Kansas State University has a horticulture research center just south of Wichita named the John C. Pair Horticultural Center. Extensive plant research is done at the center. In 2007 they established a National Elm Trial with 18 cultivars. All of these are Dutch Elm Disease (DED) Resistant with 4 being true American elms. The remainder are either hybrids or other elm species. Here are results of the trial with notes:
The four true American elms are ‘Valley Forge’, ‘Princeton’,
‘New Harmony’ and ‘Lewis and Clark’ (Prairie Expedition). All
have shown excellent tolerance to DED. Characteristics listed
below are primarily from our study at the John C. Pair Horticultural Center
but storm breakage is from the University of Minnesota.
‘Valley Forge’ Survival: 100%
Crown Shape: Vase
Lacebug damage to foliage: Minimal
European elm flea weevil damage: Minimal
Storm Breakage: Fair
Comments: Strong grower, broad spreading
‘Princeton’ Survival: 100%
Crown Shape: Vase
Lacebug damage to foliage: Minimal
European elm flea weevil damage: Minimal
Storm Breakage: Fair
Comments: Impressive grower, upright habit, attractive tree
‘New Harmony’
Survival: 100%
Crown Shape: Vase and round
Lacebug damage to foliage: Significant
European elm flea weevil damage: Minimal
Storm Breakage: Not in Minnesota study
Comments: Narrow, upright habit with strong, central axis.
‘Lews and Clark’
(Prairie Expedition)
Survival: 80%
Crown Shape: Broad oval Lacebug damage to foliage: Minimal
European elm flea weevil damage: Minimal
Storm Breakage: Good
Comments: Strong grower with broad spreading habit, some wetwood.
Storm damage can be minimized by pruning when the tree is young. Maintain a central leader but prune out all lower branches as the tree grows and branches increase in diameter so that there is room to work under the tree. Also prune out branches attached with a narrow angle as these are most likely to give way in ice or wind storms.