G x E x M approach for Fusarium Head blight control

Researchers explored FHB management strategies focusing on a systems approach of Genotype (G) x Environment (E) x Management (M) interactions. They reviewed current literature, and included a recent western Canadian FHB research project as a case study of this approach. The results showed that a systems approach of genetic resistance combined with key agronomic strategies, such as optimizing crop uniformity, crop rotation, fungicides and inclusion of winter wheat can mitigate FHB risk, DON accumulation in grain, and optimize yields.

Fusarium Head Blight (FHB) is a major risk for wheat growers, and can reduce grain yield, quality and marketability. FHB can also result in the production of mycotoxins, such as deoxynivalenol or DON, which can be a serious risk to human and animal health. Environmental conditions such as higher humidity, frequent rainfall and relatively warm night temperatures at heading can increase the risk of FHB, especially in areas where host crop residues are present.

Researchers conducted a literature review focusing on a systems approach of Genotype (G) x Environment (E) x Management (M) interactions. Managing FHB disease risk includes selection of cultivars with disease resistance (G) in high-risk environmental regions (E) combined with various agronomic and management strategies (M).

To support the review, researchers looked at a recent western Canadian FHB research project (Ye et al) as a case study of this systems approach. This project looked at G × E × M factors that included cultivar resistance, growth habit and triazole-based fungicide application in low and high FHB environments, and the potential synergies that exist for FHB mitigation.

In the Ye et al study, field trials were conducted at seven sites across the Canadian prairies. Four management factors were studied comparing a fungicide-free control with a seed treatment (ST) of Cruiser Maxx Cereals (thiamathoxam + difenoconazole + metalaxyl-M + sedaxane), an in-crop Prosaro foliar fungicide (tebuconazole + prothioconazole) treatment applied at anthesis, and a Cruiser Maxx + Prosaro fungicide treatment. These fungicide treatments were integrated with four wheat cultivars of contrasting growth habit and differing levels of resistance to FHB, including spring wheat cultivars ‘Carberry’ (moderately resistant) and ‘Harvest’ (susceptible); and winter wheat cultivars ‘Emerson’ (moderately resistant) and ‘CDC Falcon’ (susceptible).

Integrated approach better than a single practice

The results showed that genetics and fungicide treatments produced positive crop and disease responses. The in-crop foliar fungicide treatment tended to at least protect or increase yield, kernel weight and test weight in environments where the risk of FHB was high.

Seed treatments in spring wheat did not influence crop responses to FHB, which was expected. However, for winter wheat cultivars and particularly at environments where FHB was severe, seed treatments for Emerson resulted in less variable stands than for other cultivars.

Intensive disease management is particularly important for spring wheat, as shown by the greater response to management on ‘Carberry’ over the stronger genetic response in the winter wheat ‘Emerson’. With FHB resistant winter wheat, the winter growth habit and earlier maturity may help mitigate disease risk over MR spring wheat cultivars.

Although the integration of FHB tolerant cultivars with fungicide management were beneficial for disease mitigation and yield protection, the study showed that under high FHB pressure, this approach failed to reduce DON content to a level below the maximum limit of 1 ppm allowed for some end uses. A single application of foliar fungicide in a high FHB environment will be suppressive only, and growers might benefit from a second application 20 days post-anthesis. However, growers must consider the established post-harvest intervals and maximum residue limits (MRL), which may present a problem with the timing of a second 20-day post anthesis application.

The review of literature and supporting case study by Ye et al showed that a systems approach of G × E × M factors can significantly reduce risk and improve FHB disease mitigation more than relying on a single strategy or tool.

Genetics and the continued development and adoption of FHB resistant cultivars is key to managing this serious disease. However, since no cultivar is completely resistant to FHB, increased focus on management practices is required.

Crop rotations that include non-host crops are critical to break disease cycles. In addition, incorporating tools that destroy the pathogen during host phases and further disrupt completion of the FHB disease cycle, such as residue management that pulverizes fusarium-damaged kernels, could be necessary. Practices that optimize crop uniformity to shorten vulnerable crop stages can help reduce the disease levels, and also optimize fungicide application timing. Including strategies that contribute to clean seed at planting and at delivery to grain merchants are necessary. Manipulating wheat growth habit and planting winter wheat can help create asynchrony with the FHB disease cycle, reducing the risk of disease.

The review reinforced the importance of G x E x M strategies that include the integration of FHB-resistant cultivars with appropriate cultural practices to reduce the risk of FHB and optimize grain yield. These synergies highlight the advantages of using a systems approach for FHB control.

This paper was a contribution by the authors to the Joint Plenary Session entitled ‘Toxigenic Fusarium Species and Mycotoxins: Challenges and Perspective’ held during the Joint Canadian Phytopathological Society/Canadian Society of Agronomy Annual Meetings in Winnipeg, Manitoba, 18-21 June 2017.

B. L. Beres, A. L. Brûlé-Babel, Z. Ye, R. J. Graf, T. K. Turkington, M. W. Harding, H. R. Kutcher & D. C. Hooker (2018) Exploring Genotype × Environment × Management synergies to manage fusarium head blight in wheat, Canadian Journal of Plant Pathology, 40:2, 179-188, DOI: 10.1080/07060661.2018.1445661

Ye Z, Brûlé-Babel AL, Graf RJ, Mohr R, Beres BL. 2017. The role of  genetics, growth habit, and cultural practices in the mitigation of Fusarium head blight. Can J Plant Sci. 97:316–328. https://cdnsciencepub.com/doi/10.1139/CJPS-2016-0336

Ye et al was funded by the Western Grains Research Foundation and the Natural Sciences and Engineering Research Council of Canada. In-kind support was provided by Agriculture and Agri-Food Canada and the University of Manitoba.

Photo by Anita Brûlé-Babel

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