Answer: Pyracantha are subject to two diseases; scab and fire blight. But, the symptoms you describe do not completely match the usual progression of either disease. Scab disease will leave lesions on the stems and fruit (similar to apple scab), and fire blight affects an entire shoot or stem, leaves and all, turning them a reddish-brown, and leave them hanging on the branch or stem. Both problems should involve the new leaves. Unless additional symptoms appear, I'm inclined to believe the problem is cultural. If the berries were from last year, they should be dropping now to make room for new flowers and new berries. Since these are this year's crop, perhaps there was a cold snap or an extended rainy period that prevented insects from pollinating the flowers. You might want to prune off the berry clusters and remove them from the garden - just in case - and then watch the plant closely to see if additional symptoms appear.
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