Halt is a brand and isn't enough info to determine what you have. Need the total info of the ingredients on the label. You may have the thiophanate methyl (which you want) or you may not. Phyton 27, a systemic, while it is not that good for fusarium, is good for many things including bacterial problems that none of the other fungicides handle, and is the only fungicide so far that my husband has not complained about the smell. This is very useful when repotting in the spring when I have to repot in the kitchen because it is too cold outside yet and I want to treat all my cuts and root breaks with something. Here is a site you may find interesting:
http://www.chattanoogarose.org/MOA%20Entire%20Paper.htm