CGN apple collection

The history of the collection starts in the 1970s. Workers from experimental orchard "De Schuilenburg", then part of the TNO institute, initiated the collection of old varieties that were no longer used in commercial fruit production.

The first plantation in 1976 was situated at the former institute IMAG in Wageningen and a more extended collection in Zeewolde, where the first trees were planted in the spring of 1978. The collection in Wageningen was mainly meant to introduce resistance to the main fungal diseases scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha). Furthermore, also research on the introduction of resistance to pests, which appear early in the season (aphids, winter moth, apple blossom weevil, apple sawfly) using late sprouting and late flowering varieties was also an important aim (phenology of variety and pest insect).

The IMAG orchard in Wageningen in 1982 comprised approximately 70 varieties. In Zeewolde almost 360 varieties were planted, among which several of the IMAG-varieties. The main goal of the research in Zeewolde was identification of the collected accessions and observation of resistance to scab and mildew. Also pomological and phenological observations were carried out. Another research aim in Zeewolde was to assess the influence of varieties on the development of other diseases and pests. To monitor this, a series of observation years and a heterogeneous collection of sufficient size was required. The influence of differences in hairiness and leaf texture on the biological control of red spider mite and apple rust mite (Aculus schlechtendali) by predatory mites (Typhlodromus sp.) and the importance of antagonists of scab on leaves of different varieties have been studied too.

The collection

In order to develop a diverse collection, the trees in the Zeewolde orchard were screened and phenotyped with the use of existing descriptions from (old) handbooks and literature. Dependent on availability, completeness, and correctness a revised register was made with attention to synonyms. Also a possible overlap with the well-known UK National Apple Collection (Brogdale) was taken into consideration.

After the screening, 184 varieties remained. It was decided to particularly conserve varieties with certain extreme characteristics with respect to fruit size, flowering time, picking time, skin (smooth or russet), etc. To enable an informed choice, a list was made with 20 fruit and tree characteristics, based upon all the observations that were available. Fruit and tree characteristics, eating quality, bitter pit, production, abundance of flowering, second flowering, fruit set drop, June drop, fruit size, russeting, scab, and mildew have been used for the selection, with emphasis on the first three characteristics mentioned. Finally, 82 varieties were selected and planted in in the experimental orchard of the former Research Station for Fruit Growing (PFW) in Wilhelminadorp in the province of Zeeland, the Netherlands, in the spring of 1986; all with 2 x 2 trees on M.9 rootstock.

Ten years later, in August 1996, new trees were made by chip budding on M.9. In the spring of 1998, these trees were planted in the experimental orchard of Wageningen University & Research in Randwijk. One year later, the trees were replanted to their current plot. Foreign varieties, research material and wild species have been added. The number of accessions was extended from 124 in 2004 to 204 in 2018.

Since January 2002, the collection has been under management of CGN and forms part of the National Genetic Resources Program, financed by the Ministry of Agriculture, Fisheries, Food Security and Nature. In 2017, CGN started to focus more on the conservation of old Dutch varieties. In cooperation with the Dutch Fruit Network (NFN), most of the foreign varieties, research material and wild species are currently replaced by rare Dutch varieties. The total number of varieties is more than 250.

Maintenance

Unlike 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 years. After two years, the new trees are sent back and planted in the spot of the removed tree.

Within the European Union, it is obligatory to check for two quarantine diseases when apple material (trees, scions) is distributed. Therefore, the orchard is checked twice a year for Fire Blight (Erwinia amylovora) and Apple Proliferation disease by the Netherlands Inspection Service for Horticulture (NAKtuinbouw). The material can be distributed in the European Union, accompanied by a plant passport.

Since 2017, part of the collection has been planted on Wageningen Campus and can be considered as a safety duplicate. 110 accessions in a timeline show apple cultivation from the past until the present. Some wild species, about 20 varieties, are grafted on a high trunk and strong rootstocks, and a small orchard with 80 old varieties on weak rootstock are grown on Campus.

Composition

Presently (2024), the collection consists of 263 accessions, each with three trees present. The collection, which started in 1976, was initially built for safeguarding obsolete varieties. About two-thirds of the collection is of Dutch origin.

One-third is formed by foreign varieties which were grown in the Netherlands and a series of wild apples (Malus sieversii) collected in Kazakhstan by the USDA.

In 2017-2018, the collection of old cultivars was checked by a group of Dutch pomologists. Together with molecular data obtained in 2004 (Van Treuren et al. 2010), it was possible to verify most old varieties. These accessions are marked in the so-called ‘highlights’ field of the internal CGN collection database, as being verified. Several duplicates have been removed.

Characterisation and evaluation

Many data have been collected in the past. which have been used to compile the collection. Unfortunately, these paper archives were lost.

Until present more than 3000 characterisation and evaluation data were scored (Gabay 2012) and made publicly available on the CGN website. Scores can be found for fruit quality, appearance and production, architectural traits, and disease susceptibility.

Cooperation

In the Netherlands, there are several pomological agro-initiatives maintaining old apple cultivars. In 2017, the Dutch Fruit Network was established. CGN is partner in this network, of which the goal is to make an inventory of all old Dutch apple varieties and develop a plan to safeguard this unique Dutch heritage.

Go to

• De Nederlandse appeldatabase (Dutch)
• Nederlands Fruit Netwerk (Dutch)