Tree careTree diseasesrhizosphaera needle cast symptoms on a tree

Have you noticed needles on your spruce tree turning brown and falling off? Your tree may have needle cast, a disease caused by the rhizosphaera kalkhoffii fungus.

What Is Needle Cast Disease?

Needle cast disease will cause old needles to turn brown and fall off, creating a thinned canopy that makes for an ugly tree. Repeat infections will cause branches to die, further declining the health of the tree. Here is what you need to know about needle cast, including how we can treat it.

What Trees Are Vulnerable?

All spruce trees can be infected with needle cast, but it is more prevalent in species that are not adapted to our environment, such as the blue spruce. The fungus is more likely to attack stressed trees, which makes most spruce trees susceptible even if the species is more resistant against the disease.

Symptoms you can spot:

  • Yellow/tan needles that turn brown/purple
  • Discolored needles drop throughout late summer and into early fall
  • Very few needles near the trunk of the tree
  • Thin canopy
  • Damage will generally start lower on the tree and progress upwards

In the images, you can see the thinned canopy and dieback that will occur.

blue spruce tree with needle cast disease

Treating & Preventing Needle Cast

There are a few things you can do to help prevent the fast spread of needle cast disease in the planting process. You can leave spaces between spruce trees, diversify your landscape, and plant in sunny locations. By diversifying your trees and giving space between spruce trees, you stop the potential spread of needle cast which could save you a lot of trouble in the long run. Not only does it prevent the potential to spread, but the space also improves air circulation.

Planting in sunny locations is another good idea as it will dry the needles quickly. Last but not least, proper mulching can help with prevention. We recommend 3 or 4 inch deep even layers of mulch around the trees.

If your spruce trees already have needle cast disease, they can luckily be treated with fungicides! However, you need to act swiftly since the treatment window is short.

When Is The Right Time To Apply Fungicides?

We recommend applying two applications of a fungicide spray that will prevent the spread of needle cast to new growth and other uninfected parts of the tree. The first application should be when the needles are half-elongated, usually around late spring/early summer, and the follow-up application 2-3 weeks after.

Hire Jackson Tree Service

If you have any concerns about your spruce tree, contact Jackson Tree Service, the local St. Louis tree experts! Jackson Tree Service is as St. Louis as you are. We know summers are for float trips, baseball lasts through October, and pizza should be on a wafer-thin crust. As a local, family-run business, we are extremely honored by the national & international recognitions we receive.

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