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by Swingle Lawn, Tree & Landscape Care
A common site this September are trees with brown leaves, early fall color, and dead branches. What is causing these maladies?
Record cold October 2009
Many trees and shrubs were not ready for the second coldest October on record. In Denver, record lows were recorded on October 2, 9 and 10. The record low of 17 degrees recorded on the 10th froze many landscape plants.
Dry winter
The first quarter of 2010 was especially dry with only 1.17 inches in the precipitation bucket. Meaningful moisture did not reach us until the last days of April. The extreme dryness resulted in root desiccation. When trees loose roots they compensate by making themselves smaller. One way to do this is by shedding (deadwood) branches.
Late spring
May 2010 began as the coldest on record since 1872. Temperatures moderated towards the end of the month, however many trees and shrubs were a good two weeks late in leafing out. Late springs favor diseases such as anthracnose and fireblight. These opportunistic diseases attack trees when they are dormant. The longer the winter dormancy, the more severe diseases become. Fireblight on crabapples is common.
Increase in insect activity
This year saw a marked increase in damaging pests. Scale insects are sucking sugars from the twigs and branches. Ash and honeylocust are being infested by a new false pit scale. European elm scale is heavy on American elm. Wood boring insects such as ash borer are prevalent and we are seeing more instances of high-country mountain pine bark beetle infesting urban landscaped pines.
What to do now
Make plans now to water during the winter months. Make sure you have access to your hoses during the winter – or have a commercial tree care company to do this service for you. This will guard against a DRY WINTER.
Note those trees and shrubs with dead branches. The dormant timeframe is the right time to prune. Arborists are able to tell between dead and live wood in the winter.
Inspect your trees and shrubs for scale insects. Many scales are hard to detect and it is a good idea to contact your tree care company for an evaluation.
Swingle Lawn, Tree & Landscape Care | 8585 East Warren Avenue | Denver | CO | 80231