Rhizosphaera

• Rhizosphaera is a fungus infection that attacks mainly Colorado blue spruce. The needles turn yellow in mid to late summer and brown or purple by late winter or early spring. Examine the needles with a magnifying glass and look for tiny black spots in rows. These are the fungal spores. Chlorothalonil should be sprayed on new needles in the spring.
  
  

Lirula Needle Blight

• Lirula needle blight strikes Colorado blue spruce and white spruce the most. The disease will appear in the second year of infection when the needles become yellow or brown. In the third year, a raised black line will appear along the mid-rib of the needles. The needles will turn greyish brown, but will stay on the tree for years. Chlorothalonil or Bordeaux should be applied when the new needles reach half the length of the mature ones and then again a month later. This needs to be done each of the three years of the life cycle of the Lirula.
  
  

Spruce Needle Rust

• Spruce needle rust attacks Colorado blue spruce, white spruce and black spruce. This disease attacks the new needles and turns them yellow. During the summer, pale orange to white tube-like projections will appear on the needles. These will release powdery orange spores. The infected needles will fall off in early fall. This is mostly a cosmetic problem and no action is needed.
  
  

Cytospora Canker

• Cytospora Canker can damage most varieties of spruce trees and it usually attacks trees that are at least 10 years old. Needles will turn brown or purple/brown and fall off. Branches will die in different parts of the tree and the branches will ooze a bluish white resin. It is very rarely fatal to the tree, but can cause a great deal of damage.
  
  

Tomentosus Root Rot

• Tomentosus root rot attacks black, white, Colorado blue, larch and Norway spruce. The heartwood of both the roots and trunk will turn reddish brown. Cross sections of infected wood looks like a honeycomb. Trees will have stunted growth, produce more than the usual amount of cones and then die. Take precautions like mulching around the base of the tree so it will not become damaged by a lawn mower because the root rot will enter through a wound.