These plants we call "flag" locally have taken over ditches and swamps all over my part of WNY through the last 15 years. The seeds seemed to spread rapidly. They crowd out and kill all the cattails.
Muskrats have declined and all but disappeared where these take over. Doesn't seem that the muskrat eats any of it.
Anyone else across the nation seen this invasive plant?

Not only do they crowd out the cattails but they seem to drink up all of the water. Sad to see so many swampy areas dry up and become void of rats.

We they them here as well. Thankfully they seem to stay refined to very shallow areas, wetland deserts.

We call it Canary grass up here,it does soak up the moisture.Some of the area's with it the deer love to bed in it.

It’s all over the Eastern Shore….worse than Johnson Grass.

We have some of it around drainage ditches in the river bottoms.

Been here a LONG time.
And TONS of $$$ spent on control.
I worked with a guy who was working on control 40 years ago.

Curiously enough, it turns out that there IS a native variety of phragmites, and there are still a few small stands here

Haven't noticed it here

western Colorado, aphids get in it and make it a sticky mess when doing beaver work!

We've had it forever, don't know if it's the native or invasive variety, but it does take over. deer use it for cover and bedding, muskrats try to subsist on the roots but they're soon gone.
We call it cat tails here, and we call cat tails punks, don't know why, lol, but a lot less "punks" now, the "cat tails" take over eventually.... There's been some half hearted efforts to control it but it's a hopeless cause.

Was planted along rivers by the gold companies to stabilize banks and cut erosion of arsenic laden soils I was told.

Rick look closely that is the invasive species of phragmites. The tops are larger and it is still a green stem colour. The native species has turned a golden colour now the stems and the seed heads are hand size .

The worst spreader of it is the railways as it seeds get on the trains and travel to fall off miles away during a rain or wind storm. As well the burnt rail-right-of -ways is a perfect germination spot for the seeds then

Around here the towns, county's and states spread them like wildfire cutting the ditches and dispersing the seed

Canary grass and phragmites are two different species. Both grow so aggressively that they choke out any other food sources. It's a shame what they do to a marsh.

User name checks out!
But AMEN to your post!

They're real bad here around Green Bay. Just about every low ditch has em. You can cut em down, but they just come right back. I heard they can even propagate from chunks of stem the size of your fingernail.

One of the attempts to control them was to make a tight fence enclosure and fill it with goats, they did eat the phragmites but they just bounce back, just a tiny piece of runner will re sprout...

The non-native phragmites is a huge issue in WI as well. We also have the native variety but it plays well with others. It doesn't get as tall or as dense and doesn't cowd out the other native species. You can tell the difference several ways. Some were stated earlier. I like to look at the base of the stems. Our WI native species has a smooth stem. The non native has ridges/grooves running parallel with the stem, like a sharpening steel. As the non native phrag moves in the plant diversity goes down and the rats move out. Less cattails (punks), arrowheads, sweet flag, bur reed and wild rice. This means less food AND material to build huts. Purple loosestrife does the same thing as non native phrag. Rats don't use it. The best way to prevent spreading seeds or plants is to clean your gear AND especially boots before going to the next Marsh/spot.

Muskrats will eat it and build houses with them.
But it doesn't have the minerals or the nutriments they need it seems.
Rats are much smaller than normal when caught in places that that grass is found.
Also , many times you find houses, and no rats.
They just seem to disappear.
I always thought it came from people buying it at a nursery , to plant as an ornamental plant.
I don't like it at all, it spreads through it's roots more than by seed.

Here, you can have an exposed mud flat from dredge spoil, and within a year it's covered with that stuff....you can see the runners on top and they go a long way.....

Deer will use it for bedding, the trails are narrow and cut deep, on a windy day, you can sneak through with the wind in your face and can practically walk up to them, look for the white triangle cause they blend in so well....