NEWS BULLETIN…
HIGH TREE MORTALITY in 2010
The following is an excerpt from a LANTA News Bulletin Release (June 21, 2010)
Plant Information Bulletin from the LANTA Nursery Growers
High Mortality in Urban Trees
...Urban tree and shrub mortality rates in Alberta have spiked this year (2010) mainly due to a weather phenomenon in the autumn of 2009 and successive years of drought.
Plant nursery growers and garden centres are reporting higher than normal returns on newly planted (1- 2 year) trees and shrubs, particularly in the Calgary region, which is the hardest hit. Similarly, property owners across the province are noticing a large number of plants that failed to leaf out this past spring.*
One nursery grower in the Calgary region has reported losses of between 25% - 30% of newly planted trees and almost 100% loss of one particular tree variety that was planted over six years ago.
So what happened to cause such a large loss of plants? Simply put, in the fall of 2009 there was a sudden and sharp drop in temperature that caused extensive tissue damage in the plants – this is technically called an advective freeze and resulted in what is called consequential dormancy. In Calgary this occurred between October 6th and 15th when temperatures suddenly dropped from above freezing to -16C. (Officially recorded at a Calgary weather station on October 12th, although in some areas the temperature was unofficially recorded at -19 degrees Celsius.)...
This sudden freezing ...indicated by leaves frozen in place on the plants. The result of the tissue damage was not seen until this spring, when many plants failed to break dormancy as they normally would.
Another cause of tree mortality is drought. Although 2010 has so far been wet, successive dry years since 2001 have taken a significant toll on a number of tree species throughout the province. Many drought-stressed trees (ash in particular) have also been attacked by an insect called the cottony psyllid (Psyllopsis discrepans) and this has further contributed to tree mortality...
To view the full Bulletin please click here.
For more information contact PRO-CARE Landscaping at info@procarelandscaping.ca or LANTA at www.landscape-alberta.com
