It's been 5 years since my first batch of logs started producing shiitake. Five years seems to be the limit for most logs. The shiitake fungus has used up most of the nutrients in the log, replacing dense mineral and sugar laden tissue with spongy mushroom mycellium. I can see and feel this happening. Logs get much lighter, mushroom crops get smaller and less numerous. Its time to retire a log. I keep data on each log, it has a unique numbered tag. If the bark is falling off and production for the whole season falls below 5 oz, then the log will be retired to the fire pit. So, not quite the end, it can still produce a cheery flame in the campfire.
