotypes

14 Oct

1

16

22 Oct

1

18

23 Oct

1

12

26 Oct

1

10

7th All genotypes

The following factors in VMP15 may have contributed to the nil PBA HatTrick treatments having poorer yields than in prior VMP trials:

(a) Parts of VMP15 were waterlogged during Jun/Jul; we know from past experience and commercial crops that any stress including waterlogging compromises PBA HatTrick’s moderate resistance to Ascochyta.

(b) Interaction between herbicide damage and Ascochyta resistance – VMP15 sustained minor herbicide injury in August.  This may have also compromised PBA HatTrick’s moderate resistance to Ascochyta.

(c) Change in the pathogen; the isolates used in VMP10 were collected from crops in 2008 and 2009 compared to the isolates used in VMP15 which were collected from 1999 to 2014. Recently collected isolates have shown a higher level of agressiveness on PBA HatTrick. See Ascochyta Variability GRDC Update paper for further information.

Table 2.  Number and rate/ha of chlorothalonil sprays, cost of spraying, grain yield, and gross margin for seven desi and three kabuli chickpea varieties on red soil in the Tamworth VMP15 trial.  (GMs also take into account other production costs estimated at $300/ha; chickpea price desi $730/t; kabuli $1000/t) Yield P<0.001, lsd 417kg/ha; GM P<0.001, lsd $354/ha

Variety and treatment

No. Sprays

Cost $/ha

Yield kg/ha

GM $/ha

CICA0912 1.0L

7

105

1853

984

Genesis425 1.0L

7

105

1875

1470

CICA1007 1.0L

7

105

1846

982

PBA Boundary 1.0L

7

105

1755

876

PBA Monarch 1.0L

7

105

1274

869

PBA HatTrick 1.0L

7

105

1722

852

CICA1302 1.0L    

7

105

1864

954

CICA1303 1.0L    

7

105

1949

1018

Kyabra 1.0L

7

105

1862

954

Kalkee 1.0L

7

105

1659

1254

CICA0912 Nil

0

0

1568

844

Genesis425 Nil

0

0

1144

844

CICA1007 Nil

0

0

1083

491

PBA Boundary Nil

0

0

1233

600

PBA Monarch Nil

0

0

887

587

PBA HatTrick Nil

0

0

417

4

CICA1302 Nil   

0

0

0

-300

CICA1303 Nil  

0

0

0

-300

Kyabra Nil

0

0

0

-300

Kalkee Nil

0

0

1589

1289

Table 3.  Number and rate/ha of chlorothalonil sprays, cost of spraying, grain yield, and gross margin for four desi chickpea varieties in the Tamworth VMP10 trial.  (GMs also take into account other production costs estimated at $300/ha; chickpea price $450/t)

Variety and treatment

No. Sprays

Cost $/ha

Yield kg/ha

GM $/ha

Jimbour  1.0L

14

294

2988

750

aKyabra  1.0L

14

294

2549

553

PBA HatTrick  1.0L

14

294

2604

578

PBA Boundary  1.0L

14

294

2410

491

Jimbour Nil

0

0

0

–300

Kyabra Nil

0

0

0

–300

PBA HatTrick Nil

0

0

1707

468

PBA Boundary  Nil

0

0

2320

744

aKyabra 1.0L one of the four reps was severely affected by water logging which (i) compromised Ascochyta control and (ii) impacted on yield

Acknowledgements

This research is made possible by the significant contributions of growers through both trial cooperation, field access and the support of the GRDC; the authors most gratefully thank them and the GRDC.  Thanks to Woods Grains, Goondiwindi and Glen Coughran, “Beefwood”, Moree for providing seed for the trials. We also thank agronomists for help with the crop inspections and submitting specimens, Gordon Cumming, Pulse Australia for industry liaison and chemical companies who provide products for research purposes and trial management.

Contact details

Kevin Moore
NSW DPI
Ph: 02 6763 1133
Mb: 0488 251 866
Fx: 02 6763 1100
Email: kevin.moore@dpi.nsw.gov.au

Kristy Hobson
NSW DPI
Ph: 02 6763 1174
Mb: 0400 955 476
Fx: 02 6763 1100
Email: kristy.hobson@dpi.nsw.gov.au

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