Plant Appraisal Guide Status Update

    UPDATE:  MAY 2018 BELOW      
Recent news from the ISA-PVAC (Plant Appraisal & Valuation Committee). Various RPACs (Regional Plant Appraisal Committees) have expressed a desire or intention to revise their supplemental regional guidance including species ratings and regional costs. CTLA (Council of Tree & Landscape Appraisers) has confirmed that the Guide for Plant Appraisal, 10th Edition will change significantly from the 9th Edition, including the way in which depreciation is applied.  CTLA may also encourage RPACs to develop regional guidance in a number of additional, new areas that are important for plant appraisers.

Both PAVC and CTLA are concerned that RPACs that are eager to move forward with their revisions might invest volunteer resources in developing guidance that will not be optimized for the 10th Edition. PAVC recommends that RPACs postpone any major revisions of their supplemental regional guidance and associated publishing expenses until after the 10th Edition is published. RPACs may certainly continue update nursery tree costs, review species ratings for those trees subject to problems like Emerald Ash Borer or Sudden Oak Death, or address other situations requiring particular guidance before the 10th Edition is published.

So, continuing to gather local information is important. The response to “Installation Costs” has been low to date so please fill out and submit the form (more details below). Please specify if you are quoting installation costs or installed costs. Responses so far have shown that a factor of 2.5x for easy installation and/or multiple trees for installed costs is still recommended. The factor may go up to 3.5x for more difficult installations. Documentation on how you came up with the unit tree cost is always the best approach to take.

How you can assist. Your Regional Plant Appraisal Committee has made the following recommendations. Please look closely and define your assignment first. If you can work successfully with a real estate appraiser and can research the comparable data for the tree(s) contribution to real estate market value, then I expect that CTLA will mandate this approach where ever possible. If you have any questions, contact

1) RPAC Installation Cost Survey (download pdf file). Any arborist that plants trees for customers please fill out this form. 

2) RPAC Species Survey. Follow this link:
Please complete the survey only for the species that you work with on a regular basis. We will use this information to determine updated specific species rating percentages for Canadian Climatic Zones. Note: list the zone that you typically work but not necessarily live in. Species list as of February 2009 (download pdf file). If you prefer not to fill out the survey online, here is a pdf of the google survey and an Excel file for data entry. A sample record is provided in the excel sheet as an example. Please email the completed survey to the ISAO office at .

3) If you are using a cost approach, then decide whether replacement cost, cost of cure, cost of repair, or the trunk formula method is best suited for the valuation. On the Trunk Formula Method Appraisal (download pdf file), note that the revised unit tree cost calculation will be based on retail installed cost – not a generic utc based on wholesale cost only as we used in the past supplement (dated 1997).

4) Largest Commonly Available Size for Each Tree Species (download Excel file). To qualify as such, the selected largest size of each species must be available from at least two wholesale nurseries. If a tree species is not shown in the table, then we recommend that you use a similar species that will provide the lost benefits of the appraised tree. Please ensure that the tree size is available from your local nursery and then choose a median nursery to finalize the price of the tree. As we develop up-to-date species factors, we will post a revised table. Until then, we recommend that you use the factors supplied in the Ontario supplement to the 8th edition.

5) Finally, for installation costs, you will need to verify prices with a local contractor. At this point, we recommend that you include all material, labour, delivery, overhead, profit and a two year guarantee to complete the final retail installed cost. The ISAO RPAC has found a common factor of 2.5 times wholesale cost to closely represent retail installed cost for most “frontyard” applications.

Once CTLA has completed the 10th edition to the Guide for Plant Appraisal, we hope to publish our regional supplement.

Published 2011.

Revision April 2015:
The Council is working on the 10th edition but progress is slow.  CTLA recommends that Chapters hold off on any revision of the Species Ratings Guide (Appendix 2) for the time being.  It is CTLA's hope that a second draft will be available for review by Spring of 2016.

Revision April 2016:

The Council is hoping that the DRAFT version of the 10th edition will be ready by the end of 2016.  ISAO is awaiting recommendations on how to proceed with Appendix 2, after the DRAFT version has been released. 

          Revision February 2017            

Guide for Plant Appraisal (10th Edition)
The Council of Tree and Landscape Appraisers (CTLA) put the draft manuscript out for peer review by member organizations in January of 2017.  Comments were welcomed until March of 2017.  The Council is still reviewing the outcome.  Questions?

              February 2018               

There has been no update from the CTLA.   ISA Ontario  will wait for direction from the 10th Edition with respect as to what to do with the Species Rating Guide and the formation of a new RPAC Committee, if needed.

                  May 2018                  

CTLA has announced that they will be releasing the 10th edition at the ISA Annual conference in Columbus, Ohio in August, 2018.  Conference attendees will have the opportunity to attend a session to help them understand the new edition.  Also, CTLA is putting on a full day workshop on Sunday, 5 August, for those interested.   Click HERE for conference information.

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