BayCEER Workshop 2022

Apple Replant Disease - Which soil properties play a role on regional scales?

Apple replant disease (ARD) is a major economic problem in fruit-growing regions worldwide. Repeated cultivation of apple trees on the same fields results in growth depression and significant yield reduction. The altered microbial community in the soil is the suspected main cause of growth depression, but it is not fully understood how soil properties, e.g. texture, water holding capacity, humus and nutrient stocks with their controls on microbial activity and microbial functions, may affect the intensity of replant disease. We are investigating the influence of soil properties on replant disease using the example of apple as part of the BMBF-funded project ORDIAmur (Overcoming Replant Disease by an Integrated Approach). In this study, shoot and root length of apple plants as well as soil respiration parameters were used as parameters for replant disease and the activity of soil microorganisms. In a previous field experiment (Mahnkopp et al. 2018) we learned from a limited number of reference sites and these results indicated a correlation between ARD intensity and soil texture: sandy sites were more affected than loess-loam sites. In sandy soils, soil respiration measurements showed a significantly increased metabolic quotient, which can be interpreted as an indicator of microbial stress, as well as signs of lower nutrient availability. However, these results are site-specific and need to be tested for a higher number of soils. Hence, we now continue with ARD intensity mapping on a regional scale in order to be able to prove the relationship between replant disease and soil properties.

References

Mahnkopp, F., Simon, M., Lehndorff, E., Pätzold, S., Wrede, A., Winkelmann T. (2018). Induction and diagnosis of apple replant disease (ARD): a matter of heterogeneous soil properties? Scientia Horticulturae 241, 167-177