A puff of leaves on otherwise barren deciduous trees near West Winnie Lane in north Carson City on June 9.
Photo by Scott Neuffer.
Having undertook an investigation into noticeable tree decline, the Carson City Parks, Recreation and Open Space Department issued their findings on June 26, saying approximately 250 trees were being removed.
“Carson City staff, in collaboration with state and local plant health experts, have inspected and identified the primary factors contributing to tree and landscape decline in several public right of way, parks, and streetscapes throughout the city,” said a news release. “The team of experts included two independent ISA certified arborists, Nevada Department of Agriculture entomologist, a municipal urban forester, University of Cooperative Extension horticulturist and a licensed pesticide contractor.”
City officials listed key findings of the investigation:
• Heat stress: Heat stress from rising air temperatures over time and the use of rock mulch around trees have contributed to increasing soil temperatures. Drought-intolerant species, such as Red Oaks, were particularly struggling, showing signs of stress from heat and not adapting well to the local climate.
• Herbicide exposure: In some areas, trees and shrubs have shown signs of herbicide exposure. Herbicides are used to manage invasive weeds, which, if left uncontrolled, can outcompete healthy vegetation and can compromise tree health. Herbicides are typically filtered naturally by rain and snow over the winter months but may have remained at a higher concentration level due to the light winter.
• Insect infestation: Scale insects and powdery mildew were noted, often occurring in already weakened and stressed trees.
• Irrigation: Upon continued inspection of irrigation systems, staff have since encountered some irrigation breaks, pinched distribution lines, and aging equipment, which can contribute to inconsistent watering. Staff is repairing and replacing irrigation as needed.
• Overplanting and competition: Some trees were planted improperly, unsuitable species were identified in certain locations, and many areas were overplanted, causing roots to compete for water and nutrients in the soil.
“The city coordinated with a local licensed tree company to remove trees that were no longer viable,” said the news release. “The majority of the trees being removed are in the Silver Oak and Northridge areas. It is estimated that approximately 250 trees will be removed. Trees demonstrating viability will remain and continue to be monitored.”
The city also listed the following action items:
• The city is coordinating with the University of Nevada Cooperative Extension horticulturist regarding soil sampling for chemical residues in key areas. Once soil sampling is complete, all areas will be properly flushed out to reduce any residue.
• Staff are reviewing herbicide practices and irrigation schedules and have already made many repairs and adjustments to watering schedules.
• Landscaping practices may be revised to provide a more conducive growing environment and reduce soil temperatures for healthier root systems. For example, rock mulch may be removed from tree trunks and replaced with organic mulch, such as wood chips.
• Staff will continue monitoring affected trees and prioritize removal or replacement where recovery is not feasible.
• Staff is preparing a replanting plan to be implemented in the fall.
Residents observing tree stress and decline on private property may want to contact a certified arborist for guidance and assistance, the city advised.
More information: www.treesaregood.org/findanarborist or https://extension.unr.edu/default.aspx.
David Navarro, parks operations superintendent, can be reached at dnavarro@carson.org or 775-283-7346.