Steps in the propagation of the Royal Parade Elms (Ulmus procera).
Royal Parade is one of the most distinguished and pre-eminent plantings of Elms in the World. The sense of scale and enclosure provided by this boulevard is one of Melbourne's greatest assets. Many of the Elms within this Boulevard are beginning to show decline, due to their age (approximately 100+ years) and the environmental stresses of growing within a built (streetscape) environment. New young stock is needed to reduce the risk of amenity loss as some of these 100+ year-old trees begin their decline and will be removed within the coming years. 4.0m trees were considered to be large enough to provide visual substance. With lead times of 3 years from budding to produce a 4.0m tree, Oliver Pohls and Ian Shears from the City of Melbourne's Parks and Recreation Department contacted Metro Trees in late 2003 to collect bud material and propagate to provide Melbourne City with tree stock in 2007.
Material was carefully selected from trees located on the Western side of Royal Parade which showed strong vigor and which had material within reach of 2.0 - 3.0m from ground level. We then provided the bud material to our expert propagator in January of 2004. These were budded in late January onto Ulmus glabra (Scotch Elm), a DED resistant and low suckering rootstock. In July 2005 we received 420 bare - root trees, approximately 1.5-1.7m in height and potted these into our 40 Litre SpinOut™ treated (430mm height x 320mm width) containers. Most small deciduous trees are transplanted bare root during the Winter-period as it is the most convenient for space shipping and price. The SpinOut™ treatment is an inert copper containing paint, which helps reduce major root circling within the plastic walled container. The soil-less media used for the potting of these Elms was specially formulated to suit tree growth and certified by ISO-9002.
All trees were carefully examined for root faults prior to potting, and all circling or deformed roots were removed/severed. Canopies were assessed for strong central leaders and any major bifurcations (co-dominant stems) removed. Follow up structural pruning then took place once in October 2005 and then again in February 2006, to further develop strong central leaders and radial branching.
These Elms are susceptible to elm leaf beetle infestation, requiring treatment with Confidor ™, an elm leaf beetle systemic insecticide, which we co-incidentally time for treatment Melbourne Cup week every year, when the larvae are at a specific life stage.
Currently (Feb 2007) the trees are 2.8-3.4m in height and have been repotted from 40 Litre to 75 Litre to provide 4.0m height trees for the City of Melbourne's various Elm renewal projects, both in Royal Parade, Parkville and other locations throughout the city for delivery 2008.
