An arborist’s report says “excessive weight” is the reason a Sonoma Plaza tree dropped three limbs in the past month – two of them mildly injuring passersby.
“The cause of these branch failures is excessive weight, particularly in the outer portions of the limbs,” Sherburn Sanborn wrote in his July 23 letter to Sonoma Park Foreman Dave Chavoya. “Elms in general are fast-growing trees. Those in the Plaza Park are healthier than most because they get plenty of water. All trees naturally shed branches, and when planted in urban settings they need periodic pruning.”
The elm shades two picnic tables on the Plaza’s north, or Spain Street, side. A bushy 20-foot bough fell on a German tourist July 14 in a leafy embrace that caused more surprise than injury. A 19-year-old woman suffered minor injuries after the July 22 Farmers Market when a 40-foot branch dropped on her head.
City officials are keeping an eye on this Plaza elm tree on Spain Street after two people have been injured by falling limbs. Photo by Ryan Lely/Sonoma Valley Sun
“Obviously, we’re extremely concerned about public safety in such a highly public location,” City Manager Linda Kelly said last week. “In the meantime, we’re not taking any chances.”
Currently, the tree and environs are cordoned off. City parks worker Terry Melberg said the tree’s canopy was partly pruned July 23 – a move which was in the works before the previous evening’s incident.
“We had already set up with a tree service and an arborist on site,” Melberg said July 24. “What happens when we have the hot weather, the trees draw up a lot of moisture and that increases the weight of the limbs.”
Sanburn said more work needs to be done in the elm’s center and upper crown, but suggested it be done in the fall “when the trees are dormant.” He also noted that several elms in the Plaza and throughout Sonoma have been infected with Dutch elm disease, and suggested treating them with injectible fungicide.
“This elm and the two large elms at opposite corners of the Plaza on Spain Street should also be pruned this fall. Both trees should be thinned and their crowns reduced from the outside,” Sherburn said. “These elms and all elms should be inspected and pruned, if necessary, every three years. The trees are very healthy and can provide many years of public enjoyment.“
