November’s Frigid Polar Vortex Now Impacting Area Foliage

Same Tree, Different Branch

Despite the welcome rains from this spring, Prowers County residents have noticed that some of their trees are in distress, losing leaves as if it were already autumn.  According to Shelly Simmons,  Assistant District Forester of the Colorado State Forest Service, La Junta District, a part of the situation stems from the intense cold snap we experienced this past fall.

National newscasts were paying particular attention to what was termed a Polar Vortex, a fast moving weather system with extremely frigid temperatures which followed warmer than usual weather through parts of the nation, Colorado included.  A flyer posted by CSU Extension indicates that a sudden, dramatic temperature drop in early November of last year would have lingering impacts on trees in the impact area.  Through early and mid-fall, warm temperatures persisted, in some cases setting record highs with temperatures into the low 80s last October.  Dramatic fluctuations preceded the deep freeze in the days leading up to the event, with daytime highs hovering around 60 and 30s for nighttime lows.  These changes impacted trees and plants in the middle of their annual chemical and physical transition from warm to colder weather, a process that is lengthy and helps protect the plants during winter months and sets them up to return to a leafy state in the spring.

In parts of Colorado, on November 10 last year, there was a temperature drop of over 50 degrees from day to night and trees and shrubs had not completed the ‘hardened off’ transition for the winter.  Many conifers and deciduous trees showed immediate freeze damage with straw-colored needles or flash-frozen leaves.  The effects on some of the trees wouldn’t be recognized until the spring.  Some evidence is black, shriveled shoots or buds.  Evergreens may have dry buds and brittle twigs.  If the twig or branch is soft and supple it should be able to sustain new growth through this spring.  If the bud is dry and brittle, it will be dead.  Sycamore trees, for example, have shown damage from the sudden fall freeze, exhibiting a condition called anthracnose, a fungus which causes a rapid wilting of newly emerging leaves.  Infected leaves will often curl and turn brown and eventually drop off the branches.  If the tree is healthy enough, a second crop of leaves may be produced by mid June to early July.  This second set of leaves can be protected with fungicide sprays if a cool and moist condition exists.

The care a tree requires this spring is directly tied to the level of freeze damage it sustained from the fall.  Additional fertilizer is not recommended.  Conifers may come out of the damage with new growth masking the frozen needles.  Deciduous trees may need pruning to remove the dead twigs and branches.  Simmons noted that in La Junta, English Elm trees were affected, “But those have been found mostly in La Junta and very few other areas in our region,” she said.  Simmons noted that Siberian or Chinese Elms could be impacted, as well as fruit-bearing trees.

By Russ Baldwin