We have been fighting a losing battle w/water primrose all summer. We've been removing it manually, but I think we've just managed to spread it even more. Time to get the chemicals. Is it too late in the year to do it now, or should I wait for warmer temps? I know many products are more effective w/warmer temps than with cooling ones, but I know nothing about fighting aquatic weeds. I've also got phragmites, which I also need to eradicate.

http://aquaplant.tamu.edu/ look at this site under the plants you have and check the options (systemic vs. contact) and then the temp requirements.

For example

http://aquaplant.tamu.edu/management-options/water-primrose/

I see you are in South Central Illinois too. I'm near Olney and the WP is horrible around here. I had it severely in my pond until I had it cleaned out and made larger about 3 years ago. This summer it showed up again. One good thing about it, once it started growing good, my FA stopped growing completely. I think the WP used up the nutrients. I also see a lot of minnows like to hide in the stuff. I prefer it to FA and am just going to spot treat the WP around about 2/3 of the pond and let the rest go. I fought it for years in my pond and had no luck eradicating it.

Brook,

+1 on what Poppy said! I had some wp issues a few years ago, killed it all (mistake one of about 1000 for me) and then battled FA for a number of years until wp and other vegetation came back.

I will gladly put up with some wp in exchange for very limited FA. I also spot treat mine as needed. But did use a systemic in late summer. I won't treat again until next spring or summer.

I have sure done some doozies, but I believe getting rid of all the wp was one of the biggest.

Cmm

Thanks, ewest. That was very helpful, and it looks like there are a lot of options available. Temps are to plummet this weekend, so I think I'll just wait till next year and stable temps.

Poppy, it pretty much covered my neighbor's small pond, so I knew I'd get it sometime. It's just a little frightening how much it spread in just one season despite our efforts to keep it in check. Until this year, I have had little trouble w/FA. The primrose is good cover, and I wouldn't mind having some of it. I just want to control it.

CMM, mistakes are part of the learning experience. I always seem to learn more from mistakes than I do successes. May I ask what systemic you used? I'm resigned to having this vegetation and will spot treat it just so it doesn't take over everything.