There appears to be a negative interaction of Echelon herbicide and urea (46-0-0) on tall fescue.This interaction is showing up as injury on tall fescue.Echelon is a pre-package mix of prodiamine and sulfentrazone.Echelon has been tested in many university trials in recent years and, at the proper rate, turfgrass tolerance has not been an issue.However, when mixed with 46-0-0, several lawn care operators have called to say they have observed injury on tall fescue.We followed these complaints up with a research trial at the Lake Wheeler Turfgrass Field Laboratory and we have confirmed that there is significant injury on tall fescue.
It is important to point out there have been no reports of fescue death from this combination.It is also important to point out that, at this time, we have only had reports of this injury on tall fescue.It may or may not occur with other turf species.
The accompanying chart shows injury from various mixtures in our research trial.
Note that Echelon alone caused minimal (and acceptable) injury to tall fescue.However, when mixed with 46-0-0, injury increased from 6% along to 26% at 5 days after treatment.Also note the addition of a 4-4-5 with 6% iron actually reduced the injury (acted as a safener) but still provided 15% injury.The mixture of Echelon + 46-0-0 + 4-4-5 + 3-way herbicide gave about the same injury as Echelon + 46-0-0 + 4-4-5.
The photo below shows the level of injury from Echelon + 46-0-0 (treated area is between white dots).It should also be emphasized
the injured tall fescue appears to be recovering. However, until this interaction can be sorted out, it would be advisable to refrain from mixing Echelon with urea.This is not an issue with Echelon alone.It only has implications for Echelon use with urea.Further testing will be underway to determine if this interaction occurs with other forms of nitrogen as well as with other turf species.