Pulse diseases in 2015

Changes in Ascochyta blight in pulse crops

Chickpeas

Ascochyta blight was observed in chickpea crops in SA including Genesis™090. Severity in Genesis™090 was low to moderate in SA but severe infection on this variety was observed in at least one site in Victoria. Isolates from these two states were tested at SARDI in controlled conditions against an old SA isolate. Reactions shows that Genesis™090 has a susceptible reaction to the Victorian isolate but not to the other two isolates. Ambar, Neelam and Genesis™079 demonstrated resistance to all three isolates; Almaz had a moderate reaction to the new SA isolate but a good level of resistance to the other two isolates; PBA Maiden had a moderate reaction to all three isolates; Genesis Kalkee, PBA Monarch, and PBA Slasher have a moderate to susceptible reactions to all three isolates while PBA Striker had a susceptible reaction to all three isolates (Figure 1). These results still need to be confirmed with field data.

Figure 1: Reaction of chickpea NVT lines against three isolates of A. rabiei tested in controlled conditions at SARDI, December 2015.

Figure 1: Reaction of chickpea NVT lines against three isolates of A. rabiei tested in controlled conditions at SARDI, December 2015.

Lentils and faba beans

Changes in Ascochyta blight reactions on cultivars are being monitored on faba beans and lentils. Collections of isolates have been made from SA, Victoria and New South Wales and these have been tested against specific cultivars in controlled conditions to identify any changes in response.  Research of previous years identified new pathotypes in both A. lentis and A. fabae in major growing regions, that is, resistance in Nipper lentils is no longer effective in SA nor Victoria, and resistance in Farah faba beans and partial resistance in PBA Rana have been overcome in Mid North of SA.

Sixty three isolates of A. lentis collected during 2014 were tested in controlled conditions on five hosts including Nipper and Northfield. Seventy per cent were aggressive on Nipper and 90 per cent were aggressive on Northfield, an increase over previous years in which less than 20 per cent of isolates could infect one or other of these cultivars. These cultivars need to be managed similar to Nugget with a fungicide spray during podding to prevent pod infection and abortion, and in high risk situations may require a spray during early flowering. This study has found that the population of A. lentis is naturally variable and high intensity cropping of a single variety leads to the selection of the resistance breaking isolates. Consequently, the rapid and dominant uptake of PBA Hurricane XT, particularly on Yorke Peninsula, threatens the longevity of Ascochyta blight resistance in this cultivar. In 2015 Ascochyta blight was observed in susceptible lentil crops such as PBA Flash, and very small lesions of this disease were also detected in a few PBA Hurricane XT crops. If resistance in PBA Hurricane XT becomes ineffective this will potentially impact on numerous other cultivars and breeding lines that share a common resistance. 

Thirty eight isolates of A. fabae collected during 2014 and 2015 were tested in controlled conditions on five hosts including PBA Rana, Nura and PBA Samira. The majority of the isolates (71%) were the new pathotype that is virulent on PBA Rana and Farah. The majority of these were collected from crops and trials in the Mid North region of SA, confirming this as the major region affected by the change, although two isolates were from Victoria and a weakly aggressive isolate was from the south east of SA, indicating a potential for further spread of the new pathotype. A test of 25 historical isolates collected through the Mid North from 1991 to 2013 were also tested and showed that the new pathotype was present in 2012, one year earlier than field observations detected the change. Faba bean crops should be monitored regularly for Ascochyta blight to allow timely fungicide responses and any anomalies in resistant cultivars reported to SARDI. 

Foliar fungicides for Ascochyta blight of field peas

Weather patterns experienced early in 2015 resulted in growers in many districts being advised by DAFWA’s Blackspot Manager Prediction model to sow field peas late. This timing was often out of alignment with optimal sowing times based on best agronomic practice for some districts. Growers in these districts had to decide whether to choose an alternative crop, sow field pea into high blackspot-risk situations, or delay sowing date past the optimal window for successful production. In situations such as these, growers could revise their blackspot management strategy and consider fungicide applications being recommended to manage this disease. This is becoming more feasible while grain prices are high. If going against the Blackspot Manager recommendations, and choosing to sow into periods where a high risk of blackspot spore showers are predicted in your region, growers should consider an alternative break crop to field pea. However, if field peas are preferred it is important to consider the following to reduce the risk of blackspot outbreaks:

  • Apply P-pickel T® seed treatment (PPT) to seed prior to sowing and follow up with current recommended fungicide strategies of two applications of Mancozeb®, one at eight weeks after sowing and one early flowering ɸ
  • Select paddocks with no history of field pea, or paddocks with a long break period from field pea and history of a low incidence of blackspot
  • Avoid close proximity to previous field pea stubbles, particularly downstream to prevailing wind direction
  • Delay sowing as long as possible.

ɸ Timing of spray application listed on the FMC and Innova mancozeb labels is: first sign of infection and repeat at seven to 10 day intervals (dry food consumption) or first sign of infection and repeat at two to three week intervals (fresh food consumption).

A number of industry support groups have reported the economic benefit of using fungicide in controlling blackspot in field pea. SARDI through the Southern Pulse Agronomy project is conducting field research to further investigate these economic benefits, and evaluate different fungicide application strategies to manage blackspot in field peas, with trials being conducted in different growing districts. Preliminary results in 2015 showed the current fungicide application strategy, using PPT® and two Mancozeb® applications, suppressed blackspot at most sites, but previous yield benefits reported from this treatments were not realised due to the dry spring experienced in 2015. However, new fungicide actives and formulations were also evaluated in these trials and showed significant increases in efficacy for controlling blackspot compared to both untreated plots and those treated with Mancozeb®. Furthermore, a significant yield benefit (approx. 15%) was also identified in these treatments this year. Further trials are planned in 2016 to explore these results.

Other pulse disease observations in SA during 2015

PBA Hurricane XT is moderately susceptible to botrytis grey mould (BGM) and required one or two sprays before the dry spring set in while PBA Jumbo 2 exhibited high resistance to BGM. Frost conditions seemed to interact with BGM causing yellowing in a number of crops, especially on northern Yorke Peninsula.

Chocolate spot in faba beans and vetch as well as botrytis grey mould in lentils (and tares) started to cause problems in the lower north of SA, and both Yorke and Eyre Peninsula from August 2015. Chocolate spot continued to spread on lower Eyre Peninsula until spring conditions dried crops out. This disease was especially common in early sown bulky crops.

Low levels of powdery mildew in field peas and rust on faba beans were observed in upper north crops, but the dry spring held these diseases back in most areas.

Field mould studies on faba beans

The agronomic practices of crop topping and windrowing on faba bean grain quality, as well as the impact of mechanical damage (e.g. wheel-tracks), were examined in field trials conducted in three growing regions (Eyre Peninsula, mid north and south east). This research is funded by SAGIT to examine the issue of field mould in faba bean, and is conducted in collaboration with the Southern Pulse Agronomy project funded by the GRDC. Several grain quality attributes were examined on seed harvested from the different treatments: total number of blemished seed (accumulative measure), 200 grain weight, grain uniformity (visual – colour and size score), number of weather-stained seed, number or shrivelled seed, number of seed with Ascochyta staining, number of seed with residual adhesions from pod wall. These parameters were used to measure seed quality, and their potential interaction with the incidence of field mould which has led to down grading or rejection lots at grain receival silos in past seasons.

The results from trials conducted in 2014 are discussed in this paper. That season was not favourable to the development of field mould on seed at the sites due to the mild and dry spring conditions. Though conductive conditions to disease were experienced in winter, the lack of spring rains did not perpetuate the development of Ascochyta staining on seed and minimised abiotic stresses affecting the developing pods. However, affects observed from this study can be used to provide a guide as to the dynamics of factors affecting seed development that may occur in seasons of wet conditions in spring or early summer.

The key take home messages of the impact of agronomic practices examined in faba bean seed quality were:

  • Variety has a significant effect on seed quality. The older varieties Fiesta and Nura (and Farah included in the EP trial) were consistently shown to have poorer seed quality than newer varieties PBA Rana (and PBA Zahra in the Mid North trials – see Table 1)
  • Traffic damage (wheel-tracks) significantly affected seed quality at all three sites (Tables 2, 3 and 4). This effect was significantly exacerbated in Fiesta and Nura compared to PBA Rana seen by varietal differences at all sites. However, ‘flattened plants’ were actively ‘picked-up’ during harvest to examine seed, which may not occur in large scale commercial applications
  • The practice of windrowing in itself had no adverse effect on seed quality (data not shown). Significant differences such as colour, grain weight and uniformity was driven by variety type (PBA Rana being superior to Fiesta and Nura)
  • The influence of windrowing timing (early, late or nil), examined in the Mid North trial, had little effect on seed quality. However, when windrowed treatments were combined with a late harvest treatment (mimicking leaving windrow for longer period before pickup) a significant reduction in seed quality was seen (data not presented). Varieties Fiesta and Nura were more susceptible to this effect than PBA Rana
  • In 2014, crop topping timing had a little to no effect on seed quality at all sites. However, mild and dry ripening conditions may have suppressed this effect compared to wetter conditions experienced in 2013, where an effect of crop topping on seed quality was shown by a trial in the Mid North
  • The superior seed quality of PBA Rana showed it was more tolerant to the variation of agronomic practises that might affect seed quality examined in this study, compared to Fiesta and Nura which have less consistent colour and size.

Table 1: Crop topping x variety trial conducted at Tarlee, Mid North, in 2014 to examine effects on faba bean seed quality.

Crop Top x Variety - Mid North PBA Samira PBA Zahra AF 06104-1 AF 06125-4 AF 07125 AF 08035 AF 08161 AF 09062 AF 09167 AF 09169 AF 10089 Farah Fiesta PBA Rana Nura LSD (P) 0.05
Blemish total 5.3 3.1 2.7 12.3 4.6 2.1 3.9 3.8 2.8 4.3 3.6 7.5 7.1 1.8 18.3 2.75
Uniformity 1.9 1.9 2.2 2.3 2.2 2.3 1.9 2.0 1.4 2.3 2.0 2.7 2.8 1.4 2.8 0.46
Pod Wall 2.8 0.2 0.2 7.2 1.2 0.9 1.8 0.7 0.8 0.6 1.8 2.7 2.3 0.4 13.6 2.18
Stain 1.5 1.7 0.8 1.8 2.1 0.4 0.3 1.5 1.3 1.8 0.8 2.2 1.8 0.4 0.8 1.06
Shriveling 1.1 1.3 1.7 3.4 1.3 0.8 1.8 1.7 0.7 1.0 1.0 2.8 3.0 1.0 2.2 1.28
200 grain wt 140.5 160.4 126.4 145.0 147.6 115.5 127.7 136.2 136.6 141.2 142.8 127.8 135.6 145.2 126.4 3.48

Significance at P<0.05 is indicated in bold and the Least Significance Difference (LSD0.05) is provided to compare means for each seed quality attribute assessed.

Table 2: Traffic damage x variety trial conducted at Cockaleechie, Eyre Peninsula, in 2014 to examine effects on faba bean seed quality.

Wheeltrack treat Eyre Peninsula Fiesta x Traffic Rana x Traffic Nura x Traffic Rana x None Fiesta x None Nura x None LSD (P) 0.05 Fiesta Mean Nura Mean Rana Mean  LSD (P) Traffic Mean None Mean LSD (P) 0.05
Blemish total NS NS NS NS NS NS - NS NS NS - 32.1 15.9 8.04
Pod Wall NS NS NS NS NS NS - 2.2 9.9 2.4 5.37 NS NS -
Uniformity NS NS NS NS NS NS - NS NS NS - 3.5 2.2 0.87
Stain 20.0 5.5 3.5 1.3 3.5 1.0 6.90 11.6 2.3 3.4 5.28 9.7 1.9 5.15
Shriveling NS NS NS NS NS NS - NS NS NS - 15.6 6.4 5.45
20 grain wt NS NS NS NS NS NS - 128.3 105.7 141.4 15.98 113.9 136.4 18.78

Significance at P<0.05 is indicated in bold and the Least Significance Difference (LSD0.05) is provided to compare means for each seed quality attribute assessed.

Table 3: Traffic damage x variety trial conducted at Bool Lagoon (south east) in 2014 to examine effects on faba bean seed quality.

Wheeltrack treat South East Fiesta x Traffic Rana x Traffic Nura x Traffic Rana x None Fiesta x None Nura x None LSD (P) 0.05 Fiesta Mean Nura Mean Rana Mean LSD (P) Traffic Mean None Mean LSD (P) 0.05
Blemish total NS NS NS NS NS NS - 22.8 25.8 10.0 6.91 26.8 12.2 9.29
Pod Wall NS NS NS NS NS NS - 3.4 15.9 1.5 4.48 NS NS -
Uniformity NS NS NS NS NS NS - 2.9 2.5 1.8 0.46 3.3 1.4 0.67
Stain NS NS NS NS NS NS - 10.4 4.6 4.7 3.85 10.8 2.3 7.18
Shriveling 12.5 1.3 7.0 2.5 2.8 1.8 4.96 7.6 4.4 1.9 1.82 NS NS -
200 grain wt NS NS NS NS NS NS - 130.3 118.2 143.9 2.73 122.1 139.6 5.31

Significance at P<0.05 is indicated in bold and the Least Significance Difference (LSD0.05) is provided to compare means for each seed quality attribute assessed.

Table 4: Traffic damage x variety trial conducted at Tarlee (mid north) in 2014 to examine effects on faba bean seed quality.

Wheeltrack treat Mid North Fiesta x Traffic Rana x Traffic Nura x Traffic Rana x None Fiesta x None Nura x None LSD (P) 0.05 Fiesta Mean Nura Mean Rana Mean LSD (P) Traffic Mean None Mean LSD (P) 0.05
Blemish total 25.8 14.0 37.0 0.8 7.3 10.3 8.49 16.5 23.6 7.4 4.85 25.6 6.1 8.69
Pod Wall 2.3 1.3 23.8 0.3 3.0 6.8 4.17 2.6 15.3 0.8 3.45 9.1 3.3 2.18
Uniformity NS NS NS NS NS NS - 2.9 3.0 1.9 0.72 3.2 2.0 0.69
Stain NS NS NS NS NS NS - NS NS Ns - 4.4 0.8 1.56
Shriveling NS NS NS NS NS NS - 9.8 6.9 4.5 3.47 12.1 2.0 8.00
200 grain wt 110.4 130.9 108.7 148.7 137.6 127.8 4.50 124.0 118.2 139.8 2.90 116.7 138.0 4.31

Significance at P<0.05 is indicated in bold and the Least Significance Difference (LSD0.05) is provided to compare means for each seed quality attribute assessed.

Further analyses are being conducted on the effect of crop topping on newer variety types, and seed from the 2015 trials are being collected for assessment. 

Fungicide information 

Chlorothalonil

Pulse Australia’s application has been denied by the Australian Pesticides and Veterinary Medicine Authority (APVMA) for an emergency use permit to allow for the use of non-registered chlorothalonil formulations. There are a small number of registered chlorothalonil products that have label instructions that do allow for grazing. PIRSA’s Rural Chemicals Operations group of Biosecurity SA provided advice for growers regarding the restrictions on grazing Instructions when using Chlorothalonil applied to pulse crops. Under SA’s Agricultural and Veterinary Chemical (Control of Use) legislation, chemical users are required to follow all mandatory instructions and withholding period advice on the label specific to the chemical product and label they are using. For most chlorothalonil products, the label instructions for grazing states "Do not graze livestock on treated crops." This advice not to graze livestock must be followed when using a product that has this statement. 

Chemical users should be aware that there are a small number of registered chlorothalonil products that have label instructions that do allow for grazing providing the relevant withholding period and export slaughter Interval information on the label is followed. These labels state, "Do not graze for 14 days after application," and have additional export slaughter Interval statements for livestock going for export that states, "Livestock that have been grazed or fed treated forage, fodder or stubble should be placed on clean feed for 63 days (nine weeks) prior to export slaughter." These label statements are the result of the chemical companies that manufactured those specific products providing data when registering the product with the APVMA that supports these grazing claims. Grazing is only allowed when the specific products with label statements that allow for grazing are used. Producers should check with their chemical reseller or consultant which chlorothalonil products allow for grazing.

APVMA minor use permits have been secured by Pulse Australia for the following:

Amistar®Xtra Fungicide (200g/l azoxystrobin & 80g/l cyproconazole) APVMA Permit PER81470. This permit is in force from 7 August 2015 to 30 June 2018.

For use in chickpea and lentil for the control of Ascochyta blight. Use rates; 400ml/ha.

Withholding period (harvest & grazing); 28 days. Export slaughter interval; 7 days.

Prosaro®420 SC Foliar Fungicide (210g/l prothioconazole & 210g/l tebuconazole) APVMA Permit PER81474 . This permit is in force from 7 August 2015 to 30 June 2018.

For use in chickpea and lentil for the control of Ascochyta blight. Use rates; 600–750ml/ha plus BS1000 at a rate of 0.25 per cent. Withholding period (harvest & grazing); 21 days.

Captan (800 & 900g/kg Captan products) APVMA Permit PER81406. This permit is in force from 28 July 2015 to 30 September 2018.

For use in chickpea and lentil for the control of Ascochyta blight and Grey Mould ɸ.

Use rates; 1.25kg/ha (800 g/kg products) 1.11kg/ha (900g/kg products). Withholding period (harvest & grazing); 14 days. Export slaughter interval; 7 days.

ɸ Permit also lists for control of chocolate spot

Acknowledgement

Funding for this work was provided through the GRDC Project DAS000139, UM00051, DAV00113, DAN00151, S1203 and S1208.  Their support is gratefully acknowledged.

Contact details

Jenny Davidson 
GPO Box 397, Adelaide
08 83039389

Rohan Kimber
GPO Box 397, Adelaide
08 83039380

Christine Walela
SARDI Clare
08 88426264

Larn McMurray
SARDI Clare
08 88426265

GRDC Project code: DAS000139, UM00051, CUR00023, DAV00113, DAN00151, S1203, S1208.