United States
Under the EPA Experimental Use permit, yearly approximately 2.500 American elm trees have been treated yearly with Dutch Trig® in the period 1995-2005. In 2005 full EPA registration was obtained. The following companies and cities participate in the Program:
- Bartlett Tree Experts (Chicago, IL, and various city's on the East Coast)
- The Care of Trees (Chicago, IL, and Hamden, CT)
- Autumn Tree Care Experts (Chicago, IL)
- Davey Tree Expert Company (Chicago, IL and Akron, OH)
- Swingle Tree and Landscape Care (Denver, CO)
- Arbor Green (Chicago, IL)
- Mc Ginty Brothers (Chicago, IL)
- Morton Arboretum (Chicago, IL)
- River Forest Golf Club (Chicago, IL)
- Cantigny Golf (Chicago, IL)
- Glenview Golf Course (Chicago, IL)
- Village of Fox Point (Fox Point, WI)
- City of Seattle, Seattle Parks Department (Seattle, WA)
Thanks to the insight, trust and efforts of these participants, and their customers, Dutch Trig® has achieved full registration in the US.
Early research in the United States
In 1996 and 1997 field experiments were performed with Dutch Trig® in both Charlotte by Bartlett Tree Research Laboratories and in Blacksburg at the Virginia Tech Polytechnic Institute and State University.
The numbers of trees involved and the results of all the field tests are summarized below.
Treatment |
Number of trees |
Number of trees |
Dutch Trig® Inoculated and DED Challenged |
114 |
2 (1,75 %) |
Dutch Trig® Treated |
69 |
0 |
DED Challenged |
61 |
18 (29,5 %) |
Control (No treatment) |
65 |
0 |
Table 1: Cumulative results of Dutch Trig® efficacy testing in the US. Firstly, these cumulative results indicate that the disease incidence among Dutch Trig® treated and DED infected trees (1,75%), is much lower than the disease rate amongst untreated artificially infected trees (29,5%). Secondly, on none of the Dutch Trig® treated trees, any (naturally occurring) DED or symptoms or side effects of the Dutch Trig® treatment were found.
Further research in the US
Bartlett's early research has been elaborated by The University of Wisconsin in Madison by Ray Guries and Karel Jacobs of the Morton Arboretum in Chicago. In co-operation, a greenhouse Dutch Trig Efficacy study was conducted. The report can be found on the downloadpage.
At the University of Washington, Seattle a non target host study was conducted: 20 different tree species were injected with Dutch Trig and monitored for one growing season to assess the effect of Dutch Trig on non-elm species. Also this report can be downloaded.
Reflection
In the Netherlands and the United States Dutch Trig® has been a very welcome additional tool in the fight against Dutch elm disease. Especially in combination with good sanitation practices, Dutch elm disease losses can be kept to an absolute minimum, sustaining valuable street and park(way) elms in big cities. Experiences have taught that, preserving as much as possible of the present elm population and green character of a city or village can very well be regarded as one of the most favourite common goals for all parties involved, being the city's inhabitants, politicians and the city's green-managers.
