Higher surfaces of a crop in the landscape increase outbreak risks the following growing season

The use of fungicides and insecticides by farmers represents a major threat to biodiversity 1 , endangering agriculture itself 2,3 . Landscapes could be designed 4 to take advantage of the dependencies of pests 5,6 , pathogens 7 and their natural enemies 8 on landscape elements. However, the complexity of the interactions makes it difficult to establish general rules. Despite initial enthusiasm 9 , the many studies opposing cultivated and semi-natural habitats have not revealed a homogeneous response of pests 10 and pathogens 11 to semi-natural habitats. In addition, the question of the impact of crop diversity on pests and pathogens remains largely open 12 . Based on about half a million observations over nine years on 30 major field crop pests and pathogens spread over all latitudes of metropolitan France, we show that the outbreak risk increases with the area of the host crop in the landscape the previous growing season. The impact on the risk of the host crop area the ongoing growing season diverges between animal pests and pathogens. We also confirm that woodlands, scrublands, hedgerows and grasslands do not have a consistent effect over the spectrum of pests. The spatial and temporal distribution of the resource, the host crop, generally prevails over the effects of potential alternative habitats. Territorial and temporal coordination generally promoting crop diversity but excluding a crop at risk a given year may prove to be key levers for reducing pesticide use 14 .