The
History of
Leafy Spurge
Control in
North Dakota
Rodney G. Lym, Professor
Calvin G. Messersmith, Professor
Department
of
Plant
Sciences
January 2003
The following two articles tell the story of how the fight to control the dreaded leafy spurge evolved into coordinated research and control efforts. The infrastructure needed to first slow and eventually stop the spread of leafy spurge on a local level in North Dakota led to the formation of federal and state research teams, biological control consortiums, and the North Dakota Weed Control Association.
No matter how much coordination, planning, and enthusiasm for fighting
a weed is in place, one must have the methods available to actually kill the plant. The original state-wide efforts to control leafy spurge during the 1950s failed not because of a lack of will, man power, or even funding. Rather those fighting leafy spurge had little chance of success when the best methods available were high rates of sodium chlorate or hoeing. Today there are a variety of tools available to control leafy spurge including herbicides, biological control agents, and cultural methods including grazing and competitive grasses.
The leafy spurge control program led to the formation of the North Dakota Weed Control Association. Today when a new threat such as saltcedar or yellow toadflax is identified, the resources are in place for rapid identification, mapping, and control efforts. This quick response is due to the coordinated efforts between county, state, and federal agencies originally established to control leafy spurge.
The following two articles were first published in the 1990s. As you read them you will see several improvements for controlling weeds have been made even since these articles were written. To plan for our future we must first know our past.
Rodney G. Lym
Abstract
Leafy spurge (Euphorbia esula
L.) is a long-lived perennial weed that has led to the establishment
of a region-wide research effort and a state-wide control program which
have both become models for future noxious weed control efforts. Leafy
spurge was first found growing in Fargo in 1919 and spread freely to
infest nearly 1 million acres by 1997. Velva Rudd, a North Dakota Agricultural
College (NDAC) masters student, conducted the first in-depth study of
leafy spurge in 1931. Her work led to the first Agriculture Experiment
Station bulletin about leafy spurge (published in 1934) and to the addition
of the plant to the North Dakota noxious weed list in 1935. NDAC and
the state legislature began a series of control efforts in the 1950s,
but these were generally unsuccessful because of both poor available
control methods and a lack of consistent state-wide control programs.
North Dakota became the leader in leafy spurge research and control
with the formation of an integrated research program in 1979 and the
North Dakota Weed Control Association in 1983. By the late 1990s several
methods of controlling leafy spurge were available, including chemical,
biological, grazing with livestock, and seeding of competitive grasses.
The cooperation established between various state and federal agencies
needed to control leafy spurge should prevent further noxious weed invasions
and preserve the state's agricultural enterprises and native plant species.
The first in-depth analysis of leafy spurge in North Dakota was conducted by Velva E. Rudd in 1931 and 1932 as part of her masters degree research.
Introduction
Leafy spurge (Euphorbia esula
L.) is a long-lived, difficult to control perennial weed with a large
deep-growing root system. The recorded history of the weed in the state
is also long and entangled. The story is sometimes humorous, sometimes
serious to the point of despair, but always educational. To trace the
history of control of this weed is to reflect on the past accomplishments
and failures in noxious weed control. The farmers of North Dakota had
no experience in fighting such a tenacious invader as leafy spurge. There
were no statewide control plans or cooperative efforts between land owners
and state or federal agencies. The knowledge gained from those experiences
will help the people of the state combat future noxious weed problems
more efficiently.
Discovery
Scientists at the North Dakota
Agricultural College (NDAC) recognized leafy spurge could be a problem
soon after it was first identified in the state, growing along a Fargo
street in 1909 (2). However, the plant was not added to the noxious weed
list, which had been in effect since statehood (25) and listed over 50
weeds (24), because the potential statewide threat was not recognized.
W. R. Porter, superintendent of the demonstration farms, and O. A. Stevens,
seed analyst and botanist, wrote in March 1919 that "it (leafy spurge)
seems to spread freely from the roots and should be watched closely"(21).
They recommended that control methods be the same as for toadflax "
. . . plant clean seed and destroy small patches by smothering or by cultivation."
Hand hoeing and mowing were recommended for control in pasture.
Rudd later earned a Ph.D. in botany in 1953 from George Washington University (1). She became known world-wide as a specialist in legume taxonomy and a curator of the Botanical Herbarium at the Smithsonian Institution in Washington, D.C. Dr. Rudd moved to Reseda, California, upon "retirement" and is a senior research fellow in the department of biology at California State University-Northridge. Velva Rudd was honored as a North Dakota State University outstanding alumnae on October 7, 1994 during homecoming. She stated that Dr. Herbert Hanson gave her a choice of plants to study and she "had never heard of leafy spurge, so I chose that one." She did not have to travel far to do her research. The plant was growing densely in what is now near-north Fargo.
Leafy
spurge had become a problem for farmers in other states before North Dakota.
The date of introduction into the United States is not known, but a specimen
preserved in the Torrey Herbarium of Columbia University, deposited at
the New York Botanical Garden, was collected at Newbury, Massachusetts,
by William Oakes in 1827 (3). He annotated the label of the plant sent
to another botanist, “I want to find this at another place; have
you met with it, or heard of it?” For many years it was not noted
again until the first edition of Gray’s Manual of Botany was published
in 1848, when the author stated “it was likely to become a troublesome
weed.” Leafy spurge probably entered North America as seed from
ship ballast deposited in New England and then spread west (6). It may
also have been introduced into the northern Great Plains as a contaminant
in oat and wheat seed.
Leafy spurge was also known as
‘Faitour’s Grass’ or ‘Tithymal’ (3). At
first the spread of the weed was slow. It was found in New York in 1875
and in Michigan in 1881, where it was still noted as rare. However, by
1913 it was found from Michigan to New York and from New Jersey to Ontario
and was considered a menace to pastures. Concern about the spread of this
weed was widespread enough that the New York Herald wrote an editorial
about it on February 9, 1921 (20). The writer was concerned that this
weed was going to taint the milk that was shipped to New York City (Figure
2). The New York Agricultural Experiment Station pledged to a plan of
eradication using such heroic methods as spreading 10 tons of crude dried
salt to the acre and saturating leafy spurge patches with kerosene. It
was not stated, but it is safe to assume these efforts failed.
Figure 2. A portion of the New York Herald
editorial page, February 9, 1921, showing
great concern about the spread of leafy spurge in Orange county, New York
(20).
| Leafy
spurge was added to the North Dakota noxious weed list in 1935 (25).
A survey for five “cancerous weeds in North Dakota”
was made the following year by Malcolm Plath and William Kleunder
of the Botany Department at NDAC (23). Leafy spurge was found growing
in all but 10 counties, but no estimate of state-wide acreage was
given. However, Foster County was noted as having the largest single
infestation of 193 acres in a single township. Fourteen counties
had eradication programs in progress (Figure 3)(5).
Top
|
 Figure 3. Leafy spurge infestations in North Dakota in 1936. The shaded counties were conducting leafy spurge "eradication" programs (5). |
Field bindweed (Convolvulus arvensis L.) was found in all 53 counties, while Canada thistle [Cirsium arvense (L.) Scop.] was a problem mainly in counties east of the Missouri river (23). Russian knapweed (Centaurea repens L.) was found almost exclusively in western North Dakota at about the same infestation levels as today. Perennial peppergrass [Cardaria repens (Schrenk) Jarmolenko], commonly called hoary cress today, was the other problem weed in the survey.
 Figure 4. Cover of the first leafy spurge control circular issued by the NDAC Experiment Station in June 1934 (2). |
Control of leafy spurge and review of literature on chemical weed control” from May 1934, was the first leafy spurge control bulletin published by the Agricultural Experiment Station at NDAC (2). Chemicals discussed to control leafy spurge included sodium chloride (salt) at 2 to 13 pounds per square rod, which was a concentration “greater than that recommended for any other weed.” Other compounds evaluated included sodium arsenite, calcium cyanamid and arsenic pentoxide. Chemicals applied “to leafy spurge at flowering time in early summer” gave the best results. Mid-June is still the ideal time to apply most herbicides used to control this weed. Similar advice was given in circular 55 published in June 1934 (Figure 4) (4). |
1937 report from the LaMoure County
agent explained that the county was in the fourth year of an intensive
fight against leafy spurge (27). The county commissioners and 13 townships
were cooperating in the spraying of 14 acres of leafy spurge with sodium
chlorate (Atlacide), stated to be equivalent to 34 cultivations per year
or grazing with sheep. In 1951, 14 years later, the LaMoure county agent
reported they still had a leafy spurge problem, but their control program
was considered quite effective. By 1996, the 14 acres had expanded to
an estimated 41,000 acres and no one was all that optimistic about control
(25).
Chemical control recommendations
remained relatively unchanged for the next two decades after initial research
in the early 1930s. Sodium chlorate was still the treatment of choice
in a May 1944 bulletin (14). The dangers of chemical use were noted by
author W. J. Leary, an extension agronomist. He stated “sodium chlorate
mixed with organic matter, such as clothing, wood or plant growth . .
. becomes a serious fire hazard.” One should use caution starting
the wood stove after spraying leafy spurge! Mr. Leary also recommended
a combination of cultivation and competitive crops for both leafy spurge
and creeping jenny (field bindweed) control. This is the first known recommendation
of an integrated approach to the control of leafy spurge.
The first North Dakota Bimonthly
Bulletin was published in September 1938 and included methods to
control leafy spurge with sheep (11). This abstract was followed by complete
reports in 1939 (12) and 1942 (10). Among the conclusions were that sheep
could graze leafy spurge without ill effects and that the weed was controlled
while grass production was increased. Over 50 years later similar experiments
were conducted, only this time goats (usually Angora) replaced sheep as
the grazing animal. The use of sheep to control leafy spurge in North
Dakota never became popular. Angora goats were starting to be used for
leafy spurge control in the 1990s until the government incentive program
for mohair production was curtailed. Because there was no market for the
meat in the state and the hair prices were low, it became uneconomical
to keep Angora goats just to control leafy spurge.
Post-War
Control and Education
An 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.
|
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 “contain, 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. |
Conclusion
It
is likely leafy spurge will always be a part of the North Dakota landscape,
although at levels below the economic threshold. Leafy spurge caused the
framework to be set for a statewide weed control organization. Because
of the attention given to this weed, threatened invasions from newly introduced
alien species such as spotted knapweed (Centaurea maculosa Lam.)
and purple loosestrife (Lythrum salicaria L.) can be identified
early and a control program initiated promptly. The plan of cooperation
established between various state and federal agencies needed to control
leafy spurge on a state wide basis is now in place and ready to use for
other control efforts. Thus, the legacy of leafy spurge could be the prevention
of further noxious weed invasions and the preservation of the state's
agricultural enterprises and natural plant species.
History has taught that a state-wide coordinated effort by land-managers, state and federal legislatures, and university and federal researchers and extension specialists are needed to successfully stop the spread of a noxious weed. This framework must be maintained to stop the future invasion of noxious weeds.