Pond Boss Forums INTRO Questions & Observations Pond Weeds

Our one acre pond has blugill and bass. This summer we added tilapia to the pond and the pond also has a feeder. There are also so many weeds you can't fish any were in the pond. My question is will the weeds kill or stop the growth of the fish or is the only problem not being able to fish? How can you remove the weeds and keep them gone?

Just a few questions first. What type of weeds do you have? About what percentage of the pond contains the weeds? What is the average depth of the pond/about how much is less than 4 ft? Is there alot of nutrient rich runoff entering your pond? There are 3 ways to eliminate the weeds currently in your pond and a couple of ways to reduce the chances of massive weed growth. They can be eliminated by physical means such as a rake or grabbing and pulling, you won't get them all, but you could thin them out. If the primary concern with the pond is fishing it'd be ideal to leave 10-20% of the existing grass, but there is always the chance of it spreading wild again without some maintanence. There are biological methods such as grass carp that could be placed in the pond. They are somewhat selective in there feeding but if they find what they like they could virtually descimate your weeds for years. The down side of that is little cover for future generations of fish. There is a book from the Illinois Natural History Survey that gives recommendations on grass carp stocking. The recommendations are for IL ponds, but there may not be a huge difference. The book is called "Controlling Aquatic Vegetaion with Triploid Grass Carp" and it's circular #57. The 3rd option is chemical applications. This time of year is probably the worst to try and kill all of your veg. due to poor oxygen levels. It'd be better to kill 1/2-1/3 every 2 weeks. You'll have to do some research to find out what will kill the types of weeds present in your pond. Ideally one would want to treat his pond earlier in the year when the water temps are in the 60's and the veg is first starting to emerge. This will decrease the amount of veg in your pond over the course of the year and save you money in chemicals. It'll also decrease your chances of a fish kill. There can be opportunities to prevent weeds before they start also. If you know how nutrients are entering your pond you could try and filter some of them out with a good wide stand of grass in areas where water runs into the pond. If yard fertilizers are entering the pond, try avoiding fertilizing on slopes that may directly enter the pond. Alot of times though ponds are nutrient rich just because of the soils and I don't think there is a lot to do about that. Another option could be aquatic dyes. These will act like a blanket over your pond decreasing the depth light can penetrate, which next to nutrients is a huge factor in weed growth. In the same breath though, adding a dye to decrease light COULD Possibly decrease the amounts of invertabrates in your pond which means less food for younger fish. (I don't know that for a fact, but I've seen that point argued and it made sense to me). Personally, in a pond I would use primarily for fishing I wouldn't use it. Back to your original question of killing fish or stunting growth...too many weeds could kill your fish if the weeds died around the same time and at the wrong time your oxygen levels could crash causing a fish kill. Chances are you'll probably be O.K. In the long run, year after year of thick veg. it could cause some stunting due to the vast amounts of hiding places for young fish eventually creating a large abundance of fish that couldn't be naturally thinned out by predators. Conversly though a small amount of veg in a pond can create cover for small fish in a beneficial way. Sorry this is so long, it's been a while since my last post and I felt like writting.

If I were you I would attempt to manually create a few bankside fishing spots. The 'V' shaped weed cutter sold through the magazine is a great tool. It takes work but I think is a better environmental solution then the chemical route. However, duck weed? you got to spray that crap.
Toby

I certainly can't add to what Greenhead said, but I can tell you what I've learned so far on my pondmiester adventure.
First -identify the weed. If you don't know what you got, you won't know how to treat it. Do a google search on aquatic plant identification. Check this site out-http://www.tpwd.state.tx.us/fish/infish/vegetation/vegplan2001.htm
Second- Now that you know what the plant is you can find the best way to treat it- chemical, carp or manual labor.
I have 60% water milfoil coverage on my 8 acre pond. The fish population is very well balanced on all species. The LMB are only 80% of thier ideal wieght. They are not overpopulated and there is plenty of forage, but the forage hides too well in all the milfoil and the LMB can't get to them.I've worked at raking the milfoil out, it's like chipping away at the great wall of china with a dull spoon.It may work on your small pond.(bigger is not necessarily better with pond management!) This spring I will fertilize to create a bloom to reduce sunlight penetration, and add grass carp, even though some say they don't eat milfoil all that well. Other folks say they have had great success with carp vs. milfoil.(environmental variables) If I fertilize too late though I will just be feeding the plants. Its a tricky business.
Aquatic plants need 3 things- water, sunlight, and nutrients. Eliminate one of the big 3,(usually sunlight penetration) you're on your way. You can rake it all out, but it will grow back. As Bob Lusk says, It's like mowing your pond.
Good luck with it!

Roadtrip - if you're planning to shade out the milfoil with a fertilization program, you should know that both Eurasian watermilfoil and Hydrilla are two exotic plant species that require minimal amounts of sunlight (compared to other plants) in order to thrive. It is their tolerance to low-light conditions that allow these two species to rapidly displace native plant populations. So, it is highly unlikely that you will control an existing EWM population through efforts to reduce water-clarity.

Also, EWM has a very high tolerance to cold temps - actually growing under ice in many regions.

The original posts on your pond (Oct/'03) covered several treatment options. And your dose-rate question earlier this month indicated that you were considering a herbicide treatment (though too late this year). What prompted you to pursue a fertilization program in hopes of controlling the EWM?

BTW: fertilizing a EWM infested pond will likely prompt a significant filamentous algae explosion. These types of algae normally orginate on (attached to) the bottom of clear ponds where abundant nutrients are present. However, if EWM is already growing within a few feet of the surface (though the depth may be 10+ feet) filamentous algae will treat the ceiling of EWM growths as the "bottom" and spring forth from that "elevated platform".