DUTCH ELM DISEASE AS A MUNICIPAL
PROBLEM IN ILLINOIS
RICHARD CAMPANA

Introduction

Elm populations throughout Illinois face possible destruction either by Dutch elm disease alone or by Dutch elm disease and elm phloem necrosis together, unless adequate and timely control measures are taken by municipalities against one or both diseases. Wherever the diseases occur together measures must be taken against both diseases or control efforts are not warranted at all.¹ Since elm phloem necrosis appears to be limited at an epidemic level to the southern two-thirds of Illinois, since it has already destroyed so many elm populations there, and since controlling both diseases is very costly, the brightest hope for preventing destruction of municipal elm populations in Illinois is principally in the northern third of the state where Dutch elm disease is the only significant threat. The problem of Dutch elm disease is a grim economic reality which no municipality with many elms can afford to disregard. Extensive elm populations in Illinois have been destroyed by Dutch elm disease alone in some communities, and there is every indication that this disease will continue to increase its toll each year wherever it spreads uncontrolled until the majority of the elms are destroyed.

Where the disease has occurred for many years, its seriousiness is well recognized, in many cases too late. But in areas where the disease has not yet occurred, or has not yet become well established, there is often the complacent attitude that it probably has been oversold as a real threat. Whether a community recognizes the seriousness of the threat and prepares to meet it squarely, or for any reason fails to recognize it for what it is, the Dutch elm disease is real, is destructive, and is moving. Subject only to control or ultimate decimation of the elms, it will continue to be a major shade tree problem for many years to come. In any event its presence is going to be an expense of moderate or major proportions. It is already costing the citizens of communities affected considerable money, both collectively as taxpayers and individually as homeowners. In Champaign-Urbana, Illinois, merely for removal of diseased or dead trees, the cost of Dutch elm disease over the past five years is estimated conservatively to exceed $300,000, an average of $60,000 per year. How destructive or how costly, it may become in any particular area depends to a great degree on recognition by municipal officials of the magnitude and scope of the problem before the disease becomes well established.

Unfortunately, there is much misunderstanding about the disease and there are many false and conflicting ideas. As a result, when initially confronted with the disease, the municipal official does not know whom to believe, what to do, or whether action is necessary at all. For the officials of most communities, this problem is a completely new and disturbing experience. Municipal officials are now raising many practical questions about a satisfactory solution to the problem. Why is the Dutch elm disease such a threat? Can it actually be satisfactorily controlled? What constitutes satisfactory control? Why do some control programs fail ? What has been done toward education on control in Illinois? Do any municipalities in Illinois have effective control programs? What can be done to provide more effective control? The purpose of this paper is to provide accurate and complete information in an effort to answer such question's.

Why So Great A Threat?

Dutch elm disease is different from any other shade tree disease in the Midwest. It is a major problem because: it cannot be prevented from spreading over wide areas; all species and varieties of elms (European, Asiatic, and American) are susceptible to it to some degree; there is no proven cure for trees affected; in the American elm, the most widely distributed and valued elm species, there is little if any resistance to it; the American elm is the most susceptible of all elm species; the American elm is the most abundant shade tree in most urban areas; and most urban elm plantations include identical or similar strains within their populations. Contrary to reports, young and vigorous trees are just as susceptible to the disease as older and overmature trees. To the present time, there has been no genuine evidence produced that feeding elms to keep them in good health and vigor makes them less susceptible to infection by the fungus, which causes Dutch elm disease, after they become exposed to it. In spite of all these adverse factors, it has been demonstrated that the disease can be kept to low levels, and that it is sound economics to prevent the ruin of entire elm populations in urban areas.

Is Control Actually Possible?

The Dutch elm disease can be controlled in the sense that its destruction can be reduced or kept to low levels within specific urban ureas. Prevention of disease, however, can neither be complete for any area, nor guaranteed for any individual tree. Nor should it be assumed that satisfactory control is possible in woodland areas where large numbers of wild elms are present. Costs for control of the disease are justified only where the value of the elms to be protected and the anticipated costs for their removal exceed by several times the cost to protect them for 25 to 30 years. Using such a yardstick, it is obvious that only institutional, park, private property and urban trees of moderate or substantial real estate value warrant costs for complete protection as is possible from the disease.

Control of Dutch elm disease involves prevention of feeding of elm

Dr. Richard Campana, 39, Associate Plant Pathologist of the Illinois State Natural History Survey, is a native of metropolitan Boston, Massachusetts and a graduate of Everett High School '36. Before spending three years in the United States Army in World War II, he received a BS in Forestry from the University of Idaho in 1943. Following the war he was on the teaching staffs of Pennsylvania State University and the University of North Carolina. He received both master's and doctorate degrees in forest pathology from Yale University. Recipient of a research fellowship during doctorate study at Yale. He was also assistant forest pathologist in the Division of Forest Pathology, United States Department of Agriculture for three years. Since coming to Illinois in 1952 he has been concerned primarily with research and education on the two lethal elm diseases, elm phloem necrosis and Dutch elm disease- Currently serving as president of the Illinois Technical Foresters Association, vice president of the Midwestern Chapter of the National Shade Tree Conference, member of the Board of Governors and chairman of the Nomenclature and Standards Committee of the National Shade Tree Conference, he is senior author of "Guide for Community-wide Control of Dutch Elm Disease", a brochure recently published by the Midwestern Chapter of the Conference. Dr. Campana has studied the spread of Dutch elm disease in Illinois intensively and has been most active toward informing the public in Illinois about the nature of the disease and the methods for its control.

1. Campana, R. J., and J. C. Carter, Dutch Elm Disease and Elm Phloem Necrosis. Proc. Mid. Chap., National Shade Tree Conf. 13:17-25. 19S8.

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bark beetles on healthy trees, because in their feeding and breeding habits the beetles carry, the fungus from diseased to such healthy trees. This can be accomplished through sanitation and spraying. The object of sanitation is to prevent breeding of bark beetles in large numbers and to destroy beetles already breeding. Sanitation involves destruction of actual or potential sources of beetles by burning bark of diseased, dead or dying stumps, trunks, branches and twigs. In such a manner the beetle population is reduced and with it the probability of infection of healthy trees. In addition, reservoirs of fungus spores are destroyed; destruction of these spores contributes further to the improbability of infection. Healthy trees are inoculated with fungus spores carried by the bark beetles. The object of spraying is to coat all bark surfaces of the tree with a poison (a DDT emulsion) that kills the spore-carrying beetles before they are able to penetrate these surfaces. In their feeding the beetles chew through the bark into the wood in the crotches of young twigs. Either the beetles are killed by the DDT deposited on the bark in spraying, or are paralyzed and thus unable to inoculate the trees with the fungus causing the disease.

What Is Satisfactory Control?

Control of Dutch elm disease is considered satisfactory where the annual incidence of the disease has been held or reduced to 1-2 percent of the elm population under protection for a period of 5-7 years. Generally, such control can be accomplished only through intensive sanitation and spraying, the only. proven methods of Dutch elm disease prevention. The organization of a successful program for both effective sanitation and spraying depends to a great degree on an evaluation of the entire elm population through a tree by tree survey and periodic scouting to detect new cases of the disease. A competent survey by a professional forester should provide an accurate inventory of the trees to be protected as well as those not worth protecting.

Generally, destruction of known diseased trees and of beetle-breeding material should take precedence over all other activities. In most situations, greater reliance should be placed on sanitation than on spraying, because: (1) its results are more certain, (2) it must be practiced eventually, and (3) it requires less skill and knowledge than spraying. ² In areas where the disease is absent or scarce, sanitation should definitely, have precedence over spraying. However, where adequate sanitation is physically impossible or almost so, such as on sites near woodlands studded with wild elms, spraying should have precedence over sanitation. Generally, where the disease is present but not out of control, both sanitation and spraying are necessary and desirable as effective supplements to each other. Although highly desirable, general elm maintenance which may involve feeding, watering, surgery, or protection from ordinary pests, is of minor importance as a control measure compared with spraying and sanitation; and it is not warranted except as a supplement to either sanitation or spraying or both. Survey, scouting, sanitation, and to a less degree, spraying, serve to make possible a reduction of the total incidence of disease in the area for the whole elm population ; whereas maintenance, and in most cases spraying, serve only to prevent disease in individual trees. Accordingly, spraying and maintenance should be restricted to elms whose value warrants full protection.

Elimination of real or potential sources of elm bark beetles, destruction of dead, diseased or dying elm trees, is the basis of successful control. The approach to sanitation depends on the level of the disease in the area. Sanitation before the disease is known in the area requires priority. for protection of most valued elms. Sanitation after the disease is first found requires attention to areas nearby known diseased trees. Sanitation after the disease is well established requires detailed priorities to reduce the general level of a massive beetle population.³

Community-wide spraying is not warranted in absence of the disease fungus, or in absence of sanitation. Spraying to prevent infection of elms requires complete coverage of all bark surfaces. Only a single dormant application of DDT is recommended for large numbers of trees. Only individual trees of special value should be sprayed a second time in the same season. Foliar sprays are of limited value, if of any value at all, in preventing the disease. To minimize bird mortality, special precautions are in order: use of mist blowing machines; avoiding when possible applications of spray from April 1 to November 1; keeping spray, dosages to an effective minimum; if effective, use of methoxychlor instead of DDT because of less toxicity; elimination of puddles formed from excess spray: flushing with water or covering bird baths. Maximum protection to elms requires dormant spray before May 1. Successful spraying programs require more instruction and supervision of personnel than for any previous spraying required in protection of shade trees from insect pests. Bad public relations have resulted from inadequate or ineffective spraying and unnecessary injury to birds and ornamentals.

Disease control is basically, a problem of organization, promotion, and administration. To achieve the maximum value possible, professional direction is essential, and only effective application of known control measures will result in success.

Why Do Control Programs Fail?

Programs for the control of Dutch elm disease may fail or appear to fail as a result of any one or more of the following reasons:

1. Absence of a sound program.

2. Failure of municipal officials to understand the problem.

3. Reliance on unsound advice and information.

4. Absence of professional direction.

5. Reliance on incompetent, untrained, or irresponsible commercial tree "experts."

6. Inadequate supervision of irresponsible labor.

7. Undue reliance on spraying alone.

8. Irresponsible sales pressure by commercial suppliers.

9. Inadequate education of private-property owners.

10. Priority of political over administrative considerations.

11. Inadequate financial support. Many communities currently are under the illusion that they have control programs, but actually some have never made what could be considered a sound beginning, or they have failed to maintain the program on an annual basis. Although several communities have endorsed the principle of control, some have not taken positive steps toward control, and others have floundered badly, their initial efforts and nuances wasted. After several years of exposure to the disease there are some communities and institutions which do not yet have a full appreciation of the nature or the scope of the problem.

A frequent cause of failure is misinformation. The municipal officials of many communities have been willing to accept misleading and inaccurate information, in some cases disregarding reliable information to accept the ideas of misinformed people. Of particular concern is the "pseudo-expert" who guarantees a "sure cure" of trees affected with the disease.

To the present time there is no-known cure for Dutch elm disease once a tree has become infected. Contrary to recent reports, a genuine cure has yet to be demonstrated. The Illinois Natural History Survey has been in-frequent contact with all agencies in the United States doing genuinely scientific research on Dutch elm dis-

2. Welch, D., plant Pathologist. Cornell University, Personal conversation

3. Campana, R. J., Dutch Elm Disease Control Program: Sanitation. Proc. Midw. Chap. National Shade Tree Cont, 11:48-58. Chicago, 1956.

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Many people claim to have a cure for Dutch elm disease. Persons claiming to have a cure have failed to present evidence that is recognized as valid by responsible plant pathologists. Such evidence can be obtained only from trees positively known to be infected with the Dutch elm disease fungus. The evidence must show differences in results between trees treated and trees remaining untreated. Tests of this type must be carried on over a period of several years and must involve a sufficiently large number of trees to have statistical significance. Members of the Survey staff do not know of any elm tree positively known to have Dutch elm disease that was cured.

Many responsible research agencies in the United States, including the Illinois Natural History Survey, are (searching for a chemical which will prevent or cure the disease. Each year many chemicals are found that halt or suppress growth of the Dutch elm disease fungus in die laboratory under artificial conditions. But when the fungus is introduced into trees either before or after treatment with such chemicals, the trees die of the disease. In addition, there are well-intentioned but misguided "experts" of long experience and creditable reputation as arborists, who make recommendations of dubious merit; the recommendations are based on casual observations only and lack confirmation by qualified scientific research. Community officials should insist on using methods and material exclusively recommended on the basis of evidence obtained through genuine scientific procedure.

Probably the major reason why community programs may not be successful is the absence of direct professional advice and administration. The most outstandingly successful programs are those directed by professionally trained and competent foresters. The programs of Greenwich, Connecticut, Brookline, Massachusetts, and Detroit, Michigan, which have some of the most outstanding records of control, without exception are administered by professionally trained foresters. Where programs have been undertaken in the absence of immediate professional direction, they have been successful only under the direction of one or more intelligent and dynamic individuals who have sought and followed professional direction in a systematic manner. One community in Illinois has made an outstanding start on a program in such a way, and excellent control has resulted to date. Another community, however, after a good beginning has discontinued professional direction with results that could only be described as deplorable.

The reliance by community officials on incompetent, untrained, or unscrupulous commercial tree experts is often a major cause of failure of a control program. The self-styled expert gains acceptance of his ideas because of the well known threat of the disease in the absence of sufficient, widely distributed, accurate information on the problem. However well-meaning such individuals may be, their advice often has been disastrous when founder on false premises. Unfortunately, some "experts" are deliberately. dishonest; and, even though well informed, give unsound advice when it is financially profitable. Much wrong- information is currently available from both the uninformed and the fraudulent. The reputable and well-informed arborist is at a distinct disadvantage, because he can offer no sure cure, no easy solution to a difficult problem, or no below-cost charges. In addition, many diseases and troubles of elms, similar and related but distinct from Dutch elm disease, add to the confusion. Sometimes a tree may have several complicating troubles which easily may lead to a wrong diagnosis.

Many control programs fail as a result of inadequate supervision of irresponsible or untrained labor. This may occur even though tile executives of the tree expert organization know and understand the disease, but fail or are unable to take the pains and trouble to educate, train, and supervise workers doing the actual work of sanitation and sprayins. In many cases the writer has found that men so employed often have little if any unders landing of the disease or how it is supposed to be controlled. Often such personnel disregard instructions completely, are unaware that such neglect is irresponsible, and may jeopardize the effectiveness of the whole operation. When activities of untrained labor remain unsupervised, failure to achieve satisfactory control can be expected to result.

Unfortunately, many programs may fail because a disproportionate and unwarranted reliance is placed on spraying as a control measure at the expense of sanitation. In my opinion, this is one of the most serious mistakes a community can make. Most people do not really appreciate the merits of sanitation even after they are explained. Spraying appears to be both a dramatic and an easy solution to the problem, whereas sanitation appears difficult, time-consuming and costly, particularly if the accumulation of potential beetle-breeding elm wood is as great as it frequently is. Yet sanitation is indispensable to the success of a control program, and elm wood debris must be removed inevitably whether the program succeeds or fails. The greater value and significance of sanitation as a control measure has seldom been given sufficient attention in the opinion of the writer. Since it is known that infected trees will die, and it is known that presence of diseased trees is a direct threat to nearby healthy trees, it should be evident that early removal and destruction of diseased trees will be of value. The municipal officials of the community, not only have a responsibility to their constituents to remove diseased trees; their obligation is no less to remove diseased trees as quickly as they can be detected without waiting for such trees to die.

Irresponsible sales pressure by commercial suppliers has been instrumental in both waste of funds and effort, and in contributing to faulty practice in control programs. Commercial suppliers in most cases include individuals or firms offering chemicals, spraying machines, or services. The writer is aware of chemicals claimed to offer protection against elm bark beetles for which no genuine evidence has been produced. Several community have bought and used thousands of gallons of such materials, and has not been provided the protection which they paid. The pressure sale of spraying machines has often become so intense that exaggerated and sometimes inaccurate claims have resulted in purchase of machines not adequate for the job to be done, in settlement for machines of dubid value or capacity. In addition, exaggeration of the value of spraying has become so gross that the vital role of sanitation actually has been repudiated by salesmen unqualified to make such evaluations. The urge to sell chemicals, machines, and services has resulted in the sale of all these items to communities where Dutch elm disease did not occur and where expenditure of large sums of public money were totally unwarranted.

Successful control of Dutch elm disease requires not only cooperation of municipal officials, but also support and cooperation of private property owners. Not only must private citizens be adequately informed to support expenditure of large sums of money for control, but they themselves must exercise similar control practices on their own elms. Too often this aspect of the control effort has either been disregarded completely or handled ineptly or with indifference. Often after a flurry of initial enthusiasm in radio and press, publication education has been abandoned. For success, public education on control of the disease must consist of sustained, timely, and accurate publicity throughout the year. Sensational publicity is a poor substitute for

4. Proceedings, Illinois State Chamber of Commerce Conferences on Dutch Elm Disease Control, Chicago, Illinois. 1955 and 1956.

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good taste and judicious emphasis on genuinely- important issues. Unfortunately, misleading and inaccurate information has often been allowed to spread without challenge by responsible officials and well-informed authorities. Such information must be challenged with clarity, vigor, authority, and timeliness. Only accurate information can possibly present the whole problem in the proper perspective to stress the real seriousness of the disease, while calmly pointing out the genuine possibilities for control.

One of the most difficult aspects of Dutch elm disease control is the necessity of combating it on a municipal level requiring governmental action. While the mills of self-government may grind eventually, they sometimes grind slowly. Unfortunately, the Dutch elm disease has no respect either for time requirements of parliamentary procedure or political jurisdiction. In addition, it is obvious that there is intense competition in municipal government for funds for a multiplicity of worth-while purposes. In competition for such funds, control of Dutch elm disease can be justified only as an ultimate saving to the municipality in prevention of wholesale losses of trees requiring large and immediate costs for removal. Because timeliness is a vital factor in control, the disease should be considered as an emergency situation and be given priority over many other publicly supported projects. Unfortunately, this is rarely done unless public support for disease control is manifestly greater than support for more popular projects promising more effective political approval. Sometimes funds appropriated for control of Dutch elm disease by municipalities in Illinois have been wasted in futile or hopeless efforts contrary to recognized recommendations, even after acquiring such funds through referenda promising recognized procedure. The writer is aware of one situation where many thousands of dollars appropriated for disease control were spent largely to re move trees (other than elms) considered undesirable by key city officials.

What Has Been Done Toward
Education On Control

Since the disease has become established in the northern third of the state where phloem necrosis is not a problem and prospects for control are favorable, much has been done to make available the most accurate, the most recent, and the most nearly complete information possible on control of the disease. Working cooperatively with a variety of public-spirited and educational organizations, the Illinois Natural History Survey has studied intensively the problem of disease spread and control and has stimulated, aided, and guided the control efforts of scores of Illinois communities. From the first appearance of the disease in the state, the Natural History Survey has maintained a constant watch and reported regularly the progress of the disease.

In cooperation, with the Survey the Illinois State Chamber of Commerce sponsored two statewide conferences on the disease. With the Survey participating, the Illinois Municipal League has held informal discussions on the problem as part of its last two annual meetings. After a two year study and consultation with national authorities on the disease, the Midwestern Chapter of the National Shade Tree Conference has published a 35 page "Guide for Community-Wide Control of Dutch Elm Disease."

All of these activities and many more have been designed to make clear the nature of the disease, the requirements for satisfactory control, and the significance of the Dutch elm disease as a municipal problem.

Do Illinois Municipalities Have Effective Control?

It is too early, yet to evaluate current control programs accurately. Urban elm populations beyond the epidemic range of elm phloem necrosis (i.e. in the northern third of the state) in most cases have not been exposed to Dutch elm disease long enough to show conclusive results. Many community control programs with which the writer is familiar, either will be discontinued or will not be effective for one or more of the reasons mentioned previously. However, with many others, the problem is being handled in such a careful and systematic manner that these programs have every promise of success. The writer is aware of at least a score of programs in the Chicago area which appear to be holding the disease to very low levels at moderate expense after three years. However, there are many officials conducting what they consider to be effective programs with only small losses apparent, who are failing to satisfy requirements for effective control, but whose areas have not yet been fully exposed to the disease. In such cases claims for successful control would appear to be premature. Municipal officials, who would like to evaluate their local control programs, might ponder some of the following questions: do you know how many elm trees you are trying to protect, their sizes and locations; has a professional evaluation been made of the potential scope of your local problem; are known diseased or known or potentially beetle-infested elm trees and wood sought, detected, and destroyed promptly; are you providing complete protection, including spraying, to your most valuable elms in the community; is your spraying being done in accordance with prescribed recommendations, by trained, reputable men, using proper formulations, at the proper time of year; do you actually know how many diseased trees are occurring from year to year? After considering such questions with respect, to communities where the disease appears to be getting out of control. the writer has always been able to understand why. At the present time I do not know of any community in Illinois which has practiced approved control recommendations faithfully that has not had promising (if yet inconclusive) results toward effective control.

What More Can Be Done?

To provide more effective control than appears possible at present, there are several courses of action that might be considered both at the state and local level. There is a need for legislation that would authorize local municipal government on its own behalf to enforce compulsory removal of known diseased trees on private property. Several municipalities currently have ordinances to this effect, but such ordinances may need a legal statute to support them should they he challenged. Such an authorization law need not be compulsory for local government, but could invest it with legal sanction to make removal compulsory at its own discretion under an ordinance. State statutes of this type have been of much value to local control of Dutch elm disease in Wisconsin and Michigan and have prevented negation of city ordinances requiring compulsory removal. At present. while the State Department of Agriculture in Illinois has this power, it has neither manpower, funds, nor legitimate incentive to enforce this law. Such a law would be in keeping with the recent acknowledged philosophy of government in Illinois to provide tor more "home rule," one of the avowed aims of the Illinois Municipal League.

More effective control of the disease should be possible through the fol lowing steps at a community level; (1) adoption of suitable city ordinances regulating various activities concerned with disease control and other tree operations; (2) obtaining full or part time genuine professional services of a competently trained or experienced forester or arborist who would have no commercial interest in control operations: (3) insistence on recommended specifications for control as published by the Midwestern Chapter of the National Shade Tree Conference in awarding contracts for services of commercial arborists; (4) adoption of a carefully planned replanting program either to replace in a short time elms lost through disease, or to diversify deliberately the composition of the shade tree population as a general safeguard against serious losses from one or two diseases or insect pests; (5) adoption of a carefully designed plan for complete and

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Fig. 3. Rows of elms killed by disease in Urbana, Illinois.

permanent management and maintenance on a systematic basis at minimum expense of the entire shade'tree population; (6) organization on an area, county, or statewide basis with other municipalities to pool ideas, exchange information and stimulate approved practices in care and management of municipal tree populations. All of these suggestions are offered with the realization that while the Dutch elm disease happens to be the most serious problem of the day, to some degree its seriousness results from neglect and complacence concerning the valuable municipal assets of urban tree population, until now so greatly taken for granted.

Destruction of elms from Dutch elm disease should serve as a classic example of the need for more careful management of municipal tree populations. Even in the absence of the Dutch elm disease, this need has become more and more apparent in increased annual costs (beyond inflation) for care, maintenance, and removal of public trees. With the ever expanding encroachments of urban development and further restriction of already inadequate space for normal root development of urban trees, the problem, so clearly dramatized by the advent of Dutch elm disease, appears destined to become increasingly, acute and expensive in the development of additional disease, insect, and nutritional disturbances anticipated as a result of such encroachment.

Fig. 4. Rows of stumps on street almost completely denuded of elms in Champaign, Illinois.

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