The phrase "to trade unions" means to involve or address trade unions in a particular matter, issue or situation. A trade union is an organization that represents workers and their interests in negotiations with employers over wages, hours, and working conditions. When someone says they are going to "trade unions," it usually refers to taking action or seeking support from the trade union movement as a whole. This can include things like joining a labor union, attending union meetings, or advocating for worker's rights within the context of a particular issue or dispute.