Diagnostic Forecast

The big snowstorm in January and its after math certainly dominates the big picture and has laid down a few hair-pin turns as we navigate a new year’s tree and landscape season.

While snow totals were heaviest in the western parts of the metropolitan area, and tree damage was most severe there, eastern areas have also been experiencing damage to trees. Lost and split branches, tree tops, and in some cases snapped roots, are a few examples of injuries that must be addressed and stress that has accumulated for Southeast Wisconsin trees.

Tree stress is what drives most insect and disease cycles. These are opportunistic and are either initiated now or are made worse as attack advances on trees that have depleted energy reserves and weakened defenses. Deep drought over the last two summers has also been dramatic. Stresses tend to be cumulative and “gang up” to start many a tree on a decline spiral.

On the insect side of the attack ledger, a main class of insects that will exploit weakened trees is borers. When attack begins, their damage will also accumulate and enable subsequent generations of borers to attack even easier, further accelerating the death spiral. Birch, ash, oak, linden, hickory, honeylocust, pines, and iron wood have important borer enemies, but literally all trees have potential borer pest(s) to watch out for.

Aphids and scale insects that harm trees by sucking out plant sap (i.e., they suck) are other types expected to see a rise in population with this opportunity.

Spongy moth (formerly gypsy moth), had a surge in population already last year; oaks that were defoliated by this pest and then additionally had some storm damage now may need extra help.

On the disease side of the attack ledger, Verticillium wilt will be able to enter more root systems and cause portions of trees to wither.

Root rots of various kinds have been increasing with the alternating drought and wet soil conditions of the last 2 years (at least) and seeing more evidence of their damage is inevitable, I believe.

Canker diseases that form slowly, expanding dead areas on trunks or branches, will be able to advance more quickly, needing mitigation by pruning or treatment.

All of the tools that we wield in tree care will be needed to help trees through this difficult patch. Pruning, fertilizing, cabling & bracing, root zone enhancements, other root treatments, insect and disease programs, tree injection, and others will all have roles to play in helping guide trees and shrubs to survive and thrive again. Call your ISA Certified Arborist at Wachtel to help assess your tree collection and determine the ones that may need our carefully considered care.

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