Rhizosphaera needle cast

Asked January 19, 2019, 12:50 PM EST

Greetings. My twenty-year old Colorado spruces have this affliction. The trees are too big to treat safely with a fungicide. Is it okay to just leave them alone? Will it kill the trees? Thanks very much.

Stearns County Minnesota

2 Responses

There is rarely a Blue Spruce in Minnesota that is not effected by this fungus at some time. Description and treatment is explained in the link below. As you mention, the size of your trees prohibits full treatment unless by a professional company. You can slow progression by removing branches that appear more effected. Over time the stress of the disease makes the tree more succeprable to other insects and disease. https://ag.umass.edu/landscape/fact-sheets/rhizosphaera-needle-cast

There is rarely a Blue Spruce in Minnesota that is not effected by this fungus at some time. Description and treatment is explained in the link below. As you mention, the size of your trees prohibits full treatment unless by a professional company. You can slow progression by removing branches that appear more effected. Over time the stress of the disease makes the tree more succeprable to other insects and disease. https://ag.umass.edu/landscape/fact-sheets/rhizosphaera-needle-cast