Late blight

Late blight is a devastating plant disease caused by the oomycete Phytophthora infestans. It is widely recognized as one of the most destructive pathogens for solanaceous crops, primarily targeting potatoes and tomatoes, leading to total crop failure if left unmanaged.

Symptoms typically begin with dark, water-soaked spots on foliage and stems. Under high humidity, a distinct white, fuzzy growth emerges on the underside of leaves, which are the sporangia of the pathogen. Eventually, the entire plant may collapse, and tubers or fruits may rot due to the infection.

The life cycle of Phytophthora infestans is highly efficient. It survives the winter in infected tubers or as dormant oospores in soil. In the growing season, it produces zoospores that are dispersed by wind and splashing rain, allowing the pathogen to colonize new plant tissue rapidly through stomata or directly through the cuticle.

Development is heavily dependent on specific climatic conditions. The pathogen thrives in cool, wet weather, particularly when temperatures remain between +15°C and +22°C with high relative humidity or persistent fog. Under these conditions, the infection cycle can repeat in less than a week, creating an epidemic outbreak.

• Planting certified disease-free seeds and resistant cultivars.
• Implementing strict crop rotation programs.
• Monitoring weather patterns to time preventive fungicide applications.
• Applying both contact and systemic fungicides as part of an IPM strategy.
• Prompt removal and destruction of infected plant debris after harvest.