From what I can tell from pesticide labels and other references, the only way that propiconazole would be effective against Dutch elm disease is to inject it into the tree's vascular system at the root flares.  This sort of application requires a trained arborist with the proper certifications for handling the product.  I do see that propiconazole fungicides are available through on-line marketers like Amazon, but I suspect that the formulations they would offer are not suitable (probably not even legal) for trunk injection.

I was told by one of you to get the kind that you use to flood the roots every spring; I did it last year but can't remember what I used.

Hello Maria,
I’m sorry but, if it was ever available as a soil drench, it is not now. I checked several places for you:

-The manufacturer’s label. By law, the label states exactly all the affective and legal ways to apply the product for each disease it can treat. Oak wilt is prevented by applying propiconazole by injection only.( other diseases on other plants are treated by spray application but not oak wilt.) I checked 3 different brands, all were the same application.

-I checked with  MSU’s Oak Wilt specialist, Ruth Marcy. Here is her response

“No- it is not used as a soil drench for oak wilt. However, there are some disreputable tree workers who have done that before, so it may be that was the case. It is not effective used as a soil drench.”

Ruth”

Ruth Dorando Marcy

Michigan State University Extension

Your option is to have the tree injected  by a certified arborist or reputable tree service. These treatments are typically effective for two years. Be sure your service uses propiconazole.

Be sure not to wound or prune the tree during the growing season(April-July, or April -October is even safer). If a cut in the bark occurs during that time, immediately paint the cut with latex house paint( 5 minutes or less) so sap beetles that carry the fungi  are not attracted by the sap.

Find professionals and details on prevention here

https://www.michiganoakwilt.org/

Please let me know if you have more questions.

I am not talking about an oak tree.  It is a dutch elm and I was definitely given the information from someone at MSUextension!~

So sorry, of course I meant dutch elm disease! ( we answer many on elm and oak, and the two diseases are treated by injection). 
Of course, yes, an earlier response suggested that a soil drench may be available. That was Dr Crain at MSU. I will verify with him whether, indeed, one is still available or not. There may not be, and I will work with Dr. Crain to verify if it is the case.
Thank you for ‘straightening me out’
Regards, Laura

Thank you so much. 

In May, you mentioned that you had spoken with someone previously and applied a product by soil drench. I assumed that was propiconazole, but now that I have checked more carefully, that product is not labeled for control of Dutch elm disease by soil drench, only by injection. I apologize for not taking the time to look more closely at the labels. I suspect that you may have applied something like Neem oil, which is a systemic insecticide sometimes recommended by others (though not by us) as part of a strategy to protect against Dutch elm disease. The problem with systemic insecticides is that they will not prevent the initial feeding by elm bark beetle, which allows the fungus to enter the plant. They also do not protect against spread through root grafts. Therefore, we don't recommend their use. 

Since your trees are small, you could spray the bark with an insecticide. However, as I mentioned previously, trees of that size are not a primary target of bark beetles and really do not need any preventative pesticides unless mature, infected elms are within 100 feet. Keep them properly watered, and they will most likely be fine without any sprays. The best prevention in your case is just keeping the trees stress-free. A healthy tree can tolerate a lot. It's larger trees, particularly those suffering from drought-stress, that are most at risk.