A silent threat hangs over blueberry plantations due to a pathogenic fungus, Erysiphe vacciniiresponsible for the disease known as powdery mildew, is spreading globally, seriously affecting blueberry production, particularly in Morocco.
According to a study conducted by North Carolina State University, the fungus, native to the eastern United States, has been introduced to several regions of the world, including Morocco, Peru and Portugal. Two distinct strains have been identified: one having colonized areas such as China, Mexico and California, while the other, of particular concern for the Kingdom, has spread to the Maghreb and Southern Europe.
Impact on Moroccan cultures
In Morocco, where blueberry crops play a growing role in export agriculture, powdery mildew threatens to disrupt the balance of this strategic sector. The fungus forms a white powdery coating on the surface of leaves, hindering photosynthesis and depriving plants of essential nutrients, weakening their growth and reducing their yield.
The economic losses caused by this disease are considerable: the global blueberry industry suffers annual costs estimated between 47 million and 530 million dollars, due to the increased use of fungicides and reductions in production. For Morocco, these costs could prove particularly heavy, given the dependence of certain regions on red fruit exports.
Spread through international trade
The study points to the role of international trade in the spread of the fungus. The movement of infected plants across borders would have accelerated the introduction of the disease into new growing areas. “If you ship plant material globally, you risk carrying this fungus with it”says Michael Bradshaw, assistant professor of plant pathology at North Carolina State University.
This observation underlines the urgency of increased vigilance within the agricultural trade, particularly in countries like Morocco, where climatic conditions, combining humidity and moderate temperatures, could favor the lasting establishment of the pathogen.
Towards proactive disease management
To anticipate risks and limit damage, researchers have developed a public database to identify the different strains of powdery mildew. This tool provides farmers with crucial information on the virulence of strains present in their crops and their possible resistance to fungicides. In Morocco, coordinated efforts between researchers, producers and agricultural authorities will be essential to slow the progression of powdery mildew. The introduction of suitable cultural practices, such as limiting cultivation under tunnels, could also help to reduce the severity of infections.
This fungal threat reminds us of the importance of rigorous phytosanitary surveillance and strengthened international cooperation to preserve strategic crops in the face of emerging pathogens. For Morocco, not only the resilience of its red fruit sector is at stake, but also its competitiveness on the world market.
