Effects of production systems on populations of nematodes harmful to arable crops: a search for practical methods of diagnosis and risk management

For the most part, the most recent large-scale studies on nematodes associated with arable crops date back some thirty years. The damage observed in fields is rarely attributed to the presence of these pests, as detecting them requires specific and costly analyses, and their distribution across the country remains, with a few exceptions, poorly understood. The aim of this project was therefore to revive such studies in a context that has been profoundly transformed by the increase in the area under rapeseed for diester production, new guidelines on the management of catch crops to meet the requirements of the Nitrates Directive, and the need to reduce the use of chemical solutions in favour of resistant and/or tolerant varieties. The species studied in this project are those that are harmful to beet, rapeseed, durum wheat and maize crops. The experiments carried out are intended to: i) assess the effect of new crops and catch crops on nematode populations, ii) identify methods that can be used during the catch-crop period to limit population growth, iii) develop decision-support systems. Although they sometimes need to be consolidated, the results obtained provide new data on the distribution, biology and damage potential of species that are sometimes poorly understood. They also contribute to the development of optimised management of resistant and/or tolerant varieties, intercropping and alternative control methods, aimed at maintaining these populations at levels compatible with the quantitative and qualitative requirements of the supply chains.