Search results

The two most asked questions of the week are 1) how long will Imprelis persist in the soil and 2) will Imprelis damaged trees recover.

The answers are:

1. Imprelis is known to be quite persistent in soil, but how long it will last depends on a variety of factors. These include rainfall, soil type, organic matter content of the soil, temperature conditions through fall and spring and other variables that will be different from region to region. As a result, there is no clear answer to that question. I would expect that most of the material applied this spring at label rate will be gone by next season, but again, it will vary by location and conditions on the site.

2. The answer to question 2 is also going to vary. At this point, no one knows for sure what is going to happen next year.

There are already companies coming up with questionable solutions. See

https://sharepoint.cahnrs.wsu.edu/blogs/urbanhort/archive/2011/07/18/spin-cycle.aspx

My recommendation is to water the damaged trees, but don't water to excess. Otherwise, leave them alone and see what happens next spring. Stay away from the home remedies and concoctions that are being recommended. If you kill the tree by something that you did, you will likely not get a settlement on it.

Here is my best guess on what is going to happen. It will depend of the extent of the damage.

The tree below has damage limited to 2011 new growth. I'm betting that it will recover next year, but of course I will not know for sure until next spring or summer.

The tree in the next picture is border line. If it recovers, I will be surprised.

This one, which is located on the same course in Chicago as the other two, is likely dead and will show no recovery next year.

The only thing you can do at this time is get good photographic record of the damage and wait until next year to see what recovers.

Imprelis (aminocyclopyrachlor) was released by DuPont Professional Products into the turf market this spring as a broadleaf control. It is part of a new chemical subclass called pyrimidine carboxylic acids. We have studied this product experimentally at Iowa State for the past couple of years and have found it to be very effective against a broad spectrum of broadleaf weeds. Its advantage is that it is effective against several hard to control weeds such as ground ivy, violets, and henbit. It also has the advantages of being applied at very low rates of active ingredient and is rainfast, meaning that it does not need to remain on the weed leaves for a period of time. It's safe on most cool-season grasses and some warm-season grasses, including zoysiagrass.

In early June, a number of reports on tree damage on areas treated with Imprelis began to come in. The first reports that I heard were from the east coast. Then pictures and reports started coming in from Chicago. Yesterday, I heard that there are several reports from the Atlanta area. The two most commonly damaged trees have been Norway spruce and white pine.

It is important to note that there are many locations where the product was used and no tree damage has occurred. Also, not all trees on the treated areas are damaged.

The pictures below are Norway Spruce and were taken in the Chicago area. The damage appears to be systemic, meaning that the material is being taken up by the roots and translocated to new growth. On this site, about 20 trees out of approximately 120 susceptible plants were damaged. In this case, there was heavy rain after treatment that may have increased movement of the product into the rootzone.

Dupont released a letter last night to users of the product. Their recommendation is as follows:

"As a precaution, until we can more fully understand the circumstances, and whether Imprelis may have contributed to the observed symptoms, do not apply Imprelis where Norway Spruce or White Pine are present on, or in close proximity to, the property to be treated.  Additionally, when applying Imprelis, be careful that no spray treatment, drift or runoff occurs that could make contact with trees, shrubs and other desirable plants, and stay well away from exposed roots and the rootzone of trees and shrubs.  Consult a certified arborist if you are uncertain about the root zone of specific tree species."

My personal recommendation is to be very cautious with the use of this product until we know exactly what is going on. This story is just developing and I will keep you posted as new information is released.

Here are some additional links.

http://www.ppdl.purdue.edu/PPDL/hot11/6-10.html

http://bygl.osu.edu/#5

http://extension.psu.edu/greenindustry/giec/news/2011/heads-up-spruce-and-pine-injury