Foundation Arboretum Wespelaar Year Report 2019 2019 started with an early spring: by mid-March the early magnolias were in full flower. Temperatures kept rising and the heat record was broken in July, making the summer of 2019 one to be recorded in history books. Luckily, small rain showers and increased irrigation capacities ensured that we lost very few plants. In March 2019, the construction of the Artois Pavilion started in the Artois Meadow, at the end of two important vistas. The design is inspired by the old pavilion along the canal in the Park of Wespelaar. In the new Arboretum de Marche, a total of 189 trees have been planted in the past two years. In collaboration with Natagora, five ponds were created and a 5ha plot was sown with wild seed to create a meadow of native grasses and flowers. The building permit for the visitors centre and technical facilities was obtained. 2019 was a very active year for both Arboretum Wespelaar and Arboretum de Marche, as is described in more detail in this Year Report. Arboretum Wespelaar – Year Report 2019 1 THE COLLECTIONS ‘Patty’ can be planted in the Arboretum in due time. The living collection of woody plants in the Arboretum currently (as of 30 January 2019) Once again, our winter was not worth contains 5,116 specimens representing 2,340 mentioning and by mid-March we could have different taxa (versus 16,376 specimens and opened the Arboretum for our visitors because 4,955 taxa on the whole of the estate). These the early magnolias were already in full flower! numbers include the 629 new accessions on On March 11th however, we had a serious the estate during 2019 of which 108 (or 17%) storm with accompanying damage and much are of documented wild origin. cleaning up. A large pin oak (Quercus palustris) fell over in the Werner Wood and the crown of a beech tree along the cobblestone road of the domain of Wespelaar collapsed on the fence of the Arboretum in the southwest corner of the Marnef Wood. We therefore decided not to advance our opening date. Photo 1: Spectacular flowering of the early magnolias in mid-March Around 37 woody plants were removed from the collection as part of an ongoing effort to improve the aesthetic value and health of the living collection. Although choices are often easy (ugly plant, not adapted to our climate, Photo 2: Fraxinus baroniana starts to flower for the first diseased, too many of the same taxon, etc.) time other times it is a more difficult process. On the In 2011, through our good contacts with The Artois Meadow, the new pavilion is gradually Morris Arboretum in Philadelphia (USA), we taking shape. Because of that, we obtained seeds collected in the wild from an unfortunately had to remove some beautiful extremely rare Chinese ash species, Fraxinus specimens as they would completely block the baroniana. We were very successful in growing view of this building. We were able to this plant and over the years we have planted a transplant one plant, Acer rubrum 'Morgan', dozen of these plants on the estate. In 2019, a which we received as a gift from the IDS Council Fraxinus baroniana flowered for the first time; in 2016. But two beautiful crabapples, Malus a first for Europe! We had the good surprise of hupehensis and Malus transitoria, were cut witnessing the first flowers, after 16 years, on with much regret. Also, Magnolia 'Patty', a our only surviving Magnolia decidua (formerly named selection of our cross 'David Clulow' x Manglietia decidua) in the Verlat Wood. 'Leda', had to be removed but not before we Another first for Europe in Wespelaar! This had taken material to propagate so that a new recently discovered species was introduced to Arboretum Wespelaar – Year Report 2019 2 Europe via seeds that Philippe de Spoelberch last year, we had a small rain shower every so cultivated and distributed. Magnolia decidua is often. That, plus the fact that we seriously only known from a single population in Jiangxi expanded our irrigation capacities last year and (China) and is listed as an endangered species in 2019 as well, ensured that we lost very few on the IUCN Red List. Within Manglietia, it is plants. the only species to drop its leaves in autumn. This is of course not the case within Magnolia, Plant pests and pathogens present a significant but it retained its species name "decidua". The risk to global plant health and this threat is ever thin, upright flowers themselves are less rising. Sentinel plants within botanic gardens spectacular: 4 green outer tepals and up to 11 and arboreta can play a vital role in providing very narrow, inner white tepals. We used the information on future and/or known threats. opportunity to take a photo sequence so that On April 4th the project “Belgian network and we could follow the opening of the tepals. The activities in the frame of the International flowers finished flowering within three days. Plant Sentinel Network” ended with an The tepals never fully opened: was this due to evaluation meeting in Brussels. The the somewhat cooler weather or do pollinators participating botanical gardens will keep an eye just crawl through the tepals to reach the on possible infestations and have knowledge stamens? This has not yet been fully clarified. about the procedures to inventory this in a standardized way. We uploaded the last files concerning the research of our Ulmaceae accessions in the Plant Health Checker, a database part of the Plant Sentinel Network. We also received the final results for the Sirococcus blight research (Sirococcus tsugae) but luckily no plants of ours are infested. In 2019 we also participated in the research for Rose Rosette Virus by the International Plant Sentinel Network: again, no symptoms were identified. Photo 3: Irrigation works in the Werner Wood Having a perfectly labelled and correctly The summer of 2019 will surely be recorded in identified collection is one of the main the history books. In July, the heat record was objectives of the Arboretum. Since 2014 we broken as we measured an inconceivable have significantly increased our efforts and our 41.5°C on the Magnolia Meadow! And the team continues this major inventory round at record of the highest minimum temperature the Arboretum and the dendrological was broken as well: 23.5° on the night of July collections of the surrounding private estates 25th. This heat caused problems for many of Herkenrode, the Park of Wespelaar, the collection plants: Abies, Carpinus, Stewartia, Potager de Wespelaar and Bosveld. This some Magnolia, Nothofagus, Rhododendron, important and valuable work continued in all of which suffered severely under these 2019 and a total of 121 beds have been unpleasant temperatures. But luckily, unlike thoroughly inventoried. During this inventory, Arboretum Wespelaar – Year Report 2019 3 each plant within a certain bed is localised, its health status is assessed, the identity is verified if possible and/or needed, and the label is placed on a healthy branch clearly visible for our collaborators and visitors. For the labelling of our small plants (seedlings, cuttings, small purchases or gifts) we bought a professional label printer. That should allow us to label larger quantities of young plants in a quick and more efficient way. Photo 5: The rich flowering and striking colour of Rhododendron augustinii ˈBokrijkˈ(left). VISITORS Although there is a slight decline in the total number of visitors, it is important to report that we continue to see a steady and significant increase in the annual subscription category. These are visitors who find it worthwhile to return after their initial visit and who are therefore a real indicator of success. Photo 4: Newly purchased label printer The number of individual visitors amounts to 4,791 (vs. 4,733 in 2018) and the number of We keep on monitoring and evaluating our groups totals at 91 (vs. 87 in 2017). 316 annual plants. In 2019 we registered two of our tickets for families were sold (vs. 265 last year)! rhododendrons and one horse chestnut. Rhododendron augustinii ‘Bokrijk’ and Rhododendron dauricum ‘Jelena’ were both visitor numbers registered for their rich flowering and both named in honour of their donor. Aesculus 7696 754273187146 6340 glabra ‘Herkenrode’ has always been a good 5767 3991 compact tree with great silhouette and warm 3827 2330 red-orange autumn colour. The tree has never been pruned and stays compact. This will be an interesting selection for gardens. It does not 201120122013201420152016201720182019 suffer from the horse-chestnut leaf miner (Cameraria ohridella) which is a great asset as well. As usual, a short paragraph and many We had, as every year, many visits from pictures of these plants were added on our specialized groups, both national and website in the category “our selections”. international, which reflects the importance and impact of Arboretum Wespelaar in the world of woody ornamental plant collections Arboretum Wespelaar – Year Report 2019 4 and plant connoisseurs. Amongst those were visited pages are the homepage, the contact plant specialists Dan Crowley (Acer), Raquel page, the database of woody plants of Folgado (Magnolia), Jan Spruyt (perennials), Arboretum Wespelaar, the database of images Martijn Essers (Acer) or Jean-Pierre Henin connected to the identification keys by Jan De (Styracaceae) to name just a few. We of course Langhe, and the BELTREES database. Since the had many specialist tree breeders (e.g. Paul end of 2018, the site is now fully user- Reimer of Reimer’s Nurseries Ltd. in Canada, responsive and thus adapted to smartphones Sébastien Emain and Vert’Tige from France, and tablets.