No - but its best to leave at least 4 sticks unpicked to die back naturally as autumn approaches for the health of the plant.

After August rhubarb is starting to die back and the stems are getting woody. If you can still find reasonably fresh stems then it is quite OK to eat them.

That might be so where you are bulbaholic, but mine's still growing here in London! I was just thinking yesterday I'll have to cut some more...

Mines is actually better now than it has been all year and I will certainly be using some of it.