What is Rhizosphera Needlecast?
Rhizosphera Needlecast is a common disease found on Colorado Spruce –Picea pungens – (also called Blue Spruce). It is a fungal disease that typically spreads through the air from infected spruce. Below is a photo of what an infected spruce will look like after a couple seasons:
Rhizosphera Needlecast will cause the tree to drop needles from the inside out and bottom to top. This makes the tree to look progressively more thin as the disease progresses.
How Do You Treat Needlecast?
This disease is not typically able to be treated by homeowners, unless the infected tree is very small. The treatment for Needlecast is not a true treatment either, it is mainly a prevention method to keep the disease from spreading further in the tree. If you have a large tree infected with Needlecast, it is best to contact your local, reputable tree care company.
The best way to treat Needlecast is to spray the new growth of the tree with a systemic fungicide. This will get absorbed into the needles and prevent the new growth from being infected with the disease. Older needles are not able to be treated, and will eventually get infected and fall off. This treatment is good if your tree is in the early stages of being infected by Needlecast, but is not worth it for trees in the more advanced stages of the disease.
What Trees Should I Use to Replaced Diseased Colorado Spruce?
There are many evergreens which are completely resistant to the Rhizosphera Needlecast Fungi. The list of similar evergreens to Colorado Spruce consist of: Norway Spruce, Green Giant Red Cedar, Meyer’s Spruce. These trees can be placed in the exact same spot as diseased Colorado Spruce, with zero chance of getting infected by the disease.
There are also many trees which are almost completely resistant to the disease, and can be planted anywhere except in the exact same spot as diseased Colorado Spruce. This list consists of: Black Hills Spruce, White Pine, Douglasfir.