This plant is about 7 feet tall and about 18 years old.  I is next to a trellis that is next to a side of the house.  The yellowing and dropping leaves started in earnest this spring and continues to accelerate.  I am not sure what more specific info you need or want.  Please advise.

Hi, 

It does mostly appear to be normal leaf aging and shedding that occurs in the spring. If it seems to be more than usual then maybe the plant was stressed this past year and needs to be monitored for supplemental watering. 

It possibly might be Pyracantha Scab Disease as sometimes the beginning signs are yellowing leaves. You can monitor the fruit when they form to confirm this and we wouldn't recommend treatment without knowing the disease first.

Penn State has some information on Pyracantha Diseases and treatments. If it is a scab disease that is a fungal infection and often difficult to control. The best thing to do is to plant resistance cultivars. If your plant has it, it may be a more susceptible cultivar or unfortunately has succumb to the fungus either way. You can attempt to spray a fungicide (although they are not often 100% effective) in the spring once you confirm this disease, however different fungi travel and reproduce when the weather temperatures are right and treatment would be extensive until dryer weather comes. The Penn State explains this further. For this year, it doesn't warrant treatment since you would need to start earlier in the season and continue through until weather symptoms improve. 

Let us know if you have further questions or notice more signs and symptoms of possible disease. 

Emily

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