NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
February 5, 1998
Anyone with elm firewood on hand should burn it or debark it before April 1 to prevent the possible spread of Dutch elm disease, according to Marcus Jackson, forester for the North Dakota State University Extension Service.
Firewood from diseased elms may contain the Dutch elm disease fungus. It may also contain beetles that can spread the disease considerable distances.
Beetles lay eggs between the bark and wood of the elm tree. Dutch elm disease fungus grows in both the egg galleries produced by the adult beetles and in the feeding galleries produced by the emerging larvae. The larvae mature and fly off as adults, carrying fungal spores with them. The beetles then feed on other elm trees, and infect them.
"Thousands of beetles may develop in a single stack of firewood," says Jackson. "This makes it very likely that nearby elms will be exposed to the disease. That's why the elm firewood should be burned before warm weather arrives, or else debarked so the larvae cannot develop. Elm wood collected in an area where Dutch elm disease is present should never be taken into an area of healthy elms unless the bark is first removed. In some cities it is, in fact, illegal to store elm firewood with bark intact."
Also, Jackson says, dying trees should be promptly cut down and debarked, burned, buried, or chipped and composted. This year sanitation is particularly important since beetles may be more abundant after the relatively mild winter.
Dutch elm disease was first identified in North Dakota nearly 30 years ago. By 1993 it had spread to all of the major stands of native elms in the state, and in many of those stands large numbers of trees have died. Because it is not feasible to exert much control over the disease in native stands, people have focused their efforts on saving trees in communities and in conservation areas.
"The largest cities in North Dakota have been quite successful in reducing the impact of Dutch elm disease by implementing stringent sanitation programs," says Jackson. "In those cities, losses from the disease vary from year to year, but the control programs have kept their urban forests stable. During 1997, Bismarck, Fargo and Grand Forks foresters reported reduced American elm losses from the disease, though many smaller cities where the disease was recently introduced saw a rapid loss of elms."
There are still many North Dakota cities and conservation plantings in which Dutch elm disease is not present, says Jackson. The best control option in those areas is to take strenuous measures to avoid introducing the disease.
###
Source: Marcus Jackson (701) 231-8478
Editor: Barry Brissman (701) 231-7866