Combating late blight

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Late blight (LB) is widely recognized as the single worst disease of food crops. The fungus-like pathogen Phytophthora infestans can rapidly adapt through mutation or migration, making efforts to combat it like playing leapfrog.

LB results in an estimated $10 billion worth of losses each year in potato crops of the developing world alone. The impact on developing countries is especially harsh as they are home to the majority of potato farmers, many of whom depend on potato for economic survival and food security.

An insidious problem related to LB is the health risk to farmers and their families as a result of chronic exposure to the pesticides employed to control the disease. The most common products used – dithiocarbamates, such as mancozeb – break down into suspected carcinogens.

Rising pressure from climate change is adding greater urgency to the problem. “With warming trends, which accelerate the spread of the disease, we are seeing increased risk in areas as diverse as the Andean highlands, the lake region of Sub-Saharan Africa, parts of Central Asia, and southwest China and Nepal, not to mention Northern Europe and the United States,” notes Greg Forbes, CIP plant pathologist.

In November 2009, CIP coordinated a meeting in Bellagio, Italy, uniting scientists from 21 developed and developing countries to plan a global strategy for combating LB disease.

The result was Late Blight: Action Plan for an Effective Response to a Global Threat, a white paper directed at policymakers and donors. It recommends five actions for employing rapid solutions to the LB problem based on existing capacities and technologies.

Recommended actions

  • Get resistant cultivars to farmers. Farmers still largely use susceptible cultivars and depend on fungicides to combat LB. They need access to resistant cultivars adapted to local consumer demands and microclimates.
  • Improve farmers’ capacity to manage disease. To mitigate and manage LB in the field, farmers need intensive, participatory training, which requires the support and involvement of key stakeholders, including farmers, national and international R&D organizations, donors, governments, and NGOs.
  • Know the enemy and develop a community of skilled pathogen monitors. Greater coordination and standardization at all levels is needed to track disease mutation and migration.
  • Develop ecologically based approaches to control LB. Host resistance is a primary approach, but it should be enhanced with complementary control practices, such as low-toxicity pesticides and crop management techniques.
  • Coordinate and monitor progress and risk assessment. Greater coordination among researchers through networks and other modalities is needed, along with tools, such as long-term databases of hosts and pathogens, to map and monitor progress in the use and durability of resistance and risk patterns associated with climate change.

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