Soil treatments and rootstocks for organic apple production

Summary

6 different soil treatments: Mechanical weeding to the middle of the alleyway, mechanical weeding using 3 different equipments Clemens, Humus and a dish harrow, Soil covering with wheat straw and natural vegetation were combined with 3 rootstocks: M9, J9 and M26 to find the best combination for the apple variety 'Retina'. The trees were planted in the winter 1997/1998, only sprayed at primary RIMpro warnings and drip irrigated. The tree growth, nutrient content of the leaves in august, yield and fruit quality were determined.
The rootstock J9 had the highest yield and the biggest amount marketable fruit. Mechanical cleaning to the middle of the alleyways, tree row weed control using Humus or soil covering with straw gave the highest yield and marketable fruit. A one meter weeded strip in the tree row did not remove the competition of the clover grass alleyway. Natural vegetation (weed) in the tree row reduced the yield with more than 50 percent. There was a break down of the Vf resistance of 'Retina'.