September 18, 2008

Dutch elm disease a concern during fall season

By Chris Gessele
Hazen has been named a Tree City U.S.A. for 20-plus consecutive years, and Hazen City Forrester Jeff Foster is doing everything within his powers to continue that streak.
Dutch elm disease, however, has and continues to work against him.
Dutch elm disease is an elm tree disease caused by a fungus named Ceratocystis ulmi, which is rapidly transmitted by two species of bark beetle or root grafting.
Trees infected with the fungus by beetles first show wilting, curling and yellowing of leaves on one or more branches in the upper portion of the tree. Large trees may survive and show progressively more symptoms for one or more years. Trees infected through root grafts wilt and die rapidly; this frequently occurs in the spring soon after the trees have leafed out and progresses from the base of the tree upward. Once the fungus is established within a tree, it spreads rapidly via the water-conducting vessels. The tree forms gums within these vessels in response to the presence of the fungus, causing the tree to wilt and eventually die.
According to the North Dakota State University Extension Service, DED was first found in the United States in Ohio in 1930. It has now spread throughout North America and has destroyed over half the elm trees in the northern United Sates. The disease has been reported in all states except the desert Southwest.
DED was first found in North Dakota in 1969 in Mandan. It was discovered in eastern North Dakota in 1973. By 1987 it had become established throughout eastern and central North Dakota and reported from all counties except those in the extreme northwestern part of the state.
The topic is more relevant than ever come the fall and winter months, Foster said.

The Weather Network