Carnac Predictions for 2023
Written by: Tony Arnoldi, Board Certified Master Arborist, WI-0102B
Originally published February 2023
Although I don’t claim to be a “seer,” like Johnny Carson’s Carnac (remember him from late night television years ago?), it is always fun to contemplate the dynamics of all the variables that affect the various insect, disease, and environmental responses that the plants in our landscapes will show throughout the 2023 growing season.
What the weather has done over the last year or more is one of the biggest factors driving problem increases or decreases. Last winter was extremely dry and this stress caused problems, especially for conifers and other evergreens. They needed the moisture to keep the process of life and photosynthesis going throughout the winter. Because that moisture was lacking, many needles fell and, in many cases, entire branches or whole trees were killed. Last spring and summer had more rainfall, but not enough to make up the deficit that was created in winter. So, depending on site, the stress continued last year for evergreens. This winter started a little better because of good November precipitation but has been running dry since. I have measured only about an inch of water over the course of December and January combined.
So, I would expect evergreens to continue to struggle some in spring. Ongoing fungal cankers and Tip Blights like Diplodia on Pines and Cytospora canker on spruces have been able to surge because of the weakened state of the conifers.
Some insects like Spongy Moth (formerly Gypsy Moth) had increased last year because dry weather hinders natural insect diseases that help control these pests. That surge will likely continue into 2023.
Borers, especially Ips Bark Beetles, are favored by the weakened condition of their host trees. Again, conifers were the hardest hit, but Bronze Birch Borer and Linden Borer were increasing their attack on vulnerable deciduous trees, and I suspect that trend to continue as well this year.
Fungi that attack the roots, root rots like Armillarea and Phytopthora, had increased greatly over the period of time we had saturated soils. This was a six-year period of time that ended in 2021. But the disease inoculum of fungal threads and spores remains high in the soil, and that will only decrease with time of “normal” soil moisture. You might think that these wet and dry periods simply “cancel each other out” but the severe swings of each do damage in their turn, often resulting in cumulative decline of trees.
Last spring had adequate rainfall (not necessarily a lot of moisture, but enough rain “events” that repeatedly wetted the foliage) to allow plenty of leaf diseases like Apple Scab on Crabapples, Rust on Hawthornes and Serviceberries, and Septoria Leafspots and Anthracnose on a host of different trees and shrubs. These vary in how much damage they do but are highly noticeable and detract from visual appeal so are often treated to prevent their occurrence. I suspect that rainfall needed for their appearance will happen again in 2023.
Much of the success in a given year depends on environmental conditions, and monitoring for signs of stress or pest occurrence. Trust Wachtel Tree Science to help monitor these variables and adjust your program as needed to help your trees live well and prosper!