Davey Resource Group used a tree risk assessment to catch the spread of stem canker disease among Washelli Cemetery’s Lombardy poplar trees in Seattle.
Lombardy poplars are a fast-growing, deciduous tree with a relatively short life span. This species is susceptible to stem canker disease (Dothichiza populea) which is caused by the microorganisms known as Crytodiaporthe populea. The microorganisms infect trees via open wounds in the bark that may have been caused by a variety of factors. A major contributor to the severity of the infection is water stress. Unlike the arid climate of Italy, where the species originated, Seattle has an abundantly wet climate that has furthered the presence of the canker disease in Lombardy poplars.
Washelli Cemetery was established in 1884, with grounds that cover 144 acres and have been landscaped over the years with a diverse array of tree species. This cemetery is open to the public and utilized like that of a city park, providing refuge of green space for residents and habitat for a variety of animal species in an urban environment. Washelli is a word that originated from the Makah people, a tribe native to the Pacific Northwest, and means ‘west wind’. It is, indeed, the west winds that blow through the region that has brought more awareness to the proliferation of the canker disease on the project site. Over the recent years, strong winds have resulted in the failure of multiple Lombardy poplars that the disease has weakened.
Making An Assessment For Risk Management
In 2017, Davey Resource Group (DRG), was contracted to lend expertise and help develop a strategy for managing the risks of more than 240 Lombardy poplars throughout the Washelli Cemetery property. The property’s management recognized a decline in this prominent tree species and reached out to DRG for support. DRG performed a Level 2 Tree Risk Assessment that employed the use of mallet sounding to better understand the presence of decay and inform which trees should be a priority for mitigation as well as identify the first step in the long-term proactive approach to vegetation management in the cemetery.
In 2022, DRG revisited the site to re-assess the trees as part of the five-year cyclical plan. Using the same methods to assess the trees, more deductions were made as to how extensive the disease has been spreading. Upon completion of the reassessment, the 2017 report was referenced to draw correlations and provide conclusions on how to effectively manage the vegetation in the long term. Recommended mitigation strategies were also presented to Washelli Cemetery in order to empower management with the information needed to better plan for the future of the tree population. The Davey Tree Expert Company was engaged in the process to provide a bid for proposed tree work and removals. DRG now looks ahead to the future projects that will assess and benchmark the health of other declining species present at Washelli Cemetery.