Faba beans, also known as fava or broad beans, have gained traction as an alternative crop to peas and lentils for Prairie farmers in recent years. The crop is known to perform well in cooler, moister areas of the province, such as the northern and eastern growing regions. Faba beans were first grown commercially in Saskatchewan in 1972, with research efforts continually expanding since the mid-2000s. In 2021, growers in Saskatchewan seeded 61,301 acres of faba beans across the province, accounting for more than half of Canadian faba bean production.
As with all crops, some specific challenges are associated with growing faba beans. Maturity and disease are two main concerns regarding faba bean production across various growing environments in Saskatchewan. Since faba beans are a long-season crop, it is essential to understand the impact of seeding dates on production. Additionally, faba beans can be infected by various pathogens, with the most detrimental being chocolate spot caused by Botrytis fabae and cinerea. Stemphylium blight and Alternaria can also be problematic, but typically to a lesser extent. The selection of fungicides registered for use in faba beans is limited and has yet to be extensively researched.
Two recent research projects funded by Saskatchewan Pulse Growers (SPG) explored agronomic best practices to achieve optimal maturity, maximize yields, and manage disease pressure in faba beans. Firstly, a small plot project investigated the potential effects of different seeding rates, seeding dates and the application of a foliar fungicide on faba bean maturity, plant stand, yield, and quality. The outcomes from this project provide growers with much-needed information on the parameters impacting faba bean maturity and yield. The second project was a paired field-scale replicated trial and laboratory pathogen plate screening analysis. The project aimed to determine which foliar fungicides registered for use in faba beans has activity on the leading fungal pathogens affecting crop production. The results from the lab plate screening were used to predict the outcomes and aid in planning the field scale trial. The field-scale component of the study evaluated the same fungicides as the lab plate screening and provided insight into the in-field performance of the fungicides.
Small Plot Project
Research led by Chris Holzapfel, PAg, from the Indian Head Agricultural Research Foundation in Southeastern Saskatchewan sought to determine how various agronomic parameters would impact faba bean crops grown in different growing environments throughout Saskatchewan. Parameters included seeding date (late April/early May vs. late May/early June), seeding rate (45 vs. 65 seeds / m2), and fungicide treatments (treated with Priaxor® or Dyax® foliar fungicides vs. untreated). The impact of the sites was also evaluated, which considered soil zone and precipitation patterns.
The study was conducted over three growing seasons (2021, 2022, and 2023) at 16 sites across varying soil zones in Saskatchewan, including regions where the crop has not traditionally been grown. Research sites were in Indian Head, Melfort, Outlook, Prince Albert, Swift Current, and Yorkton (Table 1). While faba beans are best suited for Black soil zones, researchers included sites in Saskatchewan’s brown and dark brown soil zones due to production challenges associated with pea and lentil, which are the typical pulse crops for these regions.
Table 1: Soil zones of each region where research sites are located.
| Site Locations | Soil Zone |
|---|---|
| Indian Head | Black |
| Melfort | Black |
| Outlook | Brown (irrigated) |
| Prince Albert | Black |
| Swift Current | Dark brown (dry) |
| Yorkton | Black |
The faba bean variety CDC Snowbird was grown at all sites except Swift Current, where CDC Snowdrop was grown instead. Snowbird has a higher yield potential than Snowdrop, which was considered in the data analysis.
The growing seasons included in the project were hotter and drier than average at most of the research sites. As such, conditions were not optimal for fulfilling faba bean yield potential or for the development of chocolate spot disease, which was the main disease of focus for the fungicide portion of the project. This is crucial information to keep in mind when interpreting the results, as such results may not be widely applicable in years when disease pressure is higher.
Seeding Dates
The results of the project agreed with prior research when it came to faba bean seeding dates. Planting faba beans early, specifically within the first two or three weeks of May, usually led to higher yields and earlier maturity dates. Based on the 16-site average, early-seeded faba beans yielded 17% higher than those seeded later. While some site years saw increased emergence with later planting dates, the differences were slight and inconsistent. Ultimately, the potential yield losses and disease pressure associated with later seeding dates outweigh the negligible potential for superior emergence, and earlier seeding dates are recommended.
Seeding Rates
Compared to many other crops, faba bean seeds are large, and thus, expenses and logistics associated with seeding faba beans can be complex. Because of this, growers are eager to understand optimal seeding rates for faba beans better.
Researchers in this project advised that, in most cases, faba bean seeding rates of 45 seeds / m2 are sufficient. This experiment’s higher seeding rate treatments yielded positive results at only three of the 16 sites. In areas where higher yields may be expected, such as cooler environments or where irrigation is available, seeding rates up to 50 seeds / m2 may be justifiable. Growers may consider a seedling mortality rate of around 10-25% when determining the seeding rates for faba beans in alignment with the state of seeding conditions.
Overall, this research suggests that high seeding rates are typically optional for faba beans, and growers should consider factors such as cost and potential yield increase when deciding on seeding rates.
Fungicides
Based on plant samples that the Saskatchewan Crop Protection Laboratory analyzed, chocolate spot, caused by Botrytis spp., was this project’s most common crop disease. However, it should be reiterated that disease pressure throughout the experiment remained low, likely due partly to the uncharacteristically warm, dry growing conditions across much of the project. Therefore, the results of this project on fungicide treatment may only be widely applicable in some typical growing seasons.
The fungicides used in this experiment were either Priaxor® or Dyax®. Priaxor® was discontinued early in the experiment, so Dyax®, currently not registered specifically for the suppression of chocolate spot, was used as an alternative since it has the same active ingredient.
Fungicide treatments had a minor impact on maturity, with slightly later maturity observed in the treatment groups where fungicides were applied. However, the effect was never enough to cause agronomic concerns. Once the costs of the fungicide product, application costs, and potential profit from the faba bean crop are considered, it is unlikely that the fungicide response would be significant enough to offset the input costs. As such, decisions on whether to apply fungicides should be based on actual disease pressures rather than preventative applications of foliar fungicides. Farmers are advised to assess disease pressures in their fields and evaluate the economic viability before deciding on fungicide treatments.
Environment & Site
This project included research sites across the province. The study determined that faba beans are well-adapted to irrigated production in the brown soil zone (observed in Outlook), while the dry dark brown soil zone (Swift Current – which consistently produced the lowest yields) may not be suitable for faba bean production compared to cooler, wetter regions of the province. This result was expected, considering the brown and dark brown zones are not typical faba bean growing areas.
The faba bean crops generally developed more slowly at sites with less moisture and cooler temperatures (Indian Head). However, there was considerable variation in maturity and yield between site years and locations. Average days to maturity across the site years ranged from 88 to 109, with Swift Current tending towards the lower end of the range and Indian Head trending towards the higher end. Often, but not always, higher days to maturity correlate to higher yields.
Disease pressure was low across all sites, where 75% of sites reportedly had disease levels <5% at early flowering based on visual inspections.
By understanding the impacts of seeding date, seeding rates, and fungicide applications on faba bean production, farmers can make informed decisions to enhance crop yields, reduce disease pressure, and ultimately maximize profits.
Paired Field-Scale & Laboratory Pathogen Plate Study
The objective of the paired field-scale and lab plate study was to evaluate the efficacy of four different fungicides (RevyPro, Delaro, Miravis® Neo, and Zolera®) currently registered for use in faba beans in controlling various pathogens, including chocolate Spot (Botrytis spp.), stemphylium blight, Alternaria, and sclerotinia stem rot. The project had two stages: a lab portion and an in-field portion.
In the first stage, researchers conducted an initial lab plate screening to determine pathogen sensitivity to the selected fungicides. Essentially, pathogens were incubated in agar plates and exposed to each fungicide at various rates. Pathogen presence was measured at 1, 3, 5, 7, and 14 days after fungicide exposure. In the laboratory pathogen plate stage of the study, all four fungicides tested were effective at controlling fungal pathogens, including Stemphylium botryosum, Stemphylium vesicarium, Botrytis fabae, and Botrytis cinerea, compared to the control, in which no pesticides were applied. This first stage of the project helped in planning the field trial.
The project’s second stage consisted of a replicated field-scale fungicide trial in Tisdale, Saskatchewan. The goal of the field trial was to assess the performance of these fungicides under typical field management practices. The faba bean crop was planted in the first week of May 2023, and the the fungicides were foliar applied at label rates and restrictions on June 28th, coinciding with mid-flower for most of the field.
The fungicide efficacy of the four products was essentially tested on Stemphylium and Botrytis cinerea since these two pathogens were confirmed on plant samples from the field trial. Alternaria and Ascochyta were also detected, but none of the tested fungicides had activity on those pathogens. Sclerotinia and Botrytis fabae were not detected in any samples collected, so the fungicides could not be evaluated for their efficacy in suppressing those pathogens.
The results of the field trial showed no significant differences in faba bean yield, maturity, or visually noticeable presence of crop disease between the different fungicide product treatments (Fig. 1). Even though there was no significant impact on yield, differences were observed in disease control, where Miravis Neo treatments showed the most considerable efficacy on suppressing both fungal pathogens tested in-field, but yielding the lowest. All fungicide products effectively controlled Stemphylium blight except for Zolera, and RevyPro was the only product that did not show efficacy on Botrytis cinerea (Fig. 2, Fig. 3).
Ultimately, the paired field and lab project provides valuable information for pulse growers in understanding the efficacy of fungicides currently available in faba bean in suppressing various crop diseases. Additionally, the study highlights the importance of conducting field-scale trials to evaluate the performance of fungicides under real-world conditions. This allows researchers and growers to assess how fungicides perform in the field, providing more accurate data on their efficacy.
Conclusion
It is widely agreed that earlier seeding dates for faba beans, typically within the first two weeks of May, offer farmers the best yields and earlier maturity dates. Additionally, seeding rates of 45 seeds / m2 are usually sufficient. Seeding rates over this tend to provide a limited return on investment.
Fungicides currently available on the market vary widely in their efficacy at controlling disease in faba beans, with negligible effects on crop yields and maturity dates. In the in-field fungicide trial, MiravisNeo and Zolero most effectively controlled chocolate spot (Botrytis Cinerea). However, Zolero did not control Stemphylium blight, and MiravisNeo plots had—although statistically insignificant—the lowest crop yields compared to the other treatments.
Of course, this should be interpreted with the understanding that fungal diseases, including chocolate spot, tend to be more prevalent in moist or humid years – which was not the situation in the studies above.
In brief, based on recent research surrounding optimal faba bean production, farmers are advised to make agronomic decisions that align with their soil type, environmental conditions, and current disease pressures. Continued research efforts will further advance our collective understanding of faba bean production, ensuring the long-term success of the crop for prairie pulse growers.
Growers can refer to this SPG webpage to stay current on fungicides registered for use in faba beans.