Works are tending the tree so in this case the service and the promoting Jehovahs name are works, The fruit will be the results of these activities.
So door to door work what are the fruits, what is the purpose behind it? If it is to make disciples then it is a poor crop. If it is to explain their faith then the world outside the organisation is still unclear on the specifics of the faith and that Jehovah is their interpretation of God's name. If it was a real tree or a crop it is very poor indeed. Just doing the work is not enough there has to be something to show for it.