What is Needle-Cast disease?

Needle cast disease comprises a number of fungal leaf pathogens that cause damage to evergreen tree species. Spruce are particularly impacted by needle cast disease but fir, pine, and hemlock can be attacked too. 

Rizophaeara is the most likely fungal pathogen, but Cytospora canker can exhibit similar branch death and may be working on a tree simultaneously.

Warm, wet, spring weather creates favorable conditions for the disease to spread through spores. Limited airflow in dense canopies contributes to the problem. 

Cultural remedies can help keep this disease at bay. Adequate air flow, spacing between trees, pruning of infected branches, and removal of dropped needles can moderate the number of spores in the environment.

If you have evergreens on your property, maintaining the environment can reduce the disease pressure.

However, if a tree has been suffering from needle cast for a while, more direct treatment will be required to reduce the disease. 

Fungicide applications involve spraying the entire canopy. Generally speaking, for any tree that is more than 20 feet tall, it will not be practical to spray.

Because the best control is through foliar fungal applications, many larger trees are left to fend for themselves.

Larger trees will not be immediately killed by the disease. Many trees live for years, slowly losing more and more branches. Their appearance begins to look really bad as more and more branches die. Secondary problems like gummosis- a tree's reaction to stress that pushes out sap in an effort to quarantine the problem - can be unsightly and messy.

Insects are also more likely to attract a weakened tree, which may accelerate a tree’s decline.

If you have large or small evergreens on your property you might consider consulting with a qualified arborist to manage the various  needle cast diseases.