A couple of weeks ago, I wrote a column in the Pacific Northwest magazine of the Seattle Times about how the Woodland Park Zoo's rose garden has gone organic. Wouldn't you expect master gardeners, of all people, to laud landscape manager E.J. Hook's efforts to ditch the chemicals? Nope. Here's master gardener Fred Werner's response to my column. And for the record...Fred misquoted me below. As far as I'm concerned the jury is out on compost tea, but I'm very impressed at the zoo's results with using compost tea as part of an organic care program for roses that are undeniably healthy and thriving....
Councilmen Rassmussen and Godden,
As members of the council that oversee the funds used at the zoo I hope you will look into my concerns. I am a King County volunteer Master Gardener who volunteers at the Bellevue Urban Demonstration Garden. In mid June we invited EJ Hook, who maintains the very nice nationally recognized rose garden at the Zoo, to come talk to a group of Master Gardeners about the Zoo Rose Garden. E J claims that one of the reasons that the roses look so well is that they spray Compost Tea on them weekly. When I told him that as a WSU Master Gardener I am not permitted to recommend the use of Compost Tea since there is no scientific evidence that it has any value. E.J told me he was aware of that but wanted to treat all the roses. I told E.J. that I had done a three year study of compost tea at the BUDG and had found it to be a very labor intensive process that had no improvement in production or reduction in disease. Few people have the circumstances or means to do a scientific study.but the Zoo has both. He said he didn't have the staff to do a study but might consider it in the future.
A week later Valerie Easton wrote an Article in the Seattle Times Pacific Northwest Magazine also suggesting that compost tea was a contributing factor in why the roses do so well. When I confronted Valerie she said she was aware that compost tea had no scientific evidence of value but she wanted to give the other side of the story. She claimed she had previously told the WSU side in her earlier articles. I felt it was poor journalism and gave the public an unjustifiable reason to try compost tea.
I'm not opposed to the Zoo spending money on spraying compost tea on the roses as long as they use part of the roses as a control to see if there is any actual improvement. They are spending a lot of man hours on something that, as of now, has no proven value. The tests to see if there is any improvement in soil biology are expensive but with the number of roses they have I think they can justify it. He would also need a person to collect and evaluate data. I'm sure the WSU Puyallup Research Station can give recommendations on how to do a proper study.
Please encourage the Zoo to do the study needed to justify their use of compost tea. If he can't justify doing the study I don't think he should be using public money in these times of tight money to use an unproven product.
Here's E.J. Hook's response to the Zoo PR director:
I did have a lengthy conversation with Fred following my presentation. I explained to him that compost tea is part of a holistic approach to pesticide free garden management used in conjunction with other tools, practices, and methods such as pruning, watering, fertilization, etc.
I also told him the difficulty in doing peer review level scientific studies including staff time, testing costs, and the difficulties presented by the lack of controllable variables.
An over riding tenet of our program, and one explained both in every presentation and to Fred personally, is that our measure of success is based on meeting an aesthetic expectation of Rose Garden visitors, especially brides and their mothers. If this expectation is met then we are successful whether science bears that out or not.
As to testing, I have soil tests, tea tests, labor analysis, and photos to add credence to the "worthiness" of our pesticide free efforts. At a presentation of this level I do not include the actual data but allude to it.
Overall diversity of soil biology has increased.
Overall availability of soil nutrients has increased to a level where we did not fertilize the roses this year.
Testing has been and continues to be done but there is no control plot for comparison.
Increased labor is offset by no re-entry restrictions.
Other City departments are interested enough in this project and sharing the results to assist in financing it.
Bottom line, the messaging in maintaining a Rose Garden of this size pesticide free has value to the public we serve and the institution we represent. We have, and never will, claim that compost tea is "the" answer. It is part of a larger maintenance program which meets the expectations of the garden and furthers the conservation and sustainability values of the Zoo.