which kind of union organization was stopped by the taft-hartley act?

The answer is that "it made closed shops illegal for all companies that are involved in interstate commerce".

The Taft-Hartley Act is a 1947 government law that disallows certain association rehearses and requires disclosure of certain budgetary and political exercises by associations. 
The Taft-Hartley Act rolled out significant improvements to the Wagner Act. In spite of the fact that Section 7 was held in place in the reexamined law, new dialect was added to give that workers had the privilege to cease from taking an interest in association or common guide exercises aside from that they could be required to end up individuals in an association as a state of business.