Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Water irises, too much of a good thing

I planted some yellow water iris a number of years
ago and it is taking over the banks of my pond now. I originally planted it to control wave erosion of the banks in certain locations and it does that beautifully. It is invasive eventually and I have had trouble eradicating it with glyphophate, even in pretty high concentrations.
Are there any better herbicides to use? 2,4 D?

Thanks for the heads up, because I planned to plant irises.

I would imagine that any plant with tuberous roots can absorb a lot of herbicide. Please keep us posted on your problem.

To be fair to the irises, it has taken 15-18 years to get out of hand.

Please, everyone, remember that plants that are invasive in one area may barely survive in another. LRunkle, it appears that your yellow iris have worked wonderfully for you. Do muskrats eat them? Rather than killing them, you might consider selling them. If you don't want to sell them yourself, you might set some kids up in the business.

Great idea Norm. We have them also. Not a problem after 25 years. But they have spread.

Here are some on the dam which are about 4 feet tall.

Norm, I have sold them in the past. The problem with these yellow irises when they are in large stands is that the rhizomes are so tough and matted together that it is like digging up bald cypress knees- i.e. it takes a two handed axe to make a dent in them, a sharp shovel does not have a chance. Imagine standing in mud and chopping these roots. The resulting mud explosion which covers you from head to toe is daunting. Only the new, tiny clumps are practical to harvest for sale or transplant. Interestingly, my grass carp root these up but don't seem to eat them or at least not all of them. I can collect them easily floating around the lake. The irises are displacing some other plantings I value-pickerel weed, thalia(American water canna) and my Black Gamecock Louisiana swamp irises.

LRunkle, what about a couple of kids and a saw? This might not be practical for you but I always like to get kids started in some kind of business.

Here in MN I've had both yellow and purple irises planted along my bank for about 5 years. They have just barely spread beyond the original area they were planted. Some plants might cover an area the size of a circle 1 foot diameter. I have a plant in the bog next to the pond that has been there 10 years and it's about 2 feet diameter. They don't seem to present the same problem here.

I have found that the yellow (Flag variety) iris are very agressive growers on ponds or garden situations. We have kept them away from the water and instead planted Louisiana Iris varieties spotted around our three acre pond in half a dozen different colors. They do spread, but are controlable and beautiful. The Louisiana Iris have been found to do well far from their native soil of Plaqumines Parish and the Pearl River Delta.

By-the-by, I pulled an eight pound large mouth out of the twenty year old pond yesterday. I put her back in, of course.

Small yellow iris stands can be controlled from spreading to other areas of the pond by removing the seed pods before they break open in the fall.

We bought a house a couple years ago with a 1/2 acre pond. There are yellow iris around about half of it. They are taking over. They are only pretty for about a week in the spring and the rest of the time they are really tall and block the view of the pond from the house as well as acting like a leaf catcher making more stuff fall in the pond. I have tried digging them out with a shovel. No way. The roots are all over the rocks that we have around the pond so when you dig you hit rock. I want to get rid of at least some of it. There are some of the plants that are a good 3 feet in diameter. What can I put on them to kill them without harming the fish? They are totally out of control. Thanks. Vicky

One of the better low volume to purchase herbicides (1 gallon size abt $32-35) that will work on iris and many other emergent shorline plants is called Shoreklear-Plus. It is glysophate based with a surfactant included. Dilute and spray. You may have to spray several times up to 2 yrs later to get everything killed that you want killed. Spray some this September and see what sprouts next April-May. Spray again before or during flowering. The iris may stay relatively green most the the year if sprayed in May. Although few of those regrow the next spring from my experience. I'm in the process of getting rid of all my yellow water iris. As you learned they are too aggressive for a smaller pond where one could do better to have other slower and shorter growing emerent shoreline plants.

Thank you Bill. I'll give it a try.
I appreciate your time.
Vicky

POLARIS (imazapyr) is available in 1-qt containers (enough for roughly 32 gal of spray-mix at a 3/4% solution).
Imazapyr is probably better than glyphosate for treating hard-to-control perennials (fewer applications required), but be careful not to use it in terrestrial sites that may harbor the roots of desirable trees since it is soil-active (available for root-uptake).
Also, IMAZAPYR 2SL is available in 1-gal containers, and is formulated with a surfactant included (unlike POLARIS).