Forest Health Program History

The State Forestry Board for Wisconsin first implemented a program for survey and control of forest insects in 1949. The program called for two components: 1) survey and control, and 2) research, teaching and extension. The survey and control responsibilities were placed with the Conservation Department in the Division of Cooperative Forestry. The research, teaching and extension responsibilities were placed with the University of Wisconsin-Madison.

In 1957, the Wisconsin Forest Pest Control Act was created (Wisconsin State Statues 26.30). This act gave the Wisconsin DNR (then WI Dept. of Conservation) the authority and jurisdiction in all matters relating to the prevention, detection and control of forest pests on forestlands of the state. In 1958, Don Renlund was hired to coordinate the forest pest control unit (now the Forest Health Protection Program), which consisted of 4 regional entomologists located in Spooner, Antigo, Oshkosh, and Black River Falls. In 1959, the DNR's first forest pathologist was hired. In 1978 a forest insect biological control specialist was hired. As the gypsy moth moved into Wisconsin from Michigan during the 1990's, the need for specialists to manage this one exotic insect was evident. The current Forest Health Protection Program has a number of specialists on staff.

Populations of insects native to Wisconsin's forests have been monitored over the past five decades. The forest tent caterpillar, (Malacosoma disstria) and jack pine budworm, (Choristoneura pinus pinus) are two native insects that tend to follow a relatively predictable pattern in their population ups and downs. The forest tent caterpillar feeds primarily on aspen and oak leaves; the jack pine budworm limits its feeding to jack pine flowers and needles. Large outbreaks of both of these insects, covering thousands of acres, occur approximately every 7-10 years. Weather, location and spatial pattern of host material or food and the population of natural enemies such as predators and parasites all influence when and where these insects will outbreak. Management of these native insects is typically limited to options such as silvicultural manipulation that create a healthy and resilient forest that will incur little mortality and salvage of dead and dying trees. Diseases native to Wisconsin such as oak wilt, caused by the fungus Ceratocystis fagacearum and Armillaria root disease caused by several species of the fungus Armillaria, are also managed primarily through silviculture. Simply limiting the possibility of wounding oak during the spring and early summer will greatly reduce the risk of oak wilt moving overland into a forest stand of oak trees. Maintaining vigor in both hardwoods and conifers will limit the impact of Armillaria root disease.

Exotic insects and diseases have long had a significant impact on Wisconsin's forests. White pine blister rust and Dutch elm disease are two examples of diseases that arrived in Wisconsin decades ago and proceeded to infect and kill thousands of Wisconsin's white pine and American elm. The gypsy moth is currently the most important exotic insect affecting Wisconsin's forests yet the Emerald Ash Borer (Agrilus planipennis) and Asian Longhorned Beetle (Anoplophora glabripennis), although not yet observed alive in Wisconsin, provide a constant threat to the ash and maple resource respectively. Fortunately, years of research on several of these exotic threats have now provided forest managers with the tools necessary to minimize their impacts.

Forest pest survey practices have changed significantly since 1957. Early survey tools were limited to labor-intensive methods where the collection and summarization of data took long hours with a pencil and paper. Current strategies utilize a combination of methods including: 1) data collection from a network of permanent plots to detect early warning signs of forest health problems, 2) annual ground surveys of known forest disturbance agents to monitor and predict levels of damage, 3) targeted surveys focusing on specific forest tree species and the agents that affect them and 4) aerial surveys to detect and monitor forest health issues on a widespread basis. Computerized mapping and data analysis tools such as Geographic Information Systems and Global Positioning Systems are used widely to locate, map and analyze the movement of forest disturbance agents.

Management tools in the 1950's and 60's were limited to the use of pesticides and sanitation including widespread eradication efforts. The lack of information on forest insect and disease life cycles and no knowledge of the effects of various silvicultural practices on these injurious agents were the limiting factors to developing management strategies. Years of research and surveys have provided an excellent base of knowledge on the life histories and impact of Wisconsin's native forest insects and disease-causing agents. During the 1970's, throughout the United States, management emphasis changed dramatically from the use of pesticides to an Integrated Pest Management approach, which integrates regulatory, chemical, cultural, biological and mechanical control methods. We now have a better understanding of the complex relationships between the health of Wisconsin's forests, the insects and diseases that affect them and the ecosystem they are all a part of.