Long-term impact of tillage system on Heterodera avenae population density

An increase of conservative agriculture is being reported throughout the World but its impact on certain cereal pathogens and parasites is still a matter of debate. In this study, the long-term effects of direct drilling, conventional and reduced tillage, either under monoculture or crop rotation regimes, on the population density of Heterodera avenae, were evaluated. As expected, H. avenae was only exceptionally found in plots where durum wheat is cultivated in alternation with faba-bean. In the case of continuous wheat cropping, significantly higher infestation levels were instead recorded on conventional tillage systems (on average 112 females per g of root and 19 cysts in 200 g of soil); moderate, but under a growing trend, was the infestation level in reduced tillage plots (on average 24 females per g of root and 5 cysts in 200 g of soil); no nematodes were recovered in the case of no-tillage. Among the factors affecting nematode diffusion, specific consideration was given to the higher compaction level and organic matter content observed in the upper soil layers of no-tillage plots in comparison to conventional and, at a lower degree, to reduced tillage. These outcomes provide an important contribution to improve the application of conservation agriculture principles, which promotes the reduction of soil disturbance and crop rotation to limit damages by the cereal cyst nematode and to achieve a sustainable and profitable cropping.