Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Coontail elimination in 4 acre feet farm pond

The exact amount of Water/Diquat/Cutrine Plus/Surfacant to tell you to use is difficult to explain because of the unknown - i.e. the operator. The amount used is also based on the amount of plants in that area to be treated. Since I am not there looking at it (and I can't give you an answer from a picture either) I can't tell you exactly how much to use. I can give you some advice though.

Also remember that you said that you cannot spray the whole pond because your sprayer won't reach out to the center of the pond. (see below why that is a bad idea anyway)

First off, all that I say is based on a correct weed ID like Bill said. Without a 100% correct plant ID all bets are off. If I have a plant ID question and I can't send a picture to any of my resources, I will hop on the Texas A&M website and start going through all the information there. TAMU Aquaplant

Using a contact herbicide, you don't want to treat the whole pond at once. Too many plants will die at once, then when they decompose, that decomposition causes a tremendous oxygen demand on the pond. That O2 demand might be more than what is in the pond for fish to survive. The way I look at O2 in a pond is that the higher the life form, the more O2 it needs. For example, bacteria can survive on less O2 than fish. Fish need roughly 5 mg/l to reliably survive although they can get by on less, depending on the species of fish. Yellow Perch are stressed when O2 levels are less than 3 mg/l. Bluegill start showing sluggish behavior around 4 mg/l.

Bill, please edit this if these numbers are wrong.

Aerobic bacteria really slows down at 2 mg/l. So, aerobic bacteria will most likely survive levels of O2 that would kill fish.

Getting back to your question. I cannot stress enough that you have to read and understand the herbicide label. Take into consideration all the warnings and caveats. More is NOT better. Plants can go into shock if too much herbicide is used, and not "suck it in" to kill the plant. That is especially true with systemic herbicides where the herbicide is translocated to the roots to kill the plant, roots and all. Contact herbicides basically just give the plant a haircut and the plants can re-grow from the roots if there are enough energy stores in that root system. i.e. Cattails and water lilies. Now if you kill the plant re-growth multiple times in a growing season you might be able to kill the plant roots and all with a contact herbicide, but it's better to use a systemic in that scenario. Coontail is not a rooted plant, so a contact herbicide will work just fine.

When using a herbicide to spray submerged plants in a pond, you have to keep the following in mind: The water in the tank is just there to ensure that you get even, optimum coverage over the area that you are treating. It does NOTHING more than that.

Surfactant - 1 fl. oz per gallon of tank mix. If you are using a 15 gallon sprayer and fill it up, put in 15 fl oz of surfactant. If you are only filling it up half way, use 7-8 fluid ounces of surfactant. That's pretty much a general rule that I use. I might use a *little bit* more per tank if there is a LOT of vegetation or algae in the area that I am treating.

Cutrine Plus Liquid - READ THE LABEL. It has rates listed on the label on how much to use for a certain area based on how much algae there is in that area that is to be treated. Use the amount that is listed in the label in Table 1. Cutrine Plus Liquid Label

Diquat - READ THE LABEL. It has rates listed on the label on how much to sue for a certain area based on how dense the weed growth is. Please read all the safety precautions on PPE gear that is in the label, then skip to page (I believe) 12 and 13 for the amount to use. Diquat Label

You have to remember that these labels are talking about how much of the concentrated herbicide/algaecide to use in the tank to cover the area that is listed in the chart on the tank. The amount of water that you use makes no difference PROVIDING you use enough water to ensure even coverage over the whole area.

If you don't spray a lot, you probably don't know how much liquid you will need to completely and evenly cover the area that you want to treat. That's perfectly normal and OK. What I would suggest to do is to fill the tank sprayer only with water and do a test run. Do it more than once if needed. There is no harm in using less of the herbicide/algaecide in the tank and having to spray the same area 2x or 3x to get even coverage over that area. Spraying a pond is different than spraying on land. It doesn't matter if you use too much water as long as you get the correct amount of herbicide sprayed on the correct area (or correct ac/ft of water). On land, using too much water can result in washing the herbicide off of the plant and onto the ground where it most likely won't work.

As a tip, I like to put pond dye in the sprayer so I can see that I am getting a good even coverage (this applies more to emergent and floating plants/algae that I am spraying than to spraying a certain area of pond water). When spraying those.I want to spray to the point right before the herbicide runs off the plant. Having dye in the spray allows me to see the coverage I am getting. The amount of dye to use depends on the strength of dye, the amount of liquid in the spray tank and the color of the vegetation that I am spraying.