You are here:

Lawns/too much pre-emergent


Hi! I have a problem, I think my contractor has applied too much pre-emergent to my lawn and I am afraid it is going to burn it all! It was 100 lbs of TurfGro professional 0-0-7 over about 13000 of lawn. It is Bermuda grass, well established, and currently dormant. The bag said no more than 6,6lb/1000 sq feet per application and the recommended rate for our region is 5/1000 sq feet. By my calculations, the applied rate was about 8.3 lb/1000 sq feet.
I guess my question is - how bad is it? Is it gonna damage existing grass?
Do I need to do anything about it or it is not that bad really?
It just happened yesterday, should I be watering it like crazy to leech some of it out? Is it bad enough that I should buy some activated charcoal (I would rather avoid that, cause that can get expensive).
My primary concern is that my beautiful lawn dies. Please help me!

No need to panic ... yet!
I tried to find out what product was used. But I could not.
You say that it was a pre-emergent.
You give the analysis as 0-0-7. I was looking for 0-0-7 with prodiamine, benefin,  oryzalin, benefin, oxadiazon   or similar pre-emergent chemical.

If no such chemical is listed on the label (that famous fine print ) then you have an all potash(K) fertilizer. Zero N, zero P, 7% K.

Again we have to go back to the LABEL. Somewhere they have listed the source material of that potash.

There are two main sources: muriate and sulfate (of potash). Muriate of Potash (MOP) is potassium chloride and has a greater 'burn potential' than SOP.

So it is now time to do the math. 7%K means that there are 7lb. of the element potash in 100 lb. of the stuff in the fertilizer bag. 100 lb. of the stuff in the fertilizer bag was applied to the lawn. That means that 7lb. of actual potash was put down; on 13000 sq. ft.
My calculator tells me that 0.5 lb. K /1000 sq. ft. was applied.
 This is perhaps as much potash that you would want to put down in a single application.

"the recommended rate for our region is 5/1000 sq feet." 7% of 5.0 lb.. is 0.35 lb./ 1000 sq.ft.  

"The applied rate was about 8.3 lb/1000 sq feet." 7% of 8.3lb. is 0.58 lb./ 1000 sq.ft.  

So, based upon what you wrote, I do not believe that the turf was harmed.
There might have been a label violation; or even a violation of local laws.

And please bear in mind that we do not yet know if there was a pre-emergent chemical in the mix.
Write back if you have new information or thoughts.  


All Answers

Answers by Expert:

Ask Experts


Ronald B Persaud


Florida (Central and South) lawns maintenance and troubleshooting.


Work experience in Garden and Technical Sales (Ace Hardware and Lesco). L&O Spray Technican/Horticulturist/Tree permitting (Local Municipality). Commercial Landscape Maintenance (Condo complex and Shopping Mall)

Past member Florida Landscape Maintenance Association (Pinellas County).

On the 'Gardenweb' under the pseudonym "Ronalawn82"

CPO certified (L&O) Florida. Hons. Graduate: Eastern Caribbean Farm Institute (now Eastern Caribbean Institute of Agriculture and Forestry), Trinidad WI.

©2017 All rights reserved.