Dutch Elm Disease (DED) Resistant Elm Species and Cultivars » WAA-ISA

When it comes to street trees, many of us
“older and wiser” folks remember driving down a residential street surrounded
by a canopy of American elm trees. However, back in the late 60’s and early 70’s,
arborists started removing thousands of dead elms, including my Detroit,
Michigan street tree. This moment was a pivotal point in my “budding” career as
a young child; I wanted to know why the trees were removed and what I could do
to help.

Once widely planted and used for its form,
shade and incredible urban tolerance, the American elm succumbed to Dutch elm
disease (DED), spreading rapidly by elm bark beetles and root grafts between
elm trees. Did this mean no more elm trees in our urban forest?  Scientists at major universities and arboreta
across the U.S. worked on solutions. From their breeding efforts, new hybrids
of various species of American, Asian and European elms were created. Many of
these trees show good resistance to DED and phloem necrosis (elm yellows),
another devastating disease of elms. Through many years of breeding, evaluation
and selection, we are now able to bring more elms back to our urban forests.

The below species, hybrids and cultivars are all
commercially available in Wisconsin or available from one of the large,
bareroot tree nurseries that supply elms to Wisconsin nurseries. I have
researched their availability for you and omitted elms that are no longer
available for sale, including several American elm cultivars. As newer
selections become available with better form or growth rate and improved insect
and disease resistance, older hybrids are no longer available. Resistance to
leaf feeding insects should be part of your selection process. Elm leaf beetle,
Japanese beetle, elm leaf miner, cankerworms, etc. can severely alter the
ornamental value of a tree, i.e. defoliation or severe leaf browning in summer,
similar to littleleaf linden trees.

I. Ulmus americana (American elm); hardy to
zone 3-4 (depends on cultivar); height and width vary with cultivar, but the
American elm hybrids all have the classic, vase-shaped form; native to eastern
and central U.S. and Canada; available cultivars are listed below

U.S. National Arboretum Introductions

‘Jefferson’:
hardy to zone 4; 70’ tall, 50’ wide; upright, vase-shaped form, deep green
leaves, DED resistant

‘New Harmony’:
hardy to zone 4b-5a; 70’ tall and wide; broad, vase-shaped crown with arching
branches; DED resistant

‘Valley Forge’:
hardy to zone 4; 60-80’ tall, 60-70’ wide; upright, vase-shaped form with
arching branches, but with wild-looking branches that need training pruning
when young to develop good form; DED resistant; resistant to elm leaf beetles,
but very susceptible to Japanese beetles

Other Nursery Introductions

‘JFS-Prince II’: Colonial
Spirit^®, hardy to zone 4; 65’ tall, 50’ wide; vase-shaped
form with arching limbs; good branch structure and more symmetrical; DED
resistant; J. Frank Schmidt and Son Nursery Introduction

‘Lewis and Clark’: Prairie
Expedition^®, hardy to zone 3a; 55’ tall, 60’ wide;
rounded to spreading, vase-shaped form; fast grower; dark green leaves;
selection from Fargo, ND; DED resistant; Bailey Nurseries introduction

‘Princeton’:
hardy to zone 4; 60-80’ tall, 40-60’ wide; more upright to vase-shaped form;
does require shaping pruning when young to develop good branch structure;
large, leathery leaves; moderately resistant to elm leaf beetles, but very susceptible
to Japanese beetles; DED resistant; Princeton Nursery introduction

‘St. Croix’: First
Editions^® St. Croix^™, hardy to zone 3; 60-75’
tall, 70-90’ wide; broadly vase-shaped to spreading form; dark green leaves;
DED resistant; from a Minnesota selection; Bailey Nurseries introduction

II. Other
non-American elm species, hybrids and cultivars

Ulmus davidiana ‘JFS-KW2UD’: Greenstone^™
David elm, hardy to zone 4; 60’ tall, 40’ wide; upright, 

vase-shaped
form; vigorous grower; strong branching with wide branch crotch angles; DED and
phloem necrosis resistant; resistant to elm leaf beetle and elm leaf miner

Ulmus davidiana var. japonica: Japanese elm; (formerly listed as Ulmus
japonica,
Ulmus
propinqua
and Ulmus wilsoniana;all combined now under U.
davidiana var. japonica); cultivars listed below; native to
Japan and Asia

’Discovery’:
hardy to zone 4; 35-40’ tall and wide; more upright to vase-shaped, compact
form; prone to co-dominant leaders; dark green leaves; DED resistant and
resistant to elm leaf beetle; good drought tolerance; selection from Manitoba,
Canada

‘JFS-Bieberich’: Emerald
Sunshine^® (formerly listed as U. propinqua): hardy to zone 5; 35’ tall, 25’ wide; vase-shaped
form; dark green, glossy, corrugated leaves; DED and phloem necrosis resistant;
resistant to elm leaf beetle and Japanese beetles; selected on western Oklahoma
plains; J. Frank Schmidt and Son Nursery Introduction

‘Prospector’
(formerly listed as Ulmus wilsoniana): hardy to zone 5a; 40’
tall, 30’ wide; dense, broad, vase-shaped form with slightly pendulous
branches; vigorous grower that will require shaping pruning to develop good
branch structure; deep green, glossy leaves; DED and phloem necrosis resistant;
resistant to elm leaf beetles, but is susceptible to leaf hoppers and Japanese
beetles; U.S. National Arboretum introduction

UW-Madison Hybrid Elm Introductions

‘Cathedral’: (hybrid
of U. pumila ´ U. japonica); hardy to zone 4b-5a; 40-50’ tall, 40-60’ wide; broad,
vase-shaped form that becomes more spreading with age; vigorous grower and will
require shaping pruning to maintain form; prone to included bark formation; larger
green leaves; DED resistant; susceptible to elm leaf beetles and leaf hoppers

‘New Horizon’: (hybrid
of U. japonica ´
U. pumila); hardy to zone 4; 50-60’
tall, 40-50’ wide; upright to vase-shaped form; vigorous grower; wide branch
crotch angles; slightly arching branches; can produce co-dominant leaders;
requires shaping pruning to develop good branch structure; larger, dark green
leaves; DED resistant, but some susceptibility to Verticillium wilt; resistant
to elm leaf miner, but very susceptible to elm leaf beetles

‘Regal’: (complex
hybrid of U. carpinifolia ´
(U. pumila ´
U. ´ hollandica),
hardy to zone 4; 50-60’ tall, 30-35’ wide; narrow, upright form when young
becoming oval to pyramidal with age with a straight terminal leader and wider
branch crotch angles; it is not vase-shaped; can produce co-dominant leaders; large,
dark green leaves; DED resistant, but there was a report in Madison of a
‘Regal’ elm that died from DED; some susceptibility to elm leaf beetle and
cankerworms

U.S. National Arboretum Hybrid Elm Introductions (Washington,
D.C.)

‘Frontier’: (hybrid
of U. carpinifolia ´
U. parvifolia); hardy to zone 5; 40-50’
tall, 30’ wide; broadly oval to vase-shaped form with ascending branches;
glossy, dark green, small leaves; showy, deep burgundy fall color late in the
season; gray bark with orange lenticels; DED resistant; moderate resistance to
elm leaf beetles; do not bareroot transplant this one due to U. parvifolia as
one parent

‘Homestead’: (complex
hybrid of U. pumila ´
U. ´ hollandica
´
U. carpinifolia); hardy to zone 4b;
55’ tall, 35’ wide; narrow, oval form with upright, arching branches; not
vase-shaped; vigorous grower; dark green leaves; DED resistant, but there are a
few reports of DED on ‘Homestead’; very susceptible to elm leaf beetles and elm
flea weevils and other leaf feeding insects

‘Patriot’: (complex
hybrid of U. wilsoniana, U. pumila, U. carpinifolia, and U.
glabra); hardy to zone 4b; 50’ tall, 40’ wide; stiffly upright, to narrow,
vase-shaped form with age; dark green, glossy leaves; DED resistant; elm leaf
beetle resistant

‘Pioneer’: (hybrid
of U. glabra ´
U. carpinifolia); hardy to zone 5;
50’ tall and wide; rounded form; vigorous grower and will require shaping
pruning to develop good form; dark green leaves; DED resistant; highly susceptible
to elm leaf beetles and other leaf feeding insects

Morton
Arboretum Hybrid Elm Introductions (Lisle, IL)

‘Morton’: Accolade^®,
(hybrid of U. japonica ´
U. wilsoniana, both now listed as U. davidiana
var. japonica); hardy to zone 4b-5a;
50-60’ tall, 30-40’ wide; vase-shaped form with upright, arching branches;
vigorous grower and will require shaping pruning to develop good form; glossy,
dark green leaves; DED and phloem necrosis resistant; but there were reports in
Minnesota of two Accolade^®
elms that died from DED, however, an overall excellent rating for DED; moderately
resistant to elm leaf beetles, Japanese beetles; good drought tolerance;
available through the Chicagoland Grows Plant Introduction Program

‘Morton Glossy’: Triumph^™,
(complex hybrid of Vanguard^™
´
Accolade^®); hardy to
zone 4; 50-60’ tall, 40-50’ wide; oval form with upright, arching branches; vigorous
grower, but easy to train in nursery; very glossy, dark green leaves; DED and
phloem necrosis resistant; elm leaf beetle, Japanese beetle and cankerworm
resistant; good drought tolerance; available through the Chicagoland Grows
Plant Introduction Program; one of the best elms in my opinion

‘Morton
Plainsman’: Vanguard^™,
(hybrid of U. japonica ´
U. pumila); hardy to zone 4; 45-50’
tall, 40-50’ wide; rounded form becoming more vase-shaped with age; vigorous
grower and will require shaping pruning to develop good form; dark green
leaves; DED and phloem necrosis resistant; susceptible to elm leaf beetles, elm
leaf miner, cankerworms and Japanese beetles; good drought tolerance; available
through the Chicagoland Grows Plant Introduction Program

‘Morton Red Tip’: Danada Charm^™,
(complex hybrid of (U. japonica ´
U. wilsoniana) ´
U. pumila); hardy to zone 4; 60-70’
tall; 50-60’ wide; rounded when young becoming vase-shaped with age; vigorous
grower that requires shaping pruning to develop good form; red-tinged, new
leaves turn dark green in summer; DED and phloem necrosis resistant;
susceptible to elm leaf and Japanese beetles, cankerworms, and gypsy moth;
available through the Chicagoland Grows Plant Introduction Program

‘Morton
Stalwart’: Commendation^™,
(complex hybrid of Accolade^™
´
(U. pumila ´
U. carpinifolia); hardy to zone
4b-5a; 50-60’ tall, 40-50’ wide; upright, oval form; symmetrical, arching
branches; vigorous grower; large, dark green leaves; DED resistant; susceptible
to elm leaf and Japanese beetles and gypsy moth; good drought tolerance; available
through the Chicagoland Grows Plant Introduction Program

Elm species used in breeding DED resistant elms:

Ulmus americana: American elm

Ulmus carpinifolia: smoothleaf elm (now called U. minor)

Ulmus glabra: Scotch elm

Ulmus ´ hollandica: Dutch
elm (hybrid of U. carpinifolia ´
U. glabra)