Needle Cast Disease

​Are the needled trees in your landscaping looking brown & sickly? There's a good chance it's due to one (or both) of the needle cast diseases sweeping though our area. Rhizosphaera Needle Cast & Stigmina Needle Cast diseases are devastating local needled tree populations. Both are caused by fungi and both can infect your trees at the same time.

The best way to prevent tree loss and the spread of both diseases is to AVOID PLANTING ALL TREES SUSCEPTIBLE TO THESE INFECTIONS. Unfortunately, most nurseries & plant catalogs are still full of them!

When a large blue spruce in our front yard began losing needles we started looking for answers online. What we found was all bad news. Most articles we read warn there is still much to be learned about Rhizosphaera & Stigmina Needle Cast Disease. Limited information is available online, even fewer options exist for successfully treating these diseases. Bottom line, we expect to lose a few of our trees and you probably will too. Here's what we know so far.

Rhizosphaera Needle Cast Disease

• Caused by several species of the Rhizosphaera Fungus.
• The ecology & pathogenicity of Rhizosphaera is poorly understood.
• Develops in mild temperatures with prolonged needle wetness.
• Starts on lower, inner growth & spreads upward through tree.
• Trees take up to 15 months after initial infection to show symptoms.
• Spores form on discolored (purple/brown) needles.
• Invades through stoma (pores used for gas exchange.)
• ​It's believed Rhizosphaera is more aggressive than Stigmina Lautii fungus.

Most Infected Species - Spruce

• Colorado Blue (Picea Pungens)
• White (Picea Glauca)
• White spruce (P. Glauca) includes Black Hills Spruce!
• Oriental (Picea Orientalis)

Rhizosphaera Also Infects

• True Firs (Abies)
• White Fir (Abies Concolor)
• Pine (Pinus)
• Hemlock (Tsuga)
• Douglas Fir (Pseudotsuga)
• True Cedars (Cedrus)

Most Resistant Species

• Norway Spruce (Picea Abies)
• Red Spruce (Picea Rubens)
• Note: Most resistant does NOT mean immune.

​
​Management

• Remove dead or dying limbs, branches & needles.
• Dispose of infected limbs & needles by burning (where allowed), burying or hot composting.
• Treat with fungicides.
• Fungicides containing copper or chlorothalonil as active ingredients are most recommended.
• Treating with fungicide does not kill active infections but can deter additional & subsequent infections.

Stigmina Needle Cast Disease

• Caused by Stigmina Lautii Fungus.
• Develops in mild temperatures with prolonged needle wetness.
• Invades through stoma.
• ​Spores form on green needles.
• Develops faster in weak or stressed trees.
• Symptoms develop during the growing season or the following year progressing over the course of 3 years.
• First indicators are tiny black spots on needles with faint yellow bands around needles.
• Stigmina will over-winter in diseased needles left on the ground or on tree.
• Stigmina Lautii is believed to be less aggressive than Rhizosphaera Fungus.

Most Infected Species - Spruce

• Colorado Blue (Picea Pungens)
• White Spruce (Picea Glauca)

Stigmina Also Infects

• Norway Spruce (Picea Abies)
• Oriental Spruce (Picea Orientalis)
• ​Serbian (Picea Omorika)

Management

• Prune out dead & dying branches.
• Remove dead needles including the dropped needles underneath trees.
• Prune declining branches as close to the trunk as possible to remove infected needles and to increase light & airflow.
• Soak tree roots during dry times. (Stigmina can be aggravated by drought.)
• Apply organic fertilizer to improve overall health of tree.
• Chemical treatments MAY help although very little information is known at this time. 
• Chemical treatments include:​

Chemical Treatments include:

1. Broad spectrum fungicide application.
2. Local & highly systemic fungicides applied in spring. Severe cases may require a 2nd fall treatment.

Our Best Advice,
Watch Your Trees Closely & Please Avoid Spreading Disease.
DO NOT PURCHASE OR PLANT SUSCEPTIBLE SPECIES
(Until more info & effective treatments become available)