| North Dakota
Agricultural Research North Dakota State University, Fargo, ND 58105
The
History of Leafy Spurge Control in North Dakota (continued) |
Abstract |
Post-War Control and EducationAn NDAC survey of 10 counties for leafy spurge was conducted in the fall of 1951 (26, 27). The 10 counties represented different areas of North Dakota varying from heavy to light infestations and included some counties in which control programs had been carried out for 25 years or more. Thirty percent of the farmers were concerned that leafy spurge was taking over their farms, another 40% did not think the weed was a serious threat, the remaining 30% were unaware of the weed. The North Dakota Cooperative Extension Service began a statewide leafy spurge control demonstration program in 1953 (26). There were 51 leafy spurge control demonstrations in 39 counties and demonstrations in two counties for creeping jenny. Most of the chemicals for the demonstrations were furnished free of charge by Lyon Chemicals (sodium chlorate), Pacific Coast Borax [(polybor chlorate and sodium tetraborate (Borascu)], and E. I. duPont de Nemours [ammonium sulfamate (Ammate) and monuron (CMU)]. A relatively new herbicide was also included, 2,4-D ester at 0.75 and 1.5 pounds per acre. A soil sterilant such as sodium chlorate or sodium tetraborate was considered a more effective control method than cultivation, mulching, and pasturing (26). An average of 68 tons per year of sodium chlorate and other chemicals had been applied in each of the 10 counties. The herbicide 2,4-D was beginning to be used on large infestations, but the failure to treat all infestations or lack of sufficient follow-up treatments were cited as reasons the plant was spreading. An effective educational program was called for in 1953 to acquaint everyone with leafy spurge and its control measures (26). County agents stated that "effective control will result only from everyone taking their full responsibility and just a county or a state program or a strict weed law cannot be as effective." This statement is still heard annually at the North Dakota Weed Control Association meeting and is as true in 1998 as it was in 1953. The first North Dakota Farm Research article about leafy spurge was written by E. A. Helgeson of the NDAC botany dept. in 1953 (7). He evaluated use of a form of gibberellic acid to break leafy spurge root bud dormancy. His results were inconsistent although his approach was insightful. The breaking and/or inhibiting of bud dormancy is a present day research project in the Department of Plant Sciences and is led by Dr. Don Galitz. The state legislature started getting involved in the campaign against leafy spurge in the late 1950s. The North Dakota Weed Laws, as revised in 1960, dealt extensively with noxious weed control (25). The county commissioners were ordered to "destroy noxious weeds in the public interest." However, they were further directed not to spend over $3000 in any one year. Thus, there have always been more acres of weeds than money available for control in North Dakota. Township supervisors were told to eradicate noxious weeds on all township roads and highways by spraying "annually, during June.@ Quackgrass [Agropyron repens (L.) Beauv.] and dodder (Cuscuta spp.) were on the noxious weeds list at this time but have since been removed. Besides leafy spurge, Canada thistle, Russian knapweed, field bindweed and hoary cress were listed then as now. Little progress in leafy spurge control was apparent during the 1950s. A leafy spurge control bulletin written in June 1959 (8) offers nearly the same control recommendations as those published in June 1952 (9). The notable difference is that a section in the 1952 edition entitled "How serious is leafy spurge?" is not found in the 1959 version. At least that question had been resolved. By the early 1960s it was becoming obvious to any casual observer that leafy spurge had increased in acreage during the past decade. It was no longer "if it was serious" and "how serious" but "how could the weed be stopped.@ In 1953 leafy spurge was not considered to be spreading rapidly (9). By the 1960s the weed was compared to a wildfire (Figure 5) (13).
The files on leafy spurge rapidly thickened after the first weed science extension specialist, Dr. Larry Mitich, was hired in 1963. He remained at NDSU for 16 years and is well remembered for his very informative and entertaining weed control presentations. One of his first assignments was to teach the landowners how to control leafy spurge. The people of the state were about to receive the three 'H' education - history, humor, and herbicides. During a communications training workshop in October 1963 Mitich, was asked to explain why leafy spurge held "the dubious honor of being North Dakota's most serious perennial noxious weed" (16). He started at the beginning. "The spurges have been around a long time. The spurge or Euphorbia family is one of the first plant families mentioned in ancient texts. King Juba II, son-in-law of Anthony and Cleopatra, found a species of Euphorbia growing on the slopes of Mt. Atlas and named it Euphorbus in honor of his personal physician. From that we get the generic name Euphorbia . . . Leafy spurge was known as a weed there (Europe) as early as 1000 AD where it was and still is known as wolf's milk" (16). Several research trials were begun by Dr. Mitich the following summer. A circular published in November 1965 recommended using two new herbicides for leafy spurge control, Banvel D (dicamba) and Tordon (picloram) (19). The recommended herbicide rates were very high. Tordon was to be applied at 1 to 2 pounds per acre, Banvel D at 6 to 8, but highest of all was 2,4-D ester at 40 pounds per acre in the fall after Sept 20. The application rates were high as was the area of infestation, now estimated at 300,000 acres. The first state-wide leafy spurge control program was initiated by the North Dakota County Agricultural Agents Association in 1966 with all counties participating (17). June was declared Leafy Spurge Control Month and 27 counties held 33 leafy spurge control demonstrations. The program lasted for about 3 years. This type of program was repeated in the early 1980s with 24 counties participating and a "leafy spurge awareness week" was declared by the governor. Tordon, 2,4-D, and Banvel were still the herbicides of choice, but the application rates did not exceed 2 pounds per acre, even with 2,4-D. Tordon was generally applied at 0.25 to 0.5 pounds per acre and combined with 2,4-D. It was realized that no single treatment would eradicate this weed regardless of the application rate. Instead, a treatment applied annually for several years was much more cost-effective. Arthur Schulz, director of the North Dakota Cooperative Extension Service, began a campaign in 1967 to expand the Agricultural Conservation Program payments from the ASCS to cost-share noxious weed control (16). The initial response was favorable, but it is not clear if this was ever done. However, this was the forerunner to the present day leafy spurge control cost-share program initiated by the state legislature in 1983. In the margins of letters received from the ASCS Dr. Mitich estimated an infestation of 377,215 acres of which 133,468 acres had been treated. He noted with exclamation that the infested area was increasing by about 6700 acres a year. The initial control campaign started in the 1960s lost momentum by the early 1970s. The infestation was now up to 500,000 acres (18) and enthusiasm for the program was fading. Clearly no treatment could eradicate this weed. Individual efforts had failed or at best were holding their own in an increasingly expensive control program. Reading Dr. Mitich's communications to and from land owners, one can sense despair and hopelessness at ever reclaiming land infested with leafy spurge. It was time for the whole state to step in and protect its lands from this foreign invader. North Dakota was behind neighboring states in gaining political support for leafy spurge control. For example, the Wyoming Leafy Spurge Control Act was passed in 1978 and provided state funding for leafy spurge control (15). Wyoming then had approximately 20,000 infested acres and spent over $1 million annually for several years to control leafy spurge. The Montana State Weed Control Conference was very active in getting support for leafy spurge control in that state. Although starting late, North Dakota would soon become the leader in leafy spurge research and control. The effort began with the Leafy Spurge Symposium, June 26 and 27, 1979, in Bismarck (15). Following this symposium, NDSU Agriculture Experiment Station Director H. R. Lund immediately committed $100,000 to fund a temporary research position. The history of the research enhancement and leafy spurge control programs in the 1980s has been documented (15). The North Dakota Weed Control Association (NDWCA) was formed in 1983 in part to provide individual counties an opportunity to interact and map a statewide strategy for leafy spurge control. Now local control program successes and failures could be compared, refined, and improved. County weed boards began to work with government agencies to control leafy spurge on public as well as private land. The NDWCA worked with the State Department of Agriculture to establish a cost-share program to help individual land owners defray the cost of leafy spurge control. Thus, for the first time in state history state revenue was used and a special county mill levee was added to control a weed. The county and state control programs combined with improved control methods achieved through research at NDSU lead directly to the first ever reports of a decline in leafy spurge infestation in the state and a very active biological control program by the early 1990s. The promise of biological control of leafy spurge began in the late 1980s (15) and came just in time to revitalize the control effort. The idea that leafy spurge would eventually be controlled by natural enemies gave land owners encouragement to Acontain, control, and manage@ the weed while waiting for the biological agents to become established. Kelly Miller, a rancher from Towner, ND and Bob Thoft, a Montana state legislator, went to Europe to see first hand if insects could control leafy spurge. Following the trip, Miller and various North Dakota livestock and farming associations started a campaign to import biological agents for leafy spurge control into North Dakota. Russell Lorenz (USDA-ARS in Mandan, ND) then wrote a proposal to the federal government that directly lead to the USDA-ARS and APHIS becoming involved in exploring Europe for leafy spurge biological control agents. Eventually APHIS constructed an insect quarantine facility on the campus of Montana State University and leafy spurge researchers were assigned to USDA-ARS facilities in Bozeman and Sidney, MT. To date, over a dozen biological control agents have been introduced into the US and Canada for leafy spurge control. Although the level of success of these agents has varied, the cooperation established between the two national governments to control a weed is unprecedented. Presently, the battle to control leafy spurge is being fought on several fronts. Herbicides remain the most widely used method to control this invader, but several species of insects for biological control have become established in every county in the state. Grazing sheep and goats to manage and contain the infestations has become more popular, and several species of grasses that compete with leafy spurge in pasture and rangeland are now available. Researchers and land managers now realize that no single method will control leafy spurge in all locations and environments. Thus, present research efforts are exploring the integration of two or more of the methods for cost-effective long-term leafy spurge control. The ultimate goal of the program is to reduce leafy spurge to just another member of the plant community.
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