How to Treat Rhizosphaera Needle Cast Disease in Your Blue Spruce Tree

Blue spruce trees thrive in the right conditions, but, like all plants, they are also susceptible to disease and can suffer from environmental stress.

Cooler temperatures and wet conditions favor potential development of needle cast diseases on blue spruce trees.

Identifying needle cast disease

If you ever take a look at a blue spruce tree and see needles at the tips but as you glance further down the branch, the needles are scarce, it is most likely being caused by needle cast disease.

closeup of blue spruce tree needlesNeedle cast disease causes spruce trees to ‘cast off’ older needles.

While this may be aesthetically unappealing, rhizosphaera needle cast disease is treatable. You can nurse that tree back to health by following a program of needle cast treatment.

First, be certain that you are correctly identifying the disease.

Experts recommend that you send a few diseased needles to a lab where tests can be done to identify the problem. If you don’t want to go that route, there is an at-home version of identifying the disease.

– Trees with Rizosphaera needle cast fungus have a distinct appearance. Learn more about what to look for here.

– Trees with the disease also tend to have needles that turn yellow in the summer time, and a purple-brown color in the winter and spring.

– If you see black dots, that indicates the fruiting bodies of the fungus. White dots are normal.

Treating rhizospharea needle cast disease

Once identified as rhizosphaera, it’s time for treatment.

Treat your blue spruce by spraying it with a fungicide twice in the spring and then once every 4 weeks during wet weather. Alternate your spray with different active ingredients, explained here.

Looking for ways to prevent or minimize the effects of the fungus?

There are several things you can do to help your blue spruce.

First, you may want to spray your blue spruce with a fungicide to protect against new infections. This needs to be applied in the spring. Find out why here.

Second, pruning the branches can also help to ward off disease and help keep the needles dry, so there is less chance of infection.

Finally, if you have just a few trees affected by the disease, you could always consider removing them, as it is likely they will be infected for the duration of their lifespan.

For any more questions or concerns about your blue spruce trees, give the experts at Spruce Point Tree Farm a call at 970-379-2241. We understand blue spruce tree care and are more than happy to help!