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 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

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:

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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