Late blight

Late blight is a devastating plant disease caused by the oomycete Phytophthora infestans. Systematically, this pathogen belongs to the kingdom Chromista. Despite being historically categorized as a fungus, it is genetically distinct and requires specific management strategies due to its rapid spread and destructive capacity in agriculture.

The disease primarily affects Solanaceous crops, with potato and tomato being the most susceptible. The infection manifests as water-soaked lesions that rapidly expand into dark necrotic areas, often accompanied by a white, fuzzy growth of spores on the underside of leaves under humid conditions.

The pathogen's life cycle is characterized by both asexual and sexual reproduction. It survives between seasons in infected tubers or as oospores in the soil. During the growing season, sporangia are dispersed by wind and splashing rain, allowing the pathogen to travel long distances and infect new host tissues.

Environmental conditions play a critical role in the development of late blight. Cool, wet weather, particularly when temperatures remain between 15°C and 25°C, creates an ideal environment for spore germination and colonization. High humidity is essential for the survival and dispersal of the pathogen.

Effective management of late blight necessitates a combination of cultural practices and chemical interventions to minimize losses:

• Application of systemic and contact fungicides based on disease forecasting models.
• Removal and destruction of infected plant debris to reduce inoculum sources.
• Cultivation of resistant or tolerant potato and tomato cultivars.