Navigating the stripe rust challenge
Stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici is a major pest in Alberta. Infection by stripe rust can cause significant impacts on photosynthetic leaf area and lead to shrivelled kernels. Southern and central Alberta are considered higher-risk areas while northern Alberta and the Peace Region are lower risk. Alberta Agriculture and Irrigation have indicated an increase in the prevalence of stripe rust in central Alberta1. Considering this pest can cause yield losses, even up to complete crop loss2, its management is vital. Luckily for farmers in Alberta, plenty of research has been conducted to mitigate the potential impacts of strip rust. In this article, we will provide an overview of the main management tactics farmers can use on operation.
Stripe rust infection and epidemics in Alberta mainly result from windborne spread of fungal spores from the United States. These spores infect host plants such as wheat, barley, triticale, and host weeds. Plant infection can occur within hours of contact with a host plant eventually causing a yellow stripe appearance that extends through the length of the leaf blade. Under conducive weather conditions (5 degrees Celsius to 15 degrees Celsius and intermittent moisture), sporulation leads to disease spread. As the season progresses, yellow infections turn into brown telispores. Infection significantly reduces photosynthetic leaf area, reducing yield and impacting grain fill.
Farmers can utilize multiple management tools to not only be aware of potential incoming infections, but also mitigate the impacts of infections if they do occur.
First, producers in higher-risk areas of the province should consider selecting varieties with higher resistance to stripe rust. Within the Alberta Seed Guide, all spring wheat and durum are rated for resistance to stripe rust. Keeping other agronomic considerations in mind, producers can select highly resistant varieties.
Producers and agronomists should use the best tools to monitor incoming infection. In season, the Prairie Crop Disease Monitoring Network creates Cereal Rust Risk reports. These reports show the risk of stripe rust infection on the prairies, considering infection levels in the United States and wind patterns that might carry fungal spores. Within the season, timely scouting and monitoring for disease are essential to catch infection early. Checking for disease during herbicide and Plant Growth Regulator timing can help spot infection. However, scouting just before the flag leaf or the penultimate it emerges is vital. A fungicide application for stripe rust is typically recommended when you have about one to five per cent of the plants showing symptoms or leaf area affected by rust3. Therefore, monitoring at this time ensures a timely application.
Finally, specific crop and field management tactics can help reduce stripe rust risk. Although winter survival of stripe rust is less likely, warmer winters may allow it to overwinter in Alberta. To lower the risk of local infection sources, producers should rotate out of cereal crops, avoid overlapping winter and spring host cereal crops, and control host weeds and volunteer cereals. Additionally, targeting earlier seeding dates for spring cereals can help crops reach maturity before rust significantly impacts yield (Alberta Agriculture and Irrigation, 2023).
Producers and agronomists should also be aware that the Alberta Wheat and Barley Commissions continue to invest research dollars into management and understanding of wheat diseases like stripe rust. This allows Alberta farmers to have continued access to the most resistant varieties and modern management practices.
Stripe rust can pose a significant threat to cereal crops in Alberta. However, through the implementation of a multi-pronged management and mitigation approach, producers and agronomists can drastically decrease the impacts that stripe rust can cause. Through appropriate biovigilance, scouting, and crop management, stripe rust management will become a more manageable and less damaging aspect of cereal production.
Reference:
1 Alberta Agriculture and Irrigation. (2023, March 1). Stripe rust 101: What is it, why do we have it, what can be done about it. Stripe Rust 101 : What Is It, Why Do We Have It, What Can BeDone about It. https://open.alberta.ca/publications/stripe-rust-101
2 Chen, X. M. (2005). Epidemiology and control of stripe rust [Puccinia striiformis f. Sp. Tritici] on wheat. Canadian Journal of Plant Pathology, 27(3) 314–337. https://doi.org/10.1080/07060660509507230. Conner, R.L., Kuzyk, A.D., & Thomas, J.B. (1988). Overwintering of stripe rust in southern Alberta. Canadian Plant Disease Survey, 68(2), 153.
3 Washington State University Extension. (2023). Stripe Rust Control. Stripe Rust. https://striperust.wsu.edu/disease-management/control/