Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Sonar treatment time

Can someone help me out with this. We treated a pond with 4 ounces or sonar A.S. The pond is calculated at 2 to 2 1/2 acre feet. It has been 1 month and the Lily's are not looking good , the rush is turning white but EWM is still looking pretty healthy. There is a lot of it brown but no white and when I pull out a hand full it is still really green underneath. No water has exited the pond and there has been very little rain. We are debating putting another 4 once in.

Assuming 2.5 ac-ft was treated with 4-oz of a 4#a.i./gal fluridone ("Sonar AS"), the fluridone concentration should've reached somewhere around 18ppb, which is a bit low for many lily species but should be quite adequate for EWM - if sustained.
At 1-month post treatment, expect to see the initial discoloration on the EWM's terminal-growth to become less noticeable since the terminal growth (meristematic tissue) detaches (abscises) from the remaining stem, leaving a "snipped-nub" at the point of abscission.
At that juncture, the remaining biomass of EWM will remain static for some time (2-4 weeks) with further visual responses occurring at glacial speed.
Eventually, and often in a matter of mere days, the plant biomass will quickly (relatively) drop to the bottom - or possibly remain suspended due to intermingled accumulations of filamentous algae (which provides buoyancy).
In your situation, I would be concerned if:
1) no initial discoloration was observed in the EWM's meristematic tissues.
2) abscission-nubs are not currently observed in place of active terminal-growth.
Inspect your EWM for the above conditions and report back.

Thanks for the informative response. I'm not near the pond right now but my buddy is, so if he pulls out a handful of EWM and the ends are green. bushy and healthy looking we need to treat again? If that is the case should we treat now or wait a couple more weeks to make sure?

The EWM that was in small areas is really looking bad, it is the areas that the matt is the thickest that its still looking healthy. Does the size and thickness of the matt have anything to do with it?

Mat size and thickness isn't relevant since such treatments affect the entire volume of water within the pond. If it works in one place, it should work everywhere.
Again, inspect the terminal growth-points of the remaining EWM. If only nubs are present, or discolored shoots, you should be in good shape. Patience!
BTW: How'd you get your hands on Sonar AS in Canada?

I am in Canada but the pond we are working on is in Michigan, That's why I am not near it right now. I will get my buddy to pull some tonight and take a bunch of pics. I was there on the weekend (went down for the Nascar race) Thanks for your help Kelly

Kelly you were right, it has been 6 weeks and the EWM is dropping fast. Thanks

Good to hear! Watch for recurrences next year and retreat IF any new growth is observed. In many cases, two consecutive annual treatments will eliminate the need for perpetual treatments every other season - except when persistent re-introductions occur.

I treated my 1.5 acre pond with a quart of Sonar/Fluridone a week ago.
I am not seeing anything yet, and starting to get nervous.
Just have to keep telling myself it takes over a month.