Nearly four years ago, Imprelis surfaced as a broadleaf weed control option that some say was as good as it gets. The product, though, created serious, long-lasting issues that still are being resolved.
Photos courtesy of Kathy Zuzek,
University of Minnesota Extension.
Photo illustration by Kelly Neis
Read this story in GCM's digital edition
Imprelis was introduced, Hillcrest Country Club superintendent Joe Aholt never
had seen anything like it for broadleaf weed control.
was a miracle product,” says Aholt, a 20-year member of GCSAA.
took just 2 ounces per acre of Imprelis to eradicate weeds at the Boise, Idaho,
course, Aholt says, and it performed admirably.
knew within a month the weed would be gone,” Aholt says. “You had to be patient
with it, but it worked. You could spray it in rain, cold, heat. It was the
cleanest my course had been, ever.”
appeared to be a game-changer. Like Aholt, others applauded its effectiveness.
Unlike some herbicides, where the smell lingers throughout the day, Imprelis
was different: It was odorless.
years after being removed from the market, Imprelis remains visible.
— the herbicide, created by DuPont for professional use on golf courses,
residential areas and institutional lawns — is no longer available for sale. It
has been that way for quite a while.
voluntarily pulled Imprelis from the market in August 2011 before the
Environmental Protection Agency (EPA) issued a mandatory stop-sale order on
Imprelis after being alerted of numerous reports from golf courses to nurseries
that the product was suspected of injuring and, in some cases, killing trees.
Norway spruce, white pines and honey locust proved to be among the species of
trees that were susceptible.
Imprelis appeared to be a gamechanger. Unlike some herbicides, where
the smell lingers throughout the day, Imprelis was different: It was odorless.
October 2013, a settlement was reached in a class-action lawsuit against E.I.
du Pont de Nemours and Co. (DuPont) over Imprelis. More than three-dozen
class-action lawsuits originally were filed in multiple federal courts
throughout the U.S. Ultimately, the class-action lawsuits were consolidated and
transferred into one case and entered into the U.S. District Court for the
Eastern District of Pennsylvania.
some instances, golf courses settled their claims directly with DuPont. Three
classes were established in the settlement. Class 1 included property owners
who own or owned property in the U.S.; Class 2 was applicators (lawn care
professionals); and Class 3 included golf courses and other Imprelis
self-applicators. They were eligible to be part of the claim if they used
Imprelis between Aug. 31, 2010, and Aug. 21, 2011, as long as they submitted or
accepted a claim through the manufacturer’s Imprelis Claims Resolution Process.
York and California were not included because Imprelis was not approved for use
in those states.
38,000 claims have been submitted through the Imprelis Claims Resolution Process,
DuPont spokesman Gregg Schmidt told GCM in March. DuPont estimates there
will be $1.175 billion in total charges to compensate customers, according to
that participated in the class-action lawsuit were Connecticut, Delaware,
Indiana, Kansas, Kentucky, Maryland, Michigan, Minnesota, Missouri, New Jersey,
North Carolina, Ohio, Pennsylvania, South Dakota and Wisconsin.
vary in scope and payouts, according to published reports. Two examples: The Owatonna
People’s Press in Owatonna, Minn., reported that the city received a check
last year from DuPont for $1.85 million for damage to trees at Brooktree Golf
Course. Lake County Forest Preserve District in Illinois received nearly
$836,000 from DuPont for damages, according to the Chicago Tribune.
are pleased with the progress we have made in resolving claims for damage,”
Schmidt says via email. “To date, we have made offers of resolution to approximately
90 percent of claimants.”
to speak with several superintendents and others in the industry for this
story. Some, because of claims that have not yet been processed, declined, a
sure signal that Imprelis has not completely vanished from the radar.
A mature white spruce shows signs of damage from Imprelis.
What’s in a name?
years, DuPont was committed to superintendents through its work with major
universities for turf field research. DuPont regularly disseminated its
research through sales representatives, associations, distributors, webcasts
and one-on-one meetings.
example, in 2010 DuPont updated its Weevil Trak website, which offered
superintendents more features to help control annual bluegrass weevil.
that year, the EPA conditionally registered aminocyclopyrachlor. That is the
active ingredient in Imprelis. According to the EPA website, “the studies
originally submitted were adequate to make a statutory finding for
EPA determined aminocyclopyrachlor was a “selective, low-toxicity herbicide
that provides pre- and post-emergent control of broadleaf weeds, woody species,
vines and grasses on several non-food use sites, such as rights of way, wildlife
management areas, recreational areas, turf/lawns, golf courses and sod farms.”
EPA also stated that DuPont conducted “roughly 400 efficacy and phytotoxicity field
trials” and that “they (DuPont) reported to EPA that they did not observe
adverse effects to trees.” Imprelis posed minimal risks to people and pets.
One of the signs of Imprelis damage in white pine
is stress or death of the tips of branches.
Imprelis was made available, Scott McElroy, Ph.D., an associate professor of
turfgrass and weed science at Auburn University, participated in research
trials of aminocyclopyrachlor about eight years ago when he was an assistant
professor of plant sciences at the University of Tennessee. He says its
broadleaf control in tall fescue was outstanding.
still probably the best broadleaf control herbicide I ever worked with,”
McElroy says. “Don’t get me wrong. We still have some great herbicides. But for
a single active ingredient at low rates and with the ability to control a wide spectrum,
specifically cool-season turf, there’s nothing like it.”
for use rates of 3.0 to 4.5 fluid ounces per acre, Imprelis was made to be
absorbed into the ground and destroy the root system of weeds. But when it came
into contact with certain tree roots, particularly shallow, succulent roots,
some of the results proved to be traumatic.
signs appeared in different ways. Needles on firs turned orange or brown.
Leaves curled up. Some fell to the ground. Tips of branches and buds showed
stress. Tumor-like growths appeared.
Tumor-like growths on a honey locust indicate
damage in this species.
part of its investigation into reports of possible damage to trees, the EPA
sought to determine whether the damage was a “result of product misuse,
inadequate warnings and use directions on the product label, persistence in soil
and plant material, uptake of the product through the root systems and absorbed
into the plant tissue, environmental factors, potential runoff issues or other
responded with action following the onslaught of damage claims.
company established open lines of communications for customers. It engaged multiple
independent, certified arborist companies to work with customers and evaluate their
claims. Among the companies that Du- Pont listed for those filing claims under
its Qualified Tree Replacement process was one that is well-known to golf
course superintendents, The Davey Tree Expert Co., who agreed to pricing and
terms for tree replacement included in the Claims Resolution Agreement (CRA)
that DuPont established. Davey, as did other arborist companies, agreed to
provide a limited warranty for the trees that the company plants. One
superintendent tells GCM the tree recovery process included slow-release fertilizers,
pest treatments and pruning.
part of the CRA, DuPont announced it would pay for care programs and
replanting. The company also provided a two-year warranty to program
participants for all replacement trees and paid for efforts to assist recovery of
other trees impacted by Imprelis use.
launched a website, http:// imprelis-facts.com, to feature the latest
information and provide an avenue to report problems to the company. DuPont also
started a toll-free hotline to handle concerns. More than one superintendent
DuPont was helpful and followed through during the claims process.
"I think in the future, product testing will be strengthened. Probably
because of it, I don’t foresee it ever happening again."
— Jared Hoyle, Ph.D.
size of a settlement depended on the size of the tree. For example, a
1-foot-tall tree was $30; a tree 96 to 100 feet high equaled $19,000. DuPont
asked those who were making claims to document damage by taking digital photos
prior to removal.
compensated golf courses for removal and disposal of impacted evergreen trees unlikely
to recover. DuPont also offered credits or refunds, depending on a
distributor’s policy, on unused Imprelis.
had a short shelf life. It was introduced in August 2010. Twelve months later,
it was gone. Late in 2012, Syngenta announced that it had acquired the DuPont
Professional Products insecticides business, which included the brands
Acelepryn, Advion and Provaunt. The closing price for the acquisition was $125
same year was DuPont’s last one as a Silver Partner through GCSAA’s Partner Recognition
Program. As a Silver Partner from 2008 to 2012, DuPont spent a minimum of $100,000
in support of GCSAA member services and programs.
also was a member in the Champions Club of GCSAA’s philanthropic organization, the
Environmental Institute for Golf (EIFG). DuPont was recognized as a member of
the Champions Club for the cumulative total of its contributions to the EIFG
($250,000 to $499,999) since 1987. Part of DuPont’s contribution included
donation of products to the EIFG’s Silent Auction.
some cases, spaces where trees have been removed because of Imprelis are no
longer vacant, another symbol of the healing process for an issue that rocked
are replanting on some sites where trees have been removed without any
problem,” says Kathy Zuzek, assistant extension professor for the University of
if anything, serves as a cautionary tale for manufacturers and superintendents.
Jared Hoyle, Ph.D., an assistant professor in horticulture, forestry and
recreational services at Kansas State University, imagines the Imprelis saga
could benefit the industry down the road.
think in the future, product testing will be strengthened,” Hoyle says.
“Probably because of it, I don’t foresee it ever happening again.”
The Country Club of Muirfield Village in Dublin, Ohio, GCSAA Class A
superintendent Dave Gribler encountered issues with some of his trees because
of Imprelis. He anticipates, and welcomes, the day when he can fully focus on
what happens below his feet.
spend too much time looking up instead of looking down at the ground,” Gribler
HowardRichman is GCM’s