Sunday, November 4, 2007

ISA HK/China --- Square Rootballs at ETF

*** Our weekly Station Mail is for the information of Station Members only, but Station Mail has given up copyright & can be freely circulated. For administrative reasons, comments from outsiders are usually not entertained & may be circulated within our system locally & overseas. Please note Station Mail is sometimes given in Blog at , although images are usually not attached due to size. ***

Dear Station Members,

This Station takes on the mission to constantly research on new arbor skills with our limited facilities at disposal. ETF is such a facility for trialling out various techniques & the results are forwarded on Station Mail form time to time for public viewing. The provision of Square Rootballs is now one of them.

Traditional rootballs are round in shape. This is described in many literature as Balled & Burlaped (B & B) trees grown & dug in field. B & B trees are nearly the standard practice for supplying landscaping trees in our territory due to low cost & a tendency of not having Girdling Roots if used fresh & not stored, in favour of Containerized Trees which frequently have developed Girdling Roots. Internationally, the recommended rootball size is about 10 x trunk diameter according to ISA education & also BS 4043, although this practice is not much observed in some of our landscape work especially in transplanting mature trees.

The idea of Square Rootballs at ETF is copied from some western tree nurseries who have been using it for some time silently maybe for commercial reasons. Square Rootballs have the following advantages as compared to traditional round rootballs:

1. More Roots --- For any given diameter, a square will have a bigger area & volume (at the same depth) than a circle, & will therefore contain more roots & soil volume to endure 'Transplant Shock'. More roots retained will favour recovery & enhance growth after transplant.

2. Transport Safety --- A cubic rootball will not roll as easily as a circular rootball in transport. Rolling can damage rootball & lead to foliage chafing & branch breaking in the canopy.

3. Preventing Girdling Roots --- Trees dug with Square Rootball can be stored up to a certain time without the development of Girdling Roots, because the new roots emerged will hit the flat sidewall & be generally deflected at 90 degree in any direction. Traditional round container will guide the roots to turn in circle to form Girdling Roots, which can strangle the tree later by constricting central vessels.

4. Storage Ease --- Square Rootball can generally stand upright on its own unlike conventional round rootball which curves from top down on the side. The side boards in a Square Rootball will perform as a square container for vertical standing.

ETF has sold trees with Square Rootballs to Govt Depts in HK & to customers in China. No adverse comments have been received so far. On the other hand, ETF will be pleased to hear any response with regard to this latest practice for improvement anytime.

HK now is pushing ahead with innovation in arbor development spear-headed by our Station with knowledge gained internationally through ISA contacts. It is this kind of trial & error that the tree care practice in our territory can advance to new height. Quality Nursery Stocks are always the first step to ensure a successful landscape besides a good design. Trees not selected & planted properly are likely to become future liability rather than asset.

This Station would welcome comments on the results of using Square Rootballs against round rootballs for open discussion anytime. Just send in your observation. Thank you.

best regards,

Sammy Au

Station Manager

The ISA Mission - Through research, technology, and education, promote the professional practice of arboriculture and foster a greater public awareness of the benefits of trees. (

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