CGN apple collection

The CGN apple collection has a special status since it is not a seed collection maintained by CGN itself. The apple collection is maintained as trees in a field on behalf of CGN by Applied Plant Research: Sector Fruit (FPO) in Randwijk. As a result, no seed requests can be made. However, material is available, and should be requested from the curator.

In 1986, 82 varieties were planted on rootstock M.9, in the experimental orchard of the former Research Station for Fruit Growing (PFW) in Wilhelminadorp in the province Zeeland, The Netherlands. The collection was enlarged with one local variety in 1987. In Augustus 1996, new trees were made by chipbudding on M.9. In the spring of 1998, these trees were planted in the experimental orchard of PPO in Randwijk. One year later, the trees have been replanted to the current plot. Since, the number of varieties has extended to 124 (2004); all present with 5 trees. From January 2002, the collection forms part of the National Genetic Resources Program, financed by the Ministry of Agriculture, Nature Management and Food quality.

History of the collection

The history of the collection, in fact a core collection, starts in the seventies of last century. Workers from experimental orchard "De Schuilenburg", then part of TNO, initiated the collection of old varieties that were not longer used in commercial fruit production. Deliberations and agreements on European and global level in the eighties, finally have resulted in the collection present in Randwijk today. The first plantation (1976) was situated in Wageningen and a more extended collection in Zeewolde. In Zeewolde, the first trees were planted in the spring of 1978. The collection in Wageningen was mainly meant for research on susceptibility to the main fungal diseases scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha). Research on susceptibility of early pests (aphids, winter moth, apple blossom weevil, apple sawfly) with late sprouting and late flowering varieties was an important aim (phenology of variety and pest insect). The IMAG orchard in Wageningen, comprised in 1982 approximately seventy varieties. At the same time, in Zeewolde, almost 360 varieties were planted, amongst several of the IMAG-varieties. The main goal in Zeewolde was identification of the collected accessions and observation of susceptibility to scab and mildew. Besides, pomological and phenological observations were done. Another aim was to assess the influence of varieties on the development of diseases and pests. To monitor this, a series of observation years and a heterogeneous collection of sufficient size is 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. In brief, in all cases it dealt with the interaction of host plants (apple varieties) and pests and diseases. In experimental orchard "De Schuilenburg" in Kesteren, also a small collection of old varieties was located. A part of these varieties was included in a plot with 5 old apple varieties (Sterappel, Zoete Ermgaard, Zijden Hemdje, Court Pendu, and Bramley’s Seedling) and 10 cultivars and selections from breeding programmes, all planted in 1978. For comparison, also the old cv. Schone van Boskoop was planted; this cultivar is considered as only medium scab susceptible. In this experimental plot, from 1979 till 1982, observations were done to notice whether and to which amount immune or field resistant varieties can help to achieve a disease free plantation.

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Utilization and research

In 1982 already, was decided to gain more knowledge about genetic variance and inheritance. This knowledge is required to enable good choices which material has to be preserved. Investigations on susceptibility to fruit tree cancer (Nectria galligena) and genetic and physiological background of resistance were considered and have been performed partly. The utilization of (field) resistant varieties to achieve reduction of pesticide use and application of such varieties in organic growing systems were also considered. At the moment, so-called QTL analysis directed to resistance genes is a common accepted approach to achieve durable resistant cultivars. In this approach, old local varieties seem to be useful as donors of resistance. Field resistant cultivars with polygenic resistance to the main pests and diseases are currently considered as the best way for a sustainable growing system. In 1983, in the IMAG orchard and in experimental orchard "De Schuilenburg" investigations were done on damage of different old apple varieties by apple-grass aphid (Rhopalosiphum insertum). During 1976 till 1982, research was done on scab, mildew, fruit tree cancer, red spider mite (Panonychus ulmi), predatory mites (e.g. Typhlodromus pyri), mottled umber moth (Erannis defoliaria), winter moth (Operophtera brumata), Orthosia sp. and tortrix moth (Archips sp.). Codling moth (Cydia pomonella), common green capsid (Lygocoris pabulinus), apple blossom weevil (Anthonomus pomorum), apple sawfly (Hoplocampa testudinea), apple-grass aphid (Rhopalosiphum insertum), rosy apple aphid (Dysaphis plantaginea), green apple aphid (Aphis pomi), woolly aphid (Eriosoma lanigerum), and apple pygmy moth (Stigmella malella) were observed too. Besides, production, flowering phenology, picking period, and spring frost susceptibility were recorded. Similar observations were done in Zeewolde. All these observations have been summarized in reports, and we hope to make these data available on the CGN web site in the future. In the old variety plot in Wilhelminadorp, from 1995 till 1999, no fungicides were applied and several observations on scab (leaf and fruit), mildew and fruit tree cancer were carried out. Vigour and tree habit were investigated too. In 1998, fruits were tasted and pomologically described. From Wilhelminadorp, seeds were sent to New Zealand with the aim to widen the genetic diversity used in the apple breeding programme. Meanwhile this material has been used with interesting results. In Randwijk, in 2001 and again in 2002 after a severe attack in winter, fruit tree cancer was observed. Observations on aphids are foreseen for future years.

Selection of the core collection

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The first screening of the collection and the compilation of the register was done with use of existing descriptions in (old) handbooks and literature. Dependent on availability, completeness, and correctness a revised register was made with attention to synonyms. Besides, the overlap with the well known UK National Apple Collection (Brogdale) was checked. After the screening, 184 varieties remained. Considering the possibility of (then mainly future) genetic engineering, it was decided to preserve particularly varieties with certain extreme characteristics, as fruit size, flowering time, picking time, skin (smooth or russet), etc.. To enable a well-considered choice, with all 184 varieties, a list was made with 20 characteristics, both fruit and tree, based upon all the systematic and non-systematic observations that were available. Finally, the 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 three first mentioned. Eighty-two of the remaining 85 varieties were planted in Wilhelminadorp in the spring of 1986; all with 2 x 2 trees on M.9 rootstock.