Project AbstractFusarium head blight (FHB) is a serious problem for grain production in Canada. Specifically, Fusarium graminearum produces high levels of deoxynivalenol (DON), a mycotoxin that interferes with acceptability of grain for livestock and human consumption and has quality and functional impacts for the brewing, milling and pasta industries. A three year, field scale study conducted in southern Alberta attempted to verify and demonstrate best management practices associated with irrigation scheduling and fungicide applications. Fusarium damaged kernels (FDK), a visual grading, were shown to be reduced up to 3.9% with irrigation management and 5.5% with a fungicide application in the co-operators fields (Tables 1-3). Fungicide treatments reduced FDK in 12 of 15 fields (%80) by up to 5.5% in 2010, 2.4% in 2011 and 1.7% in 2012. However, irrigation appears to be a key influence as 83% of Fg infected grain samples were from irrigated fields, whereas only 17% were dryland production fields Over the three year study period, 33% of fields that had Fg in the grain samples used conventional tillage, were under irrigation and had grown a host crop within two years. Net economic benefits of fungicides was positive in 4 of 5 durum fields ranging from approximately $1-$3/bu while hard red spring fields showed a positive net benefit in 6 of 9 fields ranging from $0.1 -$1.75/bu. In addition to the field-scale trials, 25 commercial wheat fields were surveyed each year to study production practices that might influence the prevalence of FHB. |
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Project Objectives
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Methods |
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All treatments assisted in identifying Fusarium management in wheat, barley, and corn. The main purpose of this study was to demonstrate and fine tune known Fusarium head blight management strategies in a practical field scale approach. In order to accomplish this, Farming Smarter worked with nine producers across southern Alberta (Field-Scale Trial) to study various fungicide and irrigation treatments in 2010 to 2012. An economic analysis of results was completed by ARD economists. We also completed an annual survey of 25 additional fields (Annual Field Survey) to better understand infection levels and linkages to common management practices |
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Field Treatments and procedures
One field in 2010 and three fields in 2011 and 2012 received a split irrigation treatment, in which a portion of the field was irrigated during flowering and for the remainder, irrigation was avoided for approximately 4-6 days during the critical flowering period.
Six fields each year received comparative fungicide treatments during the trial. Fungicide selection was left to the co-operating producers. Fungicides were applied by ground sprayer when the crop was between 75% head emergence and 50% flowering (anthesis) of heads on the main stem and according to recommended practices and rates (Anonymous 2011). The only exception to this was co-operator 5 in 2010, whose fungicide was aerially applied due to wet field conditions (Table 1).
Fungicides were applied at recommended rates, i.e. Caramba at 405 mL/ac, Folicur at 118 mL/ac, and Prosaro at 320 mL/ac (Anonymous 2011). One exception was in 2010 when co-operator 6 added a ¾ rate of Folicur to compare to the full rate treatment. In 2011, co-operators 6 and 8 tested two wheat cultivars in addition to the irrigation or fungicide treatments in their fields (Table 2).
Disease ratings were collected at the late milk to early dough stage. In each treatment, fifty heads were examined at six stops for a total of 300 heads. Percent incidence was recorded as the number of heads exhibiting visual symptoms of FHB. Percent severity was determined by examining each affected head and recording the percent spikelets infected on the head. FHB index was calculated by multiplying the % incidence by % severity and then dividing by 100.
Yield and Grain Analysis
Yield data was collected when possible for each treatment, using either yield monitor technology or determined by hand-harvesting. Hand-harvesting included 10 random locations of 1 m2 quadrats per treatment. The material was then threshed using a Hege plot combine and weighed using calibrated analytical balances.
Grain samples from each treatment were collected to assess quality including thousand kernel weight (TKW), test weight (TWT) and protein content. Thousand kernel weight was determined by taking subsamples from each grain sample, counting out and weighing 100 kernels, and multiplying by 10. Test weight was determined with a Dickey-John GAC 2000. Protein was determined with a calibrated Foss Food Technology Grain Spec.
Each grain sample was also assessed for grade and percentage of Fusarium damaged kernels (FDK). These assessments were completed by Cargill AgHorizons Ltd. in Lethbridge according to Canadian Grain Commission standards (Canadian Grain Commission, 2010). Subsamples were sent to Dr. Kelly Turkington's lab (AAFC Lacombe) for pathogen isolation (Fusarium spp., Pyrenophora tritici-repentis, Stagonospora nodorum, etc.) and to AAFC Winnipeg for grinding of samples and AAFC in Ottawa for deoxynivalenol (DON) analysis using an ELISA-based technique.
Pathogen isolation and identification procedures were similar to those reported for residue samples from 2010- 2012. For DON assessments, it was ensured that each grain sample was well mixed so that the lighter (FDK) kernels were incorporated with the heavier healthy kernels. The grain was sent to Dr. Jeannie Gilbert's lab (AAFC Winnipeg) for grinding prior to assessment of DON. For grinding, the well mixed sample was passed through the grinder. Next, exactly one gram of the ground sample was placed into a 10 ml screw cap centrifuge tube with an identification label firmly attached.
After grinding each sample, the grinder was thoroughly cleaned using an air hose and vacuum. The ground samples were then sent to Dr. B. Blackwell lab (AAFC Ottawa) and analysed for DON content. The 1.0 gram sample was taken and extracted with 5 ml methanol:water (1:9 vol/vol) in a 10 ml plastic tube, which was subjected to end-over-end mixing for 1 hour and then centrifuged at 2,000 rpm. DON analysis was performed on the filtrate by the competitive direct enzyme-linked immunosorbent assay procedure (ELISA) described by Sinha et al. (1995). Results are reported in ppm and the limit of quantitation is 0.1 ppm.
Economic Evaluation
The following outlines the key elements for evaluating BMP's related to the project. The economic evaluation of BMP's is layered over the production-based findings, extending the interpretation from simple yield and revenue results to actionable "net profitability" estimates. As such, producers were exposed to information on, and procedures to evaluate, in their own businesses, the benefits and costs associated with Fusarium mitigation strategies.
Key Production Research parameters
Project design lays out field trials and demos, differentiating treatments by:
- crop,
- timing of irrigation, and
- fungicide application.
Project results collected, by treatment, include:
- yield,
- grade,
- incidence of infestation, and
- severity of infestation
Crops were valued using local pricing, accounting for grade and yield, by treatment. Direct costs, by treatment, were estimated using fungicide and application costs as appropriate. Differentials in other direct and indirect costs will be accounted for, starting from base line AgriProfit$ benchmarks.
AgriProfit$ - Business Analysis & Research Program, Economics & Competitiveness Division, Alberta Agriculture and Rural Development
Using the RiskChoice$ approach, charting BMP's according to their likelihood (risk) and impact (net benefit) adds a much needed dimension to the presentation of trial and demo results
Evaluation Procedures
The primary focus of the economic evaluation related to short term (annual) net benefit estimation. Both risk and return components are highlighted ≥ ranking BMP's by likelihood and net benefit . This creates actionable information for producers entertaining direct or systems-related BMP's, and enhances adoption, as appropriate, based on farm-specific circumstances.
It is of significant note that, depending on the mitigation strategy selected, longer term benefits, costs, and risks can also accumulate. These are not involved in the direct scope of this project and will be addressed qualitatively. They can, however, have far reaching effects on the production, agronomic, and systems choices available to producers in the near term, spilling over to long term shifts in profitability.
Standardized partial budgeting procedures were used to quantify net change in profitability by treatment and associated BMP's. Treatments were compared regarding their added (input and operating) costs and reduced returns (driven by yield and grade), relative to a control or a base case.
As noted previously, these net benefits, or changes in profitability were then mapped relative to their associated risk (see the "BMP Risk-Return Concepts" graphic for a sample depiction). This enables producers to evaluate BMP's relative to the likelihood and severity of a Fusarium event. Mitigation strategies can be short listed according to those practices to avoid and those practices that offer the best profitability outcome.
Annual Field Survey
A head survey of approximately 25 randomly selected fields was conducted in 2010, 2011 and 2012 at the late milk to early dough stage (Table 4, Table 5, and Table 6). The survey included both irrigated and dryland fields across southern Alberta. In each field, 100 heads were examined in three locations for a total of 300 heads per field. Heads were collected, hand threshed, and grain sent to Dr. Kelly Turkington's (AAFC Lacombe) lab for pathogen identification.
Agronomic information was collected from producers including variety, crop rotation, irrigation regime and FHB history of the field surveyed as well as adjacent fields. Cultivar susceptibility was determined once variety information was collected.
Maps were created to evaluate the distribution of Fusarium damaged kernels (FDK) throughout the study for 2010- 2012 using Arc Map (Figure 8). The legal land description from each field were converted to latitude and longitude coordinates using prairie land locator that pinpoints the location to the center of a section; therefore the positions are within a ½ mile accuracy of the true field. The projection is North American Datum 1983 Universal Trans Mercator Zone 12 North, a common projection for Alberta maps.
Demonstration Trials
Demonstration plots were established in 2010 at the Farming Smarter research & demonstration site just east of Lethbridge, Alberta (Figure 39). Plots were set up with 6 susceptible varieties under standard irrigation and reduced irrigation and an application of one of three fungicides and a check.
The Fusarium demo in 2011 contained varieties from CPS, CWSWS, Triticale, Durum, CWRS, CWHWS, general purpose wheat, 2-row malt, 6-row feed & malt or 2-row feed in combination with one of four treatments; Prosaro, Caramba, untreated check or inoculated check (Figure 40).
2012 looked at one of three fungicide application timings; with herbicide, at flag leaf and FHB timing (Figure 41).
Results
Field-Scale Trials
Some good results were gathered in 2010 despite a very challenging season with regards to weather (Table 1). Seeding was delayed due to a very wet spring which led to many producers to change their cropping plans, usually from durum to spring wheat. Some fields also had multiple seeding dates due to areas drowning out after being seeded. Co-operator 2's field received no irrigation or fungicide treatments due to excess moisture.
The wet weather continued until June, leading most producers to delay irrigation until well after flowering, if at all (Figure 44, Figure 45). However, co-operators were able to administer fungicide applications, except co-operator 5, who was unable to leave a check strip due to the requirement of an aerial application. A severe hail storm caused significant damage to co-operator 7's field, which decreased the amount of data that could be collected.
In 2011, extreme spring precipitation also created complications. However, three producers were able to administer irrigation treatments and eight applied fungicide for FHB suppression (Figure 46, Figure 47). Two co-operators, 5 and 7, were unable to leave check strips when applying fungicide (Table 2). Co-operator 1 administered irrigation treatments, but had significant flooding and excess moisture issues, leading to late seeding and harvest.
2012 brought a cool, wet spring that promoted lush crop growth. Starting around July, temperatures were above normal and very little precipitation occurred during the flowering period and throughout harvest (Figure 48, Figure 49). A number of late season days over 30 degrees resulted in yields that were lower than expected. These environmental conditions favored leaf disease, but not Fusarium due to the hot and dry conditions during flowering. Heavy winds after swathing reduced yields for co-operator 1, while late season hail reduced yield on field 3; which prevented data collection of FDK, DON, grade and accurate yields.
Economic Evaluation of Field Trials
Project results from the three years of trials do show differentiation between treatments. There is an indication that some of the BMP's may show a positive short term net benefit (Figure 1-6).
However, rainfall events during one of the project's crop years removed the opportunity to gain agronomic results associated with timing of irrigation. Moisture conditions were such that irrigation was not required, effectively removing one of the conditions that allows Fusarium to thrive.
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| Fig 1. Likelihood of Net Benefit with Fungicides and Irrigation Management | Fig 2. Change in Durum Net Benefits 2010-2011 |
Results - Fungicide Applications
Trial results do reveal some of the patterns expected regarding fungicide applications and Fusarium control. Durum, which is more susceptible to Fusarium, shows a predominant pattern of improved profitability for four of the five fields in 2010 and 2011 while all five fields showed a reduction in %FDK (improvement, y-axis) (Figure 3). Please note that durum results for 2012 are not included due to incomplete trial data.
The results for the hard red spring trials are more mixed, but still visibly hold a pattern similar to durum (Figure 4). Five of nine trials showed an improvement in net benefit and % FDK relative to the average of the check fields. One trial showed a net decrease in both, while one trial result showed an increased net benefit even though the % FDK also increased compared to the average. These results could be attributed to a wide array of agronomic reasons and conditions conducive to Fusarium infestation.
The net benefit of individual fungicide applications within each trial year was reviewed for potential patterns (Figure 5). Results show that durum displays a distinct net benefit pattern in 2011. When this result was cross referenced with type of fungicide applied, this net benefit was associated with Prosaro. However, caution should be used with this result as agronomic practices and/or the 2011 growing year may have had an effect. As such, both of these areas should be considered in future research trials. Negative net benefit in the 2010 field was due to highly reduced returns associated with severe yield loss and grade reduction due to frost damage. Again, durum trial data for 2012 could not be included due to incomplete data.
However in trials of hard red spring wheat no clear pattern was found when the net benefit of fungicide application was compared among years (Figure 6). We can see that in 2011 there was a definite net benefit from fungicide application. But years 2010 and 2012 showed mixed results. Again the impact of agronomic practices and/or growing year conditions may have had an effect. Therefore, additional future research should be of consideration.
Fig 3. Change in HRS Wheat Net Benefits and %FDK with fungicide applications 2010-2012
Fig 4. Change in Durum Net Benefits associated with fungicide applications and %FDK
Results - Irrigation Timing
Prevailing moisture conditions in the first two trial years limited the ability to observe Fusarium response to delayed vs. regular irrigation timing. A few observations were available for comparison, though. In all three instances, delay of irrigation was at least indifferent or improved % FDK, without a net reduction in economic benefit (figure 7). Again, please observe that durum results for 2012 could not be included due to incomplete data.
If the pattern of delaying irrigation during flowering holds, then it may provide producers with a viable option to manage moisture conditions, thereby reducing the likelihood and severity of Fusarium within a cropping season.
Fig 5. Change in HRS Wheat Net Benefits and %FDK with fungicide applications 2010-2012 Cross-referencing with timing of irrigation should add a significant dimension to the results. Extension of these findings adds information to producers to evaluate management options.
Fig 6. Change in Durum Net Benefits and %FDK with irrigation scheduling 2010-2011
Short & Long Term Implications
The evaluation approach documented above lays out the nature of short term economic results expected from the project. However, there are longer term considerations that should also be kept in mind, predicated on the notion that "Fusarium is here".
If practical mitigation strategies are not put in place, the disease will likely increase in frequency and severity. As such:
- near term BMP's that keep FHB in check and manageable are likely more cost effective than the future, more radical treatment approaches
- crop rotations and other common cultural practices, in combination with fungicide use, may effectively minimize the impact of Fusarium in susceptible crops on a year-to-year basis. However, it would likely be best to combine fungicide use, with rotation and use of a resistant variety to provide the most effective reduction in the impact of FHB
- maintaining flexibility in crop and varietal choices for annual cropping plans is critical. Fusarium has the potential to chase current profitable and risk-beneficial crops out of rotations
- reliance on new disease resistant varieties comes at a cost, typically a yield or quality trade-off
Each of these elements can effectively diminish the long term profit prospects of crop producers in the region. This project stands to reveal some practical, realistic, and profit-motivated BMP's that could be readily adopted by producers.
Finally, the evaluation processes and logic presented are not restricted to Fusarium-related BMP's. These same principles apply to similar diseases afflicting crop production. The knowledge set associated with this project is transferrable to other cereal disease issues.
Weather Monitoring
Weather data was collected by accessing information from the closest weather station from Alberta Agriculture and Rural Developments AgroClimatic Information Service (ACIS).
Additionally, FHB risk forecasts were accessed for 2011 from the CWB for areas in southern Alberta where field trials and surveys were located (www.cwb.ca). In 2010, above average precipitation occurred in many areas of southern Alberta and likely contributed to the development of FHB in some fields
In 2011, dry conditions in July likely precluded the development of significant levels of FHB in southern Alberta. The lower levels of FHB, seed infection and DON contamination observed in 2011 in southern Alberta generally reflected the low risk of FHB that was predicted by the WeatherFarm FHB risk map forecasts generated by the Canadian Wheat Board. For example, Figure 7 has the risk forecast map for July 1, 2011 and for a wheat variety rated as poor for FHB resistance. For southern Alberta on this date, the risk of FHB was rated as low.
Given changes to the Canadian Wheat Board, forecasts were not available for 2012.
Precipitation and temperature from nearest weather stations is attached in Appendix D.
Figure 7: Fusarium head blight risk forecast for wheat varieties rated as poor for FHB, July 1, 2011. Weather Farm website, courtesy of G. Ash, Canadian Wheat Board, Winnipeg, MB.
Results Table
Results from the field-scale trials are displayed below. Table 1 summarizes the data collected in 2010, Table 2 the data from 2011, the data from 2012. Information includes spring stubble samples, cultivar susceptibility to FHB, treatment details, visual disease ratings, grain quality characteristics, % FDK, DON levels, and yield. Explanation of significant results follows the tables.
Download our report to view the tables, and our complete results:
Recommendations
Fusarium Head blight management is critical to the long term sustainability of irrigated crop production in southern Alberta. Irrigation is costly but enables producers to grow extremely valuable crops that contribute a large percentage of gross revenue to Alberta's agricultural industry. Cereal crops remain very important for both profitability and as rotational components to high value crops such as canola (seed and production), potatoes, sugar beets and dry beans. FHB can significantly reduce profitability of cereals which may result in the reduction of cereals grown in irrigated rotations. This in turn can result in higher proportions of alternative crops, creating new risks of disease outbreaks.
Community based systems approaches are clearly required for FHB management. Positive results from this study help demonstrate the effectiveness of best management practices and the real, economic impact associated with their adoption. Due to the localization of inoculum and its ability spread in the wind through spores, it is not only important for individual producers to adopt BMPs but for all neighbours to make similar efforts.
Information generated through this trial has demonstrated that fungicides can be effective while irrigation scheduling at a minimum can be accomplished without compromising yield. It also showed that awareness of FHB is continuing to grow as the problem continues to spread. While field scale research has proven valuable it is not without drawbacks. Clear and concrete statistical information was very difficult to obtain as many variables were impossible to control. Weather issues affected results as well as technical issues with yields monitors. Producers had varying equipment capabilities and management styles which lead to unique situations on every field. Nevertheless, they worked diligently in providing some real world experiences with FHB management. Future small plot and field scale work is warranted but there is a need for improved techniques.
Key messages
Moisture arrives in the crop canopy from various sources including rain, dew, fog, and irrigation and is stored in various components of the crop volume, where it can potentially influence disease development. The current PMC project illustrated the beneficial influence of fungicide application in terms of reducing disease and DON contamination, while potentially increasing crop yields and TKW. Irrigation treatment is an influential factor in the development of Fusarium head blight in dry areas such as southern Alberta, although excesses or droughty conditions can override the potential impact of irrigation management.
The Alberta field assessments from the current irrigation study, as well as results from the commercial field surveys, and field characteristics have showed that the presence and increased level of FHB and percentage seed infection with F. graminearum were more commonly associated with irrigated wheat compared with dryland production, where a susceptible variety was grown and no fungicide applied and potentially where tighter rotations with susceptible crops occur. Similar irrigation results were found by Strausbaugh and Maloy (1986) in Washington State, where scab, caused by various Fusarium spp. including F. graminearum, was found in irrigated fields, but not in dryland wheat fields.
Overall, the current study indicated that reducing irrigation at flowering and/or fungicide application and using a less susceptible variety may have a beneficial impact on disease levels, while maintaining yields when the risk of FHB is high. Although difficult to demonstrate given the nature of the current study the use these strategies in combination may help to provide more effective FHB management.
The most difficult aspect of irrigation management for FHB control in the irrigated dry regions of southern Alberta will be trying to balance the water requirements of the crop versus the need to reduce the risk of FHB. Efetha (2003) has produced a set of recommendations to help producers meet the water needs of their cereal crops, but at the same time reduce the risk of FHB and potential DON contamination of harvested grain.
Other pathologists with extensive FHB experience have indicated that irrigation should not be applied for 5-10 days after flowering to help limit humid conditions that favour infection (M. McMullen and B. Stack, North Dakota State University, personal communication). This is consistent with the results and interpretation from the current studies. Moreover, the current study suggests that reducing irrigation will likely not result in a negative impact on crop productivity, but can have a beneficial impact in relation to reducing the severity and impact of FHB.
Implementation of results
- fungicides can work well, but do not always limit FHB. It will be crucial to also look at a combination of more resistant varieties, longer rotations and irrigation management and by using these three strategies farmers may be able to limit FHB without resorting to fungicides unless the disease risk clearly warrants it
- avoid highly susceptible wheat classes and varieties
- encourage irrigation scheduling especially since no yield losses were shown with this practice
- continue to increase awareness of FHB and management practices through extension activities including video production of results and recommendations
- extend information to other wheat growing areas as FHB continues to spread and is well established in southern AB, especially under irrigation
- inform growers that dryland can be at risk as well when moisture is available
- develop continued surveys perhaps work with seed testing labs
- monitor environmental conditions during flowering critical for disease development and may limit the impacand usefulness of some or all management strategies
- work with grain graders to ensure FDK levels are correct and determine relationship with DON
- Develop ways to better communication area specific Fg inoculum levels. I.e. are you in an Fg hot spot? Fast and complete forecasts for weather during flowering
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