Effects of soil fumigation on the growth of apple and cherry rootstocks on land previously cropped with apples

Abstract

SUMMARYApple and cherry rootstocks were planted into land on which apple trees had previously been grown and which pot tests had shown to be subject to apple replant disease. Prior to planting the land was either left unfumigated or zones of progressively increasing area (0.052 m2, 0.839 m3, 3.356 m2) centred on the proposed planting holes were fumigated with chloropicrin. Fumigation greatly increased the growth of the apple rootstocks but not of the cherry rootstocks. In the first year after planting the effects of the two larger fumigated areas were identical but in later years apple rootstock growth was directly related to the size of the fumigated area. This indicated that the replant disease does not simply affect tree establishment as was previously thought to be the case. The implications of this are discussed.