Replant problems in Swiss apple production

Replant diseases in fruit production affect tree growth and reduce yields when orchards are replanted. In 2008, a survey conducted by Agroscope ACW revealed an increase in replant problems in Swiss apple orchards. Investigations on two apple orchards where trees had been planted in altered row distance, have shown significantly better growth and higher yield for trees on the old grass lane compared to those on the old tree row. Apple seedlings grown in the soil from replanted tree rows showed significantly better growth when the soil was sterilized, demonstrating the biotic nature of the poor tree growth in these orchards. In 2009, two field trials were started at ACW to investigate the usefulness of pre-plant soil treatments and different rootstock genotypes in controlling apple replant problems. Collaboration with other research institutes has been initiated for the investigation of the complex etiology of apple replant problems.