based on recent weather patterns and other cases of infected evergreens, spruces and pines I suspect it is Rhizosphaera needle cast.  This is a common disease of evergreens in Kentucky, causes needle drop on lower branches, resulting in a distinct thinned appearance. The fungal pathogen, Rhizosphaera kalkhoffii, primarily infects spruce but can also affect some pine species.  

Symptoms: 

• Become evident in summer when needles on lower branches turn purplish or brown.
• Needles fall within a few weeks and lower limbs are left bare.
• Small, dark fruiting bodies (called pycnidia) form in stomata (pores in needles) and can be used to confirm diagnoses (Photos 3 & 4). Pycnidia are most easily recognized with a hand lens, but are also visible with the naked eye.

 Life cycle:

The life cycle of the fungus extends over a 15-month period. Initial infection typically takes place in spring when spores (conidia) within pycnidia are rain splashed from needle debris onto foliage. Infection can continue as long as moisture is present. During winter or the following spring, pycnidia develop in infected needles, plugging stomata. Needle discoloration and needle drop occur during summer of the second season, resulting in thinning of lower canopies. If defoliation occurs 3 to 4 consecutive years, branch death is likely.  

 

Disease management:

• Stressed trees are more susceptible to infection by R. kalkhoffii than healthy plants, so steps should be taken to maintain plant vigor.
• Properly space plants to improve air circulation.
• Practice good sanitation habits. For additional information see the Landscape Sanitation publication.
• Homeowners can apply fungicides that contain chlorothalonil, copper, or mancozeb during needle emergence (mid-April). During rainy seasons or in plantings with a history of disease, fungicides may be applied two consecutive years during spring when fungi are most active. For more information, see Homeowner’s Guide to Fungicides.  

Apply the fungicides and keep areas under the tree free of cast needles.  If the problem begins to reappear this summer or you suspect something else once you begin seeing needles beginning to discolor please bring a sample of the branch, diseased needles and healthy needles to the Extension Office so we may have one of our plant pathologists look at the sample for a more accurate diagnosis.