Didier Andrivon from INRA directs our thoughts to potato and tomato blights in Europe and argues that multi-actor research is crucial for sustainable control.
Blights, that is late blight caused by the oomycete Phytophthora infestans and early blight caused by several Ascomycete species belonging to the genus Alternaria, are a constant source of concern for the European potato and tomato industries. They indeed impose a severe burden on crop yield and quality in both conventional and organic production systems and induce massive control costs and severe environmental pressure.
Controlling blight epidemics have long relied almost exclusively on repeated applications of synthetic fungicides. It is not uncommon for potato crops to receive 15 or 20 sprays a season to keep blights at bay. However, this strategy while efficient, is not sustainable, for three major reasons.
First, the pathogens adapt to many of the active ingredients used against them: this is the case for Alternaria strains resistant to both QoI and SDHI fungicides in Europe and North America, and for Phytophthora infestans resistant to phenylamides and more recently, to fluazinam.
Second, the number of fungicides families available is constantly decreasing, as a consequence of both pathogen evolution and strict environmental legislation.
Third, there is increasing pressure from consumers and society at large to limit or ban altogether pesticides from food products.
The key to sustainable control of blights is, therefore, Integrated Pest Management (IPM), a more complex strategy relying on a combination of control methods, such as prophylaxis (sanitation), resistant cultivars, biocontrol, decision support systems and precision agriculture.
IPM has many advantages: it is flexible (each grower can ‘tailor-make’ the strategy that suits local conditions best), it is sustainable (the reliance on multiple components within each strategy is a source of resilience), and it is environmentally-friendly.
However, it has also some major issues: it is more difficult to implement and design: it requires efficient surveillance and monitoring of crop status, and it also requires that all actors along the value chain (from agro-industry to consumers and distributors) accept and promote it.
Wider adoption of IPM can, thus, only be achieved if all actors take part in its design, implementation and valorisation. This is why multi-actor research and development activities are critically needed.