July 22, 2011

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


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.


Nick Christians Professor

Nick Christians, Ph.D. – University professor of turfgrass management, Iowa State University, Department of Horticulture, Ames, IA, and adjunct faculty, Department of Agronomy, Iowa State University, Ames, IA. Dr. Christians received his B.S. from the Colorado State University ...