Apple Replant Disease: Causes and Mitigation Strategies.

Traud Winkelmann,Andreas Wrede,Wulf Amelung,Stefan Weiß,Doris Vetterlein,Kornelia Smalla,Xorla Kanfra,Gisela Grunewaldt-Stöcker,Michael Schloter,Jürgen Grunewaldt,Rainer Meyhöfer,Gerhard Baab,Michaela Schmitz,Stefanie Reim,Sebastian Zühlke

doi:10.21775/cimb.030.089

Abstract

After replanting apple (Malus domestica Borkh.) on the same site severe growth suppressions, and a decline in yield and fruit quality are observed in all apple producing areas worldwide. The causes of this complex phenomenon, called apple replant disease (ARD), are only poorly understood up to now which is in part due to inconsistencies in terms and methodologies. Therefore we suggest the following definition for ARD: ARD describes a harmfully disturbed physiological and morphological reaction of apple plants to soils that faced alterations in their (micro-) biome due to the previous apple cultures. The underlying interactions likely have multiple causes that extend beyond common analytical tools in microbial ecology. They are influenced by soil properties, faunal vectors, and trophic cascades, with genotype-specific effects on plant secondary metabolism, particularly phytoalexin biosynthesis. Yet, emerging tools allow to unravel the soil and rhizosphere (micro-) biome, to characterize alterations of habitat quality, and to decipher the plant reactions. Thereby, deep insights into the reactions taking place at the root rhizosphere interface will be gained. Counteractions are suggested, taking into account that culture management should emphasize on improving soil microbial and faunal diversity as well as habitat quality rather than focus on soil disinfection.

Highlights

Apple replant disease (ARD) affects plant propagation in nurseries as well as apple production worldwide by strongly reducing plant growth as well as fruit yield and quality (Mazzola and Manici, 2012; Manici et al, 2013)
We summarize current knowledge on the causes of ARD and critically evaluate current lines of research to develop mitigation strategies
The abundance of antioxidative enzymes, such as peroxidases increased significantly four weeks after planting young apple rootstocks in ARD affected soil, whereas synthesis of these enzymes was lower in plants grown in gamma irradiated soil (Schmitz et al, unpublished results)

Summary

Introduction

Apple replant disease (ARD) affects plant propagation in nurseries as well as apple production worldwide by strongly reducing plant growth as well as fruit yield and quality (Mazzola and Manici, 2012; Manici et al, 2013). Introduction Apple replant disease (ARD) affects plant propagation in nurseries as well as apple production worldwide by strongly reducing plant growth as well as fruit yield and quality (Mazzola and Manici, 2012; Manici et al, 2013). Evidence for an involvement of root endophytic fungi (e.g. Cylindrocarpon-like fungi) in apple plant growth reduction on ARD affected soils was presented (Manici et al, 2013, 2018).

Results

Conclusion