By Heather Cosgriff, SFS
- PBA Samira had the highest yield under irrigation at Cressy focus site.
- Nura and new variety PBA Zahra also showed promise.
- Establishment rate of 30 plants/m2 resulted in highest yield.
- Low disease pressure meant that there was no significant difference between a moderate and intensive fungicide program.
Legume break crops are extremely important in stubble retained cereal growing systems to provide a disease and weed control break for growers.
Faba beans are one of the most water-logging tolerant grain legume species (Solaiman et al. 2007), as well as being tolerant of acid sub-soils, which should make them an ideal crop choice for Tasmanian conditions.
They are also relatively frost tolerant and respond well to cool spring conditions for pod-fill (Agriculture Victoria 20132), but they have not been popular, mostly due to the inherent susceptibility to disease and availability of other more valuable crop species, such as poppies.
In 2014 poppies suffered extensively from systemic mildew, and the uncertainty surrounding the future control of that disease renewed grower interest in alternative crops.
New, more disease-resistant (common diseases Chocolate Spot and Ascochyta Blight), varieties have recently been released, making this a good time to test them in Tasmanian conditions.
It was hypothesised that these would have a better fit for the irrigated or high rainfall zone of Tasmania than older varieties and trials were set up with funding from the GRDC Stubble Initiative to explore crop management for maximising faba bean yield.
In terms of seeding rate, current management guidelines, Pulse Australia (2016), recommend growers should establish optimum plant populations for the variety, situation and sowing time. Plant populations ranging from 20 plants/m² up to 35 plants/m² are highlighted as the optimum range for Victorian conditions, and it was worth testing these rates under Tasmanian conditions.
Location: Pisa Estate, Cressy
Sowing date: 13 May 2015
Two trials were established under irrigation at Cressy to test faba bean variety yield response to fungicide regimes and establishment rate.
Fungicide management trial
Varieties: PBA Zahra, PBA Rana, Nura established at 25 plants/m2.
- Nil – no fungicide
- Standard – fungicide at early flowering and again two-to-three weeks later. (Carbendazim 500 @ 0.5 L/ha, Chlorothalonil (Bravo) 1.3 L/ha)
- High – fungicide at early flowering and then fortnightly until flowering complete. (Carbendazim 500 @ 0.5 L/ha, Chlorothalonil 1.3 L/ha)
Sowing rate trial
Varieties: PBA Zahra, PBA Samira
Sowing rates: 10 plants/m², 20 plants/m², 30 plants/m², 20 plants/m² nil inoculant
The high fungicide management regime was utilised on the sowing rate trial, other crop inputs for both trials are shown in Table 1.
Table 1. Trial inputs for the fungicide and sowing rate trials
Reason for application
|super||200 kg||at sowing||
target yield 5t
|liquid zinc||3L||16 weeks||
correct nutrient level
|Clethodim 240||500mL||early flower||
Yields achieved were considerably higher than the target yield of 5t/ha with the exception of plots established at 10 plants/m².
The management decision that had the greatest effect on yield was seeding rate (Figure 1).
PBA Samira established at 30 plants/m² yielded 7.85 t/ha, significantly higher than any other treatment. The next highest yielding variety was Nura, with 6.65 t/ha established at 25 plants/m² in the fungicide management trial (Table 2).
These results suggest that growers should target higher seeding rates under irrigation, and we may not have found the ceiling for optimum seeding rate yet.
Table 2. Fungicide regime and variety effect on yield.
Disease levels in the trials were very low during the 2015 season. Table 2 displays disease levels recorded in the fungicide management trial in September and October. Only chocolate spot (Botrytis fabae) was detected in the crop in early September and rated on a 1-10 scale (1 = <10% of leaf area infected, 10 = 100% infection).
Plots were again rated for disease pressure a month later, with per cent of leaf area in upper third of crop canopy recorded. At this stage disease levels had reduced (most likely due to very dry conditions and lack of humidity in the canopy). There was therefore no significant difference in disease control between fungicide treatments, but a slight variety effect was recorded with PBA Zahra and Nura being more susceptible to chocolate spot infection.
Faba beans showed great promise as an alternative winter crop under irrigation.
With a high yield of 7.85 t/ha, and average just below 6t/ha, they could compare favourably with cereal crops for economic benefit.
The limitation for Tasmanian growers will be the marketing of the grain. Faba beans are exported to the Middle East for human consumption, but from Tasmania this may not be an option. Development of a local market, most likely for feed, will be critical to the success of the crop.
The stubble project – maintaining profitable farming systems in Victoria and Tasmania with retained stubble (project number BWD00024) is funded by the GRDC.
Z. Solaiman, T. D. Colmer, S. P. Loss, B. D. Thomson, K. H. M. Siddique (2007). Growth responses of cool-season grain legumes to transient waterlogging. Australian Journal of Agricultural Research 58(5) 406–412.
Agnote AG0083 1994 (updated 2013).
Pulse Australia (2015). Management Guideline. Faba bean production in the South and West.