We have a number of Colorado blue spruce. Some of them look fine, others are dying back at the bottom. We have a row of blue spruce next to a row of Norway, but the Norways are fine. Any idea what the problem is and what we can do about it?

Greetings Randy:

If only I had a dime for every blue spruce question I receive each week :-)

Blue spruce has become a tremendous “problem tree” due to environmental stressors, insects (spider mites), and disease problems (Rhizosphaera needle cast, Cytospora canker; Stigmina, Sudden Needle Drop; etc.).

I firmly believe 99% of blue spruce health problems are the direct result of planting the wrong tree (e.g., blue spruce) on the wrong sites (fine-textured, clayey soils w/ poor internal soil drainage). The situation becomes even more perilous when we further antagonize these trees via Illinois’s hot and humid summers. Remember, blue spruce is native to the Rocky Mountains (coarse textured soils; good internal soil drainage; warm, yet low-humidity summers).

Blue spruce and eastern white pine decline occupy 80% of my forest/tree health questions. My advice--do not plant blue spruce here in Illinois.

Diagnoses/Treatment Options:

Diagnoses: Contact a certified arborist for an on-site inspection, http://www.illinoisarborist.org/CertifiedArboristsNew.htm

OR submit a plant tissue sample to the University of Illinois Plant Clinic:

http://web.extension.illinois.edu/plantclinic/

Environmental Stress: adequate soil moisture; proper nutrition; good air circulation (prune lower branches; don’t let lower branches touch the ground/grass/weeds).

Spider mites: insecticidal soap or horticultural oils

Rhizosphaera Needle Cast: Chlorothalonil fungicides or copper-based fungicides

Cytospora Canker: no treatment available