Impact of Potato Crop Rotation on <i>Verticillium dahliae</i> , <i>Colletotrichum coccodes</i> and Potato Early Dying

ABSTRACT The influence of different potato rotations on potato early dying (PED) and infections by the soilborne pathogen Verticillium dahliae was investigated. The study also considered the co‐occurrence of the PED‐associated fungus Colletotrichum coccodes in the fields. Furthermore, a pot experiment was carried out to explore the correlation between wilt progression and V. dahliae levels in plants, and to assess the effects of biofumigating cover crops in the potato rotations. In the fields studied, the density of V. dahliae observed in soil and plants was significantly higher in a 2‐year potato rotation, compared to growing potatoes every 3–4 years. In addition, the study confirmed very low quantities of V. dahliae and C. coccodes in soils with an extended break (&gt; 15 years) from potatoes. In the pot experiment, there was no direct effect of the cover crops, yellow mustard and oats, on either incidence of V. dahliae infections, plant biomass, or premature wilting of potato plants. However, a strong positive correlation between V. dahliae and wilt severity was observed in potatoes without prior growing of oat or yellow mustard, which was not evident in potato plants grown after the incorporation of these cover crops. The findings demonstrate a clear association between potato crop rotation and the incidence of V. dahliae in the field; however, the inconclusive results of the effect of oat and yellow mustard cover crops on V. dahliae and PED require further investigation. This study suggests that the development of more strategic potato rotation management could reduce PED levels.