Researchers in southern Alberta are striving to gain an advantage in combatting a persistent disease that annually devastates up to 10% of Canada’s wheat harvest, resulting in significant financial losses for farmers. Known as tan spot disease, this fungal infection is characterized by small tan lesions on wheat plants’ green leaves. While it may not cause complete field destruction like some other diseases, its widespread presence poses a consistent challenge for growers.
Dr. Reem Aboukhaddour, who heads Agriculture and Agri-Food Canada’s research lab in Lethbridge, Alberta, is spearheading a global effort to enhance understanding of tan spot disease. Despite not being the most destructive pathogen, tan spot is highly prevalent, with Aboukhaddour noting its ubiquity in commercial fields.
The economic impact of tan spot disease is substantial. In 2022, wheat generated over $50 billion in revenue in Western Canada, supporting thousands of jobs. Saskatchewan leads in wheat production, followed by Alberta and Manitoba. While tan spot may not be widely recognized, it causes millions of dollars in annual losses.
Recent breakthroughs at Aboukhaddour’s lab offer promising insights into the disease’s transmission and plant infection mechanisms. These discoveries are expected to facilitate the development of wheat varieties resistant to tan spot, contributing to safeguarding the food supply chain.
One crucial aspect of combatting tan spot is understanding its virulence factors, which are the tools a pathogen employs to bypass a plant’s defense mechanisms. While tan spot’s virulence factors are not fully understood, researchers have identified certain key characteristics. The disease spreads through spores and can survive on crop stubble, particularly in monocropping systems and under temperate wet conditions with irrigation.
Tan spot’s resilience and global prevalence have been underscored by Aboukhaddour’s team, which sequenced the disease’s genome using a vast collection of samples. This dynamic genome evolution enables the fungus to adapt and persist in wheat-growing regions worldwide.
Tan spot disease, identified around 50 years ago, belongs to the leaf spot complex, a group of diseases known to significantly impact wheat yields. Despite being challenging to manage due to its persistence and lack of information on resistant wheat strains, strategies like crop rotation and fungicide use are employed by farmers.
Farmers, facing fluctuating impacts of tan spot disease, often resort to fungicide application as a preventive measure. However, there is growing emphasis on developing genetically resistant wheat varieties to combat the disease effectively. While fungicide remains crucial, concerns exist regarding its potential to mask the true extent of tan spot damage and the risk of fungal resistance.
A proactive approach to disease management, as advocated by experts, involves continuous research and vigilance within the agricultural community to address emerging challenges promptly and effectively.