Cold Spring, Trees and Aphids
Each moment is a new one and every growing season is unique. Here we are, two weeks into June in Colorado and it’s a remarkable season so far. We experienced the coldest May in 24 years. Most everyone is aware of the record snow pack up in the mountains this Spring. A-basin has 25 runs still open and Ski and snowboard bums across the front range have broken out their speedos and bathing suits for some late season Spring skiing action photos.
If you are seeing some funky symptoms on your trees this year you are not alone. It turns out the weather patterns have wreaked havoc with several tree species. Ash trees across the front range are showing peculiar signs of stress independent of the symptoms of Emerald Ash Borer. Many Green Ash have branches with buds that did not open this Spring. We’re waiting to see if these branches will push out new dormant buds and re-leaf or if the branches will die-back.
Redbud trees have also fallen victim to the variable Colorado weather with many pushing very small leaves and some not waking up at all. The same is true for Catalpa which were damaged by the Spring cold. Some trees have died completely and others have leaves on only half of their branches. Some Maples were in the process of expanding their leaves when we were hit with the cold and they will have to push new leaves from dormant buds that emerge from the twigs.
Cool wet Springs and trees with new succulent growth often support outbreaks of aphids. “Yay! Aphids”, everyone’s favorite tree pest. Dropping “Sap” on car windshields, driveways and patio furniture. Well that’s not actually sap falling from aphid infested trees. It’s a sweet sugary excrement known as “Honeydew”. Not to be confused with the common suburban household phrase of “Honey Do”.
Speaking of “Honey Do” aphids, which have been evolving for close to 280 million years, have mostly done away with the need for males. They are parthenogenetic, meaning they reproduce asexually with genetically identical females born to other females throughout the growing season. They are able to reproduce incredibly fast which is why in the matter of a couple weeks trees and patio furniture can be covered in their sweet shiny poop.
There are a number of strategies for dealing with aphids including the use of predatory insects like green lacewing larvae or ladybugs. Most aphid outbreaks don’t cause serious injury to trees. They are mostly an unsightly nuisance to the humans that live under the trees. If we didn’t have aphids the car wash industry in this country would probably suffer and there would be a lot less “Honeydew”
Photo credit UMN extension