Monday, January 14, 2019

Snow, snow, snow - Moisture has finally arrived

By Susan Carter

Is it too late for some plants and trees?  Here in Western Colorado we had one of the driest and hottest years on record.  Drought started in the Fall of 2017 and continued for a whole year.  Parts of Mesa County only received 7” of precipitation, with counties to the south receiving even less.  In the winter of 2017/2018, for the home landscape, winter watering was a must for evergreens and newly planted trees.  Even old, mature trees had issues. 

Almost immediately in the spring, I had several peach orchards call me.  One person thought he might have a new insect:  there would be an area of leaves on the branches and twigs, and then a span of a foot or two with no leaves at all, then another cluster of leaves.  It turned out to be a combination of issues, including lack of acclimation in fall followed by a dry winter.  Orchards with rockier soils had more issues.  We often don’t think much about fall temperatures but they help to transition our trees and smaller plants into dormancy.

Peach Blossoms- CSU Extension TRA
Just like us, trees do not like rapidly changing temperatures.  They prefer to have a gradual temperature change, but how often does that happen in Colorado?  Many of the peach buds had abscised, basically just dropping off the stem.  Luckily, there was enough left to still have a good peach crop.

For the home gardener, it is easier to water a few plants in winter.  But for people that live in wooded areas, or with large acreages, this is nearly impossible.  So, calls started coming into the office mid-summer and even up through mid-winter.  The Glade Park Area and the Unaweep Canyon area, and other areas south, started seeing massive amounts of Pinon pines dying, in some cases those located on rocky ledges went first followed by surrounding trees.  We first saw twig beetles, then the Ips beetles.  Even a few trees reported to be 300-400 years old did not make it.   Besides the drought, the valley had a record number of days over 90, and I am sure at higher elevations surrounding the valley one could see average temperatures even higher.

Pinon Pine with pitch tubes from Ips
This spring will be the continuation of the drought story.  I learned in a drought meeting early this week that most of our domestic water providers in our area have been able to fill their reservoirs to 100%.  But continued snow and moisture throughout 2019 will tell if levels that are needed are maintained thru the summer.  Some reservoirs in 2018 approached the 50% mark.  The good news is the moisture we are getting this year will help plants thru the winter, and the negative temperatures we had hopefully lasted long enough to impact insect populations.  Just as we get a cold when we are stressed, trees attract insects.  So, if the numbers of insects are decreased and the trees are healthier, the infestations should decrease. 

The bad news is that (for trees and plants) it may take up to 5 years or more to show the final outcome of an event such as drought or quick weather changes.  Plants use up a lot of energy getting thru these stressful time.  The overall health before the event, and conditions after the event, will be the determining factor of the long-term survivability of the trees.  In nature, there always seems to be an ebb and flow of populations, whether it be rabbits and foxes, or young pine trees and Ips beetles.

Susan Carter is the CSU Extension Tri River Area Horticulture and Natural Resource Agent

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