'NEW HORIZON' ELM

A "TOSS UP" MORNING

YOUNG NEW HORIZON ELM 

Friday, 8:30 AM.  32 degrees F and not warming up much.  Wind SW, calm with light to moderate gusts.  The morning started out with clear skies, but has rapidly become mostly cloudy, with threatening skies in the west.  The humidity has risen to 87% and the barometer, currently at 30.06", is beginning to fall.  It looks like we will get rain by mid-day.  Hopefully not snow!
   If you are much younger than fifty, you probably have few memories of the American elm, Ulmus americana, as a street tree.  Fast growing, with an overarching branching habit that created shaded tunnels of city streets and sidewalks, it was the favorite city street tree.  Of course, with all its excellent qualities it was over planted, many cities creating a monoculture of street tree elms.  That, of course, always invites eventual disaster, and the inevitable happened with the advent of Dutch Elm Disease, which from the 1950's through the '70's virtually wiped out the American elm as a street and park tree.  Although the disease, carried by elm bark beetle vectors, is invariably fatal, there are still plenty of elms growing wild, since the disease is most damaging to older trees.  So, there are plenty of young trees that continue to produce seed.  But the fate of the American elm was sealed as far as landscape use was concerned.
   And, if you are older than fifty, you remember the utter destruction of city street trees and the nakedness of the streets without their shady presence.  And, how long it took to replace those  magnificent old trees.
   Almost from the start of the Dutch elm epidemic, efforts were made to find cures for the disease, and resistant varieties of the American elm.  The disease can be treated only with great difficulty, and the success in finding and hybridizing resistant varieties has been spotty.  A few varieties of American elm  have been shown to be resistant to the disease, but the trees most resistant are those derived from Asian species, which have a much higher natural resistance, since that is where the disease (despite its "Dutch"name) originated.
   We have planted some hybrid elms in Bayfield, and although the one pictured it is not an American elm,  'New Horizon," shows promise as a street tree.
   'New Horizon' was developed by the Wisconsin Alunni Foundation, and is a cross between the Siberian elm, Ulmus pumila, and the Japanese elm, Ulmus davidiana var. Japonica.  It is extremely fast growing, withstands wet soil conditions (but not clay soils) and is very compact and upright.  It will attain a height of 40' and a width of 25' at maturity, good dimensions for most street trees applications, although it will not provide the tunnels of dense shade along our streets that the American elm once did.   Neither does it have its golden bronze fall color.
   Good urban forestry is all about choosing the right tree for the right place, as well as creating optimum diversity so that a disease or insect cannot devastate an entire street and park tree inventory, as did Dutch Elm disease.