Spruce Problem On Commercial Property

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  Recently OSU Extensioneers Tim Malinich and Jim Chatfield met with horticulturists at a property in northern Ohio to look at a number of declining spruce trees. Most of the spruces on the property appeared healthy but a number had needle browning and and branch dieback, ranging from minor to severe.

  Some of the needle discoloration ascended the tree in somewhat of a spiral pattern, sometimes it was more complete, with some trees if not dead or dying, at the least becoming aesthetic liabilities. There was no evidence on the spruces at this property of any significant infectious disease, insect, or mite problems.

 

Spiral pattern of damage on spruce
Spiral damage on spruce

 

  There was needle purpling which is often cited as a characteristic symptom of Rhizosphaera needlecast disease, but do not become blinded by this useful but limited clue. Purpling is also a generalized symptom of needle desiccation and death on spruces. As noted, we did not find evidence of Rhizosphaera needlecast or of spruce needle disease (SNEED).  

 

Needle purpling on spruce
Needle discoloration on spruce

 

  Last year was somewhat droughty in this part of Ohio, but this and other possible environmental stresses seemed unlikely as major causes of problems here although there were areas without irrigation and some areas where water pooled. Something else seemed amiss.

  We suspect herbicide injury. There was a lack of mulch for many of the spruces.  Bare roots were exposed. Glyphosate products had been applied and were mixed with diquat herbicide. Label directions warn of application directly to exposed roots. The spiraling injury on some trees is consistent with uptake of herbicides from one area of the root system and its movement up the spiraling vascular system of spruce. {This pattern is familiar to those who diagnosed Imprelis herbicide uptake and injury years ago, though Imprelis of course was not the culprit here.}

 

Growth-regulator herbicide damage on spiraea adjacent to spruces
Growth-regulatore herbicide injury from past season on spiraea adjacent to spruces

 

  Read those labels carefully and continuously expand knowledge of all products and combinations used. Protect roots with 2-3 inches of organic mulch.  And there is hope - buds are green on most plants.

Hope. Buds are greein on spruce