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.
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