Contrary to the seed collections, the apple trees need yearly maintenance. The CGN orchard is situated at the Experimental Station Randwijk and surrounded by other experimental orchards. The same maintenance regime is applied to the CGN orchard as to the others.
This means pruning in winter (February), weekly chemical control against scab during the growing season, chemical control against aphids and after harvest, 2-3 times spraying with lime against infection of apple canker. When it is very dry, the trees are watered.
Because apple trees are vulnerable to Apple Canker (Nectria galligena), they are checked and treated during pruning. Trees are treated by cutting away infected wood. When more than three large lesions are present which cannot be treated anymore, the tree will be removed. From the remaining healthy trees, five scions are cut. These scions are sent to a commercial tree nursery. This company will graft the scions on M.9 rootstock and grow the trees for two year. After two years the new trees are sent back and planted on the spot of the removed tree.