Green Horizons

Background

In spring 2011, a new DuPont herbicide with the active ingredient aminocyclopyrachlor was sold with the trade name Imprelisr and used to control weeds on many turf areas (lawns, golf courses, sports fields, etc.). Following use of the herbicide in spring 2011, lawn care companies and golf courses across the United States began reporting damage as early as June 2011 to trees and ornamentals located adjacent to the treated turf areas.

Turf professionals who reported landscape damage from a 2011 application of Imprelisr were encouraged by DuPont to file a claim in 2011. Claims were filed and processed in 2011. Although some settlements have now been reached, many are still being processed and DuPont representatives are visiting selected affected properties to assess the damage and recovery of trees and shrubs.

Did Trees Recover from Imprelisr Injury?

Some affected trees exhibit symptoms exactly like they did the previous year. They appear frozen in time, and no new growth has occurred. Some trees show signs of new growth from axillary buds but not from terminal/apical buds. In many cases, despite some recovery, trees are too damaged, so removing them is still recommended. Other trees with little injury may still recover but will likely require corrective pruning to maintain desirable form and symmetry.

Are New Symptoms Being Discovered?

Imprelis was applied to this homeowner’s yard in 2011, but the damage to this baldcypress did not appear until this spring, when leaves on last year’s shoot did not emerge.

Extension specialists are receiving reports of damage to trees and shrubs that were not reported in 2011. We cannot be exactly sure whether these are new symptoms or whether they went unnoticed in 2011. However, we are certain that symptoms are still being observed in species such as cottonwood, lilac, Norway spruce, white pine, and yellow cypress, and it appears that these are new symptoms in 2012 on plants that did not show symptoms in 2011. Laboratory tests are ongoing to confirm that spring 2011 Imprelisr applications are the cause of injury to these trees and shrubs in 2012.

What Should I Do if I Suspect Imprelisr Injured Trees BUT I Didn't Notice the Damage in 2011?

If you applied Imprelisr in 2011, did not file a claim in 2011 with DuPont, and now see what you suspect is Imprelis r damage, then contact your state's pesticide control board. In Missouri, contact the Department of Agriculture's Bureau of Pesticide Control at (573) 751-5504.

If you applied Imprelisr in 2011, filed a claim in 2011 with DuPont, and now see what you suspect is new damage from Imprelisr on previously undocumented trees, then contact DuPont at (866) 796-4783. Request a site visit and the forms you'll need to file an amendment to your claim.

Can I Do Anything to Help Trees Recover?

Trees that were injured from Imprelisr, but not killed, should be managed by watering them during dry periods to reduce drought stress and provide sufficient moisture for new growth. Avoid overwatering, which can cause waterlogged soils and contribute to root decay. The effects of fertilization on trees injured by Imprelisr are not known, so experts are hesitant to recommend fertilization to promote recovery. Pruning is recommended to remove dead and severely damaged branches - this may help reduce the possibility of infestation by secondary diseases and insects.

How and When Should I Replace Damaged Trees?

Instructions for replanting trees (for those who file claims and for property owners who remove and replace trees on their own, outside of the claims process) are available at www.imprelis-facts.com. Based on soil testing and the continued presence of Imprelisr in treated lawn soils, specialists do not recommend planting new trees in the same area where a damaged tree was removed unless the entire tree is removed (shoots, roots, bark, leaves, etc.) and several cubic feet of soil surrounding the tree are also removed. Soil removal will be necessary to protect newly planted trees from being exposed to the herbicide.

Although replanting a tree in an Imprelisr-treated area could be risky in 2012, those who filed a claim should be protected from this risk according to DuPont which states on their website (www.imprelis-facts.com):

"DuPont warrants against any damage to any tree on Owner's property (including replacement trees) caused by Imprelisr until December 31, 2013, or in the case of replacement trees, until a date two years after the date of planting."

What Do We Know Now that We Didn't Then?

We know much more in 2012 about Imprelisr than we did in 2011, but there is still much more that we don't know; like exactly how long this herbicide will persist in the soil and why some tree and shrub species were affected so quickly and others are just now showing symptoms. Current research at universities around the country is trying to answer the many questions people still have. We will keep you informed as we learn more.

What Is Taking DuPont So Long?

Many people have been asking this question. Turf professionals are getting pressure from their clients and, in some cases, their insurance companies. Unfortunately, we are not sure why the claims process is taking so long for so many people other than the fact that many claims were filed, each with several trees, and large amounts of paperwork are required in this legal process. Although some settlement offers have been made, most are still waiting to hear back from DuPont. All we can do is encourage you to contact DuPont and express your concerns regarding the process.