The main thing do initially with slippery elm is to identify that it is indeed not an American elm. Slippery elm are not affected by Dutch elm disease so treating for Dutch elm disease would be not cost effective. The main difference is in leaf size.  Slippery elm have a smaller sized leaf.  Usually 2" from tip to the base of the leaf.  While an American elm has a larger leaf.  The other major difference in the leaf that you will notice by the feel is that a slippery elm has a smooth leaf.  The American elm has a rougher feeling leaf.
Slippery elm is a great tree to plant aside from them spreading all over the place.  This tree has seeds and plenty of them.  They grow like weeds and are very easy to maintain. You do have to do some upkeep on trimming down the new little trees that will sprout.  These trees grow to be very large and make for great shade trees.  If you can get past the idea that you may need to pull up a couple of these trees every year they are perfect to plant. 
The only diseases that they get are cosmetic and usually do not get bad enough to kill the tree completely.  The root system is very vast and often protrudes from the ground.  Covering protruded roots with fresh black dirt is completely safe for the health of your tree no matter the species of tree.
Slippery elm is very well know as a medicine for humans.  It has been used dating back to native Indians where slippery elm was used for cuts, sore thoughts, bowel disease and everything in between.  Now slippery elm has been tested to treat for certain types of cancer and lymes disease. Here are some things to look for in Slippery Elm:
  • Leaf turning yellow
  • Leaves being severely damaged
  • Holes in bark from sapsucking insects
Ulmaceae family
Emerald Ash Borer, dutch elm disease, maple wilt, disease control, tree treatments
Common Name: American elm

Scientific name: Ulmus americana
Leaves: alternate, 3-9.5" long, double serrated edges, oblique base
Bark: Medium gray with large scales running vertically
Height: 100" max
Spread: 70'
General info: Large deciduous tree native to North America and can live up to 300 years.  These trees are known to be very hardy and handle difficult environments.  In Minnesota most have been devastated by Dutch elm disease.  Only around 1 million American elm remain in Minnesota today.

Pests and diseases: Dutch elm disease, leaf spot, elm yellows, Japanese beetles, aphids, and bark beetle (vector carrier of DED)
Common Name: Hackberry

Scientific name: Celtis occidentalis
Leaves: Alternate, ovate shape, 2.5-4" long, 1-2" broad, oblique at the base
Bark: Light brown to silvery gray, thick suppressed scales, distinctive pattern
Height: 30-50' tall at max
Spread: 20-30'
General info: A native tree to the United states.  Grow to the age of 200 years in ideal conditions. Can grow in many different habitats but prefer him levels of limestone. In forest conditions can be very shade tolerant.

Pests and diseases: No known fatal diseases
Common Name: Slippery elm

Scientific name: Ulmus rubra
Leaves: Alternate arrangement, oblong to ovate shape, 4-8" long, velvet texture on back
Bark: Rough dark gray bark at maturity
Height: 40-100' max
Spread: 30-70'
General info: Much more tolerant of Dutch elm disease then American elm.  This tree is most known for its use in medicine.  Bark is used for thread, twine and rope.

Pests and diseases: Dutch elm disease