Apple replant disease is widespread and has been documented in all of the major fruit-growing regions of the world. The reason for this replant problem in apple orchards is not clearly understood. Studies have shown that autotoxins in root exudates or decomposition of residues may play an important role in apple replant disease. The mechanisms involved, however, have not been extensively investigated. In order to investigate the mechanisms of autotoxicity involved in apple replant disease and provide the th...