SWEET CHERRY TREES DECAY AND MANAGEMENTS ON REPLANTED CHERRY LAND

Some high density sweet cherry orchards in Norway suffer from decay of trees resulting in death or reduced vigour of trees. A survey monitoring healthy and infected trees from several orchards found differences between cultivars and rootstocks in sensitivity of tree decay. In order to investigate this cherry tree decay further, new field trials were established in 2002 with trees of the cultivar ‘Van’ grafted on the two rootstocks Prunus avium seedling and ‘Colt’ and trained as central leader trees. Two parallel trials were planted; one in the soil of an old cherry orchard and the other in the soil from agricultural land where no fruit production had been conducted in advance. During the first year significant larger annual vegetative growth measured as trunk girth, annual shoot growth and leaf areas were registered from the trees growing in the virgin soil. In the replanted cherry soil, trees grafted on the rootstock ‘Colt’ grew more vigorously than the seedling rootstock based on leaf areas and shoot growth measurements. The rootstock ‘Colt’ may be the answer for avoiding cherry replant diseases.