Category Archives: Aquatic Environments

We were looking at some pond weeds this week and saw an Unidentified “Floating” Object. Well, it wasn’t exactly floating. But it looked like Jell-O sitting on the bottom. We picked it up and set it on the ground. It’s texture was like a jellyfish. We cut it into also.

It turned out to be an invertebrate animal referred to as ‘Bryozoan colonies.’ UGA Extension Aquatic Scientist Dr. Gary Burtle says Bryozoans live in relatively clean water. Does it have any relation to fishing? Dr. Burtle says:

They may indicate that the bream population of this pond is not very abundant. Ask about fishing success and if bream are caught.  Sometimes, in a bass overcrowded pond, the bream population is so low that these invertebrates can thrive.

Bryozoan invertebrate from a pond

Bryozoan cut in half

You may have seen these before. This is one of those, ‘you learn something knew everyday.’ The Smithsonian Marine Station has more information.

We are getting closer to water temperatures being 70 degrees which is when we start treating for pond weeds. We had a huge turnout at this year’s pond meeting in which UGA Aquatic Specialist Dr. Burtle provided us an update on fertilizing, liming, and treating weeds. A big thanks to Alan Dennard and Ken McKinnis sponsoring the meal for us as well.

Last week, I looked at my first pond of the season. This pond is completely covered with naiad, which is a submerged weed. There is not much algae and some alligator weed. We have to get weed control started soon before it becomes impossible. Diquat is commonly used for submerged weeds and is a contact herbicide. Dr. Burtle talked about different herbicides and how they behave different in the water. Sonar, which is more expensive, provides longer weed control since it stays active through the year. So there are benefits to using different compounds.

In either case, we have to ID the weed and select the correct herbicide for control. Here is a slide Dr. Burtle shared of relative cost of aquatic herbicides that may be helpful as we begin our season.

UGA Extension Scientist Dr. Gary Burtle talks about water sampling

Allen and Andrea Poppell cooked a great catfish dinner. Loved seeing the fish in the boat.

I was talking with Alan Dennard who treats ponds in our area, and like myself, he claimed this season has been lowest calls for pond weeds in a while. We’ve had much fewer pond calls this year for some reason. But lately, I’ve been catching up. The good news is that we are moving back into a period better for treatment of pond weeds. If you treat on your own during the summer, we have to be careful not to cause an oxygen depletion which would kill fish. Treating 1/4 to 1/3 of the weed infestation at a time is recommended.

Baggy Knee Grass

This week, I looked at a grass I had not seen before. It turned out to be baggy knee grass, one UGA Aquatic Specialist Dr. Gary Burtle says is showing up more and more in South GA ponds. The flower is easy to ID. To the left is a picture of that. The good news is glyphosate has activity on this weed. We pretty much start with this active ingredient for grasses nonetheless.  A 2% solution spot spray with a surfactant is the recommended rate.

Behind you’ll also notice filamentous algae. There was also a submersed weed I could not see to identify. We’d have to use copper complex herbicides for algae and diquat for underwater weeds. With temperatures in the upper 80s and low 90s, we still have to take precaution in treating that algae and submersed weeds.

Most filamentous algae control methods are similar, except for a few species. And these are one of them. This is a group of wide-spread algae that are difficult to control. Pithophora and Rhizoclonium are in the filamentous algae category. They resemble a mass of wet-green wool. Control with these types of algae is more complicated than other species.

If you ever see an algae that feels like wool when you pull it from the water, it one of these species. Pithophora may be more common. This is the first time I’ve seen Rhizoclonium. The only difference between the two is microscopic. In the water, we still need to pull samples to determine if it’s pithiphora or rhizoclonium.

Wool-like appearance

Treatment

Essentially, we can treat these “wool-like algae” the same. Use a tank mix of cutrine plus with diquat at ½ gallon each per surface cre. This pond is very, very small – probably 1/10 of an acre, if that. Weedtrine D is another choice for small ponds. It is a dilute formula of diquat that is about 1/10 the concentration of Reward or generic Diquat which are 2.0 pounds AI per gallon.

Could we use copper sulfate instead of Cutrine Plus?

Yes. This difference is that Copper sulfate is more toxic to fish in soft water. UGA Aquatic Scientist Dr. Gary Burtle says copper sulfate is okay as long as the crystals are dissolved. Add about an ounce of copper sulfate per gallon of water, and get most of it dissolved. We need to avoid using more than 4 ounces of copper sulfate per acre foot of water in a pond like this – which probably has hardness less than 10 parts per million.

I’ve had fewer pond weed calls this year of any. I was talking with Alan Dennard this morning, and he has noticed the same. Last week, I was asked about algae in a pond. Sometimes these small, floating weeds resemble algae from the road. But this is actually duckweed mixed with watermeal. Both of these weeds are commonly seen together. In the morning, they will cover the entire pond. By afternoon, they float around pushed by wind. Oxygen depletion becomes an issue once these weeds take over a pond. There were no fish in this pond, but if this was eliminated all at once, we’d likely see a fish kill. Both of these weeds tend to grow in quiet, undisturbed water.

Identification

There are different chemical recommendations for each of these weeds; however, there are also compounds that will kill both however. Both are seed bearing plants, but duckweed is separated from watermeal by its roots. Duckweed has 1 to 3 leaves or fronds with a single root hair coming down. Below is a more up close photo:

Duckweed is larger than watermeal

The microscope picture below shows the difference in size between duckweed and watermeal.

Watermeal & Duckweed

Control

We would absolutely need to kill only 1/3 of this at a time (if fish are present). Diquat (Reward) has activity on both weeds, as also does Clipper and Sonar.

Some pond scums are showing up after heavy rain from the tropical storm.. There was some in the pond behind our house as well. These blooms usually appear during the summer and fall. We do have to beware of blue-green algal blooms (cyanobacteria). These produce toxins that can be lethal to most fish and livestock. Other aquatic weeds called pond scum are duckweeds and watermeal, Euglena, diatom blooms, filamentous algae, bacterial, protozoan, and zooplankton scums.  This photo is likely blue green algae scum which was sent to me last week.

UGA Extension Aquatic Scientist Dr. Gary Burtle says, “The hot temperatures make most algaecide applications dangerous to the fish due to possible oxygen depletion. However, low dose applications of copper may thin this bloom. Try one quart to one half gallon of cutrine plus per surface acre. Then repeat each week to thin the bloom. That would be about 0.2 lb to 0.4 pounds of copper per surface acre.  Dilute 1:10 in water for application to the scum.

An alternative is to use sodium percarbonate (many different label names) at 25 lbs per surface acre and repeat weekly. Spread evenly over the pond surface with a granular spreader and boat.”

Pond Scum – Photo by John Surles

Yellow Iris Flower

Here is a yellow flower thing growing by the pond I’ve never seen. It turns out to be Yellow Iris (Iris pseudacorus). It’s an herbaceous perennial with stuff leaves. It reproduces by floating seed and rhizomes. Up North, it is listed as a noxious weed, but UGA Extension Aquaculture Scientist Dr. Gary Burtle recommends leaving a margin of these plants along the shoreline to prevent erosion. The only thing we need to do is mow to leave a 3 to 5 ft strip.

Yellow Iris

With temperatures in the 70s and above, we need to think about treating pond weeds now. It is recommended to begin with chemical treatment and follow by biological control – stocking grass carp.

There are two salvinia’s we have. One is called Giant Salvinia. With giant salvinia, the leaf hairs are joined together (in fresh samples). The salvinia pictured here is Common Salvinia (Salvinia minima).

Common salvinia

This is more of a recent invader, also called floating fern. It spreads very fast.

The leaves smaller than a man’s thumbnail indicate Common Salvinia. In salvinia species, the leaves are more round with a distinct midbrib. They will have a cupped appearance.

UGA Extension Aquatic Specialist Dr. Gary Burtle says Common Salvinia responds to contact herbicides like diquat and Cutrine-Plus. However, areas up stream and downstream from the pond usually reseed the pond so that a maintenance plan should be developed. Grass carp will help control salvinia once it has been burned back.

For more information, visit this link on Common Salvinia.