Imprelis Update: DuPont Begins Claims Resolution Process

On September 6, DuPont began a process to fairly resolve claims for impact on trees that DuPont™ Imprelis® herbicide may have caused. Below are links to documents useful to turf professionals who applied Imprelis® last fall or this spring. More information is available at http://www.imprelis-facts.com/ and at (866) 796-4783. The deadline for submission of claims is November 30, 2011.

Note on fall fertilization: Fertilizing affected trees and shrubs during 2011 is not recommended, but fertilization of the turf in the fall of 2011 is recommended per normal turf fertilizer recommendations (see recent turf tips on September 1, 2011). When damaged trees and shrubs are surrounded by turf, take care to fertilize outside the drip line of damaged trees so not to stimulate new growth of the trees.


Information From DuPont:

Letter to Lawn Care Professionals from DuPont

Claims Resolution Process Lawn Care Professional Overview

Letter to Golf Course Superintendents from DuPont

Photography Instructions Before Removing Trees

Frequently Asked Questions about the Claims Process

Updated Documents from Purdue University for Use by Turf Professionals

A Homeowner’s Guide to Imprelis® Herbicide Injury in the Landscape

A Turf Professional’s Guide to Imprelis® Herbicide Injury in the Landscape



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Purdue Turf Scientists and Their Work Highlighted in Recent Press Releases

Scientists make turfgrass safer for animals, deadly for insects

September 6, 2011

WEST LAFAYETTE, Ind. - The right combination of compounds produced by a beneficial fungus could lead to grasses that require fewer pesticides and are safer for wildlife and grazing animals, according to Purdue University scientists. Read More


Purdue 'tool box' could be ace in the hole for golf courses

August 23, 2011

WEST LAFAYETTE, Ind. - Below par looks great on the leaderboard but never when it describes the appearance and playability of golf course putting greens. Purdue University researchers are working to help course managers produce winning greens at lower cost and with less labor. Read more.


Avoid use of herbicide Imprelis, Purdue experts advise

July 22, 2011

WEST LAFAYETTE, Ind. – Lawn care providers should not use the herbicide Imprelis on residential and other properties such as golf courses as experts try to determine whether it is injuring trees and ornamental plants and can be used safely, a team of Purdue University specialists advises. Read more.



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Making Adjustments to Your Fertilizer Program

Although the Purdue University Turf Program publishes information about how to fertilize your turf with nitrogen (N)-based fertilizers including standard rates and timings, there are many factors that influence these rates and timings. It is important that each turf area be fertilized according to its needs. For example, some areas require more nitrogen fertilization because they are highly trafficked and need additional nitrogen fertilization to promote growth and recovery. In another example, some older, well-established lawns may need less nitrogen fertilization because they have more organic matter in the soil (a natural source of some N fertilization). See the table below for more of these examples and make sure to customize your fertilization program to fits your turf needs.

Dr. Aaron Patton, Turfgrass Extension Specialist
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Fall Fertilization

Cool-season turfgrass species should be fertilized mainly in the autumn. September and November are the two best times to fertilize a lawn in Indiana. Fall nitrogen promotes good root development, enhances storage of energy reserves, and extends color retention in cool-season lawns. Most of the benefits from late fall nitrogen will be seen next spring and summer with earlier green-up, improved turf density, and improved tolerance to spring diseases such as red thread and pink patch, and reduced weeds.

There are many fertilizer choices available to the homeowner. Organic, inorganic, and synthetic organic products are all available. As with all plants, turfgrasses cannot tell the difference between the sources of nutrients. Some products contain high amounts of slow-release N while others contain none. Although there are exceptions to the rule, it is good practice to use products with a greater percentage of slow-release nitrogen sources during spring and summer months and a greater percentage of quick-release nitrogen sources in the fall.

For the September application, pick a product that contains some quick and slow-release nitrogen. The timing of the September application is anytime of the month after the daytime high temperatures are no longer in the 90s °F. The target application rate for this fertilization should be 1.0 lbs. N/1000 square feet.

The late-fall or November application timing should be near or after the last mowing of the year, but while lawn is still green. Typically, there may be a month or more between your last mowing and the time the grass turns brown or goes under snow cover. Generally the first few weeks of November are when to apply. Earlier Purdue research suggests that the nitrogen must be taken-up by the plant before winter to be most effective. Therefore, a quick-release (or soluble nitrogen source) such as urea, ammonium nitrate, calcium nitrate, or ammonium sulfate is most effective. The target application rate for this November fertilization should be 0.5 to 1.0 lbs. N/1000 square feet.

More fertilizer program information is available in AY-22: Fertilizing Home lawns at www.agry.purdue.edu/turf/pubs/ay-22.pdf

If you are confused on how much of a particular product to apply to achieve a particular N-rate, use our fertilizer calculator to help determine exactly how much product to use: www.agry.purdue.edu/turf/fertcalc/Fertilization%20calc.html.

Aaron Patton, Turfgrass Extension Specialist
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Staying Dry

Many in central Indiana are coping again with drought a second year (See drought monitor images for Indiana (current and fall of 2010). While many pockets of Indiana have had sufficient moisture in the second half of summer (including Lafayette) others are facing dry conditions for a second year in a row.







September is here and so is our typical start to fall fertilization. Many are asking, “should I fertilize drought stressed areas right now?” There are two strategies that could be used. First, you might consider applying 0.75 lbs N/1000 ft2 with some slow release N source. This should help to speed recovery when rains resume but minimize any leaf burn with a lower nitrogen rate and some slow-release nitrogen. Keep in mind that drought stressed plants will not take up nitrogen, and so a response to nitrogen fertilization will only occur after a rainfall occurs and the plant has a chance to take-up the nutrient. Additionally, some injury could occur to drought stressed areas from trafficking equipment across the site while fertilizing. A second strategy would be to wait to fertilize until after the turf greens-up after the next rainfall. Agronomically, the second option makes the most sense. However, some turf professionals may need to begin the fertilization process on some turf areas due to the large number of properties that they manage.

Hopefully, rains will return soon to central Indiana. On the bright side, we could be facing exceptional drought as they are in Oklahoma and Texas. Wow!






Dr. Aaron Patton, Turfgrass Extension Specialist




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Dr. Cale Bigelow Sabbatical

Just a quick note from across the pond. I will be on study-leave/sabbatical for fall semester from 15 Aug. - 31 December, 2011. I will be collaborating with colleagues interested in urban ecology and studying alternative low input turfgrass systems in Europe (primarily the United Kingdom). Please note that during this time I will have limited access to my Purdue email but will do my best to check it at least weekly. Do not be offended if my responses are slow, I have not forgotten about you, things are just slower over here...! If you call my office phone I will be checking that number very infrequently you are better off to send me an email cbigelow@purdue.edu or simply call Jennifer Biehl directly 765-494-8039. In my absence, the Turf Team (Drs. Gibb, Jiang, Latin, Patton, Richmond and of course Ms. Jennifer Biehl) are more than able to help answer any questions you might have regarding turfgrass in Indiana. You can find loads more information on our turf home page. www.agry.purdue.edu/turf

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Imprelis® Update: Stop Sale, Use, or Removal Order. Q&A

The following post provides an update on Imprelis® herbicide in a Question and Answer format.

Q: What action has the Office of Indiana State Chemist (OISC) recently taken concerning Imprelis®?

A: The OISC issued a stop sale, use, or removal order (SSURO) on August 1, 2011 for the herbicide Imprelis®. The OISC has reason to believe that DuPont Imprelis® Herbicide, EPA Reg. #352-793, when used as directed or in accordance with commonly recognized practice, has caused injury to non-target vegetation, except weeds to which it has been applied, and is therefore MISBRANDED. Therefore, the OISC is hereby issuing a STOP SALE, USE OR REMOVAL ORDER (SSURO) to DuPont Professional Products. This SSURO requires DuPont Professional Products to cease all sale, distribution and use of DuPont Imprelis® Herbicide, EPA Reg. #352-793, in the State of Indiana, effective immediately. This SSURO pertains to any and all quantities and sizes of DuPont Imprelis® Herbicide, EPA Reg. #352-793, within the ownership, control or custody of DuPont Professional Products wherever located. In addition, DuPont Professional Products shall not commence any movement of this product from any present location without prior written approval from the OISC. Any person violating the terms or provisions of this SSURO shall be subject to civil or criminal penalties as set forth in IC 15-16-4.


Q: What is the stance of the United States Environmental Protection Agency (EPA) concerning Imprelis®?

A: On August 11, The EPA issued a SSURO for the herbicide Imprelis®. Previously, the EPA issued a letter to DuPont on August 3, 2011 stating two concerns. First, that the EPA is considering issuing an SSURO (described above). Second, the EPA is concerned about the lack of information that is being provided by DuPont to the public concerning the efficacy of Imprelis®. The EPA “strongly encourages DuPont to reconsider” providing information related to the phytotoxicity studies related to effects on trees. More information about Imprelis, including EPA registration of the herbicide, is available at: http://www.epa.gov/pesticides/regulating/imprelis.html


Q: What action has DuPont taken to comply with the OISC?

A: DuPont is implementing a voluntary suspension of sale of Imprelis® herbicide. More information is available at http://www.imprelis-facts.com/ and at (866) 796-4783.


Q: Can I still apply Imprelis® herbicide in Indiana if I have some leftover?

A: No. The SSURO issued by OISC does not allow the continued use of existing Imprelis® herbicide.



Q: What do I do if I have leftover Imprelis® herbicide?

A: DuPont has stated that they will initiate a product return and refund program in mid-August 2011. More details about this will be shared when they become available.


Q: Where can I get more information from DuPont about Imprelis®?

A: Website (http://www.imprelis-facts.com/) and hotline ((866) 796-4783) are available.


Q: Where can I get more information from Purdue and the OISC about Imprelis®?

A: Read news alerts from the Office of Indiana State Chemist at http://www.isco.purdue.edu/, read more from the Purdue University Turf Program at http://www.agry.purdue.edu/turf/, and received updates from the Plant and Pest Diagnostic Laboratory at http://www.ppdl.purdue.edu/ppdl/.


Read past documents created on July 22, 2011

A Homeowner’s Guide to Suspected Imprelis® Herbicide Injury in the Landscape

A Turf Professional’s Guide to Suspected Imprelis® Herbicide Injury in the Landscape


Aaron Patton, Turfgrass Extension Specialist



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