I have several Indian Hawthornes that were planted at our new house north of Fort Worth. I am worried because they all are already exhibiting signs of fire blight so I intend to spray with corn milk and to add a lot of corn meal to the soil around them. Is there more I should do? I think they planted them too low because when I was removed the damaged leaves yesterday I actually had to pull some branches out of the mulch they were buried under. Is there more I should do to help the little guys out? Also, is this fire blight likely to spread to Japenese Boxwoods?

In advance, thanks!
Christina