WW-03765     1993  

History of Dutch Elm Disease in Minnesota

A Problem Denied:
Dutch Elm Disease

How could anyone be convinced to spend money on any program designed to reduce losses to Dutch elm disease when the disease wasn’t even here?

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Minnesota was considered by many to be too far north for Dutch elm disease to be a problem. It was thought that the smaller European elm bark beetle, which had been the primary vector throughout the eastern states, would have difficulty surviving the harsh winters of Minnesota. It was almost impossible to convince people of the potential hazards of the disease when it was still well removed from the state’s borders.

How could anyone be convinced to spend money on any program designed to reduce losses to Dutch elm disease when the disease wasn’t even here? It wasn’t even possible to convince people to stop planting elms, and nurseries were still promoting the elm as an easily transplanted fast growing tree that was resistant to pests and tolerant of harsh urban environments. It was also promoted as a tree that grows tall, beautiful, and lasts for more than a century.

In fact, nurseries continued producing and selling elms even after the disease entered Minnesota.

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First Arrivals

We will never know exactly when Dutch elm disease first occurred in the state, but we do know it was found in the state for the first time in the early summer of 1961. This finding was identified from some branches from the Highland area of St. Paul, brought in by a tree service company. As far as was known at that time, only one tree was affected and it had wilted in 1960.

More diseased trees were found in 1961 in the Monticello area near the Mississippi River. That several trees were infected at that location suggested that the fungus had been there for at least a year, possibly longer. It is reasonable to assume that the fungus could have been present in one or more of Minnesota’s southern tier counties, which were relatively near infested Iowa counties.

Dutch elm disease was also brought into Litchfield, probably in 1961. Many think that it likely arrived there in an automobile of a person returning from a visit to relatives in Illinois, a fact that was learned about accidently in 1987. While the evidence was circumstantial, it was learned that elm wood was brought to Litchfield from Illinois in that year, and a Litchfield elm died of Dutch elm disease shortly after.

The introductions of Dutch elm disease into St. Paul and Monticello were almost certainly the result of people moving the Dutch elm disease fungus, Ceratocystis ulmi, from some relatively distant location, either on beetles or in wood contaminated with the fungus. This belief comes from knowing that the nearest existing confirmed location of Dutch elm disease to St. Paul in 1961 was 100 miles into Wisconsin. The Monticello location was 140 miles distant from the nearest known source.

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Early Opportunities Ignored

It took 30 years or longer for the fungus to move to Minnesota from Ohio and other eastern states. Thus this state had ample time to take appropriate steps to reduce or delay the ultimate losses. But people failed to believe that the beetles could survive in Minnesota.

Elms dominated yards, streets, and parks as the shade tree of choice across the upper midwest, from Iowa to Canada and Wisconsin to the Dakotas. Minnesota had about 140 million elm trees in 1950.

Our citizens and leaders should have acknowledged Minnesota’s obvious reliance on elms in our urban forests and prepared for the possibility of infection. Minnesota had relied almost entirely on the American elm for its parks, its streets, and wherever people wanted shade trees.

As early as 1912, in its 30th annual report the Minneapolis Board of Park Commissioners called for planting 2,104 trees, all elms. By the time Dutch elm disease struck in this state, Minnesota had close to 140 million elm trees, and little else, lining its streets and streams. The predominance of elms, as the shade tree of choice, stretched from Iowa to Canada and Wisconsin to the Dakotas.

What could have been done in the 1950s or earlier to minimize the possibility of future elm tree losses in Minnesota? Most obviously, we first could have stopped planting elms. Elms in nurseries should have been destroyed and no new elms planted.

A second necessary precaution would have been halting the movement of elm logs, elm firewood, or any form of elm with bark. It should all have been halted, possibly by regulation, but preferably by the potentially far more effective creation of public support through publicity and public education.

Third, sick and dying elms should have been eliminated from cities and parks as much as possible.

Fourth, elms should have been discriminated against in wild and forested areas. Every logging operation should have prescribed removal of elm. Whenever possible, these trees should have been utilized or burned.

A few ineffective attempts were made to establish procedures which would have reduced the elm population, especially those elms thought to be most vulnerable to attack by bark beetles. These attempts were made by a Dutch elm disease committee formed in the 1950s, with representatives from the Minnesota Departments of Agriculture and Natural Resources, and from the University of Minnesota.

The committee considered the steps which should be taken and encouraged appropriate actions. Unfortunately, nurseries were reluctant to cooperate. They continued selling elms, and new suburbs, parks and streets were planted with elms. No formal government restrictions were enacted. Nor was there any publicity urging voluntary restriction of shipment of elm with bark into Minnesota.

All attempts to convince the legislature of the importance of initiating control programs, such as sanitation, were to no avail. Some individual legislators were interested and concerned, but other priorities took preference over concern about a tree disease which was not here and which many thought would be of little consequence.

After a few meetings the Dutch elm disease committee effectively ceased to function, but efforts by its members continued periodically, trying to convince the State Legislature that measures were needed to prepare for the possibility of the arrival of Dutch elm disease.

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Later Opportunities Missed

Even after the disease was found in Minnesota there were excellent opportunities to take steps to reduce or slow subsequent disease losses. The state had almost a decade in which the disease remained at low levels and could have been managed. In the city of St. Paul, from 1961 through 1968 only 30 positive cases were officially reported. The disease was not found in Minneapolis until 1963.

Unfortunately, any enthusiasm for control programs was severely lacking. In fact, it seemed that the slow rate of increase simply confirmed the beliefs held by many that the European elm bark beetle would not survive well in Minnesota, and that the disease would never gain momentum.

Beetles which carry the Dutch elm disease-causing fungus are only abut one-eighth of an inch long. The holes they leave behind as they burrow into dead elm wood are barely the size of pen point.

As late as 1961, a letter from a University of Minnesota entomologist to the members of the Dutch elm disease committee urged that the initiation of sanitation procedures was not yet too late, but that time was running out: “If sanitation measures are not started immediately and effectively the devastation may shock the residents of this area. When this happens it will be too late to do something about the problem.” ¹

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¹David W. French, July 24, 1961, personal correspondence to members of Minnesota's Dutch elm disease committee.

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During the decade of the 1960s a maximum effort would have prevented the disastrous losses of elm trees experienced by Minnesota in the 1970s. There were, in fact, unfortunate delaying activities that interfered with proper sanitation. One was the notion that an elm need not be condemned or eradicated unless confirmed by laboratory diagnosis to be positive for Dutch elm disease. The laboratory exercise was essentially of little value and dependence on it slowed control programs and provided citizens with a basis for arguing that their tree not be removed.

It really made no difference whether an elm tree died from Dutch elm disease or from any other cause — every dead or dying elm should have been eradicated. Bark beetles carrying the Dutch elm disease fungus invaded dead and dying trees irrespective of the cause of a tree’s demise and each new generation of beetles emerged to carry the Dutch elm disease fungus to healthy trees. All species of elms in which bark beetles can live, not just American elms, needed to be included in a sanitation program.

Carefully managed burning should have been the disposal method of choice for beetle and fungus infected elm wood, but air pollution considerations severely restricted its use.

Even Siberian elms, which are not often killed by the Dutch elm disease fungus, will harbor bark beetle populations and fungus inoculum. Because Siberian elms are very susceptible to winter injury they often sustain considerable amounts of dieback which, while not disastrously harming the tree, is invaded by bark beetles carrying the Dutch elm disease fungus. The next generation of beetles, their progeny, emerge from these resistant elms carrying large numbers of spores of the disease fungus.

Burning has been the most expeditious method of eradicating elm material in which beetles could develop. Unfortunately, a then growing concern about our environment caused otherwise reasonable restrictions to be enacted against burning. Exceptions should have been granted to allow the burning of elm wood which could not be otherwise utilized. Reasonable numbers of fires and amounts of smoke should have been considered an acceptable environmental price to pay for being able to quickly eliminate large volumes of contaminated elm material.

History has proven that all other systems for disposal of large quantities of elm wood have been both more expensive and far less efficient than burning. If managed properly, in consideration of the energy situation, the people of the state of Minnesota could even have saved considerable amounts of money by burning elm locally, rather than insisting on its being hauled to distant disposal sites.

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Finally Legislation

It was not until 1971 that the State Legislature became concerned about Dutch elm disease. Even then, that concern was initiated and sustained by a small core of effective individual legislators. In particular, state representative Tom Berg initiated legislative involvement by forming a committee and holding extensive hearings on the subject prior to the convening of the legislature that year.

With its head start on the legislative session, the committee assembled a proposal and prepared a bill for legislative action. It moved slowly through the process, but it was ultimately passed. More than once it appeared that the bill would be tabled or voted down, but its supporters kept alive the legislation which eventually funded and set in place the largest program ever enacted by a single state to deal with a single tree disease. The bill did technically provide for programs dealing with oak wilt as well as Dutch elm disease, only a minimal effort was expended on the oak wilt problem.

At the same time that the State Legislature recognized the seriousness of Dutch elm disease and took action, congressmen from this part of the country responded at the federal level. In October of 1975, then United States Senator Walter Mondale, of Minnesota, introduced legislation to help at the congressional level. William Steigler, of Wisconsin, introduced the same legislation in the United States House of Representatives.

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