In an effort to combat Dutch elm disease, SCNA has contracted with Davey Tree since 2007 to treat 17 English elms in the north part of William Curtis Park. If an elm is infected with this vascular wilt disease, removal is warranted to help prevent the disease spread.
Elms are injected with a fungicide that protects them against Dutch elm disease and must be reapplied every three years to provide continued protection. These treatments began in response to the removal of several park elms infected with the disease. The neighborhood was concerned that all the park elms would succumb if no action was taken.
Treatment for these elms costs approximately $14,000 and is completed over a two-year period to spread out the cost. This year it’s time to treat again. But due to the Sierra 2 Center’s temporary closure and lost revenue, my recommendation to the SCNA board is not to treat the elms.
SCNA will ask the city parks department to pay for the elm treatments this year. Some residents are concerned that by not treating the elms, they will be at risk of contracting Dutch elm disease.
I believe the risk is low because these elms grow in a park setting and receive regular irrigation throughout the summer. They have not been subjected to any health-related stress issues, such as root pruning for curb, gutter or sidewalk repair or excavation/ trenching for construction. When elms are exposed to environmental stress, they attract the female elm bark beetle, which transmits Dutch elm disease.
The English elms will be monitored throughout the summer for Dutch elm disease symptoms. Monitors will look for leaves turning brown and hanging onto the branch. Trees with symptoms will be reported to the city for sampling and lab testing. The key to control is removal of infected trees as soon as possible, which helps contain this disease spread.
Two English elms north of the main park, which had been receiving the preventative Dutch elm disease treatments, were just removed. Both elms had experienced large limb failures, most recently during a windy day last October when a limb, approximately 18 inches in diameter, failed and crashed through a homeowner’s fence on Donner Way. The park’s arborist performed an aerial inspection with a bucket truck and determined both elms warranted removal because of extensive decay that compromised the elms’ structural integrity.
SCNA must balance budget considerations against the cost of protecting our park’s elm trees. With careful monitoring over the summer, we hope any disease symptoms can be spotted early.